Asymmetric Direct 1,2-Addition of Aryl Grignard Reagents to Aryl Alkyl Ketones.

PubMed

Osakama, Kazuki; Nakajima, Makoto

2016-01-15

The enantioselective addition of Grignard reagents to ketones was promoted by a BINOL derivative bearing alkyl chains at the 3,3'-positions. This is the first asymmetric direct aryl Grignard addition to ketones reported to date. A variety of tertiary diaryl alcohols could be obtained in high yields and enantioselectivities without using any other metal source.

Alkyl Aryl Ether Bond Formation with PhenoFluor**

PubMed Central

Shen, Xiao; Neumann, Constanze N.; Kleinlein, Claudia; Claudia, Nathaniel W.; Ritter, Tobias

2015-01-01

An alkyl aryl ether bond formation reaction between phenols and primary and secondary alcohols with PhenoFluor has been developed. The reaction features a broad substrate scope and tolerates many functional groups, and substrates that are challenging for more conventional ether bond forming processes may be coupled. A preliminary mechanistic study indicates reactivity distinct from conventional ether bond formation. PMID:25800679

Activated-Sludge Nitrification in the Presence of Linear and Branched-Chain Alkyl Benzene Sulfonates

PubMed Central

Baillod, Charles R.; Boyle, W. C.

1968-01-01

The effects of biodegradable linear alkyl benzene sulfonate and branched-chain alkyl benzene sulfonate detergents on activated-sludge nitrification were investigated by administering a synthetic waste containing up to 23 mg of each detergent per liter to eight bench-scale, batch, activated-sludge units. It was found that both detergents tended to promote complete oxidation of ammonia to nitrate, whereas control units produced approximately equal amounts of nitrite and nitrate. Various hypotheses are offered to explain the phenomenon. PMID:5636474

Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s.

PubMed

Jones, Gavin O; Yuen, Alexander; Wojtecki, Rudy J; Hedrick, James L; García, Jeannette M

2016-07-12

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers.

Design and synthesis of aryl ether and sulfone hydroxamic acids as potent histone deacetylase (HDAC) inhibitors.

PubMed

Pabba, Chittari; Gregg, Brian T; Kitchen, Douglas B; Chen, Zhen Jia; Judkins, Angela

2011-01-01

A series of novel hydroxamic acid based histone deacetylases (HDAC) inhibitors with aryl ether and aryl sulfone residues at the terminus of a substituted, unsaturated 5-carbon spacer moiety have been synthesized for the first time and evaluated. Compounds with meta- and para-substitution on the aryl ring of ether hydroxamic acids 19c, 20c, 19e, 19f and 19g are potent HDAC inhibitors with activities at low nanomolar levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Interfacial assignment of branched-alkyl benzene sulfonates: A molecular simulation

NASA Astrophysics Data System (ADS)

Liu, Zi-Yu; Wei, Ning; Wang, Ce; Zhou, He; Zhang, Lei; Liao, Qi; Zhang, Lu

2015-11-01

A molecular dynamics simulation was conducted to analyze orientations of sodium branched-alkyl benzene sulfonates molecules at nonane/water interface, which is helpful to design optimal surfactant structures to achieve ultralow interfacial tension (IFT). Through the two dimensional density profiles, monolayer collapses are found when surfactant concentration continues to increase. Thus the precise scope of monolayer is certain and orientation can be analyzed. Based on the simulated results, we verdict the interfacial assignment of branched-alkyl benzene sulfonates at the oil-water interface, and discuss the effect of hydrophobic tail structure on surfactant assignment. Bigger hydrophobic size can slow the change rate of surfactant occupied area as steric hindrance, and surfactant meta hydrophobic tails have a stronger tendency to stretch to the oil phase below the collapsed concentration. Furthermore, an interfacial model with reference to collapse, increasing steric hindrance and charge repulsive force between interfacial surfactant molecules, responsible for effecting of surfactant concentration and structure has been supposed.

One-step formation of bifunctionnal aryl/alkyl grafted films on conducting surfaces by the reduction of diazonium salts in the presence of alkyl iodides.

PubMed

Hetemi, Dardan; Hazimeh, Hassan; Decorse, Philippe; Galtayries, Anouk; Combellas, Catherine; Kanoufi, Frédéric; Pinson, Jean; Podvorica, Fetah I

2015-05-19

The formation of partial perfluoroalkyl or alkyl radicals from partial perfluoroalkyl or alkyl iodides (ICH2CH2C6F13 and IC6H13) and their reaction with surfaces takes place at low driving force (∼-0.5 V/SCE) when the electrochemical reaction is performed in acetonitrile in the presence of diazonium salts (ArN2(+)), at a potential where the latter is reduced. By comparison to the direct grafting of ICH2CH2C6F13, this corresponds to a gain of ∼2.1 V in the case of 4-nitrobenzenediazonium. Such electrochemical reaction permits the modification of gold surfaces (and also carbon, iron, and copper) with mixed aryl-alkyl groups (Ar = 3-CH3-C6H4, 4-NO2-C6H4, and 4-Br-C6H4, R = C6H13 or (CH2)2-C6F13). These strongly bonded mixed layers are characterized by IRRAS, XPS, ToF-SIMS, ellipsometry, water contact angles, and cyclic voltammetry. The relative proportions of grafted aryl and alkyl groups can be varied along with the relative concentrations of diazonium and iodide components in the grafting solution. The formation of the films is assigned to the reaction of aryl and alkyl radicals on the surface and on the first grafted layer. The former is obtained from the electrochemical reduction of the diazonium salt; the latter results from the abstraction of an iodine atom by the aryl radical. The mechanism involved in the growth of the film provides an example of complex surface radical chemistry.

Aryl sulfonates as neutral photoacid generators (PAGs) for EUV lithography

NASA Astrophysics Data System (ADS)

Sulc, Robert; Blackwell, James M.; Younkin, Todd R.; Putna, E. Steve; Esswein, Katherine; DiPasquale, Antonio G.; Callahan, Ryan; Tsubaki, Hideaki; Tsuchihashi, Tooru

2009-03-01

EUV lithography (EUVL) is a leading candidate for printing sub-32 nm hp patterns. In order for EUVL to be commercially viable at these dimensions, a continuous evolution of the photoresist material set is required to simultaneously meet the aggressive specifications for resolution, resist sensitivity, LWR, and outgassing rate. Alternative PAG designs, especially if tailored for EUVL, may aid in the formation of a material set that helps achieve these aggressive targets. We describe the preparation, characterization, and lithographic evaluation of aryl sulfonates as non-ionic or neutral photoacid generators (PAGs) for EUVL. Full lithographic characterization is reported for our first generation resist formulation using compound H, MAP-1H-2.5. It is benchmarked against MAP-1P-5.0, which contains the well-known sulfonium PAG, triphenylsulfonium triflate (compound P). Z-factor analysis indicates nZ32 = 81.4 and 16.8 respectively, indicating that our first generation aryl sulfonate formulations require about 4.8x improvement to match the results achieved with a model onium PAG. Improving the acid generation efficiency and use of the generated byproducts is key to the continued optimization of this class of PAGs. To that end, we believe EI-MS fragmentation patterns and molecular simulations can be used to understand and optimize the nature and efficiency of electron-induced PAG fragmentation.

Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s

PubMed Central

Yuen, Alexander; Wojtecki, Rudy J.; Hedrick, James L.; García, Jeannette M.

2016-01-01

It is estimated that ∼2.7 million tons poly(carbonate)s (PCs) are produced annually worldwide. In 2008, retailers pulled products from store shelves after reports of bisphenol A (BPA) leaching from baby bottles, reusable drink bottles, and other retail products. Since PCs are not typically recycled, a need for the repurposing of the PC waste has arisen. We report the one-step synthesis of poly(aryl ether sulfone)s (PSUs) from the depolymerization of PCs and in situ polycondensation with bis(aryl fluorides) in the presence of carbonate salts. PSUs are high-performance engineering thermoplastics that are commonly used for reverse osmosis and water purification membranes, medical equipment, as well as high temperature applications. PSUs generated through this cascade approach were isolated in high purity and yield with the expected thermal properties and represent a procedure for direct conversion of one class of polymer to another in a single step. Computational investigations performed with density functional theory predict that the carbonate salt plays two important catalytic roles in this reaction: it decomposes the PCs by nucleophilic attack, and in the subsequent polyether formation process, it promotes the reaction of phenolate dimers formed in situ with the aryl fluorides present. We envision repurposing poly(BPA carbonate) for the production of value-added polymers. PMID:27354514

Interaction of model aryl- and alkyl-boronic acids and 1,2-diols in aqueous solution.

PubMed

Marinaro, William A; Prankerd, Richard; Kinnari, Kaisa; Stella, Valentino J

2015-04-01

The goal of this work was to quantitate ester formation between alkyl and aryl boronic acids and vicinal-diols or 1,2-diols in aqueous solution. As used here, 1,2-diols includes polyols with one or more 1,2-diol pairs. Multiple techniques were used including apparent pKa shifts of the boronic acids using UV spectrophotometry (for aryl acids) and titration (for aryl and alkyl acids). Isothermal microcalorimetry was also used, with all reactions being enthalpically favored. For all the acids and 1,2-diols and the conditions studied, evidence only supported 1:1 ester formation. All the esters formed were found to be significantly more acidic, as Lewis acids, by 3-3.5 pKa units than the corresponding nonesterified boronic acid. The equilibrium constants for ester formation increased with increasing number of 1,2-diol pairs but stereochemistry may also play a role as sorbitol with five possible 1,2-diol pairs and five isomers (taking into account the stereochemistry of the alcohol groups) was twice as efficient at ester formation compared with mannitol, also with five possible 1,2-diol pairs but only three isomers. Alkyl boronic acids formed esters to a greater extent than aryl acids. Although some quantitative differences were seen between the various techniques used, rank ordering of the structure/reactivity was consistent. Formulation implications of ester formation between boronic acids and 1,2-diols are discussed. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Application of a Heterogeneous Chiral Titanium Catalyst Derived from Silica-Supported 3-Aryl H8-BINOL to Enantioselective Alkylation and Arylation of Aldehydes.

PubMed

Akai, Junichiro; Watanabe, Satoshi; Michikawa, Kumiko; Harada, Toshiro

2017-07-07

A 3-aryl H 8 -BINOL was grafted on the surface of silica gel using a hydrosilane derivative as a precursor, and the resulting silica-supported ligand (6 mol %) was employed in the enantioselective alkylation and arylation of aldehydes in the presence of Ti(O i Pr) 4 . The reactions using Et 2 Zn, Et 3 B, and aryl Grignard reagents all afforded the corresponding adducts in high enantioselectivities and yields. The silica-immobilized titanium catalyst could be reused up to 14 times without appreciable deterioration of the activity.

DETERMINATION OF ALKYLATED & SULFONATED DIPHENYL OXIDE SULFACTANT BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

EPA Science Inventory

Methods for the determination of the anionic surfactant Dowfax 8390 are described. Dowfax is a complex mixture of various alkylated and sulfonated diphenyl oxides. The primary component of Dowfax is monoalkylated disulfonated diphenyl oxide (MADS). This work uses ion pairing chro...

Effect of linear alkyl benzene sulfonate in skin of fish fingerlings (Cirrhina mrigala): observations with scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misra, V.; Chawla, G.; Kumar, V.

1987-04-01

Pathomorphological changes in the skin was noticed under the scanning electron microscope in fish fingerlings (Cirrhina mrigala) exposed to 0.005 ppm (25% of the LC50) concentration to linear alkyl benzene sulfonate. The epithelial cells present in the epidermis of the skin were found to secrete more mucus with linear alkyl benzene sulfonate (LAS) than did controls. The presence or deposition of mucus on the surface of skin indicated likely molecular interaction between constituents of mucus and LAS.

Replacing Conventional Carbon Nucleophiles with Electrophiles: Nickel-Catalyzed Reductive Alkylation of Aryl Bromides and Chlorides

PubMed Central

2012-01-01

A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (−OH, −NHTs, −OAc, −OTs, −OTf, −COMe, −NHBoc, −NHCbz, −CN, −SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki–Miyaura, Stille, and Hiyama–Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R–X) and no reaction at the nucleophilic carbon (R–[M]) for organoboron (−Bpin), organotin (−SnMe3), and organosilicon (−SiMe2OH) containing organic halides (X–R–[M]). A Hammett study showed a linear correlation of σ and σ(−) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2–1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents. PMID:22463689

Enhanced antifouling and antibacterial properties of poly (ether sulfone) membrane modified through blending with sulfonated poly (aryl ether sulfone) and copper nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Jingjing; Xu, Ya'nan; Chen, Shouwen; Li, Jiansheng; Han, Weiqing; Sun, Xiuyun; Wu, Dihua; Hu, Zhaoxia; Wang, Lianjun

2018-03-01

A series of novel blend ultrafiltration (UF) membranes have been successfully prepared from commercial poly (ether sulfone), lab-synthesized sulfonated poly (aryl ether sulfone) (SPAES, 1 wt%) and copper nanoparticles (0 ∼ 0.4 wt%) via immersion precipitation phase conversion. The micro-structure and separation performance of the membranes were characterized by field emission scanning electron microscopy (SEM) and cross-flow filtration experiments, respectively. Sodium alginate, bovine serum albumin and humic acid were chosen as model organic foulants to investigate the antifouling properties, while E. coil was used to evaluate the antibacterial property of the fabricated membranes. By the incorporation with SPAES and copper nanoparticles, the hydrophilicity, antifouling and antibacterial properties of the modified UF membranes have been profoundly improved. At a copper nanoparticles content of 0.4 wt%, the PES/SPAES/nCu(0.4) membrane exhibited a high pure water flux of 193.0 kg/m2 h, reaching the smallest contact angle of 52°, highest flux recovery ratio of 79% and largest antibacterial rate of 78.9%. Furthermore, the stability of copper nanoparticles inside the membrane matrix was also considerably enhanced, the copper nanoparticles were less than 0.08 mg/L in the effluent during the whole operation.

Acyl hydrazides as acyl donors for the synthesis of diaryl and aryl alkyl ketones.

PubMed

Akhbar, Ahmed R; Chudasama, Vijay; Fitzmaurice, Richard J; Powell, Lyn; Caddick, Stephen

2014-01-21

In this communication we describe a novel strategy for the formation of valuable diaryl and aryl alkyl ketones from acyl hydrazides. A wide variety of ketones are prepared and the mild reaction conditions allow for the use of a range of functionalities, especially in the synthesis of diaryl ketones.

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides and Sulfonates: A General Method for the Preparation of Primary Arylamines

PubMed Central

Vo, Giang D.

2010-01-01

We report that the complex generated from Pd[P(o-tol)3]2 and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader substrate scope. The utility of this method to generate amides, imides and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides. Mechanistic studies show that Pd[P(o-tol)3]2 and CyPF-t-Bu generate a more active and general catalyst than that generated from CyPF-t-Bu and palladiun(II) precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia and base. PMID:19591470

Palladium-catalyzed coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates: a general method for the preparation of primary arylamines.

PubMed

Vo, Giang D; Hartwig, John F

2009-08-12

We report that the complex generated from Pd[P(o-tol)(3)](2) and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader, substrate scope. The utility of this method to generate amides, imides, and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides, ammonia, and acid chlorides or anhydrides. Mechanistic studies show that reactions conducted with the combination of Pd[P(o-tol)(3)](2) and CyPF-t-Bu as catalyst occur with faster rates and higher yields than those conducted with CyPF-t-Bu and palladiun(II) as catalyst precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia, and base.

Acute toxicity to goldfish of mixtures of chloramines, copper, and linear alkylate sulfonate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, C.F.; McKee, J.A.

1980-01-01

The toxicity to goldfish (Carassius auratus) of mixtures of chloramines, copper, and linear alkylate sulfonate (LAS) was studied by continuous-flow toxicity tests during an exposure period of 96 hours. The individual toxicities of these three chemicals are either additive or synergistic in mixtures, depending on the rate of toxic action of the individual chemical, the toxicity ratio of the chemicals in the mixtures, and the concentration of the mixtures.

Virucidal effects of bleach activators, sodium alkyl acyloxybenzene sulfonate and acyloxybenzoic acid, against Feline calicivirus.

PubMed

Tobe, Seiichi; Hoshi, Marika; Iizuka, Kinue; Tadenuma, Hirohiko; Takaoka, Hiromitsu; Komoriya, Tomoe; Kohno, Hideki

2012-01-01

Noroviruses (NVs) are major causative pathogens of gastroenteritis. The disinfection of contaminated clothing during common household washing is desirable. The virucidal effects of 2 bleach activators, sodium alkyl acyloxybenzene sulfonate (OBS) and alkyl acyloxybenzoic acid (OBC), were studied using Feline calicivirus (FCV) as a surrogate for NVs. FCV was added to solutions containing either OBS or OBC and sodium percarbonate at various temperatures and for varying lengths of time. OBS and OBC, which generate long carbon chain peroxy acids, enhanced the virucidal effect of sodium percarbonate (PC). In particular, sodium lauroyloxybenzene sulfonate (OBS-12) and decanoyloxybenzoic acid (OBC-10) showed superior virucidal effects. Although the virucidal effect of 38-200 mg/L OBS-12 was maintained with 2-5% (v/v) horse serum, there was less of an effect with the same concentration of available chlorine. OBS and OBC have been used as ingredients in some laundry products to increase bleaching activity. It is expected that the use of OBS and OBC is also effective for the inactivation of NVs under common household washing conditions.

Toxicological properties and risk assessment of the anionic surfactants category: Alkyl sulfates, primary alkane sulfonates, and α-olefin sulfonates.

PubMed

Wibbertmann, Axel; Mangelsdorf, Inge; Gamon, Konrad; Sedlak, Richard

2011-07-01

The category of the anionic surfactants (ANS) consisting of 46 alkyl sulfates, 6 primary alkane sulfonates, and 9 α-olefin sulfonates has been assessed under the high production volume (HPV) chemicals program of the Organisation for Economic Cooperation and Development (OECD) in 2007. In this review the toxicological properties of these chemicals are summarized. The chemicals of this category are used predominantly in detergents, household cleaning products, and cosmetics. These chemicals show low acute and repeat dose toxicity. There was no evidence of genetic or reproductive toxicity, or carcinogenicity. There also was no indication for sensitizing properties. Skin and eye irritating effects in consumers are not to be expected. For consumers, the calculated body burden is about 10,000 times lower than the lowest NOAEL value in experimental animals, so that adverse effects caused by substances of the ANS category can be excluded. Copyright © 2011 Elsevier Inc. All rights reserved.

Pyrolysis of Aryl Sulfonate Esters in the Absence of Solvent: E1 or E2? A Puzzle for the Organic Laboratory

ERIC Educational Resources Information Center

Nash, John J.; Leininger, Marnie A.; Keyes, Kurt

2008-01-01

The aryl sulfonate ester, menthyl N-acetylsulfanilate, is synthesized from N-acetylsulfanilyl chloride and menthol in pyridine, then pyrolyzed (thermally decomposed) at reduced pressure. The volatile (elimination) products of the reaction are analyzed using gas chromatography, and the resulting product distribution is used to determine whether the…

Promotion of Organic Reactions by Ultrasound: Coupling of Alkyl and Aryl Halides in the Presence of Lithium Metal and Ultrasound.

ERIC Educational Resources Information Center

Lash, Timothy D.; Berry, Donna

1985-01-01

Experiments involving the coupling of alkyl and aryl halides in the presence of lithium metal and ultrasound are described. The experiments illustrate classical Wurtz and Fittig reactions in addition to being a convenient application of organic sonochemistry. (JN)

Enantioselective remote meta-C-H arylation and alkylation via a chiral transient mediator.

PubMed

Shi, Hang; Herron, Alastair N; Shao, Ying; Shao, Qian; Yu, Jin-Quan

2018-06-18

Enantioselective carbon-hydrogen (C-H) activation reactions by asymmetric metallation could provide new routes for the construction of chiral molecules 1,2 . However, current methods are typically limited to the formation of five- or six-membered metallacycles, thereby preventing the asymmetric functionalization of C-H bonds at positions remote to existing functional groups. Here we report enantioselective remote C-H activation using a catalytic amount of a chiral norbornene as a transient mediator, which relays initial ortho-C-H activation to the meta position. This was used in the enantioselective meta-C-H arylation of benzylamines, as well as the arylation and alkylation of homobenzylamines. The enantioselectivities obtained using the chiral transient mediator are comparable across different classes of substrates containing either neutral σ-donor or anionic coordinating groups. This relay strategy could provide an alternative means to remote chiral induction, one of the most challenging problems in asymmetric catalysis 3,4 .

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

PubMed Central

Shrives, Harry J.; Fernández-Salas, José A.; Hedtke, Christin; Pulis, Alexander P.; Procter, David J.

2017-01-01

Benzothiophenes are heterocyclic constituents of important molecules relevant to society, including those with the potential to meet modern medical challenges. The construction of molecules would be vastly more efficient if carbon–hydrogen bonds, found in all organic molecules, can be directly converted into carbon–carbon bonds. In the case of elaborating benzothiophenes, functionalization of carbon–hydrogen bonds at carbon-number 3 (C3) is markedly more demanding than at C2 due to issues of regioselectivity (C3 versus C2), and the requirement of high temperatures, precious metals and the installation of superfluous directing groups. Herein, we demonstrate that synthetically unexplored but readily accessible benzothiophene S-oxides serve as novel precursors for C3-functionalized benzothiophenes. Employing an interrupted Pummerer reaction to capture and then deliver phenol and silane coupling partners, we have discovered a directing group-free method that delivers C3-arylated and -alkylated benzothiophenes with complete regioselectivity, under metal-free and mild conditions. PMID:28317882

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

NASA Astrophysics Data System (ADS)

Shrives, Harry J.; Fernández-Salas, José A.; Hedtke, Christin; Pulis, Alexander P.; Procter, David J.

2017-03-01

Benzothiophenes are heterocyclic constituents of important molecules relevant to society, including those with the potential to meet modern medical challenges. The construction of molecules would be vastly more efficient if carbon-hydrogen bonds, found in all organic molecules, can be directly converted into carbon-carbon bonds. In the case of elaborating benzothiophenes, functionalization of carbon-hydrogen bonds at carbon-number 3 (C3) is markedly more demanding than at C2 due to issues of regioselectivity (C3 versus C2), and the requirement of high temperatures, precious metals and the installation of superfluous directing groups. Herein, we demonstrate that synthetically unexplored but readily accessible benzothiophene S-oxides serve as novel precursors for C3-functionalized benzothiophenes. Employing an interrupted Pummerer reaction to capture and then deliver phenol and silane coupling partners, we have discovered a directing group-free method that delivers C3-arylated and -alkylated benzothiophenes with complete regioselectivity, under metal-free and mild conditions.

In situ sulfonation of alkyl benzene self-assembled monolayers: product distribution and kinetic analysis.

PubMed

Katash, Irit; Luo, Xianglin; Sukenik, Chaim N

2008-10-07

The sulfonation of aromatic rings held at the surface of a covalently anchored self-assembled monolayer has been analyzed in terms of the rates and isomer distribution of the sulfonation process. The observed product distributions are similar to those observed in solution, though the data obtained suggest that the reaction rate and the ortho/para product ratio depend on the length of the tether anchoring the aryl ring to the monolayer interface. It was also found that the interface becomes progressively more disordered and the observed reaction rates decrease as the reaction progresses. There is no evidence for a bias in favor of reaction at the more exposed para-position nor is there evidence for an enhanced reaction rate due to the increased disorder and/or improved wetting as the reaction proceeds. This is the first detailed study of electrophilic aromatic substitution at a monolayer interface. It introduces new approaches to the spectroscopic analysis of reactions on self-assembled monolayers and provides a new general approach to the analysis of isomeric product distribution in such a setting.

A practical derivatization LC/MS approach for determination of trace level alkyl sulfonates and dialkyl sulfates genotoxic impurities in drug substances.

PubMed

An, Jianguo; Sun, Mingjiang; Bai, Lin; Chen, Ted; Liu, David Q; Kord, Alireza

2008-11-04

Derivatization LC/MS methodology has been developed for the determination of a group of commonly encountered alkyl esters of sulfonates or sulfates in drug substances at low ppm levels. This general method uses trimethylamine as the derivatizing reagent for ethyl/propyl/isopropyl esters and triethylamine for methyl esters. The resulting quaternary ammonium derivatization products are highly polar (ionic) and can be retained by a hydrophilic interaction liquid chromatography (HILIC) column and readily separated from the main interfering active pharmaceutical ingredient (API) peak that is usually present at very high concentration. The method gives excellent sensitivity for all the alkyl esters at typical target analyte level of 1-2 ppm when the API samples were prepared at 5mg/mL. The recoveries at 1-2 ppm were generally above 85% for all the alkyl esters in the various APIs tested. The injection precisions of the lowest concentration standards were excellent with R.S.D.=0.4-4%. A linear range for concentrations from 0.2 to 20 ppm has been established with R(2)>or=0.99. This general method has been tested in a number of API matrices and used successfully for determination of alkyl sulfonates or dialkyl sulfates in support of API batch releases at GlaxoSmithKline.

Electric current-producing device having sulfone-based electrolyte

DOEpatents

Angell, Charles Austen; Sun, Xiao-Guang

2010-11-16

Electrolytic solvents and applications of such solvents including electric current-producing devices. For example, a solvent can include a sulfone compound of R1--SO2--R2, with R1 being an alkyl group and R2 a partially oxygenated alkyl group, to exhibit high chemical and thermal stability and high oxidation resistance. For another example, a battery can include, between an anode and a cathode, an electrolyte which includes ionic electrolyte salts and a non-aqueous electrolyte solvent which includes a non-symmetrical, non-cyclic sulfone. The sulfone has a formula of R1--SO2--R2, wherein R1 is a linear or branched alkyl or partially or fully fluorinated linear or branched alkyl group having 1 to 7 carbon atoms, and R2 is a linear or branched or partially or fully fluorinated linear or branched oxygen containing alkyl group having 1 to 7 carbon atoms. The electrolyte can include an electrolyte co-solvent and an electrolyte additive for protective layer formation.

Copper(II)-catalyzed enantioselective hydrosilylation of halo-substituted alkyl aryl and heteroaryl ketones: asymmetric synthesis of (R)-fluoxetine and (S)-duloxetine.

PubMed

Zhou, Ji-Ning; Fang, Qiang; Hu, Yi-Hu; Yang, Li-Yao; Wu, Fei-Fei; Xie, Lin-Jie; Wu, Jing; Li, Shijun

2014-02-14

A set of reaction conditions has been established to facilitate the non-precious copper-catalyzed enantioselective hydrosilylation of a number of structurally diverse β-, γ- or ε-halo-substituted alkyl aryl ketones and α-, β- or γ-halo-substituted alkyl heteroaryl ketones under air to afford a broad spectrum of halo alcohols in high yields and good to excellent enantioselectivities (up to 99% ee). The developed procedure has been successfully applied to the asymmetric synthesis of antidepressant drugs (R)-fluoxetine and (S)-duloxetine, which highlighted its synthetic utility.

Direct Aldehyde C-H Arylation and Alkylation via the Combination of Nickel, Hydrogen Atom Transfer, and Photoredox Catalysis.

PubMed

Zhang, Xiaheng; MacMillan, David W C

2017-08-23

A mechanism that enables direct aldehyde C-H functionalization has been achieved via the synergistic merger of photoredox, nickel, and hydrogen atom transfer catalysis. This mild, operationally simple protocol transforms a wide variety of commercially available aldehydes, along with aryl or alkyl bromides, into the corresponding ketones in excellent yield. This C-H abstraction coupling technology has been successfully applied to the expedient synthesis of the medicinal agent haloperidol.

One-Pot, Three-Component Arylalkynyl Sulfone Synthesis

PubMed Central

2015-01-01

A one-pot three-component protocol for the preparation of arylsulfonyl alkynes through the reaction of ethynyl-benziodoxolone (EBX) reagents, DABSO (DABCO·SO2), and either organomagnesium reagents or aryl iodides with a palladium catalyst is reported. A broad range of aryl and heteroarylalkynyl sulfones were obtained in 46–85% overall yield. PMID:25633719

Molecular dynamics study of intermediate phase of long chain alkyl sulfonate/water systems.

PubMed

Poghosyan, Armen H; Arsenyan, Levon H; Shahinyan, Aram A

2013-01-08

Using atomic level simulation we aimed to investigate various intermediate phases of the long chain alkyl sulfonate/water system. Overall, about 800 ns parallel molecular dynamics simulation study was conducted for a surfactant/water system consisting of 128 sodium pentadecyl sulfonate and 2251 water molecules. The GROMACS software code with united atom force field was applied. Despite some differences, the analysis of main structural parameters is in agreement with X-ray experimental findings. The mechanism of self-assembly of SPDS molecules was also examined. At T = 323 K we obtained both tilted fully interdigitated and liquid crystalline-like disordered hydrocarbon chains; hence, the presence of either gel phase that coexists with a lamellar phase or metastable gel phase with fraction of gauche configuration can be assumed. Further increase of temperature revealed that the system underwent a transition to a lamellar phase, which was clearly identified by the presence of fully disordered hydrocarbon chains. The transition from gel-to-fluid phase was implemented by simulated annealing treatment, and the phase transition point at T = 335 K was identified. The surfactant force field in its presented set is surely enabled to fully demonstrate the mechanism of self-assembly and the behavior of phase transition making it possible to get important information around the phase transition point.

Effects of bleach activator, sodium alkyl acyloxybenzene sulfonate, on house dust mites (Dermatophagoides farinae).

PubMed

Tobe, Seiichi; Kamezaki, Hiroki; Watanabe, Toshiyuki; Takaoka, Hiromitsu; Sakaguchi, Masahiro

2010-01-01

House dust mites (Dermatophagoides farinae) in bedding and clothes are a major allergen. However, house dust mites cannot be killed by general washing conditions under 50 degrees C. Therefore, low-temperature washing conditions must be improved to eliminate house dust mites. Sodium alkyl acyloxybenzene sulfonate (OBS) is a bleach activator that is used to intensify the bleaching effects of some laundry products. The purpose of this study was to evaluate the effect of OBS on the elimination of house dust mites in low-temperature washing conditions. D. farinae was soaked in solutions containing different types of OBS for various durations and at various temperatures. The miticidal effects of the various washing conditions were also evaluated for D. farinae. Then sodium lauroyloxybenzene sulfonate (OBS-12) produced the highest D. farinae mortality rate among the OBS solutions that were examined and had a stronger miticidal effect than available chlorine under general washing conditions. OBS exhibited miticidal effects under general washing conditions at low temperatures. Since OBS is already used as an additive in some laundry products to increase the bleaching activity, OBS can be easily used to kill house dust mites under general washing conditions.

Synthesis and Anticancer Activity of 2-(Alkyl-, Alkaryl-, Aryl-, Hetaryl-)-[1,2,4]triazolo[1,5-c]quinazolines

PubMed Central

Kovalenko, Sergiy I.; Antypenko, Lyudmyla M.; Bilyi, Andriy K.; Kholodnyak, Sergiy V.; Karpenko, Olexandr V.; Antypenko, Olexii M.; Mykhaylova, Natalya S.; Los, Tetyana I.; Kolomoets, Olexandra S.

2013-01-01

The combinatorial library of novel potential anticancer agents, namely, 2-(alkyl-, alkaryl-, aryl-, hetaryl-)[1,2,4]triazolo[1,5-c]quinazolines, was synthesized by the heterocyclization of the alkyl-, alkaryl-, aryl-, hetarylcarboxylic acid (3H-quinazoline-4-ylidene)hydrazides by oxidative heterocyclization of the 4-(arylidenehydrazino)quinazolines using bromine, and by the heterocyclization of N-(2-cyanophenyl)formimidic acid ethyl ester. The optimal method for synthesis of the s-triazolo[1,5-c]quinazolines appeared to be cyclocondensation of the corresponding carboxylic acid (3H-quinazoline-4-ylidene)hydrazides. The compounds’ structures were established by 1H, 13C NMR, LC- and EI-MS analysis. The in vitro screening of anticancer activity determined the most active compound to be 3,4,5-trimethoxy-N′-[quinazolin-4(3H)-ylidene]benzohydrazide (3.20) in micromolar concentrations with the GI50 level (MG_MID, GI50 is 2.29). Thus, the cancer cell lines whose growth is greatly inhibited by compound 3.20 are: non-small cell lung cancer (NCI-H522, GI50=0.34), CNS (SF-295, GI50=0.95), ovarian (OVCAR-3, GI50=0.33), prostate (PC-3, GI50=0.56), and breast cancer (MCF7, GI50=0.52), leukemia (K-562, GI50=0.41; SR, GI50=0.29), and melanoma (MDA-MB-435, GI50=0.31; SK-MEL-5, GI50=0.74; UACC-62, GI50=0.32). SAR-analysis is also discussed. PMID:23833709

Sequential one-pot addition of excess aryl-Grignard reagents and electrophiles to O-alkyl thioformates.

PubMed

Murai, Toshiaki; Morikawa, Kenta; Maruyama, Toshifumi

2013-09-23

The sequential addition of aromatic Grignard reagents to O-alkyl thioformates proceeded to completion within 30 s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O-alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O-alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero-Diels-Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2-bis(phenylsulfanyl)-1,2-diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated in situ, four-component coupling products, that is, O-alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate-to-good yields. The use of silyl chloride or allylic bromides gave the adducts within 5 min, whereas the reaction with benzylic halides required more than 30 min. The addition to carbonyl compounds was complete within 1 min and the use of lithium bromide as an additive enhanced the yields of the four-component coupling products. Finally, oxiranes and imines also participated in the coupling reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of sulfonic-functionalized graphene oxide as ion-exchange material and its application into electrochemiluminescence analysis.

PubMed

Chen, Guifen; Zhai, Shengyong; Zhai, Yanling; Zhang, Ke; Yue, Qiaoli; Wang, Lei; Zhao, Jinsheng; Wang, Huaisheng; Liu, Jifeng; Jia, Jianbo

2011-03-15

Graphene oxide (GO) obtained from chemical oxidation of flake graphite was derivatized with sulfonic groups to form sulfonic-functionalized GO (GO-SO(3)(-)) through four sulfonation routes: through amide formation between the carboxylic group of GO and amine of sulfanilic acid (AA-GO-SO(3)(-)), aryl diazonium reaction of sulfanilic acid (AD-GO-SO(3)(-)), amide formation between the carboxylic group of GO and amine of cysteamine and oxidation by H(2)O(2) (CA-GO-SO(3)(-)), and alkyl diazonium reaction of cysteamine and oxidation by H(2)O(2) (CD-GO-SO(3)(-)). Results of Fourier transform infrared spectroscopy and X-ray photoelectrospectrocopy showed that -SO(3)(-) groups were attached onto GO. Thermo gravimetric analysis showed that derivatization with sulfonic groups improved thermo stability of GO. X-ray diffraction results indicated that GO-SO(3)(-) had more ordered π-π stacking structure than the original GO. GO-SO(3)(-) and cationic polyelectrote, poly (diallyldimethylammoniumchloride) (PDDA) were adsorbed at indium tin oxide (ITO) glass surface through layer-by-layer assembling to form (GO-SO(3)(-)/PDDA)(n)/ITO multilayers. After tris-(2,2'-bipyridyl) ruthenium (II) dichloride (Ru(bpy)(3)(2+)) was incorporated into the multilayers, the obtained Ru(bpy)(3)(2+)/(GO-SO(3)(-)/PDDA)(n)/ITO electrodes can be used as electrochemiluminescence sensors for detection of organic amine with high sensitivity (limit of detection of 1 nM) and stability. Copyright © 2010 Elsevier B.V. All rights reserved.

Engaging unactivated alkyl, alkenyl and aryl iodides in visible-light-mediated free radical reactions

NASA Astrophysics Data System (ADS)

Nguyen, John D.; D'Amato, Erica M.; Narayanam, Jagan M. R.; Stephenson, Corey R. J.

2012-10-01

Radical reactions are a powerful class of chemical transformations. However, the formation of radical species to initiate these reactions has often required the use of stoichiometric amounts of toxic reagents, such as tributyltin hydride. Recently, the use of visible-light-mediated photoredox catalysis to generate radical species has become popular, but the scope of these radical precursors has been limited. Here, we describe the identification of reaction conditions under which photocatalysts such as fac-Ir(ppy)3 can be utilized to form radicals from unactivated alkyl, alkenyl and aryl iodides. The generated radicals undergo reduction via hydrogen atom abstraction or reductive cyclization. The reaction protocol utilizes only inexpensive reagents, occurs under mild reaction conditions, and shows exceptional functional group tolerance. Reaction efficiency is maintained upon scale-up and decreased catalyst loading, and the reaction time can be significantly shortened when the reaction is performed in a flow reactor.

Transition-Metal-Catalyzed C-H Alkylation Using Alkenes.

PubMed

Dong, Zhe; Ren, Zhi; Thompson, Samuel J; Xu, Yan; Dong, Guangbin

2017-07-12

Alkylation reactions represent an important organic transformation to form C-C bonds. In addition to conventional approaches with alkyl halides or sulfonates as alkylating agents, the use of unactivated olefins for alkylations has become attractive from both cost and sustainability viewpoints. This Review summarizes transition-metal-catalyzed alkylations of various carbon-hydrogen bonds (addition of C-H bonds across olefins) using regular olefins or 1,3-dienes up to May 2016. According to the mode of activation, the Review is divided into two sections: alkylation via C-H activation and alkylation via olefin activation.

Photooxidation of Mixed Aryl and Biarylphosphines

PubMed Central

Zhang, Dong; Celaje, Jeff A.; Agua, Alon; Doan, Chad; Stewart, Timothy; Bau, Robert; Selke, Matthias

2010-01-01

Aryl phosphines and dialkylbiaryl phosphines react with singlet oxygen to form phosphinate esters. For mixed arylphosphines, the most electron-rich aryl group migrates to form the phosphinate, while for dialkylbiaryl phosphines migration of the alkyl group occurs. Dialkylbiaryl phosphines also yield arene epoxides, especially in electron rich systems. Phosphinate ester formation is increased at high temperature while protic solvents increase the yield of epoxide. The product distribution provides evidence for Buchwald’s recent conformational model for the aerobic oxidation of dialkylbiaryl phosphines. PMID:20527907

Aryl- and alkyl-phosphorus-containing flame retardants induced mitochondrial impairment and cell death in Chinese hamster ovary (CHO-k1) cells.

PubMed

Huang, Chao; Li, Na; Yuan, Shengwu; Ji, Xiaoya; Ma, Mei; Rao, Kaifeng; Wang, Zijian

2017-11-01

Phosphorus-containing flame retardants (PFRs) are increasingly in demand worldwide as replacements for brominated flame retardants (BFRs), but insufficient available toxicological information on PFRs makes assessing their health risks challenging. Mitochondria are important targets of various environmental pollutants, and mitochondrial dysfunction may lead to many common diseases. In the present study, mitochondria impairment-related endpoints were measured by a high content screening (HCS) assay for 11 selected non-halogen PFRs in Chinese hamster ovary (CHO-k1) cells. A cluster analysis was used to categorize these PFRs into three groups according to their structural characteristics and results from the HCS assay. Two groups, containing long-chain alkyl-PFRs and all aryl-PFRs, were found to cause mitochondrial impairment but showed different mechanisms of toxicity. Due to the high correlation between cell death and mitochondrial impairment, two PFRs with different structures, trihexyl phosphate (THP) and cresyl diphenyl phosphate (CDP), were selected and compared with chlorpyrifos (CPF) to elucidate their mechanism of inducing cell death. THP (an alkyl-PFR) was found to utilize a similar pathway as CPF to induce apoptosis. However, cell death induced by CDP (an aryl-PFR) was different from classical necrosis based on experiments to discriminate among the different modes of cell death. These results confirm that mitochondria might be important targets for some PFRs and that differently structured PFRs could function via distinct mechanisms of toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Structure-Activity Study with Aryl Acylamidases

PubMed Central

Villarreal, David T.; Turco, Ronald F.; Konopka, Allan

1994-01-01

We examined the relationship between chemical structure and biodegradability of acylanilide herbicides by using a set of model compounds. Four bacterial isolates (one gram-negative and three gram-positive) that grew on acetanilide were used. These soil isolates cleaved the amide bond of acetanilide via an aryl acylamidase reaction, producing aniline and the organic acid acetate. A series of acetanilide analogs with alkyl substitutions on the nitrogen atom or the aromatic ring were tested for their ability to induce aryl acylamidase activity and act as substrates for the enzyme. The substrate range, in general, was limited to those analogs not disubstituted in the ortho position of the benzene ring or which did not contain an alkyl group on the nitrogen atom. These same N-substituted compounds did not induce enzyme activity either, whereas the ortho-substituted compounds could in some cases. PMID:16349428

Effect of linear alkyl benzene sulfonate on germination of spores of the aquatic fern Ceratopteris thalictroides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, J.; Devi, S.

1989-07-01

Validity of fern spore germination bioassays for the effects of environmental pollution was established by many researchers. Some workers studied the phytotoxicity of linear alkyl benzene sulfonate (LAS) on the spores of Diplazium esculentum and observed that LAS levels above 0.001% are toxic to fern spores. Water pollution due to synthetic detergents has been increasing continuously during the last few years due to their extensive use in domestic life, agriculture and industry. These detergents are among the most common pollutants responsible for water pollution. In view of this fact, the phytotoxicity of LAS on germination of an aquatic fern Ceratopterismore » thalictroides spores was studied. However, in these studies, only germination pattern was taken as index and no observations were made on the developmental stages.« less

Synthesis of [.sup.13C] and [.sup.2H] substituted methacrylic acid, [.sup.13C] and [.sup.2H] substituted methyl methacrylate and/or related compounds

DOEpatents

Alvarez, Marc A [Santa Fe, NM; Martinez, Rodolfo A [Santa Fe, NM; Unkefer, Clifford J [Los Alamos, NM

2008-01-22

The present invention is directed to labeled compounds of the formulae ##STR00001## wherein Q is selected from the group consisting of --S--, --S(.dbd.O)--, and --S(.dbd.O).sub.2--, Z is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group selected from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each independently selected from the group consisting of a C.sub.1-C.sub.4 lower alkyl, an aryl, and an alkoxy group, and X is selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl group, and a fully-deuterated C.sub.1-C.sub.4 lower alkyl group. The present invention is also directed to a process of preparing labeled compounds, e.g., process of preparing [.sup.13C]methacrylic acid by reacting a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13CH.sub.2)-- aryl sulfone precursor with .sup.13CHI to form a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate, and, reacting the (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate with sodium hydroxide, followed by acid to form [.sup.13C]methacrylic acid. The present invention is further directed to a process of preparing [.sup.2H.sub.8]methyl methacrylate by reacting a (HOOC--C(C.sup.2H.sub.3).sub.2-- aryl sulfinyl intermediate with CD.sub.3I to form a (.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate, and heating the(.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate at temperatures and for time sufficient to form [.sup.2H.sub.8]methyl methacrylate.

Access to 6a-Alkyl Aporphines: Synthesis of (±)-N-Methylguattescidine.

PubMed

Ku, Angela F; Cuny, Gregory D

2016-10-21

(-)-N-Methylguattescidine (3) is an alkaloid recently isolated from Fissistigma latifolium and assigned as a rare example of a 6a-alkyl aporphine. Herein, we report the synthesis of (±)-3 and the des-hydroxyl derivative 4 using our previously reported ortho-phenol arylation methodology mediated by the XPhos precatalyst as a key synthetic step. In addition, substituents on the aryl halide portion of the ortho-phenol arylation substrates significantly influenced the formation of an oxidized side product.

Preparation and evaluation of a silica-based 1-alkyl-3-(propyl-3-sulfonate) imidazolium zwitterionic stationary phase for high-performance liquid chromatography.

PubMed

Qiu, Hongdeng; Jiang, Qiong; Wei, Zheng; Wang, Xusheng; Liu, Xia; Jiang, Shengxiang

2007-09-07

A new zwitterionic stationary phase based on silica bonded with 1-alkyl-3-(propyl-3-sulfonate) imidazolium was synthesized and characterized in this paper. The materials have been confirmed and evaluated by elemental analysis, thermogravimetric analysis and X-ray photoelectron spectroscopy. Potassium and calcium were separated simultaneously with several common inorganic anions including an iodate, chloride, bromide, nitrate and iodide on the phase. The effects of the concentration, organic solvent and pH of the eluent on the separation of anions were studied. Operated in the anion-exchange mode, this new stationary phase shows considerable promise for the separation of anions. Bases, vitamins and three imidazolium ionic liquids with different alkyl chains are also separated successfully on this column. The stationary phase has multiple retention mechanisms, such as anion-exchange, electrostatic attraction and repulsion interactions, and hydrophobic interaction between the zwitterionic stationary phase and specimens.

Indolyl aryl sulfones as HIV-1 non-nucleoside reverse transcriptase inhibitors: role of two halogen atoms at the indole ring in developing new analogues with improved antiviral activity.

PubMed

Regina, Giuseppe La; Coluccia, Antonio; Piscitelli, Francesco; Bergamini, Alberto; Sinistro, Anna; Cavazza, Antonella; Maga, Giovanni; Samuele, Alberta; Zanoli, Samantha; Novellino, Ettore; Artico, Marino; Silvestri, Romano

2007-10-04

Indolyl aryl sulfones bearing the 4,5-difluoro (10) or 5-chloro-4-fluoro (16) substitution pattern at the indole ring were potent inhibitors of HIV-1 WT and the NNRTI-resistant strains Y181C and K103N-Y181C. These compounds were highly effective against the 112 and the AB1 strains in lymphocytes and inhibited at nanomolar concentration the multiplication of the IIIBBa-L strain in macrophages. Compound 16 was exceptionally potent against RT WT and RTs carrying the K103N, Y181I, and L100I mutations.

The 3,7-diazabicyclo[3.3.1]nonane scaffold for subtype selective nicotinic acetylcholine receptor (nAChR) ligands. Part 1: the influence of different hydrogen bond acceptor systems on alkyl and (hetero)aryl substituents.

PubMed

Eibl, Christoph; Tomassoli, Isabelle; Munoz, Lenka; Stokes, Clare; Papke, Roger L; Gündisch, Daniela

2013-12-01

3,7-Diazabicyclo[3.3.1]nonane is a naturally occurring scaffold interacting with nicotinic acetylcholine receptors (nAChRs). When one nitrogen of the 3,7-diazabicyclo[3.3.1]nonane scaffold was implemented in a carboxamide motif displaying a hydrogen bond acceptor (HBA) functionality, compounds with higher affinities and subtype selectivity for α4β2(∗) were obtained. The nature of the HBA system (carboxamide, sulfonamide, urea) had a strong impact on nAChR interaction. High affinity ligands for α4β2(∗) possessed small alkyl chains, small un-substituted hetero-aryl groups or para-substituted phenyl ring systems along with a carboxamide group. Electrophysiological responses of selected 3,7-diazabicyclo[3.3.1]nonane derivatives to Xenopus oocytes expressing various nAChR subtypes showed diverse activation profiles. Compounds with strongest agonistic profiles were obtained with small alkyl groups whereas a shift to partial agonism/antagonism was observed for aryl substituents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Copper(II)-catalyzed hydroxylation of aryl halides using glycolic acid as a ligand.

PubMed

Xiao, Yan; Xu, Yongnan; Cheon, Hwan-Sung; Chae, Junghyun

2013-06-07

Copper(II)-catalyzed hydroxylation of aryl halides has been developed to afford functionalized phenols. The protocol utilizes the reagent combination of Cu(OH)2, glycolic acid, and NaOH in aqueous DMSO, all of which are cheap, readily available, and easily removable after the reaction. A broad range of aryl iodides and activated aryl bromides were transformed into the corresponding phenols in excellent yields. Moreover, it has been shown that C-O(alkyl)-coupled product, instead of phenol, can be predominantly formed under similar reaction conditions.

Photoinduced, copper-catalyzed alkylation of amides with unactivated secondary alkyl halides at room temperature.

PubMed

Do, Hien-Quang; Bachman, Shoshana; Bissember, Alex C; Peters, Jonas C; Fu, Gregory C

2014-02-05

The development of a mild and general method for the alkylation of amides with relatively unreactive alkyl halides (i.e., poor substrates for SN2 reactions) is an ongoing challenge in organic synthesis. We describe herein a versatile transition-metal-catalyzed approach: in particular, a photoinduced, copper-catalyzed monoalkylation of primary amides. A broad array of alkyl and aryl amides (as well as a lactam and a 2-oxazolidinone) couple with unactivated secondary (and hindered primary) alkyl bromides and iodides using a single set of comparatively simple and mild conditions: inexpensive CuI as the catalyst, no separate added ligand, and C-N bond formation at room temperature. The method is compatible with a variety of functional groups, such as an olefin, a carbamate, a thiophene, and a pyridine, and it has been applied to the synthesis of an opioid receptor antagonist. A range of mechanistic observations, including reactivity and stereochemical studies, are consistent with a coupling pathway that includes photoexcitation of a copper-amidate complex, followed by electron transfer to form an alkyl radical.

Synthesis of alkyl- and aryl-amino-substituted anthraquinone derivatives by microwave-assisted copper(0)-catalyzed Ullmann coupling reactions.

PubMed

Baqi, Younis; Müller, Christa E

2010-05-01

This protocol describes the efficient, generally applicable Ullmann coupling reaction of bromaminic acid with alkyl- or aryl-amines in phosphate buffer under microwave irradiation using elemental copper as a catalyst. The reaction leads to a number of biologically active compounds. As a prototypical example, the synthesis of a new, potent antagonist of human platelet P2Y(12) receptors, which has potential as an antithrombotic drug, is described in detail. The optimized protocol includes a description of an appropriate reaction setup, thin layer chromatography for monitoring the reaction and a procedure for the isolation, purification and characterization of the anticipated product. The reaction is performed without the use of a glove box and there is no requirement for an inert atmosphere. The reaction typically proceeds within 2-30 min, the protocol, including workup, generally takes 1-3 h to complete.

Direct arylation/alkylation/magnesiation of benzyl alcohols in the presence of Grignard reagents via Ni-, Fe-, or Co-catalyzed sp3 C-O bond activation.

PubMed

Yu, Da-Gang; Wang, Xin; Zhu, Ru-Yi; Luo, Shuang; Zhang, Xiao-Bo; Wang, Bi-Qin; Wang, Lei; Shi, Zhang-Jie

2012-09-12

Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp(3) C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of (n)hexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.

Dimension-controlled assemblies of anion-responsive π-electronic systems bearing aryl substituents with fan-shaped geometries.

PubMed

Lakshmi, Vellanki; Haketa, Yohei; Yamakado, Ryohei; Yasuda, Nobuhiro; Maeda, Hiromitsu

2017-03-30

Pyrrole-4-aryl-substituted dipyrrolyldiketone BF 2 complexes as anion-responsive π-electronic molecules were synthesized via a 3,5-dimethylpyrrole precursor. Mesophases were observed in derivatives that possessed long alkyl chains on the pyrrole-4-aryl groups along with their anion complexes as ion-pairing assemblies in combination with appropriate cations.

Arylation, alkenylation, and alkylation of 2-halopyridine N-oxides with grignard reagents: a solution to the problem of C2/C6 regioselective functionalization of pyridine derivatives.

PubMed

Zhang, Song; Liao, Lian-Yan; Zhang, Fang; Duan, Xin-Fang

2013-03-15

A facile arylation, alkenylation, and alkylation of functionalized 2-halopyridine N-oxides with various Grignard reagents was developed. It represented a highly efficient and selective C-H bond functionalization of pyridine derivatives in the presence of reactive C-Cl or C-Br bonds. Using Cl or Br as a blocking group, C2/C6 site-controllable functionalization of pyridine derivatives has been achieved. Various pyridine compounds can be prepared as illustrated in the total syntheses of Onychine, dielsine, and PARP-1 inhibitor GPI 16539.

Highly productive CNN pincer ruthenium catalysts for the asymmetric reduction of alkyl aryl ketones.

PubMed

Baratta, Walter; Chelucci, Giorgio; Magnolia, Santo; Siega, Katia; Rigo, Pierluigi

2009-01-01

Chiral pincer ruthenium complexes of formula [RuCl(CNN)(Josiphos)] (2-7; Josiphos = 1-[1-(dicyclohexylphosphano)ethyl]-2-(diarylphosphano)ferrocene) have been prepared by treating [RuCl(2)(PPh(3))(3)] with (S,R)-Josiphos diphosphanes and 1-substituted-1-(6-arylpyridin-2-yl)methanamines (HCNN; substituent = H (1 a), Me (1 b), and tBu (1 c)) with NEt(3). By using 1 b and 1 c as a racemic mixture, complexes 4-7 were obtained through a diastereoselective synthesis promoted by acetic acid. These pincer complexes, which display correctly matched chiral PP and CNN ligands, are remarkably active catalysts for the asymmetric reduction of alkyl aryl ketones in basic alcohol media by both transfer hydrogenation (TH) and hydrogenation (HY), achieving enantioselectivities of up to 99 %. In 2-propanol, the enantioselective TH of ketones was accomplished by using a catalyst loading as low as 0.002 mol % and afforded a turnover frequency (TOF) of 10(5)-10(6) h(-1) (60 and 82 degrees C). In methanol/ethanol mixtures, the CNN pincer complexes catalyzed the asymmetric HY of ketones with H(2) (5 atm) at 0.01 mol % relative to the complex with a TOF of approximately 10(4) h(-1) at 40 degrees C.

Catalytic performance of strong acid catalyst: Methyl modified SBA-15 loaded perfluorinated sulfonic acid obtained by the waste perfluorinated sulfonic acid ion exchange membrane

NASA Astrophysics Data System (ADS)

Jiang, Tingshun; Huang, Qiuyan; Li, Yingying; Fang, Minglan; Zhao, Qian

2018-02-01

Mesoporous molecular sieve (SBA-15) was modified using the trimethylchlorosilane as functional agent and the silylation SBA-15 mesoporous material was prepared in this work. The alcohol solution of perfluorinated sulfonic acid dissolved from the waste perfluorinated sulfonic acid ion exchange membrane (PFSIEM) was loaded onto the resulting mesoporous material by the impregnation method and their physicochemical properties were characterized by FT-IR, N2-physisorption, XRD, TG-DSC and TEM. The catalytic activities of these synthesized solid acid catalysts were evaluated by alkylation of phenol with tert-butyl alcohol. The influence of reaction temperature, weight hour space velocity (WHSV) and reaction time on the phenol conversion and product selectivity were assessed by means of a series of experiments. The results showed that with the increase of the active component of the catalyst, these catalysts still remained good mesoporous structure, but the mesoporous ordering decreased to some extent. These catalysts exhibited good catalytic performance for the alkylation of phenol with tert-butanol. The maximum phenol conversion of 89.3% with 70.9% selectivity to 4-t-butyl phenol (4-TBP) was achieved at 120 °C and the WHSV is 4 h-1. The methyl group was loaded on the surface of the catalyst by trimethylchlorosilane. This is beneficial to retard the deactivation of the catalyst. In this work, the alkylation of phenol with tert-butyl alcohol were carried out using the methyl modified SBA-15 mesoporous materials loaded perfluorinated sulfonic acid as catalysts. The results show that the resulting catalyst exhibited high catalytic activity.

Pyrimidine Nucleosides with a Reactive (β-Chlorovinyl)sulfone or (β-Keto)sulfone Group at the C5 Position, Their Reactions with Nucleophiles and Electrophiles, and Their Polymerase-Catalyzed Incorporation into DNA

PubMed Central

2018-01-01

Transition-metal-catalyzed chlorosulfonylation of 5-ethynylpyrimidine nucleosides provided (E)-5-(β-chlorovinyl)sulfones A, which undergo nucleophilic substitution with amines or thiols affording B. The treatment of vinyl sulfones A with ammonia followed by acid-catalyzed hydrolysis of the intermediary β-sulfonylvinylamines gave 5-(β-keto)sulfones C. The latter reacts with electrophiles, yielding α-carbon-alkylated or -sulfanylated analogues D. The 5′-triphosphates of A and C were incorporated into double-stranded DNA, using open and one-nucleotide gap substrates, by human or Escherichia coli DNA-polymerase-catalyzed reactions. PMID:29732453

Photooxidation of mixed aryl and biarylphosphines.

PubMed

Zhang, Dong; Celaje, Jeff A; Agua, Alon; Doan, Chad; Stewart, Timothy; Bau, Robert; Selke, Matthias

2010-07-02

Arylphosphines and dialkylbiarylphosphines react with singlet oxygen to form phosphine oxides and phosphinate esters. For mixed arylphosphines, the most electron-rich aryl group migrates to form the phosphinate, while for dialkylbiarylphosphines migration of the alkyl group occurs. Dialkylbiarylphosphines also yield arene epoxides, especially in electron-rich systems. Phosphinate ester formation is increased at high temperature, while protic solvents increase the yield of epoxide. The product distribution provides evidence for Buchwald's recent conformational model for the aerobic oxidation of dialkylbiarylphosphines.

Merging Photoredox and Nickel Catalysis: The Direct Synthesis of Ketones via the Decarboxylative Arylation of α-Oxo Acids**

PubMed Central

Chu, Lingling; Lipshultz, Jeffrey M.

2015-01-01

The direct decarboxylative arylation of α-oxo acids has been achieved via synergistic visible light-mediated photoredox and nickel catalyses. This method offers rapid entry to aryl and alkyl ketone architectures from simple α-oxo acid precursors via an acyl radical intermediate. Significant substrate scope is observed with respect to both the oxo acid and arene coupling partners. This mild decarboxylative arylation can also be utilized to efficiently access medicinal agents, as demonstrated by the rapid synthesis of fenofibrate. PMID:26014029

Docking and 3-D QSAR studies on indolyl aryl sulfones. Binding mode exploration at the HIV-1 reverse transcriptase non-nucleoside binding site and design of highly active N-(2-hydroxyethyl)carboxamide and N-(2-hydroxyethyl)carbohydrazide derivatives.

PubMed

Ragno, Rino; Artico, Marino; De Martino, Gabriella; La Regina, Giuseppe; Coluccia, Antonio; Di Pasquali, Alessandra; Silvestri, Romano

2005-01-13

Three-dimensional quantitative structure-activity relationship (3-D QSAR) studies and docking simulations were developed on indolyl aryl sulfones (IASs), a class of novel HIV-1 non-nucleoside reverse transcriptase (RT) inhibitors (Silvestri, et al. J. Med. Chem. 2003, 46, 2482-2493) highly active against wild type and some clinically relevant resistant strains (Y181C, the double mutant K103N-Y181C, and the K103R-V179D-P225H strain, highly resistant to efavirenz). Predictive 3-D QSAR models using the combination of GRID and GOLPE programs were obtained using a receptor-based alignment by means of docking IASs into the non-nucleoside binding site (NNBS) of RT. The derived 3-D QSAR models showed conventional correlation (r(2)) and cross-validated (q(2)) coefficients values ranging from 0.79 to 0.93 and from 0.59 to 0.84, respectively. All described models were validated by an external test set compiled from previously reported pyrryl aryl sulfones (Artico, et al. J. Med. Chem. 1996, 39, 522-530). The most predictive 3-D QSAR model was then used to predict the activity of novel untested IASs. The synthesis of six designed derivatives (prediction set) allowed disclosure of new IASs endowed with high anti-HIV-1 activities.

Indolyl aryl sulfones (IASs): development of highly potent NNRTIs active against wt-HIV-1 and clinically relevant drug resistant mutants.

PubMed

Silvestri, Romano; Artico, Marino

2005-01-01

Indolyl aryl sulfones (IASs) are a potent class of NNRTIs developed from L-737,126, a lead agent discovered by Merck AG. IAS derivatives are endowed with inhibitory activities against wt HIV-1 in the low nanomolar concentration range. Introduction of two methyl groups at positions 3 and 5 of the phenyl ring of the aryl sulfonyl moiety furnished IAS derivatives such as 5-chloro- or 5-bromo-3-[(3,5-dimethylphenyl)sulfonyl]indole-2-carboxyamide, which showed very potent and selective anti-HIV-1 activity against some mutants carrying NNRTI resistant mutations at positions 103 and 181 of the reverse transcriptase. IAS derivatives bearing 2-hydroxyethylcarboxyamide or 2-hydroxyethylcarboxyhydrazide groups at position 2 of the indole nucleus were more active than L-737,126 against the K103N-Y181C double mutant. A great improvement of antiviral activity against wt HIV-1 and resistant mutants was obtained by coupling 1-3 simple amino acids, such as glycine and alanine, in sequence, with the 3-[(3,5-dimethylphenyl)sulfonyl]-1H-indole-2-carbonyl moiety. The transformation of the chain terminus into amide or hydrazide, produced short peptides with high selectivity and potent activity against wt HIV-1, and the viral mutants Y181C, K103N-Y181C and EFV(R). IAS having two halogen atoms at the indole showed potent inhibitory activity against the Y181C and the EFV(R) resistant mutant strains. In particular, the introduction of a fluorine atom at position 4 of the indole ring notably contributed to improve the antiviral activities against both wt and the related resistant mutants. 5-Nitro-IASs were highly active against wt HIV-1 and exhibited low cytotoxicity. Experimental data highlighted the class IAS derivatives as promising candidates for clinical trials.

Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions† †Electronic supplementary information (ESI) available: Detailed experimental and computational results, procedures, characterization data, copies of NMR charts, and crystallographic data. CCDC 1572238. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04675h

PubMed Central

Fukuoka, Asuka; Yokoyama, Wataru; Min, Xin; Hisaki, Ichiro; Kuniyasu, Hitoshi

2018-01-01

We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C–C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C–F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C–C bond forming reactions, providing useful information for developing efficient and straightforward

EFFECTS OF PRENATAL PERFLUOROOCTANE SULFONATE (PFOS) EXPOSURE ON LUNG MATURATION IN THE PERINATAL RAT

EPA Science Inventory

Background: Perfluorooctane sulfonate (PFOS), found widely in wildlife and humans, is environmentally and metabolically stable. Environmental PFOS may be from its use as a surfactant, hydrolysis of perfluorooctanesulfonyl fluoride, and degradation of N-alkyl-perfluorooctanesulfon...

AN EFFICIENT AQUEOUS N-HETEROCYCLIZATION OF ANILINE DERIVATIVES: MICROWAVE-ASSISTED SYNTHESIS OF N-ARYL AZACYCLOALKANES

EPA Science Inventory

N-aryl azacycloalkanes, an important class of building blocks in natural product and pharmaceuticals, are synthesized via an efficient and simple eco-friendly protocol that involves double N-alkylation of aniline derivatives. The reaction is accelerated by exposure to microwaves ...

Synthesis of Amphoteric Sulfonic Ionic Liquid Surfactant and Measurement of Its Surface Properties

NASA Astrophysics Data System (ADS)

Zhao, Xiuli; Zhang, Changbao; Liu, Da; Liu, Haiyan

2018-03-01

Three kinds of amphoteric sulfonic ionic liquid surfactants were synthesized in this paper. Their functional group structures were characterized by infrared spectrometer. The surface properties of them were studied. The results show that the functional group structures of all three products conform to the structure characteristics of amphoteric sulfonic ionic liquid surfactants. The shorter the long chain alkyl carbon chain is, the closer the arrangement of surfactant on the gas-liquid surface will be, and the higher the efficiency in reducing the surface tension..

Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature.

PubMed

Liu, Wenbo; Yang, Xiaobo; Gao, Yang; Li, Chao-Jun

2017-06-28

Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.

Cross-coupling of alkenyl/aryl carboxylates with Grignard reagent via Fe-catalyzed C-O bond activation.

PubMed

Li, Bi-Jie; Xu, Li; Wu, Zhen-Hua; Guan, Bing-Tao; Sun, Chang-Liang; Wang, Bi-Qin; Shi, Zhang-Jie

2009-10-21

Iron-catalyzed cross-coupling of alkenyl/aryl carboxylates with primary alkyl Grignard reagent was described. This reaction brought a new family of electrophiles to iron catalysis. The combination of an inexpensive carboxylate electrophile and an iron catalyst would generate ample advantages.

Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.

PubMed

Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok

2014-10-01

Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211.

Synthesis of enyne and aryl vinyl sulfoxides: functionalization via Pummerer rearrangement.

PubMed

Souza, Frederico B; Shamim, Anwar; Argomedo, Luiz M Z; Pimenta, Daniel C; Stefani, Hélio A

2015-11-01

An efficient methodology for the synthesis of aryl-substituted vinyl sulfoxides through direct substitution of aryl-substituted alkynyl grignard reagents on menthyl-p-toluenesulfinate followed by Suzuki-Miyaura cross-coupling reaction has been developed. It has also been described that the reaction of alkyl-substituted and cycloalkyl-substituted alkynyl grignard reagents with menthyl-p-toluenesulfinate led to two products, i.e., alkynyl sulfoxide derivatives, as a result of substitution, and enyne sulfoxide derivatives, which resulted from substitution followed by Michael type addition. It was possible to selectively synthesize the enyne sulfoxide derivatives by changing the concentration of the grignard reagent. These alkenyl sulfoxides were transformed into the corresponding [Formula: see text]-thio aldehydes in high yields via additive Pummerer rearrangement.

Quantitative Determination of Fluorinated Alkyl Substances by Large-Volume-Injection LC/MS/MS—Characterization of Municipal Wastewaters

PubMed Central

Schultz, Melissa M.; Barofsky, Douglas F.; Field, Jennifer A.

2008-01-01

A quantitative method was developed for the determination of fluorinated alkyl substances in municipal wastewater influents and effluents. The method consisted of centrifugation followed by large-volume injection (500 μL) of the supernatant onto a liquid chromatograph with a reverse-phase column and detection by electrospray ionization, and tandem mass spectrometry (LC/MS/MS). The fluorinated analytes studied include perfluoroalkyl sulfonates, fluorotelomer sulfonates, perfluorocarboxylates, and select fluorinated alkyl sulfonamides. Recoveries of the fluorinated analytes from wastewater treatment plant (WWTP) raw influents and final effluent ranged from 77% – 96% and 80% – 99%, respectively. The lower limit of quantitation ranged from 0.5 to 3.0 ng/L depending on the analyte. The method was applied to flow-proportional composites of raw influent and final effluent collected over a 24 hr period from ten WWTPs nationwide. Fluorinated alkyl substances were observed in wastewater at all treatment plants and each plant exhibited unique distributions of fluorinated alkyl substances despite similarities in treatment processes. In nine out of the ten plants sampled, at least one class of fluorinated alkyl substances exhibited increased concentrations in the effluent as compared to the influent concentrations. In some instances, decreases in certain fluorinated analyte concentrations were observed and attributed to sorption to sludge. PMID:16433363

Design, Synthesis, and Structure--Activity Relationship of New 2-Aryl-3,4-dihydro-β-carbolin-2-ium Salts as Antifungal Agents.

PubMed

Hou, Zhe; Zhu, Li-Fei; Yu, Xin-chi; Sun, Ma-Qiang; Miao, Fang; Zhou, Le

2016-04-13

Twenty-two 2-aryl-9-methyl-3,4-dihydro-β-carbolin-2-ium bromides along with four 9-demethylated derivatives were synthesized and characterized by spectroscopic analysis. By using the mycelium growth rate method, the compounds were evaluated for antifungal activities in vitro against six plant pathogenic fungi, and structure-activity relationships (SAR) were derived. Almost all of the compounds showed obvious inhibition activity on each of the fungi at 150 μM. For all of the fungi, 10 of the compounds showed average inhibition rates of >80% at 150 μM, and most of their EC50 values were in the range of 2.0-30.0 μM. SAR analysis showed that the substitution pattern of the N-aryl ring significantly influences the activity; N9-alkylation improves the activity, whereas aromatization of ring-C reduces the activity. It was concluded that the present research provided a series of new 2-aryl-9-alkyl-3,4-dihydro-β-carbolin-2-iums with excellent antifungal potency and structure optimization design for the development of new carboline antifungal agents.

Absolute configuration in 4-alkyl- and 4-aryl-3,4-dihydro-2(1H)-pyrimidones: a combined theoretical and experimental investigation.

PubMed

Uray, G; Verdino, P; Belaj, F; Kappe, C O; Fabian, W M

2001-10-05

Structural features (orientation of the carboxyl group, ring puckering), electronic absorption, and circular dichroism spectra of 4-alkyl- and 4-aryl-dihydropyrimidones 1-5 are calculated by semiempirical (AM1, INDO/S), ab initio (HF/6-31G, CIS/6-31G, RPA/6-31G), and density functional theory (B3LYP/6-31G) methods. These calculations allow an assignment of the absolute configuration by comparison of simulated and experimental CD spectra. Although the ab initio methods greatly overestimate electronic transition energies, the general appearance of the experimental CD spectra is quite nicely reproduced by these calculations. Thus, comparison of experimental with calculated CD spectra is a reliable tool for the assignment of the absolute configuration. For 4-methyl derivatives 1, the first enantiopure DHPM examples with no additional aromatic substituent, the stereochemistry at C4 provided by the theoretical results is confirmed by X-ray structure determination of the diastereomeric salt 6. Additional support is the consistent HPLC elution order found for all investigated DHPMs on a cellulose-derived chiral stationary phase.

Synthesis of geminal difluorides by oxidative desulfurization-difluorination of alkyl aryl thioethers with halonium electrophiles in the presence of fluorinating reagents and its application for 18F-radiolabeling.

PubMed

Hugenberg, Verena; Wagner, Stefan; Kopka, Klaus; Schober, Otmar; Schäfers, Michael; Haufe, Günter

2010-09-17

Various ω-substituted 1,1-difluoroalkanes are synthesized in good yields from alkyl aryl thioethers by a new oxidative desulfurization-difluorination protocol with the reagents combination of 1,3-dibromo-5,5-dimethylhydantoin (DBH) as an oxidizer and pyridine·9HF (Py·9HF) as a fluoride source. The reaction proceeds via a fluoro-Pummerer-type rearrangement followed by an oxidative desulfurization-fluorination step. Starting from α-fluorinated thioethers, this reaction is promising for (18)F-labeling (τ(1/2) = 110 min) of ligands applicable for positron emission tomography (PET). Using the combination of DBH and carrier-added Py·9H[(18)F]F, an (18)F-labeled difluoride was synthesized from the corresponding α-fluoro thioether with a radiochemical yield of 9%.

Catalytic enantioselective synthesis of atropisomeric biaryls by a cation-directed O-alkylation

NASA Astrophysics Data System (ADS)

Jolliffe, John D.; Armstrong, Roly J.; Smith, Martin D.

2017-06-01

Axially chiral biaryls, as exemplified by 1,1‧-bi-2-naphthol (BINOL), are key components of catalysts, natural products and medicines. These materials are synthesized conventionally in enantioenriched form through metal-mediated cross coupling, de novo construction of an aromatic ring, point-to-axial chirality transfer or an atropselective transformation of an existing biaryl. Here, we report a highly enantioselective organocatalytic method for the synthesis of atropisomeric biaryls by a cation-directed O-alkylation. Treatment of racemic 1-aryl-2-tetralones with a chiral quinidine-derived ammonium salt under basic conditions in the presence of an alkylating agent leads to atropselective O-alkylation with e.r. up to 98:2. Oxidation with DDQ gives access to C2-symmetric and non-symmetric BINOL derivatives without compromising e.r. We propose that the chiral ammonium counterion differentiates between rapidly equilibrating atropisomeric enolates, leading to highly atropselective O-alkylation. This dynamic kinetic resolution process offers a general approach to the synthesis of enantioenriched atropisomeric materials.

Α-aryl-N-alkyl nitrones, as potential agents for stroke treatment: synthesis, theoretical calculations, antioxidant, anti-inflammatory, neuroprotective, and brain-blood barrier permeability properties.

PubMed

Chioua, Mourad; Sucunza, David; Soriano, Elena; Hadjipavlou-Litina, Dimitra; Alcázar, Alberto; Ayuso, Irene; Oset-Gasque, María Jesús; González, María Pilar; Monjas, Leticia; Rodríguez-Franco, María Isabel; Marco-Contelles, José; Samadi, Abdelouahid

2012-01-12

We report the synthesis, theoretical calculations, the antioxidant, anti-inflammatory, and neuroprotective properties, and the ability to cross the blood-brain barrier (BBB) of (Z)-α-aryl and heteroaryl-N-alkyl nitrones as potential agents for stroke treatment. The majority of nitrones compete with DMSO for hydroxyl radicals, and most of them are potent lipoxygenase inhibitors. Cell viability-related (MTT assay) studies clearly showed that nitrones 1-3 and 10 give rise to significant neuroprotection. When compounds 1-11 were tested for necrotic cell death (LDH release test) nitrones 1-3, 6, 7, and 9 proved to be neuroprotective agents. In vitro evaluation of the BBB penetration of selected nitrones 1, 2, 10, and 11 using the PAMPA-BBB assay showed that all of them cross the BBB. Permeable quinoline nitrones 2 and 3 show potent combined antioxidant and neuroprotective properties and, therefore, can be considered as new lead compounds for further development in specific tests for potential stroke treatment.

Synthesis Of [2h, 13c] And [2h3, 13c]Methyl Aryl Sulfides

DOEpatents

Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

2004-03-30

The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2,.sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms. The present invention is also directed to the labeled compounds of [.sup.2 H.sub.1, .sup.13 C]methyl iodide and [.sup.2 H.sub.2, .sup.13 C]methyl iodide.

Palladium-Catalyzed α-Arylation of Aryl Nitromethanes

PubMed Central

2015-01-01

Catalytic conditions for the α-arylation of aryl nitromethanes have been discovered using parallel microscale experimentation, despite two prior reports of the lack of reactivity of these aryl nitromethane precursors. The method efficiently provides a variety of substituted, isolable diaryl nitromethanes. In addition, it is possible to sequentially append two different aryl groups to nitromethane. Mild oxidation conditions were identified to afford the corresponding benzophenones via the Nef reaction, and reduction conditions were optimized to afford several diaryl methylamines. PMID:26584680

Coated phosphors, methods of making them, and articles comprising the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyons, Robert Joseph

Compositions comprising a phosphor and a compound having the formula R.sub.1R.sub.2M, wherein R.sub.1 is a substituted or unsubstituted alkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, alkoxy, alkoxyl, acyl heterocycle, haloalkyl, oxaalkyl, or silyl; R.sub.2 is a sulfate, sulfonate, or carboxylate and M is an alkali metal or an alkaline earth metal are provided. Phosphors coated with the compound, methods of making the coated phosphors and articles comprising the compositions are provided.

Silyl Radical Activation of Alkyl Halides in Metallaphotoredox Catalysis: A Unique Pathway for Cross-Electrophile Coupling.

PubMed

Zhang, Patricia; Le, Chi Chip; MacMillan, David W C

2016-07-06

A strategy for cross-electrophile coupling has been developed via the merger of photoredox and transition metal catalysis. In this report, we demonstrate the use of commercially available tris(trimethylsilyl)silane with metallaphotoredox catalysis to efficiently couple alkyl bromides with aryl or heteroaryl bromides in excellent yields. We hypothesize that a photocatalytically generated silyl radical species can perform halogen-atom abstraction to activate alkyl halides as nucleophilic cross-coupling partners. This protocol allows the use of mild yet robust conditions to construct Csp(3)-Csp(2) bonds generically via a unique cross-coupling pathway.

Design, microwave-mediated synthesis and biological evaluation of novel 4-aryl(alkyl)amino-3-nitroquinoline and 2,4-diaryl(dialkyl)amino-3-nitroquinolines as anticancer agents.

PubMed

Chauhan, Monika; Rana, Anil; Alex, Jimi Marin; Negi, Arvind; Singh, Sandeep; Kumar, Raj

2015-02-01

Design, microwave-assisted synthesis of novel 4-aryl (alkyl)amino-3-nitroquinoline (1a-1l) and 2,4-diaryl (dialkyl)amino-3-nitroquinolines (2a-2k and 3a) via regioselective and complete nucleophilic substitution of 2,4-dichloro-3-nitroquinoline, respectively in water are presented. The newly synthesized compounds were evaluated for the first time for antiproliferative activity against EGFR overexpressing human lung (A-549 and H-460) and colon (HCT-116-wild type and HCT-116-p53 null) cancer cell lines. Some notions about structure-activity relationships (SAR) are presented. Compounds 2e, 2f, 2j and 3a overall exhibited excellent anticancer activity comparable to erlotinib which was used as a positive control. Molecular modeling studies disclosed the recognition pattern of the compounds and also supported the observed SAR. Copyright © 2014 Elsevier Inc. All rights reserved.

Rh-Catalyzed Intermolecular Reactions of α-Alkyl-α-Diazo Carbonyl Compounds with Selectivity over β-Hydride Migration

PubMed Central

DeAngelis, Andrew; Panish, Robert; Fox, Joseph M.

2016-01-01

CONSPECTUS Rh-carbenes derived from α-diazocarbonyl compounds have found broad utility across a remarkable range of reactivity, including cyclopropanation, cyclopropenation, C–H insertions, heteroatom–H insertions, and ylide forming reactions. However, in contrast to α-aryl or α-vinyl-α-diazocarbonyl compounds, the utility of α-alkyl-α-diazocarbonyl compounds had been moderated by the propensity of such compounds to undergo intramolecular β-hydride migration to give alkene products. Especially challenging had been intermolecular reactions involving α-alkyl-α-diazocarbonyl compounds. PMID:26689221

Action of ethyl and methyl methane sulfonates on DNA injection and genetic recombination in T7 bacteriophage.

PubMed Central

Karska-Wysocki, B; Mamet-Bratley, M D; Verly, W G

1976-01-01

After treatment with methyl or ethyl methane sulfonate, T7 amber mutants display a reduced capacity for recombination. Moreover, alkylation reduces recombination frequency involving markers on the right-hand side of the genetic map more than it reduces recombination frequency involving markers on the left-hand side. We interpret this to mean that alkylation can stop DNA injection at any point along the DNA molecule, and that T7 phage injects its DNA in a unique fashion starting from the end carrying the genes for early proteins. PMID:183007

Alkyl sulfonic acide hydrazides: Synthesis, characterization, computational studies and anticancer, antibacterial, anticarbonic anhydrase II (hCA II) activities

NASA Astrophysics Data System (ADS)

O. Ozdemir, Ummuhan; İlbiz, Firdevs; Balaban Gunduzalp, Ayla; Ozbek, Neslihan; Karagoz Genç, Zuhal; Hamurcu, Fatma; Tekin, Suat

2015-11-01

Methane sulfonic acide hydrazide, CH3SO2NHNH2 (1), ethane sulfonic acide hydrazide, CH3CH2SO2NHNH2 (2), propane sulfonic acide hydrazide, CH3CH2CH2SO2NHNH2 (3) and butane sulfonic acide hydrazide, CH3CH2CH2CH2SO2NHNH2 (4) have been synthesized as homologous series and characterized by using elemental analysis, spectrophotometric methods (1H-13C NMR, FT-IR, LC-MS). In order to gain insight into the structure of the compounds, we have performed computational studies by using 6-311G(d, p) functional in which B3LYP functional were implemented. The geometry of the sulfonic acide hydrazides were optimized at the DFT method with Gaussian 09 program package. A conformational analysis of compounds were performed by using NMR theoretical calculations with DFT/B3LYP/6-311++G(2d, 2p) level of theory by applying the (GIAO) approach. The anticancer activities of these compounds on MCF-7 human breast cancer cell line investigated by comparing IC50 values. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Gram negative bacteria; Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442, Klebsiella pneumonia ATCC 70063 by using the disc diffusion method. The inhibition activities of these compounds on carbonic anhydrase II enzyme (hCA II) have been investigated by comparing IC50 and Ki values. The biological activity screening shows that butane sulfonic acide hydrazide (4) has more activity than the others against tested breast cancer cell lines MCF-7, Gram negative/Gram positive bacteria and carbonic anhydrase II (hCA II) isoenzyme.

Structure-based design, synthesis, and biological evaluation of novel pyrrolyl aryl sulfones: HIV-1 non-nucleoside reverse transcriptase inhibitors active at nanomolar concentrations.

PubMed

Artico, M; Silvestri, R; Pagnozzi, E; Bruno, B; Novellino, E; Greco, G; Massa, S; Ettorre, A; Loi, A G; Scintu, F; La Colla, P

2000-05-04

Pyrrolyl aryl sulfones (PASs) have been recently reported as a new class of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitors acting at the non-nucleoside binding site of this enzyme (Artico, M.; et al. J. Med. Chem. 1996, 39, 522-530). Compound 3, the most potent inhibitor within the series (EC(50) = 0.14 microM, IC(50) = 0.4 microM, and SI > 1429), was then selected as a lead compound for a synthetic project based on molecular modeling studies. Using the three-dimensional structure of RT cocrystallized with the alpha-APA derivative R95845, we derived a model of the RT/3 complex by taking into account previously developed structure-activity relationships. Inspection of this model and docking calculations on virtual compounds prompted the design of novel PAS derivatives and related analogues. Our computational approach proved to be effective in making qualitative predictions, that is in discriminating active versus inactive compounds. Among the compounds synthesized and tested, 20 was the most active one, with EC(50) = 0.045 microM, IC(50) = 0.05 microM, and SI = 5333. Compared with the lead 3, these values represent a 3- and 8-fold improvement in the cell-based and enzyme assays, respectively, together with the highest selectivity achieved so far in the PAS series.

Synthesis of 2-aryl and 3-aryl benzo[b]furan thioethers using aryl sulfonyl hydrazides as sulfenylation reagents.

PubMed

Zhao, Xia; Zhang, Lipeng; Lu, Xiaoyu; Li, Tianjiao; Lu, Kui

2015-03-06

An efficient, metal-free protocol used to synthesize aryl benzo[b]furan thioethers based on the I2-catalyzed cross-coupling of benzo[b]furans as well as the electrophilic cyclization of 2-alkynylphenol derivatives with aryl sulfonyl hydrazides was developed. Various 2-aryl and 3-aryl benzo[b]furan thioethers were obtained in moderate to good yields.

High Potency of Indolyl Aryl Sulfone Nonnucleoside Inhibitors towards Drug-Resistant Human Immunodeficiency Virus Type 1 Reverse Transcriptase Mutants Is Due to Selective Targeting of Different Mechanistic Forms of the Enzyme

PubMed Central

Cancio, Reynel; Silvestri, Romano; Ragno, Rino; Artico, Marino; De Martino, Gabriella; La Regina, Giuseppe; Crespan, Emmanuele; Zanoli, Samantha; Hübscher, Ulrich; Spadari, Silvio; Maga, Giovanni

2005-01-01

Indolyl aryl sulfone (IAS) nonnucleoside inhibitors have been shown to potently inhibit the growth of wild-type and drug-resistant human immunodeficiency virus type 1 (HIV-1), but their exact mechanism of action has not been elucidated yet. Here, we describe the mechanism of inhibition of HIV-1 reverse transcriptase (RT) by selected IAS derivatives. Our results showed that, depending on the substitutions introduced in the IAS common pharmacophore, these compounds can be made selective for different enzyme-substrate complexes. Moreover, we showed that the molecular basis for this selectivity was a different association rate of the drug to a particular enzymatic form along the reaction pathway. By comparing the activities of the different compounds against wild-type RT and the nonnucleoside reverse transcriptase inhibitor-resistant mutant Lys103Asn, it was possible to hypothesize, on the basis of their mechanism of action, a rationale for the design of drugs which could overcome the steric barrier imposed by the Lys103Asn mutation. PMID:16251294

Isotopic Measurements of Organic Sulfonates From The Murchison Meteorite

NASA Technical Reports Server (NTRS)

Cooper, G. W.; Chang, S.; DeVincenzi, Donald L. (Technical Monitor)

1995-01-01

Organic sulfonates and phosphonates have been extracted from the Murchison meteorite for stable isotope measurements. Preliminary stable isotope measurements of individual alkyl sulfonates, R-SO3H (R=C(sub n)H(sub 2n+l)), are shown. These compounds were found in aqueous extracts of Murchison. Both groups show trends similar to other homologous series of organic compounds indigenous to Murchison. Molecular abundances decrease with increasing carbon number, and all possible isomers at each carbon number (through C-4) are present. Carbon isotope measurements of the sulfonates show a decrease in the C-13/C-12 ratio with increasing carbon number. The overall objectives of this project are to obtain dime element carbon, hydrogen, and sulfur - intramolecular isotopic analyses of individual sulfonates, and isotopic measurement of carbon and hydrogen of the phosphonates as a group. The Murchison meteorite is the best characterized carbonaceous chondrite with respect to organic chemistry. The finding of organic sulfonates and phosphonates in Murchison is of interest because they are the first well-characterized series of sulfur and phosphorus containing organic compounds found in meteorites. Also, meteorites, comets, and interplanetary dust particles may have been involved in chemical evolution on the early Earth. Because of the critical role of organic phosphorus and sulfur in all living systems, it is particularly interesting to see examples of abiotic syntheses of these classes of compounds. The study of the isotopic composition of the sulfonates and phosphonates can yield insight into their possible interstellar origin as well as their mechanisms of synthesis in the early solar system. Previous isotopic analyses of other classes of organic compounds indigenous to meteorites, e.g., amino acids, carboxylic acids, and hydrocarbons indicate the possibility that interstellar molecules were incorporated into meteorite parent bodies. In these compounds the ratios of heavy to

Design and synthesis of some new 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-ureas as potent anticonvulsant and antidepressant agents.

PubMed

Mishra, Chandra Bhushan; Kumari, Shikha; Tiwari, Manisha

2016-05-01

A series of 1-phenyl-3/4-[4-(aryl/heteroaryl/alkyl-piperazine1-yl)-phenyl-urea derivatives (29-42) were designed, synthesized and evaluated for their anticonvulsant activity by using maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurotoxicity was checked by rotarod assay. Most of the test compounds were found effective in both seizure tests. Compound 30 (1-{4-[4-(4-chloro-phenyl)-piperazin-1-yl]-phenyl}-3-phenyl-urea) exhibited marked anticonvulsant activity in MES as well as scPTZ tests. The phase II anticonvulsant quantification study of compound 30 indicates the ED50 value of 28.5 mg/kg against MES induced seizures. In addition, this compound also showed considerable protection against pilocarpine induced status epilepticus in rats. Seizures induced by 3-mercaptopropionic acid model and thiosemicarbazide were significantly attenuated by compound 30, which suggested its broad spectrum of anticonvulsant activity. Interestingly, compound 30 displayed better antidepressant activity than standard drug fluoxetine. Moreover, compound 30 appeared as a non-toxic chemical entity in sub-acute toxicity studies.

Palladium-Catalyzed Indole, Pyrrole, and Furan Arylation by Aryl Chlorides

PubMed Central

Nadres, Enrico T.; Lazareva, Anna; Daugulis, Olafs

2011-01-01

The palladium-catalyzed direct arylation of indoles, pyrroles, and furans by aryl chlorides has been demonstrated. The method employs a palladium acetate catalyst, 2-(dicyclohexylphosphino)-biphenyl ligand, and an inorganic base. Electron-rich and electron-poor aryl chlorides as well as chloropyridine coupling partners can be used and arylated heterocycles are obtained in moderate to good yields. Optimization of base, ligand, and solvent is required for achieving best results. PMID:21192652

Crystal structures of five 1-alkyl-4-aryl-1,2,4-triazol-1-ium halide salts.

PubMed

Guino-O, Marites A; Talbot, Meghan O; Slitts, Michael M; Pham, Theresa N; Audi, Maya C; Janzen, Daron E

2015-06-01

The asymmetric units for the salts 4-(4-fluoro-phen-yl)-1-isopropyl-1,2,4-triazol-1-ium iodide, C11H13FN3 (+)·I(-), (1), 1-isopropyl-4-(4-methyl-phen-yl)-1,2,4-triazol-1-ium iodide, C12H16N3 (+)·I(-), (2), 1-isopropyl-4-phenyl-1,2,4-triazol-1-ium iodide, C11H14N3 (+)·I(-), (3), and 1-methyl-4-phenyl-1,2,4-triazol-1-ium iodide, C9H10N3 (+)·I(-), (4), contain one cation and one iodide ion, whereas in 1-benzyl-4-phenyl-1,2,4-triazol-1-ium bromide monohydrate, C15H14N3 (+)·Br(-)·H2O, (5), there is an additional single water mol-ecule. There is a predominant C-H⋯X(halide) inter-action for all salts, resulting in a two-dimensional extended sheet network between the triazolium cation and the halide ions. For salts with para-substitution on the aryl ring, there is an additional π-anion inter-action between a triazolium carbon and iodide displayed by the layers. For salts without the para-substitution on the aryl ring, the π-π inter-actions are between the triazolium and aryl rings. The melting points of these salts agree with the predicted substituent inductive effects.

Method for removing elemental sulfur in sour gas wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sample, T.E. Jr.

1975-09-30

A process is described for removing sulfur deposits from sour gas wells. The formation, well, and surface equipment are contacted with a chemical composition whose aqueous solution will solubilize the sulfur by primary chemical reaction and contains a wetting agent to facilitate and accelerate the sulfur dissolution and removal. The wetting agent or surfactant may be any of a wide variety of surface-active substances such as soaps, sodium or ammonium salts of alkyl or alkyl-aryl sulfates and sulfonates. Nonionic surfactants are preferred, such as ethoxylated substituted phenols. The aqueous solvents are capable of chemically reacting with sulfur to form water-solublemore » sulfur derivatives and include aqueous solutions of alkalies, bases (both inorganic and organic), ammonia, sulfites, bisulfites, etc. (6 claims)« less

Stereospecific Nickel-Catalyzed Cross-Coupling Reactions of Alkyl Grignard Reagents and Identification of Selective Anti-Breast Cancer Agents**

PubMed Central

Osborne, Charlotte A.; Moore, Curtis E.; Morrissette, Naomi S.; Jarvo, Elizabeth R.

2014-01-01

β-Hydrogen-containing alkyl Grignard reagents were used in a stereospecific nickel-catalyzed cross-coupling reaction to form sp3–sp3 carbon–carbon bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF-7 breast cancer cells. PMID:24478275

Crystal structures of five 1-alkyl-4-aryl-1,2,4-triazol-1-ium halide salts

PubMed Central

Guino-o, Marites A.; Talbot, Meghan O.; Slitts, Michael M.; Pham, Theresa N.; Audi, Maya C.; Janzen, Daron E.

2015-01-01

The asymmetric units for the salts 4-(4-fluoro­phen­yl)-1-isopropyl-1,2,4-triazol-1-ium iodide, C11H13FN3 +·I−, (1), 1-isopropyl-4-(4-methyl­phen­yl)-1,2,4-triazol-1-ium iodide, C12H16N3 +·I−, (2), 1-isopropyl-4-phenyl-1,2,4-triazol-1-ium iodide, C11H14N3 +·I−, (3), and 1-methyl-4-phenyl-1,2,4-triazol-1-ium iodide, C9H10N3 +·I−, (4), contain one cation and one iodide ion, whereas in 1-benzyl-4-phenyl-1,2,4-triazol-1-ium bromide monohydrate, C15H14N3 +·Br−·H2O, (5), there is an additional single water mol­ecule. There is a predominant C—H⋯X(halide) inter­action for all salts, resulting in a two-dimensional extended sheet network between the triazolium cation and the halide ions. For salts with para-substitution on the aryl ring, there is an additional π–anion inter­action between a triazolium carbon and iodide displayed by the layers. For salts without the para-substitution on the aryl ring, the π–π inter­actions are between the triazolium and aryl rings. The melting points of these salts agree with the predicted substituent inductive effects. PMID:26090137

Palladium-catalyzed one-pot three- or four-component coupling of aryl iodides, alkynes, and amines through C-N bond cleavage: efficient synthesis of indole derivatives.

PubMed

Hao, Wei; Geng, Weizhi; Zhang, Wen-Xiong; Xi, Zhenfeng

2014-02-24

An efficient synthesis of N-substituted indole derivatives was realized by combining the Pd-catalyzed one-pot multicomponent coupling approach with cleavage of the C(sp(3))-N bonds. Three or four components of aryl iodides, alkynes, and amines were involved in this coupling process. The cyclopentadiene-phosphine ligand showed high efficiency. A variety of aryl iodides, including cyclic and acyclic tertiary amino aryl iodides, and substituted 1-bromo-2-iodobenzene derivatives could be used. Both symmetric and unsymmetric alkynes substituted with alkyl, aryl, or trimethylsilyl groups could be applied. Cyclic secondary amines such as piperidine, morpholine, 4-methylpiperidine, 1-methylpiperazine, 2-methylpiperidine, and acyclic amines including secondary and primary amines all showed good reactivity. Further application of the resulting indole derivatives was demonstrated by the synthesis of benzosilolo[2,3-b]indole. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aryl triolborates: novel reagent for copper-catalyzed N arylation of amines, anilines, and imidazoles.

PubMed

Yu, Xiao-Qiang; Yamamoto, Yasunori; Miyaura, Norio

2008-09-01

The N arylation of primary and secondary aliphatic amines, anilines, and imidazoles with novel potassium aryl triolborates was carried out in the presence of a reoxidant and a catalytic amount of Cu(OAc)(2) (10 mol %). Aryl triolborates were found to be better reagents than aryl boronic acids or potassium aryl trifluoroborates as the former achieved high yields under mild conditions. Coupling of primary and secondary aliphatic amines to give N-aryl amines in excellent yields was performed under oxygen atmosphere. The reactions of anilines and imidazoles to provide N-aryl anilines and N-aryl imidazoles in good yields proceeded smoothly when trimethylamine N-oxide was used as an oxidant.

Cobalt co-catalysis for cross-electrophile coupling: diarylmethanes from benzyl mesylates and aryl halides† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c4sc03106g Click here for additional data file.

PubMed Central

Ackerman, Laura K. G.; Anka-Lufford, Lukiana L.; Naodovic, Marina

2015-01-01

The nickel-catalyzed cross-coupling of aryl halides with alkyl radicals derived from alkyl halides has recently been extended to couplings with carbon radicals generated by a co-catalyst. In this study, a new co-catalyst, cobalt phthalocyanine (Co(Pc)), is introduced and demonstrated to be effective for coupling substrates not prone to homolysis. This is because Co(Pc) reacts with electrophiles by an SN2 mechanism instead of by the electron-transfer or halogen abstraction mechanisms previously explored. Studies demonstrating the orthogonal reactivity of (bpy)Ni and Co(Pc), applying this selectivity to the coupling of benzyl mesylates with aryl halides, and the adaptation of these conditions to the less reactive benzyl phosphate ester and an enantioconvergent reaction are presented. PMID:25685312

Functionalized polyfluorenes for use in optoelectronic devices

DOEpatents

Chichak, Kelly Scott [Clifton Park, NY; Lewis, Larry Neil [Scotia, NY; Cella, James Anthony [Clifton Park, NY; Shiang, Joseph John [Niskayuna, NY

2011-11-08

The present invention relates to process comprising reacting a polyfluorenes comprising at least one structural group of formula I ##STR00001## with an iridium (III) compound of formula II ##STR00002## wherein R.sup.1 and R.sup.2 are independently alkyl, substituted alkyl, aryl, substituted aryl or a combination thereof; R.sup.5is H or CHO; R.sup.3 and R.sup.4 are independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl or a combination thereof; R.sup.11 and R.sup.12 taken together form a substituted or unsubstituted monocyclic or bicyclic heteroaromatic ring; R.sup.13 is independently at each occurrence halo, nitro, hydroxy, amino, alkyl, aryl, arylalkyl, alkoxy, substituted alkoxy, substituted alkyl, substituted aryl, or substituted arylalkyl; Ar is aryl, heteroaryl, substituted aryl, substituted heteroaryl, or a combination thereof; X is selected from a direct bond, alky, substituted alkyl, and combinations thereof; Y is CHO or NH.sub.2; Z is CHO or NH.sub.2 where Z does not equal Y; and p is 0, 1 or 2. The invention also relates to the polyfluorenes, which are products of the reaction, and the use of the polyfluorenes in optoelectronic devices.

Palladium-Catalyzed Direct C–H Arylation of Cyclic Enaminones with Aryl Iodides

PubMed Central

Yu, Yi-Yun; Bi, Lei

2013-01-01

A ligand-free method for the Pd-catalyzed direct arylation of cyclic enaminones using aryl iodides was developed. This method can be applied to a wide range of cyclic enaminones and aryl iodides with excellent C5-regioselectivity. Using widely available aryl iodides, the generality of this transformation provides easy access to a variety of 3-arylpiperidine structural motifs. PMID:23750615

Iron-Catalyzed Enantioselective Cross-Coupling Reactions of α-Chloroesters with Aryl Grignard Reagents.

PubMed

Jin, Masayoshi; Adak, Laksmikanta; Nakamura, Masaharu

2015-06-10

The first iron-catalyzed enantioselective cross-coupling reaction between an organometallic compound and an organic electrophile is reported. Synthetically versatile racemic α-chloro- and α-bromoalkanoates were coupled with aryl Grignard reagents in the presence of catalytic amounts of an iron salt and a chiral bisphosphine ligand, giving the products in high yields with acceptable and synthetically useful enantioselectivities (er up to 91:9). The produced α-arylalkanoates were readily converted to the corresponding α-arylalkanoic acids with high optical enrichment (er up to >99:1) via simple deprotections/recrystallizations. The results of radical probe experiments are consistent with a mechanism that involves the formation of an alkyl radical intermediate, which undergoes subsequent enantioconvergent arylation in an intermolecular manner. The developed asymmetric coupling offers not only facile and practical access to various chiral α-arylalkanoic acid derivatives, which are of significant pharmaceutical importance, but also a basis of controlling enantioselectivity in an iron-catalyzed organometallic transformation.

Room-temperature chromium(II)-catalyzed direct arylation of pyridines, aryl oxazolines, and imines using arylmagnesium reagents.

PubMed

Kuzmina, Olesya M; Knochel, Paul

2014-10-03

We report a CrCl2-catalyzed oxidative arylation of various pyridines, aryl oxazolines, and aryl imines using aromatic Grignard reagents in the presence of 2,3-dichlorobutane (DCB). Most of the reactions proceed rapidly at 25 °C and do not require any additional ligand. Benzo[h]quinoline, 2-arylpyridine, aryl oxazoline, and imines were successfully arylated in good yields under these conditions. A TMS-substituent was used to prevent double arylation. After oxidative cross-coupling the TMS-group was further converted to a second ortho-aryl substituent. Remarkably, inexpensive aryl N-butylimine derivatives are excellent substrates for this oxidative arylation.

Sulfonated reduced graphene oxide as a highly efficient catalyst for direct amidation of carboxylic acids with amines using ultrasonic irradiation.

PubMed

Mirza-Aghayan, Maryam; Tavana, Mahdieh Molaee; Boukherroub, Rabah

2016-03-01

Sulfonated reduced graphene oxide nanosheets (rGO-SO3H) were prepared by grafting sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide (rGO) under sonochemical conditions. rGO-SO3H catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). rGO-SO3H catalyst was successfully applied as a reusable solid acid catalyst for the direct amidation of carboxylic acids with amines into the corresponding amides under ultrasonic irradiation. The direct sonochemical amidation of carboxylic acid takes place under mild conditions affording in good to high yields (56-95%) the corresponding amides in short reaction times. Copyright © 2015 Elsevier B.V. All rights reserved.

A new route to synthesize aryl acetates from carbonylation of aryl methyl ethers

PubMed Central

Yang, Youdi; Li, Shaopeng; Han, Buxing

2018-01-01

Ether bond activation is very interesting because the synthesis of many valuable compounds involves conversion of ethers. Moreover, C–O bond cleavage is also very important for the transformation of biomass, especially lignin, which abundantly contains ether bonds. Developing efficient methods to activate aromatic ether bonds has attracted much attention. However, this is a challenge because of the inertness of aryl ether bonds. We proposed a new route to activate aryl methyl ether bonds and synthesize aryl acetates by carbonylation of aryl methyl ethers. The reaction could proceed over RhCl3 in the presence of LiI and LiBF4, and moderate to high yields of aryl acetates could be obtained from transformation of various aryl methyl ethers with different substituents. It was found that LiBF4 could assist LiI to cleave aryl methyl ether bonds effectively. The reaction mechanism was proposed by a combination of experimental and theoretical studies. PMID:29795781

Highly Enantioselective Rhodium-Catalyzed Addition of Arylboroxines to Simple Aryl Ketones: Efficient Synthesis of Escitalopram.

PubMed

Huang, Linwei; Zhu, Jinbin; Jiao, Guangjun; Wang, Zheng; Yu, Xingxin; Deng, Wei-Ping; Tang, Wenjun

2016-03-24

Highly enantioselective additions of arylboroxines to simple aryl ketones have been achieved for the first time with a Rh/(R,R,R,R)-WingPhos catalyst, thus providing a range of chiral diaryl alkyl carbinols with excellent ee values and yields. (R,R,R,R)-WingPhos has been proven to be crucial for the high reactivity and enantioselectivity. The method has enabled a new, concise, and enantioselective synthesis of the antidepressant drug escitalopram. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stereospecific nickel-catalyzed cross-coupling reactions of alkyl Grignard reagents and identification of selective anti-breast-cancer agents.

PubMed

Yonova, Ivelina M; Johnson, A George; Osborne, Charlotte A; Moore, Curtis E; Morrissette, Naomi S; Jarvo, Elizabeth R

2014-02-24

Alkyl Grignard reagents that contain β-hydrogen atoms were used in a stereospecific nickel-catalyzed cross-coupling reaction to form C(sp(3))-C(sp(3)) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1-diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF-7 breast cancer cells. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular engineering of porous silica using aryl templates

DOEpatents

Loy, D.A.; Shea, K.J.

1994-06-14

A process is described for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular sieves, desiccants, and catalyst supports are produced. 3 figs.

Molecular engineering of porous silica using aryl templates

DOEpatents

Loy, Douglas A.; Shea, Kenneth J.

1994-01-01

A process for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular seives, dessicants, and catalyst supports are produced.

Identification of isopropylbiphenyl, alkyl diphenylmethanes, diisopropylnaphthalene, linear alkyl benzenes and other polychlorinated biphenyl replacement compounds in effluents, sediments and fish in the Fox River System, Wisconsin

USGS Publications Warehouse

Peterman, Paul H.; Delfino, Joseph J.

1990-01-01

Five polychlorinated biphenyl replacement dye solvents and a diluent present in carbonless copy paper were identified by gas chromatography/mass spectrometry in the following matrices: effluents from a de-inking–recycling paper mill and a municipal wastewater treatment plant receiving wastewaters from a carbonless copy paper manufacturing plant; sediments; and fish collected near both discharges in the Fox River System, Wisconsin. An isopropylbiphenyl dye solvent mixture included mono-, di- and triisopropylbiphenyls. Also identified were two dye solvent mixtures marketed under the trade name Santosol. Santosol 100 comprised ethyl-diphenylmethanes (DPMs), benzyl-ethyl-DPMs, and dibenzyl-ethyl-DPMs. Similarly, Santosol 150 comprised dimethyl-DPMs, benzyl-dimethyl-DPMs, and dibenzyl-dimethyl-DPMs. Diisopropylnaphthalenes, widely used as a dye solvent in Japan, were identified for the first time in the US environment. sec-Butylbiphenyls and di-sec-butylbiphenyls, likely constituents of a sec-butylbiphenyl dye solvent mixture, were tentatively identified. Linear alkyl benzenes (C10 to C13-LABs) constituted the Alkylate 215 diluent mixture. Although known to occur as minor constituents in linear alkyl sulfonate detergents, LAB residues have not been previously attributed to commercial use of LABs.

Mass spectrometry of analytical derivatives. 1. Cyanide cations in the spectra of N-alkyl-N-perfluoroacyl-α-amino acids and their methyl esters

PubMed Central

Todua, Nino G.; Tretyakov, Kirill V.; Mikaia, Anzor I.

2016-01-01

The central mission for the development of the National Institute of Standards and Technology/National Institutes of Health/Environmental Protection Agency Mass Spectral Library is the acquisition of reference gas chromatography–mass spectrometry data for important compounds and their chemical modification products. The addition of reliable reference data of various derivatives of amino acids to The Library, and the study of their behavior under electron ionization conditions may be useful for their identification, structure elucidation, and a better understanding of the data obtained when the same derivatives are subjected to other ionization methods. N-Alkyl-N-perfluoroacyl derivatives of amino acids readily produce previously unreported alkylnitrilium cations of composition [HC≡N-alkyl]+. Homologous [HC≡N-aryl]+ cations are typical for corresponding N-aryl analogs. The formation of other ions characteristic for these derivatives involves oxygen rearrangement giving rise to ions [CnF2n+1–C≡N+–CnH2n+1] and [CnF2n+1–C≡N+-aryl]. The introduction of an N-benzyl substituent in a molecule favors a process producing benzylidene iminium cations. l-Threonine and l-cysteine derivatives exhibit more fragmentation pathways not typical for other α-amino acids; additionally, the Nω-amino group in l-lysine directs the dissociation process and provides structural information on the substitution at the amino functions in the molecule. PMID:26307698

Use of dynamic simulation to assess the behaviour of linear alkyl benzene sulfonates and their biodegradation intermediates (sulfophenylcarboxylic acids) in estuaries

NASA Astrophysics Data System (ADS)

García-Luque, E.; González-Mazo, E.; Forja, J. M.; Gómez-Parra, A.

2009-02-01

Dynamic laboratory simulation of processes affecting chemical species in their transit through estuaries is a very useful tool to characterize these littoral systems. To date, laboratory studies concerning biodegradation and sorption (onto suspended particulate matter) of LAS in an estuary are scarce. For this reason, a dynamic automated estuarine simulator has been employed to carry out different experiments in order to assess the biodegradability of linear alkyl benzene sulfonates (LAS) and their biodegradation intermediates (sulfophenylcarboxylic acids, SPCs) using environmentally representative LAS concentrations in estuaries by a continuous injection of LAS into the system. During the experiments, a great affinity of LAS for the solid phase has been found, as well as an increased adsorption in line with increased chain length. On the other hand, the presence of SPCs with chain length between 6 and 13 carbon atoms was detected. Accumulation and persistence of medium chain length SPCs (C 6-C 8) along the experiments show that their degradation constitutes the limiting step for the process of LAS mineralization. In the final zone of the simulated estuarine system, the levels of SPCs were below the limits of detection. Thus, the disappearance of SPCs indicated that LAS biodegradation had been completed along the estuary. Similar results have been described for different Iberian littoral ecosystems. Therefore, the simulator employed in this research appears to be a useful tool to anticipate the behaviour of a xenobiotic chemical in its transit through littoral systems with different salinity gradients.

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant α-Silyloxyketones

PubMed Central

Tarr, James C.

2010-01-01

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic α-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant α-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions and kinetic resolution of resultant alpha-silyloxyketones.

PubMed

Tarr, James C; Johnson, Jeffrey S

2010-05-21

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic alpha-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant alpha-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction.

Synthesis and antifungal activities of 3-alkyl substituted thieno[2,3-d]pyrimidinones

NASA Astrophysics Data System (ADS)

Wang, H. M.; Deng, S. H.; Zheng, A. H.; Zhang, Q. Y.; Chen, X. B.; Zeng, X. H.; Hu, Y. G.

2016-08-01

The 3-aryl substituted thieno[2,3-d]pyrimidinones 3 by sequential reaction of iminophosphorane 1, aromatic isocyanates and various nucleophiles (HY), found some compounds showed good antitumor and antibacterial activities. Meanwhile, aliphatic isocyanates were applied in the reaction to prepare 3-alkyl substituted thieno[2,3- d]pyrimidinones, but there are no reports of their antifungal activities. As a continuation of our research for new biologically active heterocycles, we herein wish to report a facile synthesis and antifungal activities of 3-alkyl substituted thieno[2,3-d]pyrimidinones 6 via easily accessible iminophosphorane 1. The growth inhibitory effect of one concentration (50mg/L) of compounds 6 against five fungus(Fusarium oxysporium, Rhizoctonia solani, Colletotrichum gossypii, Gibberella zeae and Dothiorella gregaria) in vitro was tested by the method of toxic medium. Compound 6d showed the best inhibition rate against Gibberella zeae with 85.68%.

Copper Mediated Fluorination of Aryl Iodides

PubMed Central

Fier, Patrick S.; Hartwig, John F.

2012-01-01

The synthesis of aryl fluorides has been a topic of considerable interest because of the importance of aryl fluorides in pharmaceuticals, agrochemicals and materials. The stability, reactivity and biological properties of aryl fluorides can be distinct from those of the corresponding arenes. Methods for the synthesis of aryl fluorides, however, are limited. We report the conversion of a diverse set of aryl iodides to the corresponding aryl fluorides. This reaction occurs with a cationic copper reagent and silver fluoride. Preliminary results suggest this reaction is enabled by a facile reductive elimination from a cationic aryl copper(III) fluoride. PMID:22709145

Synthesis and dynamic NMR study of ketenimines derived from tert-butyl isocyanide, alkyl 2-arylamino-2-oxo-acetates, and dialkyl acetylenedicarboxylates.

PubMed

Yavari, Issa; Nasiri, Farough; Djahaniani, Horieh

2004-01-01

The adduct produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped by alkyl 2-arylamino-2-oxo-acetates. When the aryl group is 2-methyl-6-nitrophenyl or 2,6-di-isopropylphenyl, the product exists as two stable rotamers at room temperature as a result of restricted rotation around the Ar-N single bond. When the aryl group is 1-naphthyl or 8-quinolinyl, dynamic NMR effects are observed in the 1H NMR spectra. The calculated free-energy of activation for interconversion of the rotational isomers in 1-naphthyl and 8-quinolinyl derivatives amounts to about 99+/-2 and 68.5+/-2 kJ mol(-1), respectively.

Metal-free, visible-light-mediated direct C-H arylation of heteroarenes with aryl diazonium salts.

PubMed

Hari, Durga Prasad; Schroll, Peter; König, Burkhard

2012-02-15

Visible light along with 1 mol % eosin Y catalyzes the direct C-H bond arylation of heteroarenes with aryl diazonium salts by a photoredox process. We have investigated the scope of the reaction for several aryl diazonium salts and heteroarenes. The general and easy procedure provides a transition-metal-free alternative for the formation of aryl-heteroaryl bonds.

Redox shuttle additives for lithium-ion batteries

DOEpatents

Zhang, Lu; Zhang, Zhengcheng; Amine, Khalil

2017-03-21

An electro lye includes a compound of Formula I or IA: where each instance of R.sup.1 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.2 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.3 is independently H, alkyl, alkenyl, aryl, or cycloalkyl; each instance of R.sup.4 is independently H, halogen, CN, NO.sub.2, phosphate, alkyl, alkenyl, aryl, heteroaryl, or cycloalkyl; x is 1, 2, 3, 4, or 5; y is 1 or 2; and z is 0, 1, 2, 3, or 4. ##STR00001##

A new family of nucleophiles for photoinduced, copper-catalyzed cross-couplings via single-electron transfer: reactions of thiols with aryl halides under mild conditions (O °C).

PubMed

Uyeda, Christopher; Tan, Yichen; Fu, Gregory C; Peters, Jonas C

2013-06-26

Building on the known photophysical properties of well-defined copper-carbazolide complexes, we have recently described photoinduced, copper-catalyzed N-arylations and N-alkylations of carbazoles. Until now, there have been no examples of the use of other families of heteroatom nucleophiles in such photoinduced processes. Herein, we report a versatile photoinduced, copper-catalyzed method for coupling aryl thiols with aryl halides, wherein a single set of reaction conditions, using inexpensive CuI as a precatalyst without the need for an added ligand, is effective for a wide range of coupling partners. As far as we are aware, copper-catalyzed C-S cross-couplings at 0 °C have not previously been achieved, which renders our observation of efficient reaction of an unactivated aryl iodide at -40 °C especially striking. Mechanistic investigations are consistent with these photoinduced C-S cross-couplings following a SET/radical pathway for C-X bond cleavage (via a Cu(I)-thiolate), which contrasts with nonphotoinduced, copper-catalyzed processes wherein a concerted mechanism is believed to occur.

Identification of 1-Aryl-1H-1,2,3-triazoles as Potential New Antiretroviral Agents.

PubMed

Gonzaga, Daniel T G; Souza, Thiago M L; Andrade, Viviane M M; Ferreira, Vitor F; de C da Silva, Fernando

2018-01-01

Low molecular weight 1-Aryl-1H-1,2,3-triazoles are endowed with various types of biological activities, such as against cancer, HIV and bacteria. Despite the existence of six different classes of antiretroviral drugs in clinical use, HIV/AIDS continue to be an on growing public health problem. In the present study, we synthesized and evaluated thirty 1-Aryl-1H-1,2,3-triazoles against HIV replication. The compounds were prepared by Huisgen 1,3-dipolar cycloaddition protocol catalyzed by Cu(I) between aryl azides and propargylic alcohol followed by further esterification and etherification from a nucleophilic substitution with acid chlorides or alkyl bromides in good yields. The compounds were submitted to the inhibition of HIV replication and evaluation of their cytotoxicity. Initially, the compounds were screened at 10 µM and the most active were further evaluated in order to obtain some pharmacological parameters. Thirty molecules were evaluated, six were selected - because they inhibited more than 80% HIV replication. We further showed that two of these compounds are 8-times more potent, and less cytotoxic, than nevirapine, an antiretroviral drug in clinical use. We identified very simple triazoles with promissing antiretroviral activities that led to the development of new drugs against AIDS. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Modification of epoxy-reinforced glass-cloth composites with a perfluorinated alkyl ether elastomer

NASA Technical Reports Server (NTRS)

Rosser, R. W.; Chen, T. S.; Taylor, M.

1984-01-01

A perfluorinated alkyl ether diacyl fluoride prepolymer (molecular weight about 1500) was coreacted with Epon 828 epoxy resin and diamino diphenyl sulfone to obtain an elastomer-toughened, glass-cloth composite. Improvements in flexural toughness, impact resistance, and water resistance, without loss of strength, modulus of elasticity or a lowering of the glass-transition temperature, were realized over those of the unmodified composite. Factors concerning optimization of the process are discussed. Results suggest that a simultaneously interpenetrating polymer network may be formed which gives rise to a measured improvement in composite mechanical properties.

Sodium Polystyrene Sulfonate

MedlinePlus

Sodium polystyrene sulfonate is used to treat hyperkalemia (increased amounts of potassium in the body). Sodium polystyrene sulfonate is in a class of medications called potassium-removing agents. It works by ...

Ligand-Enabled meta-Selective C-H Arylation of Nosyl-Protected Phenethylamines, Benzylamines, and 2-Aryl Anilines.

PubMed

Ding, Qiuping; Ye, Shengqing; Cheng, Guolin; Wang, Peng; Farmer, Marcus E; Yu, Jin-Quan

2017-01-11

A Pd-catalyzed, meta-selective C-H arylation of nosyl-protected phenethylamines and benzylamines is disclosed using a combination of norbornene and pyridine-based ligands. Subjecting nosyl protected 2-aryl anilines to this protocol led to meta-C-H arylation at the remote aryl ring. A diverse range of aryl iodides are tolerated in this reaction, along with select heteroaryl iodides. Select aryl bromides bearing ortho-coordinating groups can also be utilized as effective coupling partners in this reaction. The use of pyridine ligands has allowed the palladium loading to be reduced to 2.5 mol %. Furthermore, a catalytic amount of 2-norbornene (20 mol %) to mediate this meta-C-H activation process is demonstrated for the first time. Utilization of a common protecting group as the directing group for meta-C-H activation of amines is an important feature of this reaction in terms of practical applications.

Chlorine resistant desalination membranes based on directly sulfonated poly(arylene ether sulfone) copolymers

DOEpatents

McGrath, James E [Blacksburg, VA; Park, Ho Bum [Austin, TX; Freeman, Benny D [Austin, TX

2011-10-04

The present invention provides a membrane, kit, and method of making a hydrophilic-hydrophobic random copolymer membrane. The hydrophilic-hydrophobic random copolymer membrane includes a hydrophilic-hydrophobic random copolymer. The hydrophilic-hydrophobic random copolymer includes one or more hydrophilic monomers having a sulfonated polyarylsulfone monomer and a second monomer and one or more hydrophobic monomers having a non-sulfonated third monomer and a fourth monomer. The sulfonated polyarylsulfone monomer introduces a sulfonate into the hydrophilic-hydrophobic random copolymer prior to polymerization.

78 FR 50147 - 2012 Liquid Chemical Categorization Updates

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-16

..., Alkenyl(C12+) acid ester mixture... Alkyl acrylate-Vinylpyridine copolymer in toluene *.... Y Alkylbenzene...) phenylamine in aromatic solvents Y Alkyl(C9+) benzenes Y Alkyl(C11-C17) benzene sulfonic acid Y Alkylbenzene sulfonic acid (4% or less) Alkyl dithiocarbamate (C19-C35) Y Alkyl dithiothiadiazole (C6-C24) Y Alkyl ester...

The photocatalyzed Meerwein arylation: classic reaction of aryl diazonium salts in a new light.

PubMed

Hari, Durga Prasad; König, Burkhard

2013-04-26

The use of diazonium salts for aryl radical generation and C-H arylation processes has been known since 1896 when Pschorr first used the reaction for intramolecular cyclizations. Meerwein developed it further in the early 1900s into a general arylation method. However, this reaction could not compete with the transition-metal-mediated formation of C(sp(2))-C(sp(2)) bonds. The replacement of the copper catalyst with iron and titanium compounds improved the situation, but the use of photocatalysis to induce the one-electron reduction and activation of the diazonium salts is even more advantageous. The first photocatalyzed Pschorr cyclization was published in 1984, and just last year a series of papers described applications of photocatalytic Meerwein arylations leading to aryl-alkene coupling products. In this Minireview we summarize the origins of this reaction and its scope and applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A new hypercrosslinked supermicroporous polymer, with scope for sulfonation, and its catalytic potential for the efficient synthesis of biodiesel at room temperature.

PubMed

Bhunia, Subhajit; Banerjee, Biplab; Bhaumik, Asim

2015-03-25

We have designed a new hypercrosslinked supermicroporous polymer (HMP-1) with a BET surface area of 913 m(2) g(-1) by FeCl3 via a catalyzed Friedel-Crafts alkylation reaction between carbazole and α,α'-dibromo-p-xylene. Upon sulfonation HMP-1 yielded a very efficient solid acid catalyst for the production of biodiesels via esterification/transesterification of free fatty acids (FFA)/esters at room temperature.

The Ketene-Surrogate Coupling: Catalytic Conversion of Aryl Iodides to Aryl Ketenes via Ynol Ethers**

PubMed Central

Zhang, Wenhan; Ready, Joseph M.

2014-01-01

tert-Butoxyacetylene is shown to undergo Sonogashira coupling with aryl iodides to yield aryl-substituted tert-butyl ynol ethers. These intermediates participate in a [1,5]-hydride shift, which results in the extrusion of isobutylene and the generation of aryl ketenes. The ketenes are trapped in situ with multiple nucleophiles or undergoelectrocyclic ring closure to yield hydroxynaphthalenes and quinolines. PMID:24975840

Fe-Catalyzed C–C Bond Construction from Olefins via Radicals

PubMed Central

2017-01-01

This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C–C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl and aryl groups, additional efforts culminated in the expansion of the scope of the substitution to various heteroatom-based functionalities, providing a unified olefin reactivity. A vinyl sulfone acceptor olefin was developed, which allowed for the efficient synthesis of sulfone adducts that could be used as branch points for further diversification. Moreover, this reactivity was extended into an olefin-based Minisci reaction to functionalize heterocyclic scaffolds. Finally, mechanistic studies resulted in a more thorough understanding of the reaction, giving rise to the development of a more efficient second-generation set of olefin cross-coupling conditions. PMID:28094980

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral BINOL-derived zincate catalyst.

PubMed

Li, Hong; Da, Chao-Shan; Xiao, Yu-Hua; Li, Xiao; Su, Ya-Ning

2008-09-19

Direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral metal complex is reported for the first time herein. Two novel semicrown chiral ligands 1a and 1b were synthesized from (S)- and (R)-BINOL, respectively, and then employed to catalyze the direct asymmetric aldol addition of aryl ketones to aryl aldehydes. Introduced with 2.0 equiv of diethylzinc, 1b had higher enantioselectivity than 1a. Up to 97% yield and up to 80% enantioselectivity were achieved.

Aryl imidazylates and aryl sulfates as electrophiles in metal-free ArS(N)1 reactions.

PubMed

Qrareya, Hisham; Protti, Stefano; Fagnoni, Maurizio

2014-12-05

Some oxygen-bonded substituents were investigated as leaving groups in photoinduced ArS(N)1 reactions. Irradiation of aryl imidazylates and of the corresponding imidazolium salts mainly caused homolysis of the ArO-S bond. However, previously unexplored trifluoroethoxy aryl sulfates were found to undergo efficient metal-free arylation. The sulfates were conveniently generated in situ by dissolving the corresponding imidazolium salts in basic 2,2,2-trifluoroethanol.

Facile N-Arylation of Amines and Sulfonamides and O-Arylation of Phenols and Arenecarboxylic Acids

PubMed Central

Liu, Zhijian; Larock, Richard C.

2008-01-01

An efficient, transition-metal free procedure for the N-arylation of amines, sulfonamides and carbamates and O-arylation of phenols and carboxylic acids has been achieved by allowing these substrates to react with a variety of o-silylaryl triflates in the presence of CsF. Good to excellent yields of arylated products are obtained under very mild reaction conditions. This chemistry readily tolerates a variety of functional groups. PMID:16599619

Ionic liquids composed of phosphonium cations and organophosphate, carboxylate, and sulfonate as lubricant antiwear additives

DOE PAGES

Zhou, Yan; Dyck, Jeffrey; Graham, Todd; ...

2014-10-20

Oil-soluble phosphonium-based ionic liquids (ILs) have recently been reported as potential ashless lubricant additives. This study is to expand the IL chemistry envelope and to achieve fundamental correlations between the ion structures and ILs’ physiochemical and tribological properties. Here we present eight ILs containing two different phosphonium cations and seven different anions from three groups: organophosphate, carboxylate, and sulfonate. The oil solubility of ILs seems largely governed by the IL molecule size and structure complexity. When used as oil additives, the ranking of effectiveness in wear protection for the anions are: organophosphate > carboxylate > sulfonate. All selected ILs outperformedmore » a commercial ashless anti-wear additive. Surface characterization from the top and the cross-section revealed the nanostructures and compositions of the tribo-films formed by the ILs. Some fundamental insights were achieved: branched and long alkyls improve the IL’s oil solubility, anions of a phosphonium-phosphate IL contribute most phosphorus in the tribofilm, and carboxylate anions, though free of P, S, N, or halogen, can promote the formation of an anti-wear tribofilm.« less

Process for selective production of di- and tri-alkylamines

DOEpatents

Klier, Kamil; Herman, Richard G.; Vedage, Gamini A.

1984-01-01

A primary alkyl amine and an alcohol of up to 12 carbon atoms are reacted at low temperature (50.degree.-250.degree. C.) over specific catalysts (alkali-treated catalysts generally or binary Cu/ZnO and Pd/SiO.sub.2 systems, with or without alkali treatment) to produce, with good selectivity, secondary and tertiary alkylamines of the general formula, R.sub.1 N(R.sub.2).sub.2, wherein R.sub.1 is a lower alkyl or an aryl group, and R.sub.2 is hydrogen or another lower alkyl or aryl group, with at least one of R.sub.2 's being an alkyl or aryl group.

In search of Flavivirus inhibitors part 2: tritylated, diphenylmethylated and other alkylated nucleoside analogues.

PubMed

Saudi, Milind; Zmurko, Joanna; Kaptein, Suzanne; Rozenski, Jef; Neyts, Johan; Van Aerschot, Arthur

2014-04-09

Several flaviviruses, such as the yellow fever virus and the dengue virus cause severe and potentially lethal infection in man. Following up on our initial hit 3',5'-bistritylated uridine 1, a series of alkylated nucleoside analogues were synthesized and evaluated for their in vitro antiviral activities against dengue fever virus and yellow fever virus. Hereto, alkyl and aryl groups were attached at various positions of the sugar ring combined with subtle variation of the heterocyclic base. Among the new series of derivatives, 3',5'-di-O-trityl-5-fluoro-2'-deoxyuridine (39) was the most efficient in this series and inhibited both yellow fever virus and dengue virus replication with a 50% effective concentration (EC₅₀) of ∼1 μg/mL without considerable cytotoxicity. The other fluorinated derivatives proved more toxic. Almost all diphenylmethylated pyrimidine nucleosides with 3',5'-di-O-benzhydryl-2'-deoxyuridine (50) as the example were endowed with strong cytotoxic effects down to 1 μg/mL. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Preparation of catalytically active, covalent α-polylysine-enzyme conjugates via UV/vis-quantifiable bis-aryl hydrazone bond formation.

PubMed

Grotzky, Andrea; Manaka, Yuichi; Kojima, Taisuke; Walde, Peter

2011-01-10

Covalent UV/vis-quantifiable bis-aryl hydrazone bond formation was investigated for the preparation of conjugates between α-poly-d-lysine (PDL) and either α-chymotrypsin (α-CT) or horseradish peroxidase (HRP). PDL and the enzymes were first modified via free amino groups with the linking reagents succinimidyl 6-hydrazinonicotinate acetone hydrazone (S-HyNic, at pH 7.6) and succinimidyl 4-formylbenzoate (S-4FB, at pH 7.2), respectively. The modified PDL and enzymes were then conjugated at pH 4.7, whereby polymer chains carrying several enzymes were obtained. Kinetics of the bis-aryl hydrazone bond formation was investigated spectrophotometrically at 354 nm. Retention of the enzymatic activity after conjugate formation was confirmed by using the substrates N-succinimidyl-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide (for α-CT) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, for HRP). Thus, not only a mild and efficient preparation and convenient quantification of a conjugate between the polycationic α-polylysine and enzymes could be shown, but also the complete preservation of the enzymatic activity.

The reaction of Grignard reagents with Bunte salts: a thiol-free synthesis of sulfides.

PubMed

Reeves, Jonathan T; Camara, Kaddy; Han, Zhengxu S; Xu, Yibo; Lee, Heewon; Busacca, Carl A; Senanayake, Chris H

2014-02-21

S-Alkyl, S-aryl, and S-vinyl thiosulfate sodium salts (Bunte salts) react with Grignard reagents to give sulfides in good yields. The S-alkyl Bunte salts are prepared from odorless sodium thiosulfate by an SN2 reaction with alkyl halides. A Cu-catalyzed coupling of sodium thiosulfate with aryl and vinyl halides was developed to access S-aryl and S-vinyl Bunte salts. The reaction is amenable to a broad structural array of Bunte salts and Grignard reagents. Importantly, this route to sulfides avoids the use of malodorous thiol starting materials or byproducts.

2-Aryl-2-nitroacetates as Central Precursors to Aryl Nitromethanes, α-Ketoesters, and α-Amino Acids

PubMed Central

Metz, Alison E.

2013-01-01

Nitroarylacetates are useful small molecular building blocks that act as precursors to α-ketoesters and aryl nitromethanes as well as α-amino acids. Methods were developed that produce each of these compound types in good yields. Two different conditions for decarboxylation are discussed for substrates with neutral and electron-poor aryl groups versus electron-rich aryl groups. For formation of the α-ketoesters, new mild conditions for the Nef disproportionation were identified. PMID:23245626

Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

NASA Astrophysics Data System (ADS)

Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

2005-08-01

Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

Structure–Reactivity Studies, Characterization, and Transformation of Intermediates by Lithium Chloride in the Direct Insertion of Alkyl and Aryl Iodides to Metallic Zinc Powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Chao; Easter, Quinn T.; Blum, Suzanne A.

Employment of fluorophore-tagged alkyl and aryl iodides permitted detection of persistent surface intermediates during their direct insertion to commercially available zinc powder. The sensitivity of this subensemble microscopy technique enabled structure–reactivity studies in the formation of intermediates that are present in quantities sufficiently low as to have been undetected previously by traditional ensemble analytical techniques. In these surface intermediates we transformed them using lithium chloride, which lead to the assignment of the mechanistic role of lithium chloride as changing the rate-determining step in the reaction by lowering the barrier for solubilization of these otherwise persistent surface organometallic intermediates. The temperaturemore » dependence/qualitative barrier of the direct insertion step was determined independently from the solubilization step and from the barrier for the overall reaction. Detection of these zinc surface intermediates at the single-molecule level, i.e., of individual surface organometallic species, has been achieved for the first time. Energy dispersive X-ray spectroscopy (EDS) measurements of the elemental composition of the surface of the zinc powder determined that lithium chloride does not clean the surface of the oxides; instead, pretreatment of the surface with TMSCl effects partial removal of surface oxides after the 2 h pretreatment time previously reported in the empirically optimized synthetic procedure. The current limitations of this microscopy approach are also determined and discussed with respect to the addition of solid reagents during in operando imaging. Characterization of the resulting soluble fluorophore-tagged organozinc/LiCl complex by 1H NMR spectroscopy, mass spectrometry, and fluorescence spectroscopy provided insight into its solution dynamics and chemical exchange processes.« less

Structure–Reactivity Studies, Characterization, and Transformation of Intermediates by Lithium Chloride in the Direct Insertion of Alkyl and Aryl Iodides to Metallic Zinc Powder

DOE PAGES

Feng, Chao; Easter, Quinn T.; Blum, Suzanne A.

2017-02-03

Employment of fluorophore-tagged alkyl and aryl iodides permitted detection of persistent surface intermediates during their direct insertion to commercially available zinc powder. The sensitivity of this subensemble microscopy technique enabled structure–reactivity studies in the formation of intermediates that are present in quantities sufficiently low as to have been undetected previously by traditional ensemble analytical techniques. In these surface intermediates we transformed them using lithium chloride, which lead to the assignment of the mechanistic role of lithium chloride as changing the rate-determining step in the reaction by lowering the barrier for solubilization of these otherwise persistent surface organometallic intermediates. The temperaturemore » dependence/qualitative barrier of the direct insertion step was determined independently from the solubilization step and from the barrier for the overall reaction. Detection of these zinc surface intermediates at the single-molecule level, i.e., of individual surface organometallic species, has been achieved for the first time. Energy dispersive X-ray spectroscopy (EDS) measurements of the elemental composition of the surface of the zinc powder determined that lithium chloride does not clean the surface of the oxides; instead, pretreatment of the surface with TMSCl effects partial removal of surface oxides after the 2 h pretreatment time previously reported in the empirically optimized synthetic procedure. The current limitations of this microscopy approach are also determined and discussed with respect to the addition of solid reagents during in operando imaging. Characterization of the resulting soluble fluorophore-tagged organozinc/LiCl complex by 1H NMR spectroscopy, mass spectrometry, and fluorescence spectroscopy provided insight into its solution dynamics and chemical exchange processes.« less

Electrografting of alkyl films at low driving force by diverting the reactivity of aryl radicals derived from diazonium salts.

PubMed

Hetemi, Dardan; Kanoufi, Frédéric; Combellas, Catherine; Pinson, Jean; Podvorica, Fetah I

2014-11-25

Alkyl and partial perfluoroalkyl groups are strongly attached to carbon surfaces through (i) the abstraction of the iodine atom from an iodoalkane by the sterically hindered 2,6-dimethylphenyl radical and (ii) the reaction of the ensuing alkyl radical with the carbon surface. Since the 2,6-dimethylphenyl radical is obtained at -0.25 V/Ag/AgCl by reducing the corresponding diazonium salt, the electrografting reaction is facilitated by ∼1.7 V by comparison with the direct electrografting of the iodo compounds. Layers of various thicknesses, including monolayers, are obtained by controlling the time duration of the electrolysis. The grafted films are characterized by electrochemistry, IR, XPS, ellipsometry, and water contact angles.

Bioaccumulation of per- and polyfluorinated alkyl substances (PFAS) in selected species from the Barents Sea food web.

PubMed

Haukås, Marianne; Berger, Urs; Hop, Haakon; Gulliksen, Bjørn; Gabrielsen, Geir W

2007-07-01

The present study reports concentrations and biomagnification potential of per- and polyfluorinated alkyl substances (PFAS) in species from the Barents Sea food web. The examined species included sea ice amphipod (Gammarus wilkitzkii), polar cod (Boreogadus saida), black guillemot (Cepphus grylle) and glaucous gull (Larus hyperboreus). These were analyzed for PFAS, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs). Perfluorooctane sulfonate (PFOS) was the predominant of the detected PFAS. Trophic levels and food web transfer of PFAS were determined using stable nitrogen isotopes (delta(15)N). No correlation was found between PFOS concentrations and trophic level within species. However, a non-linear relationship was established when the entire food web was analyzed. Biomagnification factors displayed values >1 for perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), PFOS and SigmaPFAS(7). Multivariate analyses showed that the degree of trophic transfer of PFAS is similar to that of PCB, DDT and PBDE, despite their accumulation through different pathways.

Methoxy-Directed Aryl-to-Aryl 1,3-Rhodium Migration

PubMed Central

Zhang, Jing; Liu, Jun-Feng; Ugrinov, Angel; Pillai, Anthony F. X.; Sun, Zhong-Ming; Zhao, Pinjing

2015-01-01

Through-space metal/hydrogen shift is an important strategy for transition metal-catalyzed C-H bond activation. Here we describe the synthesis and characterization of a Rh(I) 2,6-dimethoxybenzoate complex that underwent stoichiometric rearrangement via a highly unusual 1,3- rhodium migration. This aryl-to-aryl 1,3-Rh/H shift was also demonstrated in a Rh(I)-catalyzed decarboxylative conjugate addition to form a C-C bond at a meta position instead of the ipso-carboxyl position. A deuterium-labeling study under the conditions of Rh(I)-catalyzed protodecarboxylation revealed the involvement of an ortho-methoxy group in a multi-step pathway of consecutive sp3 and sp2 C-H bond activations. PMID:24171626

Alkyl–Alkyl Suzuki Cross-Couplings of Unactivated Secondary Alkyl Chlorides**

PubMed Central

Lu, Zhe; Fu, Gregory C.

2010-01-01

The first method for achieving alkyl–alkyl Suzuki reactions of unactivated secondary alkyl chlorides has been developed. Carbon–carbon bond formation occurs under mild conditions (at room temperature) with the aid of commercially available catalyst components. This method has proved to be versatile: without modification, it can be applied to Suzuki reactions of secondary and primary alkyl bromides and iodides, as well as primary alkyl chlorides. Mechanistic investigations suggest that oxidative addition is not the turnover-limiting step of the catalytic cycle for unactivated secondary alkyl iodides and bromides, whereas it may be (partially) for chlorides. PMID:20715038

Morphological studies of sulfonated polystyrene and sulfonated EPDM ionomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, D.A.

1992-12-31

Two ionomer systems have been investigated in this research. Sulfonated polystyrene (SPS) is a typical random ionomer and is a good material for studies into the nature of phase separation in ionomers. A series of narrow molecular weight distribution (MWD) zinc neutralized SPS samples of varying sulfonation levels were prepared and analyzed through small angle x-ray scattering (SAXS). Results indicated that the correlation distance varied with both molecular weight and sulfonation level. Increases in the position of the scattering maximum with sulfonation level is the result of a greater number of ionic groups. Increasing molecular weight led to the movementmore » of the scattering maximum to smaller scattering vectors, an indication of larger distances. It was also observed that ionomer peak occurred at smaller scattering vectors for the narrow MWD samples than in corresponding materials of greater dispersity. SAXS was also used to examine the morphology of zinc stearate (ZnSt) filled sulfonated EPDM (S-EPDM) ionomers and the nature of the interaction between the plasticizer and the ionomer. S-EPDM is a material that may find use as a thermoplastic elastomer, although its melt viscosity is too high to allow for convenient processing. The addition of of ZnSt as a plasticizer greatly reduces the melt viscosity of S-EPDM. ZnSt exists in this system as very small crystallites which are associated with ionic groups. As the temperature is increased, the crystallites anneal briefly into larger crystals before melting and diffusing into the S-EPDM matrix. Above the melting temperature of the ZnSt, it solvates the ionic groups of the ionomer, decreasing their self-association and the viscosity of the system. Increasing ZnSt loading is seen in the SAXS as an increase in scattering in the low angle region. However, this increase in intensity is not linear with concentration, showing that ZnSt exists in different environments at higher concentrations.« less

Multimetallic Catalysis Enabled Cross-Coupling of Aryl Bromides with Aryl Triflates

PubMed Central

Ackerman, Laura K.G.; Lovell, Matthew M.

2015-01-01

Transition metal-catalyzed strategies for the formation of new C-C bonds have revolutionized the field of organic chemistry, enabling the efficient synthesis of ligands, materials, and biologically active molecules.1–3 In cases where a single metal fails to promote a selective or efficient transformation, the synergistic cooperation4 of two distinct catalysts – multimetallic catalysis – can be employed instead. Many important reactions rely on multimetallic catalysis,5 including the Wacker oxidation of olefins6–8 and the Sonogashira coupling of alkynes with aryl halides.9–10 However, the application of this strategy, even in recently developed methods11, has largely been limited to the use of metals with distinct reactivities, with only one metal catalyst undergoing an oxidative addition.12 In this manuscript, we demonstrate that cooperativity between two d10 metal catalysts, (bipyridine)nickel and (1,3-bis(diphenylphosphino)propane)palladium, enables a general cross-Ullman reaction.13–15 Our method couples aryl bromides with aryl triflates directly, eliminating the use of arylmetal reagents and avoiding the challenge of differentiating between multiple C–H bonds that is required for many C–H activation methods.16–17 The selectivity does not require an excess of either substrate and originates from the orthogonal activity of the two catalysts and the relative stability of the two arylmetal intermediates. While (dppp)Pd reacts preferentially with aryl triflates to afford a persistent intermediate, (bpy)Ni reacts preferentially with aryl bromides to form a transient, reactive intermediate. Although each catalyst forms less than 5% cross product in isolation, together they are able to achieve up to 94% yield. Our results reveal a new, general method for the synthesis of biaryls, heteroaryls, and dienes, as well as a new mechanism for selective transmetalation between two catalysts. We anticipate that this reaction will simplify the synthesis of

Resting State and Elementary Steps of the Coupling of Aryl Halides with Thiols Catalyzed by Alkylbisphosphine Complexes of Palladium

PubMed Central

Alvaro, Elsa

2010-01-01

Detailed mechanistic studies on the coupling of aryl halides with thiols catalyzed by palladium complexes of the alkylbisphosphine ligand CyPF-tBu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylferrocene) are reported. The elementary steps that constitute the catalytic cycle, i.e. oxidative addition, transmetalation and reductive elimination, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF-tBu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)2 and CyPF-tBu, a combination of Pd(dba)2 and CyPF-tBu, or the likely intermediate Pd(CyPF-tBu)(Ar)(Br). These show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc)2 and CyPF-tBu was the palladium bis-thiolate complex [Pd(CyPF-tBu)(SR)2] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd2(dba)3 and CyPF-tBu was the binuclear complex [Pd(CyPF-tBu)]2(μ2, η2-dba) (9). The resting state of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF-tBu)(p-tolyl)(Br)] (3a) was the hydridopalladium thiolate complex [Pd(CyPF-tBu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF-tBu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc)2 or Pd(dba)2. Our data indicate that the resting states of these reactions are similar to each other and that our mechanistic conclusions about reactions catalyzed by palladium and CyPF-tBu can be

Neurobehavioral Teratogenicity of Perfluorinated Alkyls in an Avian Model

PubMed Central

Pinkas, Adi; Slotkin, Theodore A.; Brick-Turin, Yael; Van der Zee, Eddy A.; Yanai, Joseph

2010-01-01

Perfluorinated alkyls are widely-used agents that accumulate in ecosystems and organisms because of their slow rate of degradation. There is increasing concern that these agents may be developmental neurotoxicants and the present study was designed to develop an avian model for the neurobehavioral teratogenicity of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Fertilized chicken eggs were injected with 5 or 10 mg/kg of either compound on incubation day 0. On the day of hatching, imprinting behavior was impaired by both compounds. We then explored underlying mechanisms involving the targeting of protein kinase C (PKC) isoforms (α, β, γ) in the intermedial part of the hyperstriatum ventrale, the region most closely associated with imprinting. With PFOA exposure, cytosolic PKC concentrations were significantly elevated for all three isoforms; despite the overall increase in PKC expression, membrane-associated PKC was unaffected, indicating a defect in PKC translocation. In contrast, PFOS exposure evoked a significant decrease in cytosolic PKC, primarily for the β and γ isoforms, but again without a corresponding change in membrane-associated enzyme; this likely partial, compensatory increases in translocation to offset the net PKC deficiency. Our studies indicate that perfluorinated alkyls are indeed developmental neurotoxicants that affect posthatch cognitive performance but that the underlying synaptic mechanisms may differ substantially among the various members of this class of compounds, setting the stage for disparate outcomes later in life. PMID:19945530

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, W.A.; Kubas, G.J.

The present invention provides: a composition of the formula M{sup +x}(Ga(Y){sub 4}{sup {minus}}){sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R){sub x}Q{sup +}Ga(Y){sub 4}{sup {minus}} where Q is selected from themore » group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M{sup +x}{sub y}[X(GaY{sub 3}){sub z}]{sup {minus}y}{sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.« less

Gallium based low-interaction anions

DOEpatents

King, Wayne A.; Kubas, Gregory J.

2000-01-01

The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

Interrogating alkyl and arylalkylpolyamino (bis)urea and (bis)thiourea isosteres as potent antimalarial chemotypes against multiple lifecycle forms of Plasmodium falciparum parasites.

PubMed

Verlinden, Bianca K; de Beer, Marna; Pachaiyappan, Boobalan; Besaans, Ethan; Andayi, Warren A; Reader, Janette; Niemand, Jandeli; van Biljon, Riette; Guy, Kiplin; Egan, Timothy; Woster, Patrick M; Birkholtz, Lyn-Marie

2015-08-15

A new series of potent potent aryl/alkylated (bis)urea- and (bis)thiourea polyamine analogues were synthesized and evaluated in vitro for their antiplasmodial activity. Altering the carbon backbone and terminal substituents increased the potency of analogues in the compound library 3-fold, with the most active compounds, 15 and 16, showing half-maximal inhibitory concentrations (IC50 values) of 28 and 30 nM, respectively, against various Plasmodium falciparum parasite strains without any cross-resistance. In vitro evaluation of the cytotoxicity of these analogues revealed marked selectivity towards targeting malaria parasites compared to mammalian HepG2 cells (>5000-fold lower IC50 against the parasite). Preliminary biological evaluation of the polyamine analogue antiplasmodial phenotype revealed that (bis)urea compounds target parasite asexual proliferation, whereas (bis)thiourea compounds of the same series have the unique ability to block transmissible gametocyte forms of the parasite, indicating pluripharmacology against proliferative and non-proliferative forms of the parasite. In this manuscript, we describe these results and postulate a refined structure-activity relationship (SAR) model for antiplasmodial polyamine analogues. The terminally aryl/alkylated (bis)urea- and (bis)thiourea-polyamine analogues featuring a 3-5-3 or 3-6-3 carbon backbone represent a structurally novel and distinct class of potential antiplasmodials with activities in the low nanomolar range, and high selectivity against various lifecycle forms of P. falciparum parasites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Construction of divergent fused heterocycles via an acid-promoted intramolecular ipso-Friedel-Crafts alkylation of phenol derivatives.

PubMed

Yokosaka, Takuya; Shiga, Naoki; Nemoto, Tetsuhiro; Hamada, Yasumasa

2014-05-02

Two different cascade cyclization processes were developed using aryl group-substituted propargyl alcohol derivatives with a p-hydroxybenzylamine unit as common substrates. Using TFA as an acid promoter, an intramolecular ipso-Friedel-Crafts alkylation of phenol derivatives, formation of an iminium cation via a rearomatization-promoted C-C bond cleavage, an aza-Prins reaction, and a 6-membered ring formation proceeded sequentially, producing a variety of fused-tricyclic dihydroquinoline derivatives in 45-99% yield. In addition, a one-pot sequential silver acetate-catalyzed hydroamination/etherification-acid-promoted skeletal rearrangement was examined using the same series of substrates, affording fused-tricyclic indole/benzofuran derivatives in 66-89% yield.

Simulation study of sulfonate cluster swelling in ionomers

NASA Astrophysics Data System (ADS)

Allahyarov, Elshad; Taylor, Philip L.; Löwen, Hartmut

2009-12-01

We have performed simulations to study how increasing humidity affects the structure of Nafion-like ionomers under conditions of low sulfonate concentration and low humidity. At the onset of membrane hydration, the clusters split into smaller parts. These subsequently swell, but then maintain constant the number of sulfonates per cluster. We find that the distribution of water in low-sulfonate membranes depends strongly on the sulfonate concentration. For a relatively low sulfonate concentration, nearly all the side-chain terminal groups are within cluster formations, and the average water loading per cluster matches the water content of membrane. However, for a relatively higher sulfonate concentration the water-to-sulfonate ratio becomes nonuniform. The clusters become wetter, while the intercluster bridges become drier. We note the formation of unusual shells of water-rich material that surround the sulfonate clusters.

40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to reporting...

40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to reporting...

40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to reporting...

40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to reporting...

40 CFR 721.1875 - Boric acid, alkyl and substituted alkyl esters (generic name).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Boric acid, alkyl and substituted... Significant New Uses for Specific Chemical Substances § 721.1875 Boric acid, alkyl and substituted alkyl... chemical substance boric acid, alkyl and substituted alkyl esters (PMN P-86-1252) is subject to reporting...

Sulfonimide-containing poly(arylene ether)s and poly(arylene ether sulfone)s, methods for producing the same, and uses thereof

DOEpatents

Hofmann, Michael A.

2006-11-14

The present invention is directed to sulfonimide-containing polymers, specifically sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, and processes for making the sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, for use conductive membranes and fuel cells.

Electrochemical Grafting of Graphene Nano Platelets with Aryl Diazonium Salts.

PubMed

Qiu, Zhipeng; Yu, Jun; Yan, Peng; Wang, Zhijie; Wan, Qijin; Yang, Nianjun

2016-10-26

To vary interfacial properties, electrochemical grafting of graphene nano platelets (GNP) with 3,5-dichlorophenyl diazonium tetrafluoroborate (aryl-Cl) and 4-nitrobenzene diazonium tetrafluoroborate (aryl-NO 2 ) was realized in a potentiodynamic mode. The covalently bonded aryl layers on GNP were characterized using atomic force microscopy and X-ray photoelectron spectroscopy. Electrochemical conversion of aryl-NO 2 into aryl-NH 2 was conducted. The voltammetric and impedance behavior of negatively and positively charged redox probes (Fe(CN) 6 3-/4- and Ru(NH 3 ) 6 2+/3+ ) on three kinds of aryl layers grafted on GNP reveal that their interfacial properties are determined by the charge states of redox probes and reactive terminal groups (-Cl, -NO 2 , -NH 2 ) in aryl layers. On aryl-Cl and aryl-NH 2 garted GNP, selective and sensitive monitoring of positively charged lead ions as well as negatively charged nitrite and sulfite ions was achieved, respectively. Such a grafting procedure is thus a perfect way to design and control interfacial properties of graphene.

Aryl-Aryl Interactions in Designed Peptide Folds: Spectroscopic Characteristics and Placement Issues for Optimal Structure Stabilization

PubMed Central

Anderson, Jordan M.; Kier, Brandon; Jurban, Brice; Byrne, Aimee; Shu, Irene; Eidenschink, Lisa A.; Shcherbakov, Alexander A.; Hudson, Mike; Fesinmeyer, R. M.; Andersen, Niels H.

2017-01-01

We have extended our studies of Trp/Trp to other Aryl/Aryl through-space interactions that stabilize hairpins and other small polypeptide folds. Herein we detail the NMR and CD spectroscopic features of these types of interactions. NMR data remains the best diagnostic for characterizing the common T-shape orientation. Designated as an edge-to-face (EtF or FtE) interaction, large ring current shifts are produced at the edge aryl ring hydrogens and, in most cases, large exciton couplets appear in the far UV circular dichroic (CD) spectrum. The preference for the face aryl in FtE clusters is W≫Y≥F (there are some exceptions in the Y/F order); this sequence corresponds to the order of fold stability enhancement and always predicts the amplitude of the lower energy feature of the exciton couplet in the CD spectrum. The CD spectra for FtE W/W, W/Y, Y/W, and Y/Y pairs all include an intense feature at 225–232 nm. An additional couplet feature seen for W/Y, W/F, Y/Y and F/Y clusters, is a negative feature at 197–200 nm. Tyr/Tyr (as well as F/Y and F/F) interactions produce much smaller exciton couplet amplitudes. The Trp-cage fold was employed to search for the CD effects of other Trp/Trp and Trp/Tyr cluster geometries: several were identified. In this account, we provide additional examples of the application of cross-strand aryl/aryl clusters for the design of stable β-sheet models and a scale of fold stability increments associated with all possible FtE Ar/Ar clusters in several structural contexts. PMID:26850220

Emissive polymeric materials for optoelectronic devices

DOEpatents

Shiang, Joseph John [Niskayuna, NY; Chichak, Kelly Scott [Clifton Park, NY; Cella, James Anthony [Clifton Park, NY; Lewis, Larry Neil [Scotia, NY; Janora, Kevin Henry [Schenectady, NY

2011-07-05

Polymers including at least one structural unit derived from a compound of formula I or including at least one pendant group of formula II may be used in optoelectronic devices ##STR00001## wherein R.sup.1, R.sup.3, R.sup.4 and R.sup.6 are independently hydrogen, alkyl, alkoxy, oxaalkyl, alkylaryl, aryl, arylalkyl, heteroaryl, substituted alkyl; substituted alkoxy, substituted oxaalkyl, substituted alkylaryl, substituted aryl, substituted arylalkyl, or substituted heteroaryl; R.sup.1a is hydrogen or alkyl; R.sup.2 is alkylene, substituted alkylene, oxaalkylene, CO, or CO.sub.2; R.sup.2a is alkylene; R.sup.5 is independently at each occurrence hydrogen, alkyl, alkylaryl, aryl, arylalkyl, alkoxy, carboxy, substituted alkyl; substituted alkylaryl, substituted aryl, substituted arylalkyl, or substituted alkoxy, X is halo, triflate, --B(OR.sup.1a).sub.2, or ##STR00002## located at the 2, 5- or 2, 7-positions; and L is derived from phenylpyridine, tolylpyridine, benzothienylpyridine, phenylisoquinoline, dibenzoquinozaline, fluorenylpyridine, ketopyrrole, 2-(1-naphthyl)benzoxazole)), 2-phenylbenzoxazole, 2-phenylbenzothiazole, coumarin, thienylpyridine, phenylpyridine, benzothienylpyridine, 3-methoxy-2-phenylpyridine, thienylpyridine, phenylimine, vinylpyridine, pyridylnaphthalene, pyridylpyrrole, pyridylimidazole, phenylindole, derivatives thereof or combinations thereof.

Synthesis and Properties of Poly(ether sulfone)s with Clustered Sulfonic Groups for PEMFC Applications under Various Relative Humidity.

PubMed

Lee, Shih-Wei; Chen, Jyh-Chien; Wu, Jin-An; Chen, Kuei-Hsien

2017-03-22

Novel sulfonated poly(ether sulfone) copolymers (S4PH-x-PSs) based on a new aromatic diol containing four phenyl substituents at the 2, 2', 6, and 6' positions of 4,4'-diphenyl ether were synthesized. Sulfonation was found to occur exclusively on the 4 position of phenyl substituents by NMR spectroscopy. The ion exchange capacity (IEC) values can be controlled by adjusting the mole percent (x in S4PH-x-PS) of the new diol. The fully hydrated sulfonated poly(ether sulfone) copolymers had good proton conductivity in the range 0.004-0.110 S/cm at room temperature. The surface morphology of S4PH-x-PSs and Nafion 212 was investigated by atomic force microscopy (tapping-mode) and related to the percolation limit and proton conductivity. Single H 2 /O 2 fuel cell based on S4PH-40-PS loaded with 0.25 mg/cm 2 catalyst (Pt/C) exhibited a peak power density of 462.6 mW/cm 2 , which was close to that of Nafion 212 (533.5 mW/cm 2 ) at 80 °C with 80% RH. Furthermore, fuel cell performance of S4PH-35-PS with various relative humidity was investigated. It was confirmed from polarization curves that the fuel cell performance of S4PH-35-PS was not as high as that of Nafion 212 under fully hydrated state due to higher interfacial resistance between S4PH-35-PS and electrodes. While under low relative humidity (53% RH) at 80 °C, fuel cells based on S4PH-35-PS showed higher peak power density (234.9 mW/cm 2 ) than that (214.0 mW/cm 2 ) of Nafion 212.

21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Ethylene polymer, chloro-sulfonated is produced by chloro-sulfonation of a carbon tetrachloride solution of... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene polymer, chloro-sulfonated. 177.2210... as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated...

Improvement of electrochemical performances of sulfonated poly(arylene ether sulfone) via incorporation of sulfonated poly(arylene ether benzimidazole)

NASA Astrophysics Data System (ADS)

Hong, Young Taik; Lee, Chang Hyun; Park, Hyung Su; Min, Kyung A.; Kim, Hyung Joong; Nam, Sang Yong; Lee, Young Moo

In the present study, modified acid-base blend membranes were fabricated via incorporation of sulfonated poly(arylene ether benzimidazole) (SPAEBI) into sulfonated poly(arylene ether sulfone) (SPAES). These membranes had excellent methanol-barrier properties in addition to an ability to compensate for the loss of proton conductivity that typically occurs in general acid-base blend system. To fabricate the membranes, SPAEBIs, which served as amphiphilic polymers with different degrees of sulfonation (0-50 mol%), were synthesized by polycondensation and added to SPAES. It resulted in the formation of acid-amphiphilic complexes such as [PAES-SO 3] - +[H-SPAEBI] through the ionic crosslinking, which prevented SO 3H groups in the complex from transporting free protons in an aqueous medium, contributing to a reduction of ion exchange capacity values and water uptake in the blend membranes, and leading to lower methanol permeability in a water-methanol mixture. Unfortunately, the ionic bonding formation was accompanied by a decrease of bound water content and proton conductivity, although the latter problem was solved to some extent by the incorporation of additional SO 3H groups in SPAEBI. In the SPAES-SPAEBI blend membranes, enhancement of proton conductivity and methanol-barrier property was prominent at temperatures over 90 °C. The direct methanol fuel cell (DMFC) performance, which was based on SPAES-SPAEBI-50-5, was 1.2 times higher than that of Nafion ® 117 under the same operating condition.

The tuning of P-donor ligands: the aryl and other pendent group effects (PGEs) revisited.

PubMed

Poë, Anthony J

2009-03-21

Electronic and steric effects of P-donor ligands can be modified by varying the pendent groups attached to the phosphorus atoms. However, the so-called "Aryl Effects" of phosphites and other P-donor ligands that contain no aryl groups can be shown simply to be additional examples of electronic Pendent Group Effects (PGEs) by which effects are transmitted to the phosphorus atoms or through them. These effects are quite distinct from those caused by varying sigma-donicity and pi-acidity parameters, and are strictly proportional to the number of pendent groups of a particular type. In each case, the extent of the effect is determined by the difference between the actual property observed and that predicted on the basis that the ligand behaves in the same way as alkyl phosphines after allowing for steric and pi-acidity effects. The PGEs are therefore unique to particular pendent groups and to the method of measuring their effects. They are not "parameters" in the sense of being generally applicable in Linear Free Energy Relationships. The PGEs of a variety of pendent groups are derived from the so-called "aryl effects" determined by Giering & Prock et al. for vertical ionization potentials (IPs) and some other properties of the P-donor ligands. In almost all cases the IPs are reduced by the PGEs, and the extent of the reduction (in eV) decreases in the sequence C(6)F(5) (-0.67) approximately Cl (-0.67) < Pyrr (-0.53) < Ph (-0.49) < OR (-0.19) < OCH(2)CH(2)Cl (-0.07) < etpb (-0.03) < N(C(4)H(8)) (+0.01). Different PGEs are found for other P-donor-dependent properties although they are simply related to each other.

40 CFR 721.10035 - Alkylbenzene sulfonate (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylbenzene sulfonate (generic). 721... Substances § 721.10035 Alkylbenzene sulfonate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkylbenzene sulfonate (PMN-02...

40 CFR 721.10035 - Alkylbenzene sulfonate (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkylbenzene sulfonate (generic). 721... Substances § 721.10035 Alkylbenzene sulfonate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkylbenzene sulfonate (PMN-02...

C-H Bond Functionalization via Hydride Transfer: Formation of α-Arylated Piperidines and 1,2,3,4-Tetrahydroisoquinolines via Stereoselective Intramolecular Amination of Benzylic C-H Bonds

PubMed Central

Vadola, Paul A.; Carrera, Ignacio; Sames, Dalibor

2012-01-01

We here report a study of the intramolecular amination of sp3 C-H bonds via the hydride transfer cyclization of N-tosylimines (HT-amination). In this transformation, 5-aryl-aldehydes are subjected to N-toluenesulfonamide in the presence of BF3•OEt2 to effect imine formation and HT-cyclization, leading to 2-aryl-piperidines and 3-aryl-1,2,3,4-tetrahydroisoquinolines in a one-pot procedure. We examined the reactivity of a range of aldehyde substrates as a function of their conformational flexibility. Substrates of higher conformational rigidity were more reactive, giving higher yields of the desired products. However, a single substituent on the alkyl chain linking the N-tosylimine and the benzylic sp3 C-H bonds was sufficient for HT-cyclization to occur. In addition, an examination of various arenes revealed that the electronic character of the hydridic C-H bonds dramatically affects the efficiency of the reaction. We also found that this transformation is highly stereoselective; 2-substituted aldehydes yield cis-2,5-disubstituted piperidines, while 3-substituted aldehydes afford trans-2,4-disubstituted piperidines. The stereoselectivity is a consequence of thermodynamic control. The pseudo-allylic strain between the arene and tosyl group on the piperidine ring is proposed to rationalize the greater stability of the isomer with the aryl ring in the axial position. This preferential placement of the arene is proposed to affect the observed stereoselectivity. PMID:22672002

Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

DOEpatents

Martinez, Rodolfo A. , Unkefer; Clifford J. , Alvarez; Marc, A [Santa Fe, NM

2012-06-12

The present invention is directed to the labeled compounds, ##STR00001## wherein C* is each either .sup.13C and .sup.12C where at least one C* is .sup.13C, each hydrogen of the methylene group is hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is sulfide, sulfinyl, or sulfone, Z is an aryl group such as 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, or a phenyl group ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently either hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group such as NH.sub.2, NHR and NRR' where R and R' are each independently either a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms. The present invention is also directed to the labeled compounds ##STR00003##

Synthesis of Heteroaryl Sulfonamides from Organozinc Reagents and 2,4,6-Trichlorophenyl Chlorosulfate

PubMed Central

2016-01-01

A method for the preparation of aryl and heteroaryl sulfonamides using 2,4,6-trichlorophenyl chlorosulfate (TCPC) is described. The reaction of 2-pyridylzinc reagents with TCPC resulted in 2,4,6-trichlorophenyl (TCP) pyridine-2-sulfonates, and the parent pyridine-2-sulfonate was shown to react with amines. Less electron-rich aryl- and heteroarylzinc reagents reacted with TCPC to afford sulfonyl chlorides that were converted in situ to sulfonamides. PMID:26065317

Induction by alkylating agents of sister chromatid exchanges and chromatid breaks in Fanconi's anemia.

PubMed

Latt, S A; Stetten, G; Juergens, L A; Buchanan, G R; Gerald, P S

1975-10-01

Sister chromatid exchanges, which may reflect chromosome repair in response to certain types of DNA damage, provide a means of investigating the increased chromosome fragility characteristic of Fanconi's anemia. By a recently developed technique using 33258 Hoechst and 5-bromodeoxyuridine, it was observed that the baseline frequency of sister chromatid exchanges in phytohemagglutinin-stimulated lymphocytes from four males with Fanconi's anemia differed little from that of normal lymphocytes. However, addition of the bifunctional alkylating agent mitomycin C (0.01 or 0.03 mug/ml) to the Fanconi's anemia cells during culture induces less than half of the increase in exchanges found in identically treated normal lymphocytes. This reduced increment in exchanges in accompanied by a partial suppression of mitosis and a marked increase in chromatid breaks and rearrangements. Many of these events occur at sites of incomplete chromatid interchange. The increase in sister chromatid exchanges induced in Fanconi's anemia lymphocytes by the monofunctional alkylating agent ethylmethane sulfonate (0.25 mg/ml) was slightly less than that in normal cells. Lymphocytes from two sets of parents of the patients with Fanconi's anemia exhibited a normal response to alkylating agents, while dermal fibroblasts from two different patients with Fanconi's anemia reacted to mitomycin C with an increase in chromatid breaks, but a nearly normal increment of sister chromatid exchanges. The results suggest that chromosomal breaks and rearrangements in Fanconi's anemia lymphocytes may result from a defect in a form of repair of DNA damage.

Palladium-catalysed carbonylative α-arylation of nitromethane.

PubMed

Lian, Zhong; Friis, Stig D; Skrydstrup, Troels

2015-02-28

A simple and mild Pd-catalysed carbonylative α-arylation of nitromethane has been realised providing access to α-nitro aryl ketones from an array of aryl and heteroaryl iodides. The methodology requires only a mild base and uses the convenient solid CO releasing molecule, COgen in a two-chamber system. Changing to the isotopically labelled (13)COgen, [(13)C]-acyl labelling can be effected through the generation of a near stoichiometric amount of (13)CO. Lastly, the significance of the generated products as synthetic intermediates is demonstrated.

Mechanistic Studies on the Copper-Catalyzed N-Arylation of Amides

PubMed Central

Strieter, Eric R.; Bhayana, Brijesh; Buchwald, Stephen L.

2009-01-01

The copper-catalyzed N-arylation of amides, i.e., the Goldberg reaction, is an efficient method for the construction of products relevant to both industry and academic settings. Herein, we present mechanistic details concerning the catalytic and stoichiometric N-arylation of amides. In the context of the catalytic reaction, our findings reveal the importance of chelating diamine ligands in controlling the concentration of the active catalytic species. The consistency between the catalytic and stoichiometric results suggest that the activation of aryl halides occurs through a 1,2-diamine-ligated copper(I) amidate complex. Kinetic studies on the stoichiometric N-arylation of aryl iodides using 1,2-diamine ligated Cu(I) amidates also provide insights into the mechanism of aryl halide activation. PMID:19072233

Organocatalytic asymmetric arylation of indoles enabled by azo groups

NASA Astrophysics Data System (ADS)

Qi, Liang-Wen; Mao, Jian-Hui; Zhang, Jian; Tan, Bin

2018-01-01

Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon-hydrogen (C-H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives. Thus, a wide range of axially chiral arylindoles have been achieved in good yields with excellent enantioselectivities by utilizing chiral phosphoric acid as catalyst. Furthermore, highly enantioenriched pyrroloindoles bearing two contiguous quaternary chiral centres have also been obtained via a cascade enantioselective formal nucleophilic aromatic substitution-cyclization process. This strategy should be useful in other related research fields and will open new avenues for organocatalytic asymmetric aryl functionalization.

Organocatalytic asymmetric arylation of indoles enabled by azo groups.

PubMed

Qi, Liang-Wen; Mao, Jian-Hui; Zhang, Jian; Tan, Bin

2018-01-01

Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon-hydrogen (C-H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives. Thus, a wide range of axially chiral arylindoles have been achieved in good yields with excellent enantioselectivities by utilizing chiral phosphoric acid as catalyst. Furthermore, highly enantioenriched pyrroloindoles bearing two contiguous quaternary chiral centres have also been obtained via a cascade enantioselective formal nucleophilic aromatic substitution-cyclization process. This strategy should be useful in other related research fields and will open new avenues for organocatalytic asymmetric aryl functionalization.

Mechanism-based inactivation of benzo(a)pyrene hydroxylase by aryl acetylenes and aryl olefins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gan, L.S.; Lu, J.Y.L.; Alworth, W.L.

A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxgenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, 3-ethynylperylene, 2-ethynylfluorene, methyl 1-pyrenyl acetylene, cis- and trans-1-(2-bromovinyl)pyrene, and 1-allylpyrene serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene hydroxylase, while 1-vinylpyrene and phenyl 1-pyrenyl acetylene do not cause a detectable suicide inhibition of benzo(a)pyrene hydroxylase. The mechanism-based loss of benzo(a)pyrene hydroxylase caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes (suicide destruction). The suicide inhibition by these aryl acetylenesmore » therefore does not involve covalent binding to the heme moiety of the monooxygenase. Nevertheless, in the presence of NADPH, /sup 3/H-labeled 1-ethynylpyrene becomes covalently attached to the cytochrome P-450 protein; the measured stoichiometry of binding is one 1-ethynylpyrene per P-450 heme unit. The authors conclude that the inhibition of benzo(a)pyrene hydroxylase produced by 1-ethynylpyrene may be related to the mechanism of suicide inhibition of P-450 activity by chloramphenicol rather than the mechanism of suicide destruction of P-450 previously described for acetylene and propyne.« less

[Alkylating agents].

PubMed

Pourquier, Philippe

2011-11-01

With the approval of mechlorethamine by the FDA in 1949 for the treatment of hematologic malignancies, alkylating agents are the oldest class of anticancer agents. Even though their clinical use is far beyond the use of new targeted therapies, they still occupy a major place in specific indications and sometimes represent the unique option for the treatment of refractory diseases. Here, we are reviewing the major classes of alkylating agents and their mechanism of action, with a particular emphasis for the new generations of alkylating agents. As for most of the chemotherapeutic agents used in the clinic, these compounds are derived from natural sources. With a complex but original mechanism of action, they represent new interesting alternatives for the clinicians, especially for tumors that are resistant to conventional DNA damaging agents. We also briefly describe the different strategies that have been or are currently developed to potentiate the use of classical alkylating agents, especially the inhibition of pathways that are involved in the repair of DNA lesions induced by these agents. In this line, the development of PARP inhibitors is a striking example of the recent regain of interest towards the "old" alkylating agents.

Mineralization of the sulfonated azo dye Mordant Yellow 3 by a 6-aminonaphthalene-2-sulfonate-degrading bacterial consortium.

PubMed Central

Haug, W; Schmidt, A; Nörtemann, B; Hempel, D C; Stolz, A; Knackmuss, H J

1991-01-01

Under anaerobic conditions the sulfonated azo dye Mordant Yellow 3 was reduced by the biomass of a bacterial consortium grown aerobically with 6-aminonaphthalene-2-sulfonic acid. Stoichiometric amounts of the aromatic amines 6-aminonaphthalene-2-sulfonate and 5-aminosalicylate were generated and excreted into the medium. After re-aeration of the culture, these amines were mineralized by different members of the bacterial culture. Thus, total degradation of a sulfonated azo dye was achieved by using an alternating anaerobic-aerobic treatment. The ability of the mixed bacterial culture to reduce the azo dye was correlated with the presence of strain BN6, which possessed the ability to oxidize various naphthalenesulfonic acids. It is suggested that strain BN6 has a transport system for naphthalenesulfonic acids which also catalyzes uptake of sulfonated azo dyes. These dyes are then gratuitously reduced in the cytoplasm by unspecific reductases. PMID:1781678

Synthesis and properties of reprocessable sulfonated polyimides cross-linked via acid stimulation for use as proton exchange membranes

NASA Astrophysics Data System (ADS)

Zhang, Boping; Ni, Jiangpeng; Xiang, Xiongzhi; Wang, Lei; Chen, Yongming

2017-01-01

Cross-linked sulfonated polyimides are one of the most promising materials for proton exchange membrane (PEM) applications. However, these cross-linked membranes are difficult to reprocess because they are insoluble. In this study, a series of cross-linkable sulfonated polyimides with flexible pendant alkyl side chains containing trimethoxysilyl groups is successfully synthesized. The cross-linkable polymers are highly soluble in common solvents and can be used to prepare tough and smooth films. Before the cross-linking reaction is complete, the membranes can be reprocessed, and the recovery rate of the prepared films falls within an acceptable range. The cross-linked membranes are obtained rapidly when the cross-linkable membranes are immersed in an acid solution, yielding a cross-linking density of the gel fraction of greater than 90%. The cross-linked membranes exhibit high proton conductivities and tensile strengths under hydrous conditions. Compared with those of pristine membranes, the oxidative and hydrolytic stabilities of the cross-linked membranes are significantly higher. The CSPI-70 membrane shows considerable power density in a direct methanol fuel cell (DMFC) test. All of these results suggest that the prepared cross-linked membranes have great potential for applications in proton exchange membrane fuel cells.

Highly enantioselective arylation of aldehydes and ketones using AlArEt(2)(THF) as aryl sources.

PubMed

Zhou, Shuangliu; Wu, Kuo-Hui; Chen, Chien-An; Gau, Han-Mou

2009-05-01

A series of AlArEt(2)(THF) (Ar = Ph (1a), 4-MeC(6)H(4) (1b), 4-MeOC(6)H(4) (1c), 4-Me(3)SiC(6)H(4) (1d), 2-naphthyl (1e)) were synthesized from reactions of AlEt(2)Br(THF) with ArMgBr. In CDCl(3) solution, the (1)H NMR spectra showed that AlArEt(2)(THF) compounds exist as a mixture of four species of formulas of AlAr(x)Et(3-x) (THF) (x = 0, 1, 2, or 3). AlArEt(2)(THF) compounds were found to be superior and atom-economic reagents for asymmetric aryl additions to organic carbonyls. Aryl additions of AlArEt(2)(THF) to aldehydes catalyzed by the titanium(IV) complex of (R)-H(8)-BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing the amount of AlArEt(2)(THF) from 1.2 to 1.4 or to 1.6 equiv significantly improved the aryl addition products of up to >99%. On the other hand, asymmetric arylations of AlArEt(2)(THF) to ketones employing a titanium(IV) catalyst of (S)-BINOL produced optically active tertiary alcohols exclusively in excellent enantioselectivities of up to 94% ee.

Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads.

PubMed

Rocha, Igor; Lindh, Jonas; Hong, Jaan; Strømme, Maria; Mihranyan, Albert; Ferraz, Natalia

2018-03-07

Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels), coagulation activation (thrombin-antithrombin (TAT) levels) and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

General and mild Ni(0)-catalyzed α-arylation of ketones using aryl chlorides.

PubMed

Fernández-Salas, José A; Marelli, Enrico; Cordes, David B; Slawin, Alexandra M Z; Nolan, Steven P

2015-03-02

A general methodology for the α-arylation of ketones using a nickel catalyst has been developed. The new well-defined [Ni(IPr*)(cin)Cl] (1 c) pre-catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised aryl chlorides. This cinnamyl-based Ni-N-heterocyclic carbene (NHC) complex has demonstrated a different behaviour to previously reported NHC-Ni catalysts. Preliminary mechanistic studies suggest a Ni(0)/Ni(II) catalytic cycle to be at play. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A study of the effect of polystyrene sulfonation on the performance of terephthaloyl chloride-dihydroxydiphenyl sulfone copolymer/polystyrene system

NASA Astrophysics Data System (ADS)

Kahraman, R.; Kahn, K. A.; Ali, S. A.; Hamid, S. H.; Sahin, A. Z.

1998-12-01

Thermal, morphological, and mechanical properties of composites of a liquid crystalline copolymer (LCP) poly(terephthaloyl chloride)-co-(p,p’-dihydroxydiphenyl sulfone) with polystyrene (PS) and sulfonated polystyrene (SPS) are presented and discussed. Sulfonation of polystyrene was expected to improve the interfacial adhesion by introducing hydrogen bonding in the LCP/PS system. The degree of sulfonation was 11 %. The incompatibility (lack of proper interfacial adhesion) of the LCP/PS system resulted in sharp decrease in the composite tensile strength with LCP addition. The performance of the system did not change when processed at a higher temperature (270 °C instead of 225 °C). While a composite plate of 25% LCP/PS could not be fabricated, it was possible for LCP/SPS (processed at 215 °C), indicating some improvement in interfacial bonding by sulfonation. Sulfonation of PS resulted in fracture with some degree of plastic deformation for pure SPS matrix and also the LCP/SPS system with the lowest LCP content (1 wt%), whereas plastic deformation was not observed for PS used as received. The strength of the LCP/SPS system also decreased with increase in LCP content, indicating that 11% sulfonation is not sufficient to introduce significant compatibility, but it was not as dramatic as that for LCP/PS. The performance of the LCP/SPS system was not affected significantly by heat treatment at the process temperature.

Alkyl-substituted phenylamino derivatives of 7-nitrobenz-2-oxa-1,3-diazole as uncouplers of oxidative phosphorylation and antibacterial agents: involvement of membrane proteins in the uncoupling action.

PubMed

Antonenko, Yuri N; Denisov, Stepan S; Khailova, Ljudmila S; Nazarov, Pavel A; Rokitskaya, Tatyana; Tashlitsky, Vadim N; Firsov, Alexander M; Korshunova, Galina A; Kotova, Elena A

2017-03-01

In search for new effective uncouplers of oxidative phosphorylation, we studied 4-aryl amino derivatives of a fluorescent group 7-nitrobenz-2-oxa-1,3-diazol (NBD). In our recent work (Denisov et al., Bioelectrochemistry, 2014), NBD-conjugated alkyl amines (NBD-C n ) were shown to exhibit uncoupling activity. It was concluded that despite a pK a value being about 10, the expected hindering of the uncoupling activity could be overcome by insertion of an alkyl chain. There is evidence in the literature that the introduction of an aryl substituent in the 4-amino NBD group shifts the pK a to neutral values. Here we report the data on the properties of a number of 4-arylamino derivatives of NBD, namely, alkylphenyl-amino-NBD (C n -phenyl-NBD) with varying alkyl chain C n . By measuring the electrical current across planar bilayer lipid membrane, the protonophoric activity of C n -phenyl-NBD at neutral pH grew monotonously from C 1 - to C 6 -phenyl-NBD. All of these compounds increased the respiration rate and reduced the membrane potential of isolated rat liver mitochondria. Importantly, the uncoupling action of C 6 - and C 4 -phenyl-NBD was partially reversed by glutamate, diethyl pyrocarbonate (DEPC), 6-ketocholestanol, and carboxyatractyloside, thus pointing to the involvement of membrane proteins in the uncoupling activity of C n -phenyl-NBD in mitochondria. The pronounced recoupling effect of DEPC, an inhibitor of an aspartate-glutamate carrier (AGC), and that of its substrates for the first time highlighted AGC participation in the action of potent uncouplers on mitochondria. C 6 -phenyl-NBD produced strong antimicrobial effect on Bacillus subtilis, which manifested itself in cell membrane depolarization and suppression of bacterial growth at submicromolar concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Asymmetric 1,2-perfluoroalkyl migration: easy access to enantioenriched α-hydroxy-α-perfluoroalkyl esters.

PubMed

Wang, Pan; Feng, Liang-Wen; Wang, Lijia; Li, Jun-Fang; Liao, Saihu; Tang, Yong

2015-04-15

This study has led to the development of a novel, highly efficient, 1,2-perfluoro-alkyl/-aryl migration process in reactions of hydrate of 1-perfluoro-alkyl/-aryl-1,2-diketones with alcohols, which are promoted by a Zn(II)/bisoxazoline and form α-perfluoro-alkyl/-aryl-substituted α-hydroxy esters. With (-)-8-phenylmenthol as the alcohol, the corresponding menthol esters are generated in high yields with excellent levels of diastereoselectivity. The mechanistic studies show that the benzilic ester-type rearrangement reaction takes place via an unusual 1,2-migration of electron-deficient trifluoromethyl group rather than the phenyl group. The overall process serves as a novel, efficient, and simple approach for the synthesis of highly enantioenriched, biologically relevant α-hydroxy-α-perfluoroalkyl carboxylic acid derivatives.

40 CFR 721.1625 - Alkylbenzene sulfonate, amine salt.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkylbenzene sulfonate, amine salt... Substances § 721.1625 Alkylbenzene sulfonate, amine salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkylbenzene sulfonate, amine...

40 CFR 721.1625 - Alkylbenzene sulfonate, amine salt.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylbenzene sulfonate, amine salt... Substances § 721.1625 Alkylbenzene sulfonate, amine salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkylbenzene sulfonate, amine...

Pseudoephedrine-Directed Asymmetric α-Arylation of α-Amino Acid Derivatives.

PubMed

Atkinson, Rachel C; Fernández-Nieto, Fernando; Mas Roselló, Josep; Clayden, Jonathan

2015-07-27

Available α-amino acids undergo arylation at their α position in an enantioselective manner on treatment with base of N'-aryl urea derivatives ligated to pseudoephedrine as a chiral auxiliary. In situ silylation and enolization induces diastereoselective migration of the N'-aryl group to the α position of the amino acid, followed by ring closure to a hydantoin with concomitant explulsion of the recyclable auxiliary. The hydrolysis of the hydantoin products provides derivatives of quaternary amino acids. The arylation avoids the use of heavy-metal additives, and is successful with a range of amino acids and with aryl rings of varying electronic character. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Palladium- and Copper-Catalyzed Arylation of Carbon-Hydrogen Bonds

PubMed Central

Daugulis, Olafs; Do, Hien-Quang; Shabashov, Dmitry

2010-01-01

The transition-metal-catalyzed functionalization of C-H bonds is a powerful method for generating carbon-carbon bonds. Although significant advances to this field have been reported during the last decade, many challenges remain. First, most of the methods are substrate-specific and thus cannot be generalized. Second, conversions of unactivated (i.e. not benzylic or alpha to heteroatom) sp3 C–H bonds to C–C bonds are rare, with most examples limited to t-butyl groups—a conversion that is inherently simple because there are no β-hydrogens that can be eliminated. Finally, the palladium, rhodium, and ruthenium catalysts routinely used for the conversion of C–H bonds to C–C bonds are expensive. Catalytically active metals that are cheaper and less exotic (e.g. copper, iron, and manganese) are rarely used. This Account describes our attempts to provide solutions to these three problems. We have developed a general method for directing-group-containing arene arylation by aryl iodides. Using palladium acetate as the catalyst, we arylated anilides, benzamides, benzoic acids, benzylamines, and 2-substituted pyridine derivatives under nearly identical conditions. We have also developed a method for the palladium-catalyzed auxiliary-assisted arylation of unactivated sp3 C–H bonds. This procedure allows for the β-arylation of carboxylic acid derivatives and the γ-arylation of amine derivatives. Furthermore, copper catalysis can be used to mediate the arylation of acidic arene C–H bonds (i.e. those with pKa values <35 in DMSO). Using a copper iodide catalyst in combination with a base and a phenanthroline ligand, we successfully arylated electron-rich and electron-deficient heterocycles and electron-poor arenes possessing at least two electron-withdrawing groups. The reaction exhibits unusual regioselectivity: arylation occurs at the most hindered position. This copper-catalyzed method supplements the well-known C–H activation/borylation methodology, in which

Palladium- and copper-catalyzed arylation of carbon-hydrogen bonds.

PubMed

Daugulis, Olafs; Do, Hien-Quang; Shabashov, Dmitry

2009-08-18

The transition-metal-catalyzed functionalization of C-H bonds is a powerful method for generating carbon-carbon bonds. Although significant advances to this field have been reported during the past decade, many challenges remain. First, most of the methods are substrate-specific and thus cannot be generalized. Second, conversions of unactivated (i.e., not benzylic or alpha to heteroatom) sp(3) C-H bonds to C-C bonds are rare, with most examples limited to t-butyl groups, a conversion that is inherently simple because there are no beta-hydrogens that can be eliminated. Finally, the palladium, rhodium, and ruthenium catalysts routinely used for the conversion of C-H bonds to C-C bonds are expensive. Catalytically active metals that are cheaper and less exotic (e.g., copper, iron, and manganese) are rarely used. This Account describes our attempts to provide solutions to these three problems. We have developed a general method for directing-group-containing arene arylation by aryl iodides. Using palladium acetate as the catalyst, we arylated anilides, benzamides, benzoic acids, benzylamines, and 2-substituted pyridine derivatives under nearly identical conditions. We have also developed a method for the palladium-catalyzed auxiliary-assisted arylation of unactivated sp(3) C-H bonds. This procedure allows for the beta-arylation of carboxylic acid derivatives and the gamma-arylation of amine derivatives. Furthermore, copper catalysis can be used to mediate the arylation of acidic arene C-H bonds (i.e., those with pK(a) values <35 in DMSO). Using a copper iodide catalyst in combination with a base and a phenanthroline ligand, we successfully arylated electron-rich and electron-deficient heterocycles and electron-poor arenes possessing at least two electron-withdrawing groups. The reaction exhibits unusual regioselectivity: arylation occurs at the most hindered position. This copper-catalyzed method supplements the well-known C-H activation/borylation methodology, in

Ruthenium-catalyzed alkylation of indoles with tertiary amines by oxidation of a sp3 C-H bond and Lewis acid catalysis.

PubMed

Wang, Ming-Zhong; Zhou, Cong-Ying; Wong, Man-Kin; Che, Chi-Ming

2010-05-17

Ruthenium porphyrins (particularly [Ru(2,6-Cl(2)tpp)CO]; tpp=tetraphenylporphinato) and RuCl(3) can act as oxidation and/or Lewis acid catalysts for direct C-3 alkylation of indoles, giving the desired products in high yields (up to 82% based on 60-95% substrate conversions). These ruthenium compounds catalyze oxidative coupling reactions of a wide variety of anilines and indoles bearing electron-withdrawing or electron-donating substituents with high regioselectivity when using tBuOOH as an oxidant, resulting in the alkylation of N-arylindoles to 3-{[(N-aryl-N-alkyl)amino]methyl}indoles (yield: up to 82%, conversion: up to 95%) and the alkylation of N-alkyl or N-H indoles to 3-[p-(dialkylamino)benzyl]indoles (yield: up to 73%, conversion: up to 92%). A tentative reaction mechanism involving two pathways is proposed: an iminium ion intermediate may be generated by oxidation of an sp(3) C-H bond of the alkylated aniline by an oxoruthenium species; this iminium ion could then either be trapped by an N-arylindole (pathway A) or converted to formaldehyde, allowing a subsequent three-component coupling reaction of the in situ generated formaldehyde with an N-alkylindole and an aniline in the presence of a Lewis acid catalyst (pathway B). The results of deuterium-labeling experiments are consistent with the alkylation of N-alkylindoles via pathway B. The relative reaction rates of [Ru(2,6-Cl(2)tpp)CO]-catalyzed oxidative coupling reactions of 4-X-substituted N,N-dimethylanilines with N-phenylindole (using tBuOOH as oxidant), determined through competition experiments, correlate linearly with the substituent constants sigma (R(2)=0.989), giving a rho value of -1.09. This rho value and the magnitudes of the intra- and intermolecular deuterium isotope effects (k(H)/k(D)) suggest that electron transfer most likely occurs during the initial stage of the oxidation of 4-X-substituted N,N-dimethylanilines. Ruthenium-catalyzed three-component reaction of N-alkyl/N-H indoles

Symmetrical and unsymmetrical pincer complexes with group 10 metals: synthesis via aryl C-H activation and some catalytic applications.

PubMed

Niu, Jun-Long; Hao, Xin-Qi; Gong, Jun-Fang; Song, Mao-Ping

2011-05-21

Aryl-based pincer metal complexes with anionic terdentate ligands have been widely applied in organic synthesis, organometallic catalysis and other related areas. Synthetically, the most simple and convenient method for the construction of these complexes is the direct metal-induced C(aryl)-H bond activation, which can be fulfilled by choosing the appropriate functional donor groups in the two side arms of the aryl-based pincer preligands. In this perspective, we wish to summarize some results achieved by our group in this context. Successful examples include symmetrical chiral bis(imidazoline) NCN pincer complexes with Ni(II), Pd(II) and Pt(II), bis(phosphinite) and bis(phosphoramidite) PCP pincer Pd(II) complexes, unsymmetrical (pyrazolyl)phosphinite, (amino)phosphinite and (imino)phosphinite PCN pincer Pd(II) complexes, chiral (imidazolinyl)phosphinite and (imidazolinyl)phosphoramidite PCN pincer complexes with Ni(II) and Pd(II) as well as unsymmetrical (oxazolinyl)amine and (oxazolinyl)pyrazole NCN' pincer Pd(II) complexes. Among them, the P-donor containing complexes are efficiently synthesized by the "one-pot phosphorylation/metalation" method. The obtained symmetrical and unsymmetrical pincer complexes have been used as catalysts in Suzuki-Miyaura reaction (Pd), asymmetric Friedel-Crafts alkylation of indole with trans-β-nitrostyrene (Pt) as well as in asymmetric allylation of aldehyde and sulfonimine (Pd). In the Suzuki couplings conducted at 40-50 °C, some unsymmetrical Pd complexes exhibit much higher activity than the related symmetrical ones which can be attributed to their faster release of active Pd(0) species resulting from the hemilabile coordination of the ligands. Literature results on the synthesis of some related pincer complexes as well as their activities in the above catalytic reactions are also presented.

Regioselective copper-catalyzed N(1)-(hetero)arylation of protected histidine.

PubMed

Sharma, Krishna K; Mandloi, Meenakshi; Jain, Rahul

2016-09-26

We report regioselective N(1)-arylation of protected histidine using copper(i) iodide as a catalyst, trans-N,N'-dimethylcyclohexane-1,2-diamine as a ligand and readily available aryl iodides as coupling partners under microwave irradiation at 130 °C for 40 min. The reaction provides rapid access to electron-donating, electron-withdrawing and bulky group substituted N-arylated histidines in high yields, including previously inaccessible N-heteroaryl histidines. These N(1)-(hetero)aryl histidines are promising building blocks in peptide-based drug design and discovery.

Production and Application of Lignosulfonates and Sulfonated Lignin.

PubMed

Aro, Thomas; Fatehi, Pedram

2017-05-09

Lignin is the largest reservoir of aromatic compounds on earth and has great potential to be used in many industrial applications. Alternative methods to produce lignosulfonates from spent sulfite pulping liquors and kraft lignin from black liquor of kraft pulping process are critically reviewed herein. Furthermore, options to increase the sulfonate contents of lignin-based products are outlined and the industrial attractiveness of them is evaluated. This evaluation includes sulfonation and sulfomethylation of lignin. To increase the sulfomethylation efficiency of lignin, various scenarios, including hydrolysis, oxidation, and hydroxymethylation, were compared. The application of sulfonated lignin-based products is assessed and the impact of the properties of these products on the characteristics of their end-use application is critically evaluated. Sulfonated lignin-based products have been used as dispersants in cement admixtures and dye solutions more than other applications, and their molecular weight and degree of sulfonation were crucial in determining their efficiency. The use of lignin-based sulfonated products in composites may result in an increase in the hydrophilicity of some composites, but the sulfonated products may need to be desulfonated with an alkali and/or oxygen prior to their use in composites. To be used as a flocculant, sulfonated lignin-based products may need to be cross-linked to increase their molecular weight. The challenges associated with the use of lignin-based products in these applications are comprehensively discussed herein. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

From ketenimines to ketenes to quinolones: two consecutive pseudopericyclic events.

PubMed

Alajarín, Mateo; Ortín, María-Mar; Sánchez-Andrada, Pilar; Vidal, Angel; Bautista, Delia

2005-11-10

[reaction: see text] N-[2-(Alkyl- or arylthio)carbonyl]phenyl ketenimines undergo cyclization under mild thermal conditions to afford 2-alkyl(aryl)thio-3H-quinolin-4-ones by means of the 1,5-migration of the alkyl(aryl)thio group from the carbonyl carbon to the central carbon atom of the ketenimine fragment followed by the 6pi-electrocyclization of the resulting vinyliminoketene. These 1,5-migration and electrocyclization processes occur via transition states whose pseudopericyclic characteristics have been established on the basis of their magnetic properties, geometries, and NBO analyses.

Formation and Fate of Bacterial Sulfonates

DTIC Science & Technology

1989-01-05

sulfonates under phototrophic, anaerobic conditions’ Three cyanobacteria--a strain each of Synechococcus, Anabena, and Nostoc --have been examined for...their ability to utilize the sulfonate taurine as sole source of S for their oxygenic phototrophic growth; only Anabena and Nostoc were able to do so, and

Aldicarb sulfone

Integrated Risk Information System (IRIS)

Aldicarb sulfone ; CASRN 1646 - 88 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

Ion exchange materials, method of forming ion exchange materials, and methods of treating liquids

DOEpatents

Wertsching, Alan K.; Peterson, Eric S.; Wey, John E.

2007-12-25

The invention includes an ion affinity material having an organic component which is sulfonated and which is chemically bonded to an inorganic substrate component. The invention includes a method of forming a metal binding material. A solid support material comprising surface oxide groups is provided and an organic component having at least one alkyl halide is covalently linked to at least some of the surface oxide groups to form a modified support material. The at least one alkyl halide is subsequently converted into an alkyl sulfonate. The invention further includes a method and system for extracting ions from a liquid. An ion exchange material having a sulfonated alkyl silane component covalently bonded to a metal oxide support material is provided and a liquid is exposed to the ion exchange material.

Self-assembled structures of N-alkylated bisbenzimidazolyl naphthalene in aqueous media for highly sensitive detection of picric acid.

PubMed

Wu, Yan-Cheng; Luo, Shi-He; Cao, Liang; Jiang, Kai; Wang, Ling-Yun; Xie, Jie-Chun; Wang, Zhao-Yang

2017-07-11

A 2,6-dibenzimidazole-appended naphthalene derivative flanking with two N-alkyl chains (sensor 4) was designed and applied for highly sensitive detection of picric acid (PA) in aqueous media. Driven by the hydrophobicity of alkyl chain and π-π stacking effect of aryl, sensor 4 can undergo self-assembly to form an orderly rod-like structure in H 2 O/THF (v/v, 90/10) solution, as shown by the dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies. Sensor 4 shows high selectivity and sensitivity toward PA over other nitroaromatic explosives. DFT calculations and 1 H NMR, the time-correlated single photon counting (TCSPC) experiments confirm that the quenching mechanism is due to both electron and energy transfer from the electron-rich sensor 4 to the electron-deficient PA. Sensor 4 can detect as low as 0.57 ppb PA in aqueous media and 11.46 ag cm -2 PA by contact mode. Importantly, sensor 4 exhibits low interference against common solvents, metal ions and anions. Thus, it is practically applicable for sensing PA in real environmental samples and vapor phase. Copyright © 2017 Elsevier B.V. All rights reserved.

Fragrance material review on benzyl alcohol.

PubMed

Scognamiglio, J; Jones, L; Vitale, D; Letizia, C S; Api, A M

2012-09-01

A toxicologic and dermatologic review of benzyl alcohol when used as a fragrance ingredient is presented. Benzyl alcohol is a member of the fragrance structural group Aryl Alkyl Alcohols and is a primary alcohol. The AAAs are a structurally diverse class of fragrance ingredients that includes primary, secondary, and tertiary alkyl alcohols covalently bonded to an aryl (Ar) group, which may be either a substituted or unsubstituted benzene ring. The common structural element for the AAA fragrance ingredients is an alcohol group -C-(R1)(R2)OH and generically the AAA fragrances can be represented as an Ar-C-(R1)(R2)OH or Ar-Alkyl-C-(R1)(R2)OH group. This review contains a detailed summary of all available toxicology and dermatology papers related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for benzyl alcohol were evaluated then summarized and includes physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, skin sensitization, elicitation, phototoxicity, photoallergy, toxicokinetics, repeated dose, reproductive toxicity, genotoxicity, and carcinogenicity data. A safety assessment of the entire Aryl Alkyl Alcohols will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all Aryl Alkyl Alcohols in fragrances. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sensitization to radiation and alkylating agents by inhibitors of poly(ADP-ribose) polymerase is enhanced in cells deficient in DNA double-strand break repair.

PubMed

Löser, Dana A; Shibata, Atsushi; Shibata, Akiko K; Woodbine, Lisa J; Jeggo, Penny A; Chalmers, Anthony J

2010-06-01

As single agents, chemical inhibitors of poly(ADP-ribose) polymerase (PARP) are nontoxic and have clinical efficacy against BRCA1- and BRCA2-deficient tumors. PARP inhibitors also enhance the cytotoxicity of ionizing radiation and alkylating agents but will only improve clinical outcomes if tumor sensitization exceeds effects on normal tissues. It is unclear how tumor DNA repair proficiency affects the degree of sensitization. We have previously shown that the radiosensitizing effect of PARP inhibition requires DNA replication and will therefore affect rapidly proliferating tumors more than normal tissues. Because many tumors exhibit defective DNA repair, we investigated the impact of double-strand break (DSB) repair integrity on the sensitizing effects of the PARP inhibitor olaparib. Sensitization to ionizing radiation and the alkylating agent methylmethane sulfonate was enhanced in DSB repair-deficient cells. In Artemis(-/-) and ATM(-/-) mouse embryo fibroblasts, sensitization was replication dependent and associated with defective repair of replication-associated damage. Radiosensitization of Ligase IV(-/-) mouse embryo fibroblasts was independent of DNA replication and is explained by inhibition of "alternative" end joining. After methylmethane sulfonate treatment, PARP inhibition promoted replication-independent accumulation of DSB, repair of which required Ligase IV. Our findings predict that the sensitizing effects of PARP inhibitors will be more pronounced in rapidly dividing and/or DNA repair defective tumors than normal tissues and show their potential to enhance the therapeutic ratio achieved by conventional DNA-damaging agents.

Visible‐Light‐Mediated Selective Arylation of Cysteine in Batch and Flow

PubMed Central

Bottecchia, Cecilia; Rubens, Maarten; Gunnoo, Smita B.; Hessel, Volker; Madder, Annemieke

2017-01-01

Abstract A mild visible‐light‐mediated strategy for cysteine arylation is presented. The method relies on the use of eosin Y as a metal‐free photocatalyst and aryldiazonium salts as arylating agents. The reaction can be significantly accelerated in a microflow reactor, whilst allowing the in situ formation of the required diazonium salts. The batch and flow protocol described herein can be applied to obtain a broad series of arylated cysteine derivatives and arylated cysteine‐containing dipeptides. Moreover, the method was applied to the chemoselective arylation of a model peptide in biocompatible reaction conditions (room temperature, phosphate‐buffered saline (PBS) buffer) within a short reaction time. PMID:28805276

Chemical forms of sulfur in geological and archeological asphaltenes from Middle East, France, and Spain determined by sulfur K- and L-edge X-ray absorption near-edge structure spectroscopy

NASA Astrophysics Data System (ADS)

Sarret, Géraldine; Connan, Jacques; Kasrai, Masoud; Bancroft, G. Michael; Charrié-Duhaut, Armelle; Lemoine, Sylvie; Adam, Pierre; Albrecht, Pierre; Eybert-Bérard, Laurent

1999-11-01

Asphaltene samples extracted from archeological and geological bitumens from the Middle East, France, and Spain were studied by sulfur K- and L-edge X-ray absorption near-edge structure (XANES) spectroscopy in combination with isotopic analyses (δ 13C and δD). Within each series, the samples were genetically related by their δ 13C values. The gross and elemental composition and the δD values were used to characterize the weathering state of the samples. Sulfur K- and L-edge XANES results show that in all the samples, dibenzothiophenes are the dominant forms of sulfur. In the least oxidized asphaltenes, minor species include disulfides, alkyl and aryl sulfides, and sulfoxides. With increasing alteration the proportion of oxidized sulfur (sulfoxides, sulfones, sulfonates and sulfates) increases, whereas the disulfide and sulfide content decreases. This evolution is observed in all the series, regardless of the origin of the asphaltenes. This work illustrates the advantages of XANES spectroscopy as a selective probe for determining sulfur speciation in natural samples. It also shows that S K- and L-edge XANES spectroscopy are complementary for identifying the oxidized and reduced forms of sulfur, respectively.

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium mono- and dimethyl naphthalene sulfonates... sulfonates. The food additive sodium mono- and dimethyl naphthalene sulfonates may be safely used in... statement declaring the presence of sodium mono- and dimethyl naphthalene sulfonates. [42 FR 14491, Mar. 15...

From ketones to esters by a Cu-catalyzed highly selective C(CO)-C(alkyl) bond cleavage: aerobic oxidation and oxygenation with air.

PubMed

Huang, Xiaoqiang; Li, Xinyao; Zou, Miancheng; Song, Song; Tang, Conghui; Yuan, Yizhi; Jiao, Ning

2014-10-22

The Cu-catalyzed aerobic oxidative esterification of simple ketones via C-C bond cleavage has been developed. Varieties of common ketones, even inactive aryl long-chain alkyl ketones, are selectively converted into esters. The reaction tolerates a wide range of alcohols, including primary and secondary alcohols, chiral alcohols with retention of the configuration, electron-deficient phenols, as well as various natural alcohols. The usage of inexpensive copper catalyst, broad substrate scope, and neutral and open air conditions make this protocol very practical. (18)O labeling experiments reveal that oxygenation occurs during this transformation. Preliminary mechanism studies indicate that two novel pathways are mainly involved in this process.

The Scarlet Letter of Alkylation: A Mini Review of Selective Alkylating Agents

PubMed Central

Oronsky, Bryan T; Reid, Tony; Knox, Susan J; Scicinski, Jan J

2012-01-01

If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to “tame” the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it is referred to herein, constitutes an extremely nascent and dynamic field in oncology. The pharmacodynamic response to this selective strategy depends on a delicate kinetic balance between specificity and the rate and extent of binding. Three representative compounds are presented: RRx-001, 3-bromopyruvate, and TH-302. The main impetus for the development of these compounds has been the avoidance of the serious complications of traditional alkylating agents; therefore, it is the thesis of this review that they should not experience stigma by association. PMID:22937173

Novel Haloperoxidase from the Agaric Basidiomycete Agrocybe aegerita Oxidizes Aryl Alcohols and Aldehydes

PubMed Central

Ullrich, René; Nüske, Jörg; Scheibner, Katrin; Spantzel, Jörg; Hofrichter, Martin

2004-01-01

Agrocybe aegerita, a bark mulch- and wood-colonizing basidiomycete, was found to produce a peroxidase (AaP) that oxidizes aryl alcohols, such as veratryl and benzyl alcohols, into the corresponding aldehydes and then into benzoic acids. The enzyme also catalyzed the oxidation of typical peroxidase substrates, such as 2,6-dimethoxyphenol (DMP) or 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS). A. aegerita peroxidase production depended on the concentration of organic nitrogen in the medium, and highest enzyme levels were detected in the presence of soybean meal. Two fractions of the enzyme, AaP I and AaP II, which had identical molecular masses (46 kDa) and isoelectric points of 4.6 to 5.4 and 4.9 to 5.6, respectively (corresponding to six different isoforms), were identified after several steps of purification, including anion- and cation-exchange chromatography. The optimum pH for the oxidation of aryl alcohols was found to be around 7, and the enzyme required relatively high concentrations of H2O2 (2 mM) for optimum activity. The apparent Km values for ABTS, DMP, benzyl alcohol, veratryl alcohol, and H2O2 were 37, 298, 1,001, 2,367 and 1,313 μM, respectively. The N-terminal amino acid sequences of the main AaP II spots blotted after two-dimensional gel electrophoresis were almost identical and exhibited almost no homology to the sequences of other peroxidases from basidiomycetes, but they shared the first three amino acids, as well as two additional amino acids, with the heme chloroperoxidase (CPO) from the ascomycete Caldariomyces fumago. This finding is consistent with the fact that AaP halogenates monochlorodimedone, the specific substrate of CPO. The existence of haloperoxidases in basidiomycetous fungi may be of general significance for the natural formation of chlorinated organic compounds in forest soils. PMID:15294788

Rhodium Catalyzed Intramolecular C-H Insertion of α-Aryl-α-diazo Ketones

PubMed Central

Taber, Douglass F.; Tian, Weiwei

2011-01-01

Direct diazo transfer proceeds smoothly with α-aryl ketones. The derived α-aryl-α-diazo ketones cyclize efficiently with Rh catalysis to give the corresponding α-aryl cyclopentanones. PMID:17385917

Electronic states of aryl radical functionalized graphenes: Density functional theory study

NASA Astrophysics Data System (ADS)

Tachikawa, Hiroto; Kawabata, Hiroshi

2016-06-01

Functionalized graphenes are known as a high-performance molecular device. In the present study, the structures and electronic states of the aryl radical functionalized graphene have been investigated by the density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of graphene (GR). Also, the mechanism of aryl radical reaction with GR was investigated. The benzene, biphenyl, p-terphenyl, and p-quaterphenyl radicals [denoted by (Bz) n (n = 1-4), where n means numbers of benzene rings in aryl radical] were examined as aryl radicals. The DFT calculation of GR-(Bz) n (n = 1-4) showed that the aryl radical binds to the carbon atom of GR, and a C-C single bond was formed. The binding energies of aryl radicals to GR were calculated to be ca. 6.0 kcal mol-1 at the CAM-B3LYP/6-311G(d,p) level. It was found that the activation barrier exists in the aryl radical addition: the barrier heights were calculated to be 10.0 kcal mol-1. The electronic states of GR-(Bz) n were examined on the basis of theoretical results.

Synthesis, structure, theoretical and experimental in vitro antioxidant/pharmacological properties of α-aryl, N-alkyl nitrones, as potential agents for the treatment of cerebral ischemia.

PubMed

Samadi, Abdelouahid; Soriano, Elena; Revuelta, Julia; Valderas, Carolina; Chioua, Mourad; Garrido, Ignacio; Bartolomé, Begoña; Tomassolli, Isabelle; Ismaili, Lhassane; González-Lafuente, Laura; Villarroya, Mercedes; García, Antonio G; Oset-Gasque, María J; Marco-Contelles, José

2011-01-15

The synthesis, structure, theoretical and experimental in vitro antioxidant properties using the DPPH, ORAC, and benzoic acid, as well as preliminary in vitro pharmacological activities of (Z)-α-aryl and heteroaryl N-alkyl-nitrones 6-15, 18, 19, 21, and 23, is reported. In the in vitro antioxidant activity, for the DPPH radical test, only nitrones bearing free phenol groups gave the best RSA (%) values, nitrones 13 and 14 showing the highest values in this assay. In the ORAC analysis, the most potent radical scavenger was nitrone indole 21, followed by the N-benzyl benzene-type nitrones 10 and 15. Interestingly enough, the archetypal nitrone 7 (PBN) gave a low RSA value (1.4%) in the DPPH test, or was inactive in the ORAC assay. Concerning the ability to scavenge the hydroxyl radical, all the nitrones studied proved active in this experiment, showing high values in the 94-97% range, the most potent being nitrone 14. The theoretical calculations for the prediction of the antioxidant power, and the potential of ionization confirm that nitrones 9 and 10 are among the best compounds in electron transfer processes, a result that is also in good agreement with the experimental values in the DPPH assay. The calculated energy values for the reaction of ROS (hydroxyl, peroxyl) with the nitrones predict that the most favourable adduct-spin will take place between nitrones 9, 10, and 21, a fact that would be in agreement with their experimentally observed scavenger ability. The in vitro pharmacological analysis showed that the neuroprotective profile of the target molecules was in general low, with values ranging from 0% to 18.7%, in human neuroblastoma cells stressed with a mixture of rotenone/oligomycin-A, being nitrones 18, and 6-8 the most potent, as they show values in the range 24-18.4%. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

DOEpatents

Martinez, Rodolfo A [Santa Fe, NM; Unkefer, Clifford J [Los Alamos, NM; Alvarez, Marc A [Santa Fe, NM

2009-09-01

The present invention is directed to labeled compounds, of the formulae ##STR00001## wherein C* is each independently selected from the group consisting of .sup.13C and .sup.12C with the proviso that at least one C* is .sup.13C, each hydrogen of the methylene group can independently be either hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is from the group of sulfide, sulfinyl, and sulfone, Z is an aryl group from the group of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently from the group of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group from the group of NH.sub.2, NHR and NRR' where R and R' are each independently from the group of a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms.

Synthesis of labeled oxalic acid derivatives

DOEpatents

Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

2004-06-22

The present invention is directed to labeled compounds, specifically ##STR1## where each C* is selected from the group consisting of a carbon-12, i.e., .sup.12 C, or a carbon-13, i.e., .sup.13 C and at least one C* is .sup.13 C, R.sup.1 is selected from the group of C.sub.1 -C.sub.4 lower alkyl and aryl, and X is selected from the group of --NR.sup.2 R.sup.3 where R.sup.2 and R.sup.3 are each independently selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, --SR.sup.4 where R.sup.4 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, and --OR.sup.5 where R.sup.5 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl with the proviso that when R.sup.1 is methyl then R.sup.5 is other than methyl, when R.sup.1 is ethyl then R.sup.5 is other than ethyl, and when R.sup.1 is benzyl then R.sup.5 is other than benzyl.

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase.

PubMed

Kim, In-Hae; Park, Yong-Kyu; Nishiwaki, Hisashi; Hammock, Bruce D; Nishi, Kosuke

2015-11-15

Structure-activity relationships of amide-phosphonate derivatives as inhibitors of the human soluble epoxide hydrolase (sEH) were investigated. First, a series of alkyl or aryl groups were substituted on the carbon alpha to the phosphonate function in amide compounds to see whether substituted phosphonates can act as a secondary pharmacophore. A tert-butyl group (16) on the alpha carbon was found to yield most potent inhibition on the target enzyme. A 4-50-fold drop in inhibition was induced by other substituents such as aryls, substituted aryls, cycloalkyls, and alkyls. Then, the modification of the O-substituents on the phosphonate function revealed that diethyl groups (16 and 23) were preferable for inhibition to other longer alkyls or substituted alkyls. In amide compounds with the optimized diethylphosphonate moiety and an alkyl substitution such as adamantane (16), tetrahydronaphthalene (31), or adamantanemethane (36), highly potent inhibitions were gained. In addition, the resulting potent amide-phosphonate compounds had reasonable water solubility, suggesting that substituted phosphonates in amide inhibitors are effective for both inhibition potency on the human sEH and water solubility as a secondary pharmacophore. Copyright © 2015 Elsevier Ltd. All rights reserved.

40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt (PMN...

40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt (PMN...

40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt (PMN...

40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium salt...

40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt (PMN...

40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt (PMN...

Bisphenol A sulfonation is impaired in metabolic and liver disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yalcin, Emine B.; Kulkarni, Supriya R.; Slitt, Angela L., E-mail: angela_slitt@uri.edu

Background: Bisphenol A (BPA) is a widely used industrial chemical and suspected endocrine disruptor to which humans are ubiquitously exposed. The liver metabolizes and facilitates BPA excretion through glucuronidation and sulfonation. The sulfotransferase enzymes contributing to BPA sulfonation (detected in human and rodents) is poorly understood. Objectives: To determine the impact of metabolic and liver disease on BPA sulfonation in human and mouse livers. Methods: The capacity for BPA sulfonation was determined in human liver samples that were categorized into different stages of metabolic and liver disease (including obesity, diabetes, steatosis, and cirrhosis) and in livers from ob/ob mice. Results:more » In human liver tissues, BPA sulfonation was substantially lower in livers from subjects with steatosis (23%), diabetes cirrhosis (16%), and cirrhosis (18%), relative to healthy individuals with non-fatty livers (100%). In livers of obese mice (ob/ob), BPA sulfonation was lower (23%) than in livers from lean wild-type controls (100%). In addition to BPA sulfonation activity, Sult1a1 protein expression decreased by 97% in obese mouse livers. Conclusion: Taken together these findings establish a profoundly reduced capacity of BPA elimination via sulfonation in obese or diabetic individuals and in those with fatty or cirrhotic livers versus individuals with healthy livers. - Highlights: • Present study demonstrates that hepatic SULT 1A1/1A3 are primarily sulfonate BPA in mouse and human. • Hepatic BPA sulfonation is profoundly reduced steatosis, diabetes and cirrhosis. • With BPA-S detectable in urine under low or common exposures, these findings are novel and important.« less

Dual Visible Light Photoredox and Gold-Catalyzed Arylative Ring Expansion

PubMed Central

2015-01-01

A combination of visible light photocatalysis and gold catalysis is applied to a ring expansion–oxidative arylation reaction. The reaction provides an entry into functionalized cyclic ketones from the coupling reaction of alkenyl and allenyl cycloalkanols with aryl diazonium salts. A mechanism involving generation of an electrophilic gold(III)–aryl intermediate is proposed on the basis of mechanistic studies, including time-resolved FT-IR spectroscopy. PMID:24730447

Processable Electronically Conducting Polymers

DTIC Science & Technology

1991-01-01

polyheterocycles and will be discussed in detail later. The Grignard coupling reaction of alkyl substituted 1,4- dibromobenzenes was initially employed, as...R 2 ,R 3 ) along with alkyl , aryl, benzyl, and -CH 2 CN substituents on the nitrogen (R I ). Since aniline preferentially oxidatively polymerizes at...but, in the case of N-aryl substituted anilines , an alternative mecha- nism has been proposed [171], which is outlined in Scheme 9. Both poly(N

Diisopropylfluorophosphate-sensitive aryl acylamidase activity of fatty acid free human serum albumin.

PubMed

Manoharan, Indumathi; Boopathy, Rathnam

2006-08-15

Butyrylcholinesterase in human plasma and acetylcholinesterase in human red blood cells have aryl acylamidase activity toward o-nitroacetanilide, hydrolyzing the amide bond to produce o-nitroaniline and acetate. People with a genetic variant of butyrylcholinesterase that had no detectable activity with butyrylthiocholine, nevertheless had aryl acylamidase activity in their plasma. To determine the source of this aryl acylamidase activity we tested fatty acid free human albumin for activity. We found that albumin had aryl acylacylamidase activity and that this activity was inhibited by diisopropylfluorophosphate. Since the esterase activity of albumin is also inhibited by diisopropylfluorophosphate, and since it is known that diisopropylfluorophosphate covalently binds to Tyr 411 of human albumin, we conclude that the active site for aryl acylamidase activity of albumin is Tyr 411. Albumin accounts for about 10% of the aryl acylamidase activity in human plasma.

Photoswitchable Fluorescent Diarylethene Derivatives with Thiophene 1,1-Dioxide Groups: Effect of Alkyl Substituents at the Reactive Carbons

PubMed Central

Sumi, Takaki; Irie, Masahiro

2017-01-01

Photoswitching and fluorescent properties of sulfone derivatives of 1,2-bis(2-alkyl-4-methyl-5-phenyl-3-thienyl)perfluorocyclopentene, 1–5, having methyl, ethyl, n-propyl, i-propyl, and i-butyl substituents at the reactive carbons (2- and 2′-positions) of the thiophene 1,1-dioxide rings were studied. Diarylethenes 1–5 underwent isomerization reactions between open-ring and closed-ring forms upon alternate irradiation with ultraviolet (UV) and visible light and showed fluorescence in the closed-ring forms. The alkyl substitution at the reactive carbons affects the fluorescent property of the closed-ring isomers. The closed-ring isomers 2b–5b with ethyl, n-propyl, i-propyl, and i-butyl substituents show higher fluorescence quantum yields than 1b with methyl substituents. In polar solvents, the fluorescence quantum yield of 1b markedly decreases, while 2b–5b maintain the relatively high fluorescence quantum yields. Although the cycloreversion quantum yields of the derivatives with methyl, ethyl, n-propyl, and i-propyl substituents are quite low and in the order of 10−5, introduction of i-butyl substituents was found to increase the yield up to the order of 10−3. These results indicate that appropriate alkyl substitution at the reactive carbons is indispensable for properly controlling the photoswitching and fluorescent properties of the photoswitchable fluorescent diarylethenes, which are potentially applicable to super-resolution fluorescence microscopies. PMID:28869489

Sulfonated polyphenylene polymers

DOEpatents

Cornelius, Christopher J.; Fujimoto, Cy H.; Hickner, Michael A.

2007-11-27

Improved sulfonated polyphenylene compositions, improved polymer electrolyte membranes and nanocomposites formed there from for use in fuel cells are described herein. The improved compositions, membranes and nanocomposites formed there from overcome limitations of Nafion.RTM. membranes.

Method of making alkyl esters

DOEpatents

Elliott, Brian

2010-09-14

Methods of making alkyl esters are described herein. The methods are capable of using raw, unprocessed, low-cost feedstocks and waste grease. Generally, the method involves converting a glyceride source to a fatty acid composition and esterifying the fatty acid composition to make alkyl esters. In an embodiment, a method of making alkyl esters comprises providing a glyceride source. The method further comprises converting the glyceride source to a fatty acid composition comprising free fatty acids and less than about 1% glyceride by mass. Moreover, the method comprises esterifying the fatty acid composition in the presence of a solid acid catalyst at a temperature ranging firm about 70.degree. C. to about 120.degree. C. to produce alkyl esters, such that at least 85% of the free fatty acids are converted to alkyl esters. The method also incorporates the use of packed bed reactors for glyceride conversion and/or fatty acid esterification to make alkyl esters.

Visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO.

PubMed

Pramanik, Mukund M D; Rastogi, Namrata

2016-06-30

The visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO is illustrated. This is the first example of DMSO being used as the source of the methylsulfinyl group. The procedure tolerates a wide range of functional groups on (het)aryl diazonium salts and provides aryl methyl sulfoxides in excellent yields under mild reaction conditions.

Mild and selective vanadium-catalyzed oxidation of benzylic, allylic, and propargylic alcohols using air

DOEpatents

Hanson, Susan Kloek; Silks, Louis A; Wu, Ruilian

2013-08-27

The invention concerns processes for oxidizing an alcohol to produce a carbonyl compound. The processes comprise contacting the alcohol with (i) a gaseous mixture comprising oxygen; and (ii) an amine compound in the presence of a catalyst, having the formula: ##STR00001## where each of R.sup.1-R.sup.12 are independently H, alkyl, aryl, CF.sub.3, halogen, OR.sup.13, SO.sub.3R.sup.14, C(O)R.sup.15, CONR.sup.16R.sup.17 or CO.sub.2R.sup.18; each of R.sup.13-R.sup.18 is independently alkyl or aryl; and Z is alkl or aryl.

Stereoconvergent Amine-Directed Alkyl–Alkyl Suzuki Reactions of Unactivated Secondary Alkyl Chlorides

PubMed Central

Lu, Zhe; Wilsily, Ashraf; Fu, Gregory C.

2011-01-01

A new family of stereoconvergent cross-couplings of unactivated secondary alkyl electrophiles has been developed, specifically, arylamine-directed alkyl–alkyl Suzuki reactions. This represents the first such investigation to be focused on the use of alkyl chlorides as substrates. Structure-enantioselectivity studies are consistent with the nitrogen, not the aromatic ring, serving as the primary site of coordination of the arylamine to the catalyst. The rate law for this asymmetric cross-coupling is compatible with transmetalation being the turnover-limiting step of the catalytic cycle. PMID:21553917

Non-aqueous electrolyte for lithium-ion battery

DOEpatents

Amine, Khalil; Zhang, Lu; Zhang, Zhengcheng

2016-01-26

A substantially non-aqueous electrolyte solution includes an alkali metal salt, a polar aprotic solvent, and an organophosphorus compound of Formula IA, IB, or IC: ##STR00001## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently hydrogen, halogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heterocyclyl, heteroaryl, alkoxy, alkenoxy, alkynoxy, cycloalkoxy, aryloxy, heterocyclyloxy, heteroaryloxy, siloxyl, silyl, or organophosphatyl; R.sup.5 and R.sup.6 are each independently alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; R.sup.7 is ##STR00002## and R.sup.8, R.sup.9 and R.sup.10 are each independently alkyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; provided that if the organophosphorus compound is of Formula IB, then at least one of R.sup.5, and R.sup.6 are other than hydrogen, alkyl, or alkenyl; and if the organophosphorus compound is of Formula IC, then the electrolyte solution does not include 4-methylene-1,3-dioxolan-2-one or 4,5-dimethylene-1,3-dioxolan-2-one.

Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

PubMed

Ackermann, Lutz; Vicente, Rubén; Kapdi, Anant R

2009-01-01

The area of transition-metal-catalyzed direct arylation through cleavage of C-H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners--including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.

Palladium-Catalyzed Conversion of Aryl and Vinyl Triflates to Bromides and Chlorides

PubMed Central

Shen, Xiaoqiang; Hyde, Alan M.; Buchwald, Stephen L.

2010-01-01

The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl and vinyl halides can be prepared via this method in good to excellent yields. PMID:20857936

C-H bond functionalization via hydride transfer: formation of α-arylated piperidines and 1,2,3,4-tetrahydroisoquinolines via stereoselective intramolecular amination of benzylic C-H bonds.

PubMed

Vadola, Paul A; Carrera, Ignacio; Sames, Dalibor

2012-08-17

We here report a study of the intramolecular amination of sp(3) C-H bonds via the hydride transfer cyclization of N-tosylimines (HT-amination). In this transformation, 5-aryl aldehydes are subjected to N-toluenesulfonamide in the presence of BF(3)·OEt(2) to effect imine formation and HT-cyclization, leading to 2-arylpiperidines and 3-aryl-1,2,3,4-tetrahydroisoquinolines in a one-pot procedure. We examined the reactivity of a range of aldehyde substrates as a function of their conformational flexibility. Substrates of higher conformational rigidity were more reactive, giving higher yields of the desired products. However, a single substituent on the alkyl chain linking the N-tosylimine and the benzylic sp(3) C-H bonds was sufficient for HT-cyclization to occur. In addition, an examination of various arenes revealed that the electronic character of the hydridic C-H bonds dramatically affects the efficiency of the reaction. We also found that this transformation is highly stereoselective; 2-substituted aldehydes yield cis-2,5-disubstituted piperidines, while 3-substituted aldehydes afford trans-2,4-disubstituted piperidines. The stereoselectivity is a consequence of thermodynamic control. The pseudoallylic strain between the arene and tosyl group on the piperidine ring is proposed to rationalize the greater stability of the isomer with the aryl ring in the axial position. This preferential placement of the arene is proposed to affect the observed stereoselectivity.

Adsorption mechanism of mixed cationic/anionic collectors in feldspar-quartz flotation system.

PubMed

Vidyadhar, A; Hanumantha Rao, K

2007-02-15

The adsorption mechanism of mixed cationic alkyl diamine and anionic sulfonate/oleate collectors at acidic pH values was investigated on microcline and quartz minerals through Hallimond flotation, electrokinetic and diffuse reflectance FTIR studies. In the presence of anionic collectors, neither of the minerals responded to flotation but the diamine flotation of the minerals was observed to be pH and concentration dependent. The presence of sulfonate enhanced the diamine flotation of the minerals by its co-adsorption. The difference in surface charge between the minerals at pH 2 was found to be the basis for preferential feldspar flotation from quartz in mixed diamine/sulfonate collectors. The infrared spectra revealed no adsorption of sulfonate collector when used alone but displayed its co-adsorption as diamine-sulfonate complex when used with diamine. The presence of sulfonate increased the diamine adsorption due to a decrease in the electrostatic head-head repulsion between the adjacent surface ammonium ions and thereby increasing the lateral tail-tail hydrophobic bonds. The mole ratio of diamine/sulfonate was found to be an important factor in the orientation of alkyl chains and thus the flotation response of minerals. The increase in sulfonate concentration beyond diamine concentration leads to the formation of soluble 1:2 diamine-sulfonate complex or precipitate and the adsorption of these species decreased the flotation since the alkyl chains are in chaotical orientation with a conceivable number of head groups directing towards the solution phase.

Nanoscale structure and morphology of sulfonated polyphenylenes via atomistic simulations

DOE PAGES

Abbott, Lauren J.; Frischknecht, Amalie L.

2017-01-23

We performed atomistic simulations on a series of sulfonated polyphenylenes systematically varying the degree of sulfonation and water content to determine their effect on the nanoscale structure, particularly for the hydrophilic domains formed by the ionic groups and water molecules. We found that the local structure around the ionic groups depended on the sulfonation and hydration levels, with the sulfonate groups and hydronium ions less strongly coupled at higher water contents. In addition, we characterized the morphology of the ionic domains employing two complementary clustering algorithms. At low sulfonation and hydration levels, clusters were more elongated in shape and poorlymore » connected throughout the system. As the degree of sulfonation and water content were increased, the clusters became more spherical, and a fully percolated ionic domain was formed. As a result, these structural details have important implications for ion transport.« less

Alkylation of enolates: An electrophilicity perspective

NASA Astrophysics Data System (ADS)

Elango, M.; Parthasarathi, R.; Subramanian, V.; Chattaraj, P. K.

Enolates are ambient nucleophiles, and alkylation can occur either at a carbon or at an oxygen site. It is known that the ratio of C/O alkylation depends significantly on various factors, including the type of enolate, alkylating agent, site of alkylation, and solvent environment. Analysis of regioselectivity and solvent effects on alkylation of lithium enolates is investigated using various reactivity descriptors, including generalized philicity. These results point out the reliability of both global and local reactivity descriptors in providing significant information about site selectivity and chemical reactivity of lithium enolates.

Design, fabrication and evaluation of intelligent sulfone-selective polybenzimidazole nanofibers.

PubMed

Ogunlaja, Adeniyi S; du Sautoy, Carol; Torto, Nelson; Tshentu, Zenixole R

2014-08-01

Molecularly imprinted polybenzimidazole nanofibers fabricated for the adsorption of oxidized organosulfur compounds are presented. The imprinted polymers exhibited better selectivity for their target model sulfone-containing compounds with adsorption capacities of 28.5±0.4mg g(-1), 29.8±2.2mg g(-1) and 20.1±1.4mg g(-1) observed for benzothiophene sulfone (BTO2), dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) respectively. Molecular modeling based upon the density functional theory (DFT) indicated that hydrogen bond interactions may take place between sulfone oxygen groups with NH groups of the PBI. Further DFT also confirmed the feasibility of π-π interactions between the benzimidazole rings and the aromatic sulfone compounds. The adsorption mode followed the Freundlich (multi-layered) adsorption isotherm which indicated possible sulfone-sulfone interactions. A home-made pressurized hot water extraction (PHWE) system was employed for the extraction/desorption of sulfone compounds within imprinted nanofibers at 1mL min(-1), 150°C and 30 bar. PHWE used a green solvent (water) and achieved better extraction yields compared to the Soxhlet extraction process. The application of molecularly imprinted polybenzimidazole (PBI) nanofibers displayed excellent sulfur removal, with sulfur in fuel after adsorption falling below the determined limit of detection (LOD), which is 2.4mg L(-1)S, and with a sulfur adsorption capacity of 5.3±0.4mg g(-1) observed for application in the fuel matrix. Copyright © 2014 Elsevier B.V. All rights reserved.

Palladium-Catalyzed Arylation of Fluoroalkylamines

PubMed Central

Brusoe, Andrew T.; Hartwig, John F.

2015-01-01

We report the synthesis of fluorinated anilines by palladium-catalyzed coupling of fluoroalkylamines with aryl bromides and aryl chlorides. The products of these reactions are valuable because anilines typically require the presence of an electron-withdrawing substituent on nitrogen to suppress aerobic or metabolic oxidation, and the fluoroalkyl groups have steric properties and polarity distinct from those of more common electron-withdrawing amide and sulfonamide units. The fluoroalkylaniline products are unstable under typical conditions for C–N coupling reactions (heat and strong base). However, the reactions conducted with the weaker base KOPh, which has rarely been used in cross-coupling to form C–N bonds, occurred in high yield in the presence of a catalyst derived from commercially available AdBippyPhos and [Pd(allyl)Cl]2. Under these conditions, the reactions occur with low catalyst loadings (<0.50 mol % for most substrates) and tolerate the presence of various functional groups that react with the strong bases that are typically used in Pd-catalyzed C–N cross-coupling reactions of aryl halides. The resting state of the catalyst is the phenoxide complex, (BippyPhosPd(Ar)OPh); due to the electron-withdrawing property of the fluoroalkyl substituent, the turnover-limiting step of the reaction is reductive elimination to form the C–N bond. PMID:26065341

Thioimidazolium Ionic Liquids as Tunable Alkylating Agents.

PubMed

Guterman, Ryan; Miao, Han; Antonietti, Markus

2018-01-19

Alkylating ionic liquids based on the thioimidazolium structure combine the conventional properties of ionic liquids, including low melting point and nonvolatility, with the alkylating function. Alkyl transfer occurs exclusively from the S-alkyl position, thus allowing for easy derivatization of the structure without compromising specificity. We apply this feature to tune the electrophilicty of the cation to profoundly affect the reactivity of these alkylating ionic liquids, with a caffeine-derived compound possessing the highest reactivity. Anion choice was found to affect reaction rates, with iodide anions assisting in the alkylation reaction through a "shuttling" process. The ability to tune the properties of the alkylating agent using the toolbox of ionic liquid chemistry highlights the modular nature of these compounds as a platform for alkylating agent design and integration in to future systems.

Inhibition of thioredoxin reductase but not of glutathione reductase by the major classes of alkylating and platinum-containing anticancer compounds.

PubMed

Witte, Anne-Barbara; Anestål, Karin; Jerremalm, Elin; Ehrsson, Hans; Arnér, Elias S J

2005-09-01

Mammalian thioredoxin reductase (TrxR) is important for cell proliferation, antioxidant defense, and redox signaling. Together with glutathione reductase (GR) it is the main enzyme providing reducing equivalents to many cellular processes. GR and TrxR are flavoproteins of the same enzyme family, but only the latter is a selenoprotein. With the active site containing selenocysteine, TrxR may catalyze reduction of a wide range of substrates, but can at the same time easily be targeted by electrophilic compounds due to the extraordinarily high reactivity of a selenolate moiety. Here we addressed the inhibition of the enzyme by major anticancer alkylating agents and platinum-containing compounds and we compared it to that of GR. We confirmed prior studies suggesting that the nitrosourea carmustine can inhibit both GR and TrxR. We next found, however, that nitrogen mustards (chlorambucil and melphalan) and alkyl sulfonates (busulfan) efficiently inhibited TrxR while these compounds, surprisingly, did not inhibit GR. Inhibitions were concentration and time dependent and apparently irreversible. Anticancer anthracyclines (daunorubicin and doxorubicin) were, in contrast to the alkylating agents, not inhibitors but poor substrates of TrxR. We also found that TrxR, but not GR, was efficiently inhibited by both cisplatin, its monohydrated complex, and oxaliplatin. Carboplatin, in contrast, could not inhibit any of the two enzymes. These findings lead us to conclude that representative compounds of the major classes of clinically used anticancer alkylating agents and most platinum compounds may easily target TrxR, but not GR. The TrxR inhibition should thereby be considered as a factor that may contribute to the cytotoxicity seen upon clinical use of these drugs.

Nickel-catalyzed synthesis of aryl trifluoromethyl sulfides at room temperature.

PubMed

Zhang, Cheng-Pan; Vicic, David A

2012-01-11

Inexpensive nickel-bipyridine complexes were found to be active for the trifluoromethylthiolation of aryl iodides and aryl bromides at room temperature using the convenient [NMe(4)][SCF(3)] reagent. © 2011 American Chemical Society

Divergent unprotected peptide macrocyclisation by palladium-mediated cysteine arylation.

PubMed

Rojas, Anthony J; Zhang, Chi; Vinogradova, Ekaterina V; Buchwald, Nathan H; Reilly, John; Pentelute, Bradley L; Buchwald, Stephen L

2017-06-01

Macrocyclic peptides are important therapeutic candidates due to their improved physicochemical properties in comparison to their linear counterparts. Here we detail a method for a divergent macrocyclisation of unprotected peptides by crosslinking two cysteine residues with bis-palladium organometallic reagents. These synthetic intermediates are prepared in a single step from commercially available aryl bis-halides. Two bioactive linear peptides with cysteine residues at i , i + 4 and i , i + 7 positions, respectively, were cyclised to introduce a diverse array of aryl and bi-aryl linkers. These two series of macrocyclic peptides displayed similar linker-dependent lipophilicity, phospholipid affinity, and unique volume of distributions. Additionally, one of the bioactive peptides showed target binding affinity that was predominantly affected by the length of the linker. Collectively, this divergent strategy allowed rapid and convenient access to various aryl linkers, enabling the systematic evaluation of the effect of appending unit on the medicinal properties of macrocyclic peptides.

Optimization of Aryl Amides that Extend Survival in Prion-Infected Mice

PubMed Central

Giles, Kurt; Berry, David B.; Condello, Carlo; Dugger, Brittany N.; Li, Zhe; Oehler, Abby; Bhardwaj, Sumita; Elepano, Manuel; Guan, Shenheng; Silber, B. Michael; Olson, Steven H.

2016-01-01

Developing therapeutics for neurodegenerative diseases (NDs) prevalent in the aging population remains a daunting challenge. With the growing understanding that many NDs progress by conformational self-templating of specific proteins, the prototypical prion diseases offer a platform for ND drug discovery. We evaluated high-throughput screening hits with the aryl amide scaffold and explored the structure–activity relationships around three series differing in their N-aryl core: benzoxazole, benzothiazole, and cyano. Potent anti-prion compounds were advanced to pharmacokinetic studies, and the resulting brain-penetrant leads from each series, together with a related N-aryl piperazine lead, were escalated to long-term dosing and efficacy studies. Compounds from each of the four series doubled the survival of mice infected with a mouse-passaged prion strain. Treatment with aryl amides altered prion strain properties, as evidenced by the distinct patterns of neuropathological deposition of prion protein and associated astrocytic gliosis in the brain; however, none of the aryl amide compounds resulted in drug-resistant prion strains, in contrast to previous studies on compounds with the 2-aminothiazole (2-AMT) scaffold. As seen with 2-AMTs and other effective anti-prion compounds reported to date, the novel aryl amides reported here were ineffective in prolonging the survival of transgenic mice infected with human prions. Most encouraging is our discovery that aryl amides show that the development of drug resistance is not an inevitable consequence of efficacious anti-prion therapeutics. PMID:27317802

40 CFR 721.10564 - Mixed amino diaryl sulfone isomers (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed amino diaryl sulfone isomers... Specific Chemical Substances § 721.10564 Mixed amino diaryl sulfone isomers (generic). (a) Chemical... as mixed amino diaryl sulfone isomers (PMN P-08-39) is subject to reporting under this section for...

40 CFR 721.10564 - Mixed amino diaryl sulfone isomers (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed amino diaryl sulfone isomers... Specific Chemical Substances § 721.10564 Mixed amino diaryl sulfone isomers (generic). (a) Chemical... as mixed amino diaryl sulfone isomers (PMN P-08-39) is subject to reporting under this section for...

Color reduction of sulfonated eucalyptus kraft lignin.

PubMed

Zhang, Hui; Bai, Youcan; Zhou, Wanpeng; Chen, Fangeng

2017-04-01

Several eucalyptus lignins named as HSL, SML and BSL were prepared by high temperature sulfonation, sulfomethylation, butane sultone sulfonation respectively. The color properties of samples were investigated. Under optimized conditions the sulfonic group (SO 3 H) content of HSL, SML and BSL reached 1.52, 1.60 and 1.58mmol/g, respectively. Samples were characterized by UV-vis spectroscopy, FTIR spectroscopy, 1 H NMR spectroscopy, GPC and brightness test, respectively. The results revealed that BSL performed a higher molecular weight and lighter color due to the phenolic hydroxyl blocking by 1,4-butane sultone (1,4-BS). The color reduction of sodium borohydride treated BSL (labeled as SBSL) was further enhanced and the brightness value was improved by 76.1% compared with the darkest HSL. SBSL process was much better than HSL and SML process. Hydroxyl blocking effect of 1,4-BS and reducibility of sodium borohydride played important roles in the color reduction of sulfonated eucalyptus kraft lignin. Copyright © 2017 Elsevier B.V. All rights reserved.

Study of sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups as ion conductive binder in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wei, Zengbin; Xue, Lixin; Nie, Feng; Sheng, Jianfang; Shi, Qianru; Zhao, Xiulan

2014-06-01

In an attempt to reduce the Li+ concentration polarization and electrolyte depletion from the electrode porous space, sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups (SPEEK-FSA-Li) is prepared and attempted as ionic conductivity binder. Sulfonated aromatic poly(ether ether ketone) exhibits strong adhesion and chemical stability, and lithiated fluorinated sulfonic side chains help to enhance the ionic conductivity and Li+ ion diffusion due to the charge delocalization over the sulfonic chain. The performances are evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, charge-discharge cycle testing, 180° peel testing, and compared with the cathode prepared with polyvinylidene fluoride binder. The electrode prepared with SPEEK-FSA-Li binder forms the relatively smaller resistances of both the SEI and the charge transfer of lithium ion transport. This is beneficial to lithium ion intercalation and de-intercalation of the cathode during discharging-charging, therefore the cell prepared with SPEEK-FSA-Li shows lower charge plateau potential and higher discharge plateau potential. Compared with PVDF, the electrode with ionic binder shows smaller decrease in capacity with the increasing of cycle rate. Meanwhile, adhesion strength of electrode prepared with SPEEK-FSA-Li is more than five times greater than that with PVDF.

Tumor Uptake And Photodynamic Activity Of Sulfonated Metallo Phthalocyanines

NASA Astrophysics Data System (ADS)

van Lier, Johan E.; Rousseau, Jacques; Paquette, Benoit; Brasseur, N.; Langlois, Rejean; Ali, Hasrat

1989-06-01

Sulfonated metallo phthalocyanines (M-SPC) are extensively studied as sensitizers for photodynamic therapy of cancer. They strongly absorb clinically useful red light with absorption maxima between 670-680 nm. Their photodynamic properties depend on the nature of the central metal ion as well as the degree of substitution on the macrocycle. The zinc, aluminum and gallium complexes are efficient photo-generators of singlet oxygen, the species most likely responsible for their phototoxicity and tumoricidal action. Tissue distribution pattern, cell penetration and dye aggregation are strongly affected by the degree of sulfonation of the dyes. Mono- and disulfonated M-SPC have the highest tendency to form photo-inactive aggregates. However, these lower sulfonated dyes more readily cross cell membranes resulting, in vitro, in enhanced phototoxicity. In vivo, the highly sulfonated hydrophilic M-SPC show the best tumor localization properties but the lower sulfonated dyes still exhibit the best photo-activity. Variations in activities between the differently sulfonated M-SPC are far less pronounced in vivo as compared to in vitro conditions. Such discrepancies are explained by the combined action of numerous vectors including interaction of M-SPC with plasma proteins, vascular versus cellular photo-damage, tumor retention, cell penetration as well as the degree of aggregation of the dye.

Chemoselective N-arylation of aminobenzamides via copper catalysed Chan-Evans-Lam reactions.

PubMed

Liu, Shuai; Zu, Weisai; Zhang, Jinli; Xu, Liang

2017-11-15

Chemoselective N-arylation of unprotected aminobenzamides was achieved via Cu-catalysed Chan-Evans-Lam cross-coupling with aryl boronic acids for the first time. Simple copper catalysts enable the selective arylation of amino groups in ortho/meta/para-aminobenzamides under open-flask conditions. The reactions were scalable and compatible with a wide range of functional groups.

Developing force fields when experimental data is sparse: AMBER/GAFF-compatible parameters for inorganic and alkyl oxoanions.

PubMed

Kashefolgheta, Sadra; Vila Verde, Ana

2017-08-09

We present a set of Lennard-Jones parameters for classical, all-atom models of acetate and various alkylated and non-alkylated forms of sulfate, sulfonate and phosphate ions, optimized to reproduce their interactions with water and with the physiologically relevant sodium, ammonium and methylammonium cations. The parameters are internally consistent and are fully compatible with the Generalized Amber Force Field (GAFF), the AMBER force field for proteins, the accompanying TIP3P water model and the sodium model of Joung and Cheatham. The parameters were developed primarily relying on experimental information - hydration free energies and solution activity derivatives at 0.5 m concentration - with ab initio, gas phase calculations being used for the cases where experimental information is missing. The ab initio parameterization scheme presented here is distinct from other approaches because it explicitly connects gas phase binding energies to intermolecular interactions in solution. We demonstrate that the original GAFF/AMBER parameters often overestimate anion-cation interactions, leading to an excessive number of contact ion pairs in solutions of carboxylate ions, and to aggregation in solutions of divalent ions. GAFF/AMBER parameters lead to excessive numbers of salt bridges in proteins and of contact ion pairs between sodium and acidic protein groups, issues that are resolved by using the optimized parameters presented here.

CuI/L-proline-catalyzed coupling reactions of aryl halides with activated methylene compounds.

PubMed

Xie, Xiaoan; Cai, Guorong; Ma, Dawei

2005-10-13

[reaction: see text] The arylation of ethyl acetoacetate, ethyl benzoyl acetate, and diethyl malonate under the catalysis of CuI/L-proline in DMSO proceeds smoothly at 40-50 degrees C in the presence of Cs2CO3 to provide the 2-aryl-1,3-dicarbonyl compounds in good yields. Both aryl iodides and aryl bromides are compatible with these reaction conditions.

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

PubMed Central

Tajti, Ádám; Ádám, Anna; Csontos, István; Karaghiosoff, Konstantin; Czugler, Mátyás; Ábrányi-Balogh, Péter

2017-01-01

A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair. PMID:28179951

Crystal structure of zwitterionic bisimidazolium sulfonates

NASA Astrophysics Data System (ADS)

Kohmoto, Shigeo; Okuyama, Shinpei; Yokota, Nobuyuki; Takahashi, Masahiro; Kishikawa, Keiki; Masu, Hyuma; Azumaya, Isao

2012-05-01

Crystal structures of three zwitterionic bisimidazolium salts 1-3 in which imidazolium sulfonate moieties were connected with aromatic linkers, p-xylylene, 4,4'-dimethylenebiphenyl, and phenylene, respectively, were examined. The latter two were obtained as hydrates. An S-shaped molecular structure in which the sulfonate moiety was placed on the imidazolium ring was observed for 1. A helical array of hydrated water molecules was obtained for 2 while a linear array of hydrated water molecules was observed for 3.

Optimization of Aryl Amides that Extend Survival in Prion-Infected Mice.

PubMed

Giles, Kurt; Berry, David B; Condello, Carlo; Dugger, Brittany N; Li, Zhe; Oehler, Abby; Bhardwaj, Sumita; Elepano, Manuel; Guan, Shenheng; Silber, B Michael; Olson, Steven H; Prusiner, Stanley B

2016-09-01

Developing therapeutics for neurodegenerative diseases (NDs) prevalent in the aging population remains a daunting challenge. With the growing understanding that many NDs progress by conformational self-templating of specific proteins, the prototypical prion diseases offer a platform for ND drug discovery. We evaluated high-throughput screening hits with the aryl amide scaffold and explored the structure-activity relationships around three series differing in their N-aryl core: benzoxazole, benzothiazole, and cyano. Potent anti-prion compounds were advanced to pharmacokinetic studies, and the resulting brain-penetrant leads from each series, together with a related N-aryl piperazine lead, were escalated to long-term dosing and efficacy studies. Compounds from each of the four series doubled the survival of mice infected with a mouse-passaged prion strain. Treatment with aryl amides altered prion strain properties, as evidenced by the distinct patterns of neuropathological deposition of prion protein and associated astrocytic gliosis in the brain; however, none of the aryl amide compounds resulted in drug-resistant prion strains, in contrast to previous studies on compounds with the 2-aminothiazole (2-AMT) scaffold. As seen with 2-AMTs and other effective anti-prion compounds reported to date, the novel aryl amides reported here were ineffective in prolonging the survival of transgenic mice infected with human prions. Most encouraging is our discovery that aryl amides show that the development of drug resistance is not an inevitable consequence of efficacious anti-prion therapeutics. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

[Synthesis, solubility, lipids-lowering and liver-protection activities of sulfonated formononetin].

PubMed

Wang, Qiu-ya; Meng, Qing-hua; Zhang, Zun-ting; Tian, Zhen-jun; Liu, Hui

2009-04-01

A water-soluble compound, sodium formononetin-3'-sulfonate with good lipid-lowering and liver-protection activities was synthesized. It was synthesized by sulfonation reaction, and its structure was characterized by IR, NMR and elemental analyses. The solubility of sodium formononetin-3'-sulfonate in water and n-octanol/water partition coefficient were determined by UV spectrophotometry. The lipid-lowering and liver-protection activities of sodium formononetin-3'-sulfonate were tested by using rat's high fat model induce by feeding with high fat food. The results showed that sodium formononetin-3'-sulfonate not only had favorable water, solubility but also had good lipid-lowering and liver-protection activities.

Polyimides with pendant alkyl groups

NASA Technical Reports Server (NTRS)

Jensen, B. J.; Young, P. R.

1982-01-01

The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.

Transnitrilation from Dimethylmalononitrile to Aryl Grignard and Lithium Reagents: A Practical Method for Aryl Nitrile Synthesis.

PubMed

Reeves, Jonathan T; Malapit, Christian A; Buono, Frederic G; Sidhu, Kanwar P; Marsini, Maurice A; Sader, C Avery; Fandrick, Keith R; Busacca, Carl A; Senanayake, Chris H

2015-07-29

An electrophilic cyanation of aryl Grignard or lithium reagents, generated in situ from the corresponding aryl bromides or iodides, by a transnitrilation with dimethylmalononitrile (DMMN) was developed. DMMN is a commercially available, bench-stable solid. The transnitrilation with DMMN avoids the use of toxic reagents and transition metals and occurs under mild reaction conditions, even for extremely sterically hindered substrates. The transnitrilation of aryllithium species generated by directed ortho-lithiation enabled a net C-H cyanation. The intermediacy of a Thorpe-type imine adduct in the reaction was supported by isolation of the corresponding ketone from the quenched reaction. Computational studies supported the energetic favorability of retro-Thorpe fragmentation of the imine adduct.

Synthesis and electronic structure determination of N-alkyl-substituted bis(imino)pyridine iron imides exhibiting spin crossover behavior.

PubMed

Bowman, Amanda C; Milsmann, Carsten; Bill, Eckhard; Turner, Zoë R; Lobkovsky, Emil; DeBeer, Serena; Wieghardt, Karl; Chirik, Paul J

2011-11-02

Three new N-alkyl substituted bis(imino)pyridine iron imide complexes, ((iPr)PDI)FeNR ((iPr)PDI = 2,6-(2,6-(i)Pr(2)-C(6)H(3)-N═CMe)(2)C(5)H(3)N; R = 1-adamantyl ((1)Ad), cyclooctyl ((Cy)Oct), and 2-adamantyl ((2)Ad)) were synthesized by addition of the appropriate alkyl azide to the iron bis(dinitrogen) complex, ((iPr)PDI)Fe(N(2))(2). SQUID magnetic measurements on the isomeric iron imides, ((iPr)PDI)FeN(1)Ad and ((iPr)PDI)FeN(2)Ad, established spin crossover behavior with the latter example having a more complete spin transition in the experimentally accessible temperature range. X-ray diffraction on all three alkyl-substituted bis(imino)pyridine iron imides established essentially planar compounds with relatively short Fe-N(imide) bond lengths and two-electron reduction of the redox-active bis(imino)pyridine chelate. Zero- and applied-field Mössbauer spectroscopic measurements indicate diamagnetic ground states at cryogenic temperatures and established low isomer shifts consistent with highly covalent molecules. For ((iPr)PDI)FeN(2)Ad, Mössbauer spectroscopy also supports spin crossover behavior and allowed extraction of thermodynamic parameters for the S = 0 to S = 1 transition. X-ray absorption spectroscopy and computational studies were also performed to explore the electronic structure of the bis(imino)pyridine alkyl-substituted imides. An electronic structure description with a low spin ferric center (S = 1/2) antiferromagnetically coupled to an imidyl radical (S(imide) = 1/2) and a closed-shell, dianionic bis(imino)pyridine chelate (S(PDI) = 0) is favored for the S = 0 state. An iron-centered spin transition to an intermediate spin ferric ion (S(Fe) = 3/2) accounts for the S = 1 state observed at higher temperatures. Other possibilities based on the computational and experimental data are also evaluated and compared to the electronic structure of the bis(imino)pyridine iron N-aryl imide counterparts.

21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene polymer, chloro-sulfonated. 177.2210... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated...

21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene polymer, chloro-sulfonated. 177.2210... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated...

21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene polymer, chloro-sulfonated. 177.2210... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated...

21 CFR 177.2210 - Ethylene polymer, chloro-sulfonated.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene polymer, chloro-sulfonated. 177.2210... (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use Only as Components of Articles Intended for Repeated Use § 177.2210 Ethylene polymer, chloro-sulfonated. Ethylene polymer, chlorosulfonated as...

Molecular design of sequence specific DNA alkylating agents.

PubMed

Minoshima, Masafumi; Bando, Toshikazu; Shinohara, Ken-ichi; Sugiyama, Hiroshi

2009-01-01

Sequence-specific DNA alkylating agents have great interest for novel approach to cancer chemotherapy. We designed the conjugates between pyrrole (Py)-imidazole (Im) polyamides and DNA alkylating chlorambucil moiety possessing at different positions. The sequence-specific DNA alkylation by conjugates was investigated by using high-resolution denaturing polyacrylamide gel electrophoresis (PAGE). The results showed that polyamide chlorambucil conjugates alkylate DNA at flanking adenines in recognition sequences of Py-Im polyamides, however, the reactivities and alkylation sites were influenced by the positions of conjugation. In addition, we synthesized conjugate between Py-Im polyamide and another alkylating agent, 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI). DNA alkylation reactivies by both alkylating polyamides were almost comparable. In contrast, cytotoxicities against cell lines differed greatly. These comparative studies would promote development of appropriate sequence-specific DNA alkylating polyamides against specific cancer cells.

Influence of chlorine or fluorine substitution on the estrogenic properties of 1-alkyl-2,3,5-tris(4-hydroxyphenyl)-1H-pyrroles.

PubMed

Schäfer, Anja; Wellner, Anja; Strauss, Martin; Schäfer, Andreas; Wolber, Gerhard; Gust, Ronald

2012-11-26

In continuation of our previous work, several 1-alkyl-2,3,5-tris(4-hydroxyphenyl)aryl-1H-pyrroles with chlorine or fluorine substituents in the aryl residues were synthesized and tested for estrogen receptor (ER) binding at isolated ERα/ERβ receptors (HAP assay) and in transactivation assays using ERα-positive MCF-7/2a as well as U2-OS/ERα and U2-OS/ERβ cells. In the competition experiment at ERα the compounds displayed very high relative binding affinities of up to 37% (determined for 8m) but with restricted subtype selectivity (e.g., ERα/ERβ (8m) = 9). The highest estrogenic potency in ERα-positive MCF-7/2a cells was determined for 2,3,5-tris(2-fluoro-4-hydroxyphenyl)-1-propyl-1H-pyrrole 8m (EC(50) = 23 nM), while in U2-OS/ERα cells 2-(2-fluoro-4-hydroxyphenyl)-3,5-bis(4-hydroxyphenyl)-1-propyl-1H-pyrrole 8b (EC(50) = 0.12 nM) was the most potent agonist, only 30-fold less active than estradiol (E2, EC(50) = 0.004 nM). In U2-OS/ERβ cells for all pyrroles no transactivation could be observed, which indicates that they are selective ERα agonists in cellular systems.

Toward High-Performance Lithium-Sulfur Batteries: Upcycling of LDPE Plastic into Sulfonated Carbon Scaffold via Microwave-Promoted Sulfonation.

PubMed

Kim, Patrick J; Fontecha, Harif D; Kim, Kyungho; Pol, Vilas G

2018-05-02

Lithium-sulfur batteries were intensively explored during the last few decades as next-generation batteries owing to their high energy density (2600 Wh kg -1 ) and effective cost benefit. However, systemic challenges, mainly associated with polysulfide shuttling effect and low Coulombic efficiency, plague the practical utilization of sulfur cathode electrodes in the battery market. To address the aforementioned issues, many approaches have been investigated by tailoring the surface characteristics and porosities of carbon scaffold. In this study, we first present an effective strategy of preparing porous sulfonated carbon (PSC) from low-density polyethylene (LDPE) plastic via microwave-promoted sulfonation. Microwave process not only boosts the sulfonation reaction of LDPE but also induces huge amounts of pores within the sulfonated LDPE plastic. When a PSC layer was utilized as an interlayer in lithium-sulfur batteries, the sulfur cathode delivered an improved capacity of 776 mAh g -1 at 0.5C and an excellent cycle retention of 79% over 200 cycles. These are mainly attributed to two materialistic benefits of PSC: (a) porous structure with high surface area and (b) negatively charged conductive scaffold. These two characteristics not only facilitate the improved electrochemical kinetics but also effectively block the diffusion of polysulfides via Coulomb interaction.

Mass spectral analysis of long chain alkyl aromatic compounds synthesized from alpha-olefin alkylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, M.T.; Hudson, J.D.

1994-12-31

Long chain alkyl aromatic compounds are important petrochemicals with many applications. They are generally synthesized by alkylating the corresponding aromatic nucleus. In this report, the authors will describe the mass spectral fragmentation of alkylphenols and alkylsalicylates.

40 CFR 721.9892 - Alkylated urea.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under this...

NiXantphos: a deprotonatable ligand for room-temperature palladium-catalyzed cross-couplings of aryl chlorides.

PubMed

Zhang, Jiadi; Bellomo, Ana; Trongsiriwat, Nisalak; Jia, Tiezheng; Carroll, Patrick J; Dreher, Spencer D; Tudge, Matthew T; Yin, Haolin; Robinson, Jerome R; Schelter, Eric J; Walsh, Patrick J

2014-04-30

Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd-NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of aryl chloride substrates bearing heteroaryl groups and sensitive functional groups that are known to undergo 1,2-addition, aldol reaction, and O-, N-, enolate-α-, and C(sp(2))-H arylations. The advantages and importance of the Pd-NiXantphos catalyst system outlined herein make it a valuable contribution for applications in Pd-catalyzed arylation reactions with aryl chlorides.

NiXantphos: A Deprotonatable Ligand for Room-Temperature Palladium-Catalyzed Cross-Couplings of Aryl Chlorides

PubMed Central

2015-01-01

Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd–NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, the DCCP exhibits remarkable chemoselectivity in the presence of aryl chloride substrates bearing heteroaryl groups and sensitive functional groups that are known to undergo 1,2-addition, aldol reaction, and O-, N-, enolate-α-, and C(sp2)–H arylations. The advantages and importance of the Pd–NiXantphos catalyst system outlined herein make it a valuable contribution for applications in Pd-catalyzed arylation reactions with aryl chlorides. PMID:24745758

Sulfonated polystyrene and its characterization as a material of electrolyte polymer

NASA Astrophysics Data System (ADS)

Ngadiwiyana; Ismiyarto; Gunawan; Purbowatiningrum, RS; Prasetya, N. B. A.; Kusworo, T. D.; Susanto, H.

2018-05-01

The research of polystyrene modification from Styrofoam waste and its application as a main material of electrolyte polymer had been done. The sulfonation reaction of polystyrene was conducted using sulfuric acid as sufonation agent and the reactions were done with variation times of 1, 2, 3, 4 and 5 h. The characterization of the sulfonated products covered analysis of functional groups using FT-IR spectrophotometer, sulfonation degree, measurements of ion exchange capacity, conductivity and swelling degree. The sulfonated polystyrene product was white solid as confirmed by the spectra of FT-IR with the presence of wide band absorption of O=S=O at the wavenumber of 1080-1411 cm-1 as indication. The research showed the best sulfonated polystyrene prepared in 4 h as a material of electrolyte polymer, since it had the highest degree of sulfonation, ion exchange capacity, conductivity and swelling degree with the values were 28.52 %, 1.550 meg/g, 15,924.10-6 Ω-1cm-1 and 332.4 %, respectively.

Pd-Catalyzed Cross-Coupling Reactions of Amides and Aryl Mesylates

PubMed Central

Dooleweerdt, Karin; Fors, Brett P.; Buchwald, Stephen L.

2010-01-01

A catalyst, based on a biarylphosphine ligand, for the Pd-catalyzed cross-coupling reactions of amides and aryl mesylates is described. This system allows an array of aryl and heteroaryl mesylates to be transformed into the corresponding N-arylamides in moderate to excellent yields. PMID:20420379

21 CFR 177.1200 - Cellophane.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... Castor oil, sulfonated, sodium salt Cellulose acetate butyrate Cellulose acetate propionate Cetyl alcohol... trimethylenediamine (alkyl C16 to C18) Oleic acid, sulfonated, sodium salt Oleyl palmitamide N,N′-Oleoyl...

Aryl-modified graphene quantum dots with enhanced photoluminescence and improved pH tolerance

NASA Astrophysics Data System (ADS)

Luo, Peihui; Ji, Zhe; Li, Chun; Shi, Gaoquan

2013-07-01

Chemical modification is an important technique to modulate the chemical and optical properties of graphene quantum dots (GQDs). In this paper, we report a versatile diazonium chemistry method to graft aryl groups including phenyl, 4-carboxyphenyl, 4-sulfophenyl and 5-sulfonaphthyl to GQDs via Gomberg-Bachmann reaction. The aryl-modified GQDs are nanocrystals with lateral dimensions in the range of 2-4 nm and an average thickness lower than 1 nm. Upon chemical modification with aryl groups, the photoluminescence (PL) bands of GQDs were tuned in the range of 418 and 447 nm, and their fluorescence quantum yields (QYs) were increased for up to about 6 times. Furthermore, the aryl-modified GQDs exhibited stable PL (both intensity and peak position) in a wide pH window of 1-11. The mechanism of improving the PL properties of GQDs by aryl-modification was also discussed.Chemical modification is an important technique to modulate the chemical and optical properties of graphene quantum dots (GQDs). In this paper, we report a versatile diazonium chemistry method to graft aryl groups including phenyl, 4-carboxyphenyl, 4-sulfophenyl and 5-sulfonaphthyl to GQDs via Gomberg-Bachmann reaction. The aryl-modified GQDs are nanocrystals with lateral dimensions in the range of 2-4 nm and an average thickness lower than 1 nm. Upon chemical modification with aryl groups, the photoluminescence (PL) bands of GQDs were tuned in the range of 418 and 447 nm, and their fluorescence quantum yields (QYs) were increased for up to about 6 times. Furthermore, the aryl-modified GQDs exhibited stable PL (both intensity and peak position) in a wide pH window of 1-11. The mechanism of improving the PL properties of GQDs by aryl-modification was also discussed. Electronic supplementary information (ESI) available: Fluorescence quantum yield measurements, estimation of grafting ratio, TEM images, FTIR spectra, PL spectra and zeta potentials. See DOI: 10.1039/c3nr02156d

Sulfonates: A novel class of organic sulfur compounds in marine sediments

NASA Astrophysics Data System (ADS)

Vairavamurthy, Appathurai; Zhou, Weiqing; Eglinton, Timothy; Manowitz, Bernard

1994-11-01

X-ray absorption near-edge structure spectroscopy (XANES) used to measure sulfur speciation in a variety of organic-rich marine sediments has established sulfonates as a novel and major component of sedimentary organic sulfur. The origins of sulfonates in sediments are not clear, although both biological and geochemical mechanisms are possible. The accumulation of oxidized sulfonate sulfur in reducing marine sediments was not known previously; hence, a new perspective in sulfur geochemistry is established. The biogeochemical implications of the presence of sulfonates in marine sediments are discussed.

Suzuki-Miyaura Cross-Coupling Reactions of Primary Alkyltrifluoroborates with Aryl Chlorides

PubMed Central

Dreher, Spencer D.; Lim, Siang-Ee; Sandrock, Deidre L.; Molander, Gary A.

2009-01-01

Parallel microscale experimentation was used to develop general conditions for the Suzuki-Miyaura cross-coupling of diversely functionalized primary alkyltrifluoroborates with a variety of aryl chlorides. These conditions were found to be amenable to coupling with aryl bromides, iodides, and triflates as well. The conditions that were previously identified through similar techniques to promote the cross-coupling of secondary alkyltrifluoroborates with aryl chlorides were not optimal for the primary alkyltrifluoroborates, thus demonstrating the value of parallel experimentation to develop novel, substrate specific results. PMID:19271726

(E)-3-(2-Alkyl-10H-phenothiazin-3-yl)-1-arylprop-2-en-1-ones: Preparative, IR, NMR and DFT study on their substituent-dependent reactivity in hydrazinolysis and sonication-assisted oxidation with copper(II)nitrate.

PubMed

Găină, Luiza; Csámpai, Antal; Túrós, György; Lovász, Tamás; Zsoldos-Mády, Virág; Silberg, Ioan A; Sohár, Pál

2006-12-07

A series of novel 3(5)-aryl/ferrocenyl-5(3)-phenothiazinylpyrazoles and pyrazolines were obtained by substituent-dependent regioselective condensation of the corresponding (E)-3-(2-alkyl-10H-phenothiazin-3-yl)-1-aryl/ferrocenylprop-2-en-1-one with hydrazine or methylhydrazine in acetic acid. The different propensity of the primary formed beta-hydrazino adducts to undergo competitive retro-Mannich reaction was interpreted in terms of tautomerisation equilibrium constants calculated by DFT using a solvent model. The regioselectivity of the cyclisation reactions with methylhydrazine and the substituent-dependent redox properties of pyrazolines were also rationalized by comparative DFT calculations performed for simplified model molecules. On the effect of ultrasound-promoted oxidation with copper(II)nitrate phenothiazine-containing pyrazolines, enones and oxo-compounds were selectively transformed into sulfoxides. Only one sulfoxide enone was partially converted into an oxirane derivative. The structure of the novel products was determined by IR and NMR spectroscopy including COSY, HSQC, HMBC and DNOE measurements.

Stereocontrolled Alkylative Construction of Quaternary Carbon Centers

PubMed Central

Kummer, David A.; Chain, William J.; Morales, Marvin R.; Quiroga, Olga; Myers, Andrew G.

2009-01-01

Protocols for the stereodefined formation of α,α-disubstituted enolates of pseudoephedrine amides are presented followed by the implementation of these in diastereoselective alkylation reactions. Direct alkylation of α,α-disubstituted pseudoephedrine amide substrates is demonstrated to be both efficient and diastereoselective across a range of substrates, as exemplified by alkylation of the diastereomeric pseudoephedrine α-methylbutyramides, where both substrates are found to undergo stereospecific replacement of the α-C-H bond with α-C-alkyl, with retention of stereochemistry. This is shown to arise by sequential stereospecific enolization and alkylation reactions, with the alkyl halide attacking a common π-face of the E- and Z-enolates, proposed to be that opposite the pseudoephedrine alkoxide side-chain. Pseudoephedrine α-phenylbutyramides are found to undergo highly stereoselective but not stereospecific α-alkylation reactions, which evidence suggests is due to facile enolate isomerization. Also, we show that α, α-disubstituted pseudoephedrine amide enolates can be generated in a highly stereocontrolled fashion by conjugate addition of an alkyllithium reagent to the s-cis-conformer of an α-alkyl-α,β-unsaturated pseudoephedrine amide, providing α,α-disubstituted enolate substrates that undergo alkylation in the same sense as those formed by direct deprotonation. Methods are presented to transform the α-quaternary pseudoephedrine amide products into optically active carboxylic acids, ketones, primary alcohols, and aldehydes. PMID:18788739

Study on the generation of perfluorooctane sulfonate from the aqueous film-forming foam.

PubMed

Kishi, Takahiro; Arai, Mitsuru

2008-11-15

Perfluorooctane sulfonate (C(8)HF(17)SO(3)) and perfluorooctane acid (C(8)HF(15)O(2)) are artificial chemicals and have been used all over the world, mainly as water repellent agents, fluorochemical surfactants, coating agents, etc. However, perfluorooctane sulfonate and perfluorooctane acid are environmental contaminants because of their stability, bio-accumulativeness, and long-term persistence in the ecological environment. At the present day, they are diffused all over the world. Lately, this diffusion is viewed with suspicion and there is a movement towards their restriction, even if the environmental fate of them is still under investigation. Fluorochemical surfactants are key compounds in the aqueous film-forming foam (AFFF) formulations. AFFFs are used for massive conflagration such as industrial fire and petroleum fire because of their efficient fire control. On the other hand, a lot of AFFFs are used in case of massive conflagration and most of them enter ocean and groundwater. Actually, perfluorooctane sulfonate and perfluorooctane sulfonate related substances were detected from the fire-fighting facility of US forces. Therefore, there is the possibility of generating perfluorooctane sulfonate and perfluorooctane sulfonate related substances from fluorochemical surfactants in the AFFFs. In this study, activated sludge added AFFF were analyzed for perfluorooctane sulfonate and perfluorooctane acid with time. And the perfluorooctane sulfonate was directly detected after 2 days using LC-MS. This shows that AFFF can be decomposed perfluorooctane sulfonate by microorganisms easily. However, perfluorooctane sulfonate would not decompose at all. Additionally, activated sludge added N-polyoxyethylene-N-propyl perfluorooctane sulfonamide which is one of the fluorochemical surfactants used in the AFFF was analyzed for perfluorooctane sulfonate and perfluorooctane acid with time and the perfluorooctane sulfonate was detected too.

Polymer electrolytes based on sulfonated polysulfone for direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Lufrano, F.; Baglio, V.; Staiti, P.; Arico', A. S.; Antonucci, V.

This paper reports the development and characterization of sulfonated polysulfone (SPSf) polymer electrolytes for direct methanol fuel cells. The synthesis of sulfonated polysulfone was performed by a post sulfonation method using trimethyl silyl chlorosulfonate as a mild sulfonating agent. Bare polysulfone membranes were prepared with two different sulfonation levels (60%, SPSf-60 and 70%, SPSf-70), whereas, a composite membrane of SPSf-60 was prepared with 5 wt% silica filler. These membranes were investigated in direct methanol fuel cells (DMFCs) operating at low (30-40 °C) and high temperatures (100-120 °C). DMFC power densities were about 140 mW cm -2 at 100 °C with the bare SPSf-60 membrane and 180 mW cm -2 at 120 °C with the SPSf-60-SiO2 composite membrane. The best performance achieved at ambient temperature using a membrane with high degree of sulfonation (70%, SPSf-70) was 20 mW cm -2 at atmospheric pressure. This makes the polysulfone-based DMFC suitable for application in portable devices.

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations.

PubMed

Skhiri, Aymen; Ben Salem, Ridha; Soulé, Jean-François; Doucet, Henri

2017-01-01

The reactivity of 2-bromo- and 2,5-dibromoselenophenes in Pd-catalyzed direct heteroarylation was investigated. From 2-bromoselenophene, only the most reactive heteroarenes could be employed to prepare 2-heteroarylated selenophenes; whereas, 2,5-dibromoselenophene generally gave 2,5-di(heteroarylated) selenophenes in high yields using both thiazole and thiophene derivatives. Moreover, sequential catalytic C2 heteroarylation, bromination, catalytic C5 arylation reactions allowed the synthesis of unsymmetrical 2,5-di(hetero)arylated selenophene derivatives in three steps from selenophene.

Aryl-O reductive elimination from reaction of well-defined aryl-Cu(III) species with phenolates: the importance of ligand reactivity.

PubMed

Casitas, Alicia; Ioannidis, Nikolaos; Mitrikas, George; Costas, Miquel; Ribas, Xavi

2011-09-21

Well-defined aryl-Cu(III) species undergo rapid reductive elimination upon reaction with phenolates (PhO(-)), to form aryl-OPh cross-coupling products. Kinetic studies show that the reaction follows a different mechanistic pathway compared to the reaction with phenols. The pH active cyclized pincer-like ligand undergoes an initial amine deprotonation that triggers a faster reactivity at room temperature. A mechanistic proposal for the enhanced reactivity and the role of EPR-detected Cu(II) species will be discussed in detail. This journal is © The Royal Society of Chemistry 2011

E- or Z-Selective synthesis of 4-fluorovinyl-1,2,3-triazoles with fluorinated second-generation Julia-Kocienski reagents.

PubMed

Kumar, Rakesh; Singh, Govindra; Todaro, Louis J; Yang, Lijia; Zajc, Barbara

2015-02-07

A highly modular approach to N-substituted 4-(1-fluorovinyl)triazoles is described. In situ desilylation and Cu-catalyzed ligation reaction of TMS-protected α-fluoropropargyl benzothiazole sulfone with aryl, alkyl, and metallocenyl azides furnished second-generation Julia-Kocienski reagents in good to excellent yields. Condensation reactions of these reagents with aldehydes can be tuned to yield E or Z-alkenes selectively. Under mild conditions with DBU as the base, reactions of aldehydes furnished E-alkenes as the major isomer. On the other hand, in condensation reactions with LHMDS as the base and in appropriate solvents, both aldehydes and ketones reacted to yield fluoroalkenes with Z-selectivity. Stereochemical assignment of E/Z olefins obtained in the reaction of a ketone with two Julia reagents was performed via X-ray crystallographic analysis and comparisons of NMR data. The method allows efficient and ready diversification of the N1-substituent and substituents at the double bond.

E- or Z-selective synthesis of 4-fluorovinyl-1,2,3-triazoles with fluorinated second-generation Julia-Kocienski reagents

PubMed Central

Kumar, Rakesh; Singh, Govindra; Todaro, Louis J.; Yang, Lijia; Zajc, Barbara

2016-01-01

A highly modular approach to N-substituted 4-(1-fluorovinyl)triazoles is described. In situ desilylation and Cu-catalyzed ligation reaction of TMS-protected α-fluoropropargyl benzothiazole sulfone with aryl, alkyl, and metallocenyl azides furnished second-generation Julia-Kocienski reagents in good to excellent yields. Condensation reactions of these reagents with aldehydes can be tuned to yield E or Z-alkenes selectively. Under mild conditions with DBU as base, reactions of aldehydes furnished E-alkenes as the major isomer. On the other hand, in condensations with LHMDS as base and in appropriate solvents, both aldehydes and ketones reacted to yield fluoroalkenes with Z-selectivity. Stereochemical assignment to E/Z olefins obtained in the reaction of a ketone with two Julia reagents was performed via X-ray crystallographic analysis and comparisons of NMR data. The method allows efficient and ready diversification of N1-substituent and substituents at the double bond. PMID:25491086

Photoinduced, Copper-Catalyzed Carbon-Carbon Bond Formation with Alkyl Electrophiles: Cyanation of Unactivated Secondary Alkyl Chlorides at Room Temperature.

PubMed

Ratani, Tanvi S; Bachman, Shoshana; Fu, Gregory C; Peters, Jonas C

2015-11-04

We have recently reported that, in the presence of light and a copper catalyst, nitrogen nucleophiles such as carbazoles and primary amides undergo C-N coupling with alkyl halides under mild conditions. In the present study, we establish that photoinduced, copper-catalyzed alkylation can also be applied to C-C bond formation, specifically, that the cyanation of unactivated secondary alkyl chlorides can be achieved at room temperature to afford nitriles, an important class of target molecules. Thus, in the presence of an inexpensive copper catalyst (CuI; no ligand coadditive) and a readily available light source (UVC compact fluorescent light bulb), a wide array of alkyl halides undergo cyanation in good yield. Our initial mechanistic studies are consistent with the hypothesis that an excited state of [Cu(CN)2](-) may play a role, via single electron transfer, in this process. This investigation provides a rare example of a transition metal-catalyzed cyanation of an alkyl halide, as well as the first illustrations of photoinduced, copper-catalyzed alkylation with either a carbon nucleophile or a secondary alkyl chloride.

Molecular Design of Sulfonated Triblock Copolymer Permselective Membranes

DTIC Science & Technology

2008-07-03

factors governing sorption and permeability ofphosphoorganic agents in PEM made of sulfonated triblock copolymers of styrene and lower olefins by means...membrane morphology at environmental conditions, and the membrane sorption and transport properties with respect to water and nerve gas simulant...and chemical factors governing sorption and permeability of phosphoorganic agents in PEM made of sulfonated triblock copolymers of styrene and lower

Synthesis of oxazolines and oxazines

DOEpatents

Benicewicz, Brian C.; Mitchell, Michael A.

1995-01-01

A process of preparing an oxazoline or oxazine compound of the formula ##STR1## wherein X is an atom selected from the group of oxygen and sulfur, R is selected from the group consisting of C.sub.1-10 alkyl, C.sub.1-10 fluoroalkyl, aryl and substituted-aryl, and n is 2 or 3 comprising ring-closing a compound of the formula ##STR2## wherein X is an atom selected from the group of oxygen and sulfur, R is selected from the group consisting of C.sub.1-10 alkyl, C.sub.1-10 fluoroalkyl, aryl, and substituted aryl, n is 2 or 3, and Y is a bromine or chlorine atom in the presence of a basic reagent consisting essentially of a fluoride salt supported on an inorganic solid substrate is disclosed together with the compounds, 5-bromomethyl-2-phenyl-1,3-oxazoline, 5-methylene-2-phenyl-1,3-oxazine and 4,4-dimethyl-2-vinyl-1,3-oxazoline.

Cyclic Tetrapyrrole Sulfonation, Metals, and Oligomerization in Antiprion Activity▿

PubMed Central

Caughey, Winslow S.; Priola, Suzette A.; Kocisko, David A.; Raymond, Lynne D.; Ward, Anne; Caughey, Byron

2007-01-01

Cyclic tetrapyrroles are among the most potent compounds with activity against transmissible spongiform encephalopathies (TSEs; or prion diseases). Here the effects of differential sulfonation and metal binding to cyclic tetrapyrroles were investigated. Their potencies in inhibiting disease-associated protease-resistant prion protein were compared in several types of TSE-infected cell cultures. In addition, prophylactic antiscrapie activities were determined in scrapie-infected mice. The activity of phthalocyanine was relatively insensitive to the number of peripheral sulfonate groups but varied with the type of metal bound at the center of the molecule. The tendency of the various phthalocyanine sulfonates to oligomerize (i.e., stack) correlated with anti-TSE activity. Notably, aluminum(III) phthalocyanine tetrasulfonate was both the poorest anti-TSE compound and the least prone to oligomerization in aqueous media. Similar comparisons of iron- and manganese-bound porphyrin sulfonates confirmed that stacking ability correlates with anti-TSE activity among cyclic tetrapyrroles. PMID:17709470

p-Chlorophenyl methyl sulfone

Integrated Risk Information System (IRIS)

p - Chlorophenyl methyl sulfone ; CASRN 98 - 57 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for No

Nucleophilic addition of nitrogen to aryl cations: mimicking Titan chemistry.

PubMed

Li, Anyin; Jjunju, Fred P M; Cooks, R Graham

2013-11-01

The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 10(2) Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.

Sulfonated Copper Phthalocyanine/Sulfonated Polysulfone Composite Membrane for Ionic Polymer Actuators with High Power Density and Fast Response Time.

PubMed

Kwon, Taehoon; Cho, Hyeongrae; Lee, Jang-Woo; Henkensmeier, Dirk; Kang, Youngjong; Koo, Chong Min

2017-08-30

Ionic polymer composite membranes based on sulfonated poly(arylene ether sulfone) (SPAES) and copper(II) phthalocyanine tetrasulfonic acid (CuPCSA) are assembled into bending ionic polymer actuators. CuPCSA is an organic filler with very high sulfonation degree (IEC = 4.5 mmol H + /g) that can be homogeneously dispersed on the molecular scale into the SPAES membrane, probably due to its good dispersibility in SPAES-containing solutions. SPAES/CuPCSA actuators exhibit larger ion conductivity (102 mS cm -1 ), tensile modulus (208 MPa), strength (101 MPa), and strain (1.21%), exceptionally faster response to electrical stimuli, and larger mechanical power density (3028 W m -3 ) than ever reported for ion-conducting polymer actuators. This outstanding actuation performance of SPAES/CuPCSA composite membrane actuators makes them attractive for next-generation transducers with high power density, which are currently developed, e.g., for underwater propulsion and endoscopic surgery.

Degradation of Perfluorooctanoic Acid and Perfluoroctane Sulfonate by Enzyme Catalyzed Oxidative Humification Reactions

NASA Astrophysics Data System (ADS)

Huang, Q.

2016-12-01

Poly- and perfluoroalkyl substances (PFASs) are alkyl based chemicals having multiple or all hydrogens replaced by fluorine atoms, and thus exhibit high thermal and chemical stability and other unusual characteristics. PFASs have been widely used in a wide variety of industrial and consumer products, and tend to be environmentally persistent. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are two representative PFASs that have drawn particular attention because of their ubiquitous presence in the environment, resistance to degradation and toxicity to animals. This study examined the decomposition of PFOA and PFOS in enzyme catalyzed oxidative humification reactions (ECOHR), a class of reactions that are ubiquitous in the environment involved in natural organic humification. Reaction rates and influential factors were examined, and high-resolution mass spectrometry was used to identify possible products. Fluorides and partially fluorinated compounds were identified as likely products from PFOA and PFOS degradation, which were possibly formed via a combination of free radical decomposition, rearrangements and coupling processes. The findings suggest that PFOA and PFOS may be transformed during humification, and ECOHR can potentially be used for the remediation of these chemicals.

Inhibitors of glycogen synthase 3 kinase

DOEpatents

Schultz, Peter; Ring, David B.; Harrison, Stephen D.; Bray, Andrew M.

2000-01-01

Compounds of formula 1: ##STR1## wherein R.sub.1 is alkyl, cycloalkyl, aryl, aralkyl, heteroaryl, or heteroaralkyl, substituted with 0-3 substituents selected from lower alkyl, halo, hydroxy, lower alkoxy, amino, lower alkyl-amino, and nitro; R.sub.2 is hydroxy, amino, or lower alkoxy; R.sub.3 is H, lower alkyl, lower acyl, lower alkoxy-acyl, or amnino-acyl; R.sub.4 is H or lower alkyl; and pharmaceutically acceptable salts and esters thereof; are effective inhibitors of GSK3.

Inhibitors of glycogen synthase 3 kinase

DOEpatents

Schultz, Peter; Ring, David B.; Harrison, Stephen D.; Bray, Andrew M.

2006-05-30

Compounds of formula 1: ##STR00001## wherein R.sub.1 is alkyl, cycloalkyl, aryl, aralkyl, heteroaryl, or heteroaralkyl, substituted with 0 3 substituents selected from lower alkyl, halo, hydroxy, lower alkoxy, amino, lower alkyl-amino, and nitro; R.sub.2 is hydroxy, amino, or lower alkoxy; R.sub.3 is H, lower alkyl, lower acyl, lower alkoxy-acyl, or amino-acyl; R.sub.4 is H or lower alkyl; and pharmaceutically acceptable salts and esters thereof; are effective inhibitors of GSK3.

Palladium-Catalyzed Borylation of Primary Alkyl Bromides

PubMed Central

Joshi-Pangu, Amruta; Ma, Xinghua; Diane, Mohamed; Iqbal, Sidra; Kribs, Robert J.; Huang, Richard; Wang, Chao-Yuan

2012-01-01

A mild Pd-catalyzed process for the borylation of alkyl bromides has been developed using bis(pinacolato)diboron as a boron source. This process accommodates the use of a wide range of functional groups on the alkyl bromide substrate. Primary bromides react with complete selectivity in the presence of a secondary bromide. The generality of this approach is demonstrated by its extension to the use of alkyl iodides and alkyl tosylates, as well as borylation reactions employing bis(neopentyl glycolato)diboron as the boron source. PMID:22774861

Solvent-Free Addition of Indole to Aldehydes: Unexpected Synthesis of Novel 1-[1-(1H-Indol-3-yl) Alkyl]-1H-Indoles and Preliminary Evaluation of Their Cytotoxicity in Hepatocarcinoma Cells.

PubMed

Tocco, Graziella; Zedda, Gloria; Casu, Mariano; Simbula, Gabriella; Begala, Michela

2017-10-17

New 1-[1-(1 H -indol-3-yl) alkyl]-1 H -indoles, surprisingly, have been obtained from the addition of indole to a variety of aldehydes under neat conditions. CaO, present in excess, was fundamental for carrying out the reaction with paraformaldehyde. Under the same reaction conditions, aromatic and heteroaromatic aldehydes afforded only classical bis (indolyl) aryl indoles. In this paper, the role of CaO, together with the regiochemistry and the mechanism of the reaction, are discussed in detail. The effect of some selected 3,3'- and 1,3'-diindolyl methane derivatives on cell proliferation of the hepatoma cell line FaO was also evaluated.

Preparation of water-soluble magnetic nanocrystals using aryl diazonium salt chemistry.

PubMed

Griffete, Nébéwia; Herbst, Frédéric; Pinson, Jean; Ammar, Souad; Mangeney, Claire

2011-02-16

A novel and facile methodology for the in situ surface functionalization of Fe(3)O(4) nanoparticles is proposed, based on the use of aryl diazonium salts chemistry. The grafting reaction involves the formation of diazoates in a basic medium. These species are unstable and dediazonize along a homolytic pathway to give aryl radicals which further react with the Fe(3)O(4) NPs during their formation and stop their growth. Advantages of the present approach rely not only on the simplicity, rapidity, and efficiency of the procedure but also on the formation of strong Fe(3)O(4)-aryl surface bonds, highly suitable for further applications.

MATERNAL AND DEVELOPMENTAL TOXICITY OF PERFLUOROOCTANE SULFONATE IN THE RAT

EPA Science Inventory

MATERNAL AND DEVELOPMENTAL TOXICITY OF PERFLUOROOCTANE SULFONATE IN THE RAT.
C. Lau and J.M. Rogers, Reproductive Toxicology Division, NHEERL, ORD, USEPA, Research Triangle Park, NC, USA

Perfluorooctane sulfonate (PFOS), an environmentally persistent compound used ...

Chitin nanowhisker-supported sulfonated poly(ether sulfone) proton exchange for fuel cell applications.

PubMed

Zhang, Chan; Zhuang, Xupin; Li, Xiaojie; Wang, Wei; Cheng, Bowen; Kang, Weimin; Cai, Zhanjun; Li, Mengqin

2016-04-20

To balance the relationship among proton conductivity and mechanic strength of sulfonated poly(ether sulfone) (SPES) membrane, chitin nanowhisker-supported nanocomposite membranes were prepared by incorporating whiskers into SPES. The as-prepared chitin whiskers were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) mediated oxidation of α-chitin from crab shells. The structure and properties of the composite membranes were examined as proton exchange membrane (PEM). Results showed that chitin nanowhiskers were dispersed incompactly in the SPES matrix. Thermal stability, mechanical properties, water uptake and proton conductivity of the nanocomposite films were improved from those of the pure SPES film with increasing whisker content, which ascribed to strong interactions between whiskers and between SPES molecules and chitin whiskers via hydrogen bonding. These indicated that composition of filler and matrix got good properties and whisker-supported membranes are promising materials for PEM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Rh-Catalyzed Intermolecular Reactions of α-Alkyl-α-Diazo Carbonyl Compounds with Selectivity over β-Hydride Migration.

PubMed

DeAngelis, Andrew; Panish, Robert; Fox, Joseph M

2016-01-19

Rh-carbenes derived from α-diazocarbonyl compounds have found broad utility across a remarkable range of reactivity, including cyclopropanation, cyclopropenation, C-H insertions, heteroatom-hydrogen insertions, and ylide forming reactions. However, in contrast to α-aryl or α-vinyl-α-diazocarbonyl compounds, the utility of α-alkyl-α-diazocarbonyl compounds had been moderated by the propensity of such compounds to undergo intramolecular β-hydride migration to give alkene products. Especially challenging had been intermolecular reactions involving α-alkyl-α-diazocarbonyl compounds. This Account discusses the historical context and prior limitations of Rh-catalyzed reactions involving α-alkyl-α-diazocarbonyl compounds. Early studies demonstrated that ligand and temperature effects could influence chemoselectivity over β-hydride migration. However, effects were modest and conflicting conclusions had been drawn about the influence of sterically demanding ligands on β-hydride migration. More recent advances have led to a more detailed understanding of the reaction conditions that can promote intermolecular reactivity in preference to β-hydride migration. In particular, the use of bulky carboxylate ligands and low reaction temperatures have been key to enabling intermolecular cyclopropenation, cyclopropanation, carbonyl ylide formation/dipolar cycloaddition, indole C-H functionalization, and intramolecular bicyclobutanation with high chemoselectivity over β-hydride migration. Cyclic α-diazocarbonyl compounds have been shown to be particularly resilient toward β-hydride migration and are the first class of compounds that can engage in intermolecular reactivity in the presence of tertiary β-hydrogens. DFT calculations were used to propose that for cyclic α-diazocarbonyl compounds, ring constraints relieve steric interaction for intermolecular reactions and thereby accelerate the rate of intermolecular reactivity relative to intramolecular �

Composite proton exchange membrane based on sulfonated organic nanoparticles

NASA Astrophysics Data System (ADS)

Pitia, Emmanuel Sokiri

As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion

Enhancement of alkylation catalysts for improved supercritical fluid regeneration

DOEpatents

Ginosar, Daniel M [Idaho Falls, ID; Petkovic, Lucia [Idaho Falls, ID

2009-09-22

A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

Enhancement of alkylation catalysts for improved supercritical fluid regeneration

DOEpatents

Ginosar, Daniel M.; Petkovic, Lucia M.

2010-12-28

A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate.

PubMed

Molander, Gary A; Cavalcanti, Livia N

2012-05-04

Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF(4)). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.

NITROSATION OF ARYL AND HETEROARYLTRIFLUOROBORATES WITH NITROSONIUM TETRAFLUOROBORATE

PubMed Central

Cavalcanti, Livia N.

2012-01-01

Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups. PMID:22524190

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.824 Sodium mono- and dimethyl naphthalene sulfonates. The food additive sodium mono- and dimethyl naphthalene sulfonates may be safely used in...

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane dye...

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane dye...

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane dye...

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane dye...

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane dye...

Cellulose nanofiber-embedded sulfonated poly (ether sulfone) membranes for proton exchange membrane fuel cells.

PubMed

Xu, Xianlin; Li, Rui; Tang, Chenxiao; Wang, Hang; Zhuang, Xupin; Liu, Ya; Kang, Weimin; Shi, Lei

2018-03-15

Cellulose nanofibers were embedded into sulfonated poly (ether sulfone) matrix to heighten the water retention and proton conductivity of proton exchange membranes (PEMs). Cellulose nanofibers were obtained by hydrolyzing cellulose acetate nanofibers, which were prepared via electrostatic-induction-assisted solution blow spinning. Morphology, thermal stability, and mechanical properties of the PEMs were investigated. The results showed that proton conductivity, water uptake, and methanol permeability of the composite membranes were improved. Hydrophilicity of the composite membranes was gradually improved with the addition of nanofibers. When the content of nanofibers was 5 wt%, the highest proton conductivity was 0.13 S/cm (80 °C, 100% RH). Therefore, the cellulose nanofiber could be used as support materials to enhance the performance of proton exchange membranes, the composite membranes have potential application in Direct methanol fuel cells (DMFCs). Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

40 CFR 721.10367 - Hydroxy-aryl, polymer with substituted benzene, cyanate (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... benzene, cyanate (generic). 721.10367 Section 721.10367 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10367 Hydroxy-aryl, polymer with substituted benzene... substance identified generically as hydroxy-aryl, polymer with substituted benzene, cyanate (PMN P-10-83) is...

Enantioselective synthesis of chiral oxazolines from unactivated ketones and isocyanoacetate esters by synergistic silver/organocatalysis.

PubMed

Martínez-Pardo, Pablo; Blay, Gonzalo; Muñoz, M Carmen; Pedro, José R; Sanz-Marco, Amparo; Vila, Carlos

2018-03-15

A multicatalytic approach that combines a bifunctional Brønsted base-squaramide organocatalyst and Ag + as Lewis acid has been applied in the reaction of unactivated ketones with tert-butyl isocyanoacetate to give chiral oxazolines bearing a quaternary stereocenter. The formal [3+2] cycloaddition provided high yields of the corresponding cis-oxazolines with good diastereoselectivity and excellent enantioselectivity, being applied to aryl-alkyl and alkyl-alkyl ketones.

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

PubMed Central

Hama, Takuo; Ge, Shaozhong; Hartwig, John F.

2013-01-01

The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching lithium enolates of esters with zinc chloride. The use of zinc enolates, instead of alkali metal enolates, greatly expands the scope of the arylation of esters. The reactions occur at room temperature or at 70 °C with bromoarenes containing cyano, nitro, ester, keto, fluoro, enolizable hydrogen, hydroxyl or amino functionality and with bromopyridines. The scope of esters encompasses acyclic acetates, propionates, and isobutyrates, α-alkoxyesters, and lactones. The arylation of zinc enolates of esters was conducted with catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) or the highly reactive dimeric Pd(I) complex {[P(t-Bu)3]PdBr}2. PMID:23931445

Light-Induced C-H Arylation of (Hetero)arenes by In Situ Generated Diazo Anhydrides.

PubMed

Cantillo, David; Mateos, Carlos; Rincon, Juan A; de Frutos, Oscar; Kappe, C Oliver

2015-09-07

Diazo anhydrides (Ar-N=N-O-N=N-Ar) have been known since 1896 but have rarely been used in synthesis. This communication describes the development of a photochemical catalyst-free C-H arylation methodology for the preparation of bi(hetero)aryls by the one-pot reaction of anilines with tert-butyl nitrite and (hetero)arenes under neutral conditions. The key step in this procedure is the in situ formation and subsequent photochemical (>300 nm) homolytic cleavage of a transient diazo anhydride intermediate. The generated aryl radical then efficiently reacts with a (hetero)arene to form the desired bi(hetero)aryls producing only nitrogen, water, and tert-butanol as byproducts. The scope of the reaction for several substituted anilines and (hetero)arenes was investigated. A continuous-flow protocol increasing selectivity and safety has been developed enabling the experimentally straightforward preparation of a variety of substituted bi(hetero)aryls within 45 min of reaction time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and effectiveness of overbased magnesium and calcium petroleum sulfonates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fialkovskii, R.V.; Romanyutina, L.V.; Korbut, L.F.

Overbased sulfonate additives are widely used to improve the service properties of motor oils. This paper describes the preparation of an overbased magnesium sulfonate additive from MSG-8 oil and an investigation of its functional properties. In experiments, the solution of ammonium sulfate, fat diluted with I-20A oil to a 38% concentration, was heated and stirred continuously in the presence of water and excess magnesium oxide for a period of 4 h at 80-120/degree/C while stripping out the liberated ammonia with nitrogen. The resulting oil solution of magnesium sulfonate was dissolved in toluene. The toluene solution after cleanup was held undermore » vacuum to remove the solvent; the residue was an oil solution of overbased magnesium sulfonate. Their properties are tabulated. Comparative data are shown in Table 1 for a calcium sulfonate additive synthesized from the same intermediate (ammonium sulfate), using calcium hydroxide as the base. Test results on M-11 oil containing 5% of the magnesium or calcium additive are listed. It is shown that the magnesium additive gave better results from the calcium additive at the same concentration in terms of oxidation stability, corrosion properties, detergency, and dispersancy. 9 refs.« less

Stable trifluorostyrene containing compounds grafted to base polymers, and their use as polymer electrolyte membranes

DOEpatents

Yang, Zhen-Yu; Roelofs, Mark Gerrit

2010-11-09

A fluorinated ion exchange polymer prepared by grafting at least one grafting monomer on to at least one base polymer, wherein the grafting monomer comprises structure 1a or 1b: wherein Z comprises S, SO.sub.2, or POR wherein R comprises a linear or branched perfluoroalkyl group of 1 to 14 carbon atoms optionally containing oxygen or chlorine, an alkyl group of 1 to 8 carbon atoms, an aryl group of 6 to 12 carbon atoms or a substituted aryl group of 6 to 12 carbon atoms; RF comprises a linear or branched perfluoroalkene group of 1 to 20 carbon atoms, optionally containing oxygen or chlorine; Q is chosen from F, --OM, NH.sub.2, --N(M)SO.sub.2R.sup.2.sub.F, and C(M)(SO.sub.2R.sup.2.sub.F).sub.2, wherein M comprises H, an alkali cation, or ammonium; R.sup.2.sub.F groups comprises alkyl of 1 to 14 carbon atoms which may optionally include ether oxygens or aryl of 6 to 12 carbon atoms where the alkyl or aryl groups may be perfluorinated or partially fluorinated; and n is 1 or 2 for 1a, and n is 1, 2, or 3 for 1b. These ion exchange polymers are useful in preparing catalyst coated membranes and membrane electrode assemblies used in fuel cells.

Direct catalytic cross-coupling of organolithium compounds

NASA Astrophysics Data System (ADS)

Giannerini, Massimo; Fañanás-Mastral, Martín; Feringa, Ben L.

2013-08-01

Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern synthetic chemistry. However, the high reactivity and poor selectivity of common organolithium reagents have largely prohibited their use as a viable partner in direct catalytic cross-coupling. Here we report that in the presence of a Pd-phosphine catalyst, a wide range of alkyl-, aryl- and heteroaryl-lithium reagents undergo selective cross-coupling with aryl- and alkenyl-bromides. The process proceeds quickly under mild conditions (room temperature) and avoids the notorious lithium halogen exchange and homocoupling. The preparation of key alkyl-, aryl- and heterobiaryl intermediates reported here highlights the potential of these cross-coupling reactions for medicinal chemistry and material science.

N-aryl pyrrolo-tetrathiafulvalene based ligands: synthesis and metal coordination.

PubMed

Balandier, Jean-Yves; Chas, Marcos; Dron, Paul I; Goeb, Sébastien; Canevet, David; Belyasmine, Ahmed; Allain, Magali; Sallé, Marc

2010-03-05

A straightforward general synthetic access to N-aryl-1,3-dithiolo[4,5-c]pyrrole-2-thione derivatives 6 from acetylenedicarbaldehyde monoacetal is depicted. In addition to their potentiality as precursors to dithioalkyl-pyrrole derivatives, thiones 6 are key building blocks to N-aryl monopyrrolo-tetrathiafulvalene (MPTTF) derivatives 10. X-ray structures of four of these thiones intermediates, reminiscent of the corresponding MPTTF derivatives, are provided. When the aryl group is a binding pyridyl unit, the MPTTF derivative 10a can coordinate M(II) salts (M = Pt, Pd). The first examples of metal-directed orthogonal MPTTF-based dimers 11-14, obtained through coordination of 10a to cis-blocked square planar Pt or Pd complexes are described. Studies on the parameters influencing the dimer construction are presented, as well as first recognition properties of the resulting electron-rich clip for C(60).

Pyrolysis Pathways of Sulfonated Polyethylene, an Alternative Carbon Fiber Precursor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Younker, Jarod M; Saito, Tomonori; Hunt, Marcus A

2013-01-01

Sulfonated polyethylene is an emerging precursor for the production of carbon fibers. Pyrolysis of sulfonated polyethylene was characterized by thermogravimetric analysis (TGA). n-heptane-4-sulfonic acid (H4S) was selected as a model compound for the study of sulfonated polyethylene. Density functional theory and conventional transition state theory were used to determine the rate constants of pyrolysis for H4S from 300-1000 K. Multiple reaction channels from two different mechanisms were explored: 1) internal five-centered elimination (Ei 5) and 2) radical chain reaction. The pyrolysis of H4S was simulated with kinetic Monte Carlo (kMC) to obtain TGA plots that compared favorably to experiment. Wemore » observed that at tem- peratures < 550 K, the radical mechanism was dominant and yielded the trans-alkene, whereas cis-alkene was formed at higher temperatures from the internal elimination. The maximum rates of % mass loss became independent of initial OH radical concentration at 440-480 K. Experimentally, the maximum % mass loss occurred from 440-460 K (heating rate dependent). Activation energies derived from the kMC-simulated TGAs of H4S (26-29 kcal/mol) agreed with experiment for sulfonated polyethylene ( 31 kcal/mol). The simulations revealed that in this region, decomposition of radical HOSO2 became competitive to H abstraction by HOSO2, making OH the carrying radical for the reaction chain. The maximum rate of % mass loss for internal elimination was observed at temperatures > 600 K. Low-scale carbonization utilizes temperatures < 620 K; thus, internal elimination will not be competitive. Ei5 elimination has been studied for sulfoxides and sulfones, but this represents the first study of internal elimination in sulfonic acids. Nonlinear Arrhenius plots were found for all bimolecular reactions. The most significant nonlinear behavior was observed for reactions where the barrier was small. For reactions with low activation barriers, nonlinearity was traced

Post-sulfonation of cellulose nanofibrils with a one-step reaction to improve dispersibility

Treesearch

Jeffrey Luo; Nikolay Semenikhin; Huibin Chang; Robert J. Moon; Satish Kumar

2018-01-01

Cellulose nanofibrils (CNF) were sulfonated and the dispersion quality was compared to unfunctionalized and 2,2,6,6-tetramethylpiperdine-1-oxyl radical (TEMPO) post-oxidation treatment of existing CNF (mechanically fibrillated pulp). A post-sulfonation treatment on existing CNF in chlorosulfonic acid and dimethylformamide (DMF) resulted in sulfonated CNF that retained...

Graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated poly(arylene ether sulfone) for PEMFC applications.

PubMed

Zhang, Xuan; Hu, Zhaoxia; Luo, Linqiang; Chen, Shanshan; Liu, Jianmei; Chen, Shouwen; Wang, Lianjun

2011-07-15

Novel poly(arylene ether ketone) polymers with fluorophenyl pendants and phenoxide-terminated wholly sulfonated poly(arylene ether sulfone) oligomers are prepared via Ni(0)-catalyzed and nucleophilic polymerization, respectively, and subsequently used as starting materials to obtain graft-crosslinked membranes as polymer electrolyte membranes. The phenoxide-terminated sulfonated moieties are introduced as hydrophilic parts as well as crosslinking units. The chemical structure and morphology of the obtained membranes are confirmed by (1) H NMR and tapping-mode AFM. The properties required for fuel cell applications, including water uptake and dimensional change, as well as proton conductivity, are investigated. AFM results show a clear nanoscale phase-separation microstructure of the obtained membranes. The membranes show good dimensional stability and reasonably high proton conductivities under 30-90% relative humidity. The anisotropic proton conductivity ratios (σ(formula see text) ) of the membranes in water are in the range 0.65-0.92, and increase with an increase in hydrophilic block length. The results indicate that the graft-crosslinked membranes are promising candidates for applications as polymer electrolyte membranes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A direct method to visualise the aryl acylamidase activity on cholinesterases in polyacrylamide gels

PubMed Central

Jaganathan, Lakshmanan; Boopathy, Rathanam

2000-01-01

Background In vertebrates, two types of cholinesterases exist, acetylcholinesterase and butyrylcholinesterase. The function of acetylcholinesterase is to hydrolyse acetylcholine, thereby terminating the neurotransmission at cholinergic synapse, while the precise physiological function of butyrylcholinesterase has not been identified. The presence of cholinesterases in tissues that are not cholinergically innervated indicate that cholinesterases may have functions unrelated to neurotransmission. Furthermore, cholinesterases display a genuine aryl acylamidase activity apart from their predominant acylcholine hydrolase activity. The physiological significance of this aryl acylamidase activity is also not known. The study on the aryl acylamidase has been, in part hampered by the lack of a specific method to visualise this activity. We have developed a method to visualise the aryl acylamidase activity on cholinesterase in polyacrylamide gels. Results The o-nitroaniline liberated from o-nitroacetanilide by the action of aryl acylamidase activity on cholinesterases, in the presence of nitrous acid formed a diazonium compound. This compound gave an azo dye complex with N-(1-napthyl)-ethylenediamine, which appeared as purple bands in polyacrylamide gels. Treating the stained gels with trichloroacetic acid followed by Tris-HCl buffer helped in fixation of the stain in the gels. By using specific inhibitors for acetylcholinesterase and butyrylcholinesterase, respectively, differential staining for the aryl acylamidase activities on butyrylcholinesterase and acetylcholinesterase in a sample containing both these enzymes has been demonstrated. A linear relationship between the intensity of colour developed and activity of the enzyme was obtained. Conclusions A novel method to visualise the aryl acylamidase activity on cholinesterases in polyacrylamide gels has been developed. PMID:11231883

A direct method to visualise the aryl acylamidase activity on cholinesterases in polyacrylamide gels.

PubMed

Jaganathan, L; Boopathy, R

2000-01-01

In vertebrates, two types of cholinesterases exist, acetylcholinesterase and butyrylcholinesterase. The function of acetylcholinesterase is to hydrolyse acetylcholine, thereby terminating the neurotransmission at cholinergic synapse, while the precise physiological function of butyrylcholinesterase has not been identified. The presence of cholinesterases in tissues that are not cholinergically innervated indicate that cholinesterases may have functions unrelated to neurotransmission. Furthermore, cholinesterases display a genuine aryl acylamidase activity apart from their predominant acylcholine hydrolase activity. The physiological significance of this aryl acylamidase activity is also not known. The study on the aryl acylamidase has been, in part hampered by the lack of a specific method to visualise this activity. We have developed a method to visualise the aryl acylamidase activity on cholinesterase in polyacrylamide gels. The o-nitroaniline liberated from o-nitroacetanilide by the action of aryl acylamidase activity on cholinesterases, in the presence of nitrous acid formed a diazonium compound. This compound gave an azo dye complex with N-(1-napthyl)-ethylenediamine, which appeared as purple bands in polyacrylamide gels. Treating the stained gels with trichloroacetic acid followed by Tris-HCl buffer helped in fixation of the stain in the gels. By using specific inhibitors for acetylcholinesterase and butyrylcholinesterase, respectively, differential staining for the aryl acylamidase activities on butyrylcholinesterase and acetylcholinesterase in a sample containing both these enzymes has been demonstrated. A linear relationship between the intensity of colour developed and activity of the enzyme was obtained. A novel method to visualise the aryl acylamidase activity on cholinesterases in polyacrylamide gels has been developed.

β-Selective C-H arylation of pyrroles leading to concise syntheses of lamellarins C and I.

PubMed

Ueda, Kirika; Amaike, Kazuma; Maceiczyk, Richard M; Itami, Kenichiro; Yamaguchi, Junichiro

2014-09-24

The first general β-selective C-H arylation of pyrroles has been developed by using a rhodium catalyst. This C-H arylation reaction, which is retrosynthetically straightforward but results in unusual regioselectivity, could result in de novo syntheses of pyrrole-derived natural products and pharmaceuticals. As such, we have successfully synthesized polycyclic marine pyrrole alkaloids, lamellarins C and I, by using this β-selective arylation of pyrroles with aryl iodides (C-H/C-I coupling) and a new double C-H/C-H coupling as key steps.

Expedient synthesis of C-aryl carbohydrates by consecutive biocatalytic benzoin and aldol reactions.

PubMed

Hernández, Karel; Parella, Teodor; Joglar, Jesús; Bujons, Jordi; Pohl, Martina; Clapés, Pere

2015-02-16

The introduction of aromatic residues connected by a C-C bond into the non-reducing end of carbohydrates is highly significant for the development of innovative structures with improved binding affinity and selectivity (e.g., C-aril-sLex). In this work, an expedient asymmetric "de novo" synthetic route to new aryl carbohydrate derivatives based on two sequential stereoselectively biocatalytic carboligation reactions is presented. First, the benzoin reaction of aromatic aldehydes to dimethoxyacetaldehyde is conducted, catalyzed by benzaldehyde lyase from Pseudomonas fluorescens biovar I. Then, the α-hydroxyketones formed are reduced by using NaBH4 yielding the anti diol. After acetal hydrolysis, the aldol addition of dihydroxyacetone, hydroxyacetone, or glycolaldehyde catalyzed by the stereocomplementary D-fructose-6-phosphate aldolase and L-rhamnulose-1-phosphate aldolase is performed. Both aldolases accept unphosphorylated donor substrates, avoiding the need of handling the phosphate group that the dihydroxyacetone phosphate-dependent aldolases require. In this way, 6-C-aryl-L-sorbose, 6-C-aryl-L-fructose, 6-C-aryl-L-tagatose, and 5-C-aryl-L-xylose derivatives are prepared by using this methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sorbate-nitrite interactions: acetonitrile oxide as an alkylating agent.

PubMed

Pérez-Prior, M Teresa; Gómez-Bombarelli, Rafael; González-Pérez, Marina; Manso, José A; García-Santos, M Pilar; Calle, Emilio; Casado, Julio

2009-07-01

Because chemical species with DNA-damaging and mutagenic activity are formed in sorbate-nitrite mixtures and because sorbic acid sometimes coexists with nitrite occurring naturally or incorporated as a food additive, the study of sorbate-nitrite interactions is important. Here, the alkylating potential of the products resulting from such interactions was investigated. Drawn were the following conclusions: (i) Acetonitrile oxide (ACNO) is the compound responsible for the alkylating capacity of sorbate-nitrite mixtures; (ii) ACNO alkylates 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, forming an adduct (AD; epsilon = 1.4 x 10(4) M(-1) cm(-1); lambda = 519 nm); (iii) the NBP alkylation reaction complies with the rate equation, r = d[AD]/dt = k(alk)(ACNO)[ACNO][NBP]-k(hyd)(AD)[AD], k(alk)(ACNO) being the NBP alkylation rate constant for ACNO and k(hyd)(AD) the rate constant for the adduct hydrolysis reaction; (iv) the small fraction of ACNO forming the adduct with NBP, as well as the small magnitude of the quotient (k(alk) (ACNO)/k(hyd)(ACNO)) as compared with those reported for other alkylating agents, such as some lactones and N-alkyl-N-nitrosoureas, reveals the ACNO effective alkylating capacity to be less significant; (v) the low value of the NBP-ACNO adduct life (defined as the total amount of adduct present along the progression of the NBP alkylation per unit of alkylating agent concentration) points to the high instability of this adduct; and (vi) the obtained results are in accordance with the low carcinogenicity of ACNO.

Metallocene catalyst containing bulky organic group

DOEpatents

Marks, T.J.; Ja, L.; Yang, X.

1996-03-26

An ionic metallocene catalyst for olefin polymerization which comprises: (1) a cyclopentadienyl-type ligand, a Group IVB transition metal, and alkyl, aryl, or hydride substituents, as a cation, and (2) a weakly coordinating anion comprising boron substituted with halogenated, such as tetrafluoro-aryl substituents preferably containing silylalkyl substitution, such as para-silyl t-butyldimethyl.

Metallocene catalyst containing bulky organic group

DOEpatents

Marks, Tobin J.; Ja, Li; Yang, Xinmin

1996-03-26

An ionic metallocene catalyst for olefin polymerization which comprises: (1) a cyclopentadienyl-type ligand, a Group IVB transition metal, and alkyl, aryl, or hydride substituents, as a cation, and (2) a weakly coordinating anion comprising boron substituted with halogenated, such as tetra fluoro, aryl substituents preferably containing silylalkyl substitution, such as para-silyl t-butyldimethyl.

The formation of quasi-alicyclic rings in alkyl-aromatic compounds

NASA Astrophysics Data System (ADS)

Straka, Pavel; Buryan, Petr; Bičáková, Olga

2018-02-01

The alkyl side chains of n-alkyl phenols, n-alkyl benzenes and n-alkyl naphthalenes are cyclised, as demonstrated by GC measurements, FTIR spectroscopy and molecular mechanics calculations. Cyclisation occurs due to the intramolecular interaction between an aromatic ring (-δ) and a hydrogen of the terminal methyl group (+δ) of an alkyl chain. In fact, conventional molecules are not aliphatic-aromatic, but quasi-alicyclic-aromatic. With the aromatic molecules formed with a quasi-alicyclic ring, the effect of van der Waals attractive forces increases not only intramolecularly but also intermolecularly. This effect is strong in molecules with propyl and higher alkyl substituents. The increase of intermolecular van der Waals attractive forces results in bi-linearity in the GC retention time of the compounds in question, observed in the dependence of the logarithm of the relative retention time on the number of carbons in a molecule in both polar and nonpolar stationary phases with both capillary and packed columns. The role of van der Waals forces has been demonstrated using the potential energies of covalent and noncovalent interactions for 2-n-alkyl phenols, n-alkyl benzenes and 1-n-alkyl- and 2-n-alkyl naphthalenes.

Ruthenium(η⁶,η¹-arene-CH₂-NHC) Catalysts for Direct Arylation of 2-Phenylpyridine with (Hetero)Aryl Chlorides in Water.

PubMed

Kaloğlu, Nazan; Özdemir, İsmail; Gürbüz, Nevin; Arslan, Hakan; Dixneuf, Pierre H

2018-03-13

A series of new benzimidazolium halides were synthesized in good yields as unsymmetrical N -heterocyclic carbene (NHC) precursors containing the N-CH₂-arene group. The benzimidazolium halides were readily converted into ruthenium(II)-NHC complexes with the general formula [RuCl₂(η⁶,η¹-arene-CH₂-NHC)]. The structures of all new compounds were characterized by ¹H NMR (Nuclear Magnetic Resonance), 13 C NMR, FT-IR (Fourier Transform Infrared) spectroscopy and elemental analysis techniques. The single crystal structure of one benzimidazole ruthenium complex, 2b , was determined. The complex is best thought of as containing an octahedrally coordinated Ru center with the arene residue occupying three sites, the remaining sites being occupied by a (carbene)C-Ru bond and two Ru-Cl bonds. The catalytic activity of [RuCl₂(η⁶,η ¹ -arene-CH₂-NHC)] complexes was evaluated in the direct (hetero)arylation of 2-phenylpyridine with (hetero)aryl chlorides in water as the nontoxic reaction medium. These results show that catalysts 2a and 2b were the best for monoarylation with simple phenyl and tolyl chlorides. For functional aryl chlorides, 2d , 2e , and 2c appeared to be the most efficient.

Phenanthridine synthesis through iron-catalyzed intramolecular N-arylation of O-acetyl oxime.

PubMed

Deb, Indubhusan; Yoshikai, Naohiko

2013-08-16

O-Acetyl oximes derived from 2'-arylacetophenones undergo N-O bond cleavage/intramolecular N-arylation in the presence of a catalytic amount of iron(III) acetylacetonate in acetic acid. In combination with the conventional cross-coupling or directed C-H arylation, the reaction offers a convenient route to substituted phenanthridines.

Copper-catalyzed direct synthesis of diaryl 1,2-diketones from aryl iodides and propiolic acids.

PubMed

Min, Hongkeun; Palani, Thiruvengadam; Park, Kyungho; Hwang, Jinil; Lee, Sunwoo

2014-07-03

Benzil derivatives such as diaryl 1,2-diketones are synthesized via the direct decarboxylative coupling reaction of aryl propiolic acids and their oxidation. The optimized conditions are that the reaction of aryl propiolic acids and aryl iodides is conducted at 140 °C for 6 h in the presence of 10 mol % CuI/Cu(OTf)2 and Cs2CO3, after which HI (aq) is added and further reacted. The method shows good functional group tolerance toward ester, aldehyde, cyano, and nitro groups. In addition, symmetrical diaryl 1,2-diketones are obtained from aryl iodides and propiolic acid in the presence of palladium and copper catalysts.

Alkylsilyl Peroxides as Alkylating Agents in the Copper-Catalyzed Selective Mono-N-Alkylation of Primary Amides and Arylamines.

PubMed

Sakamoto, Ryu; Sakurai, Shunya; Maruoka, Keiji

2017-07-06

The copper-catalyzed selective mono-N-alkylation of primary amides or arylamines using alkylsilyl peroxides as alkylating agents is reported. The reaction proceeds under mild reaction conditions and exhibits a broad substrate scope with respect to the alkylsilyl peroxides, as well as to the primary amides and arylamines. Mechanistic studies suggest that the present reaction should proceed through a free-radical process that includes alkyl radicals generated from the alkylsilyl peroxides. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reactions of Tributylstannyl Anioniods with Alkyl Bromides.

DTIC Science & Technology

1981-09-28

g (12 mmol) of cesium tert-butoxide was added to the reaction vessel before the addition of n-butyllithium. Alkylation of Tributylstannyl Anionoids...Dry reaction vessels were purged with argon. The desired alkyl halide (1.0 mmol unless noted) and any desired additive were added to the reaction ...OFFICE OF NAVAL RESEARCH Contract N00014-79-C-0584 Task No. NR 053-714 TECHNICAL REPORT No. 2 Reactions of Tributylstannyl Anionoids with Alkyl

Nickel-catalyzed amination of aryl chlorides with ammonia or ammonium salts.

PubMed

Green, Rebecca A; Hartwig, John F

2015-03-16

The nickel-catalyzed amination of aryl chlorides to form primary arylamines occurs with ammonia or ammonium sulfate and a well-defined single-component nickel(0) precatalyst containing a Josiphos ligand and an η(2)-bound benzonitrile ligand. This system also catalyzes the coupling of aryl chlorides with gaseous amines in the form of their hydrochloride salts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sulfonation and anticoagulant activity of botryosphaeran from Botryosphaeria rhodina MAMB-05 grown on fructose.

PubMed

Mendes, Simone Ferreira; dos Santos, Osvaldo; Barbosa, Aneli M; Vasconcelos, Ana Flora D; Aranda-Selverio, Gabriel; Monteiro, Nilson K; Dekker, Robert F H; Sá Pereira, Mariana; Tovar, Ana Maria F; Mourão, Paulo A de Souza; da Silva, Maria de Lourdes Corradi

2009-10-01

Botryosphaeran (EPS(FRU)), an exopolysaccharide of the beta-(1-->3,1-->6)-d-glucan type with 31% branching at C-6, is produced by the fungus Botryosphaeria rhodina MAMB-05 when grown on fructose as carbon source. Botryosphaeran was derivatized by sulfonation to induce anticoagulant activity. The effectiveness of the sulfonation reaction by chlorosulfonic acid in pyridine was monitored by the degree of substitution and FT-IR analysis of the sulfonated EPS(FRU) (once sulfonated, EPS(FRUSULF); and re-sulfonated, EPS(FRURESULF)). Activated partial thromboplastin time (APTT) and thrombin time (TT) tests of EPS(FRURESULF) indicated significant in vitro anticoagulant activity that was dose-dependent. EPS(FRU) did not inhibit any of the coagulation tests.

Polyimides and Process for Preparing Polyimides Having Thermal-Oxidative Stability

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B. (Inventor)

2001-01-01

Polyimides and the process for preparing polyimides having improved thermal-oxidative stability derived from the polymerization of effective amounts of one or more of the polyamines such as the aromatic diamines, one or more of the tetracarboxylic dianhydrides and a novel dicarboxylic endcap having formula with an R1 group of either hydrogen or an alkyl radical of one to four carbons, an R2 group of either OH, NH2, F, or Cl radical, an R3 group of either H, OH, NH2, F, Cl or an alkylene radical, an R4 group of either an alkyl, aryl, aryloxy, nitro, F, or Cl radical, and/or an R5 group of either H, alkyl, aryl, alkoxy, aryloxy, nitro, F, or Cl radical. The polyimides are useful particularly in the preparation of prepegs and PMR composites.

Alkylation Damage by Lipid Electrophiles Targets Functional Protein Systems*

PubMed Central

Codreanu, Simona G.; Ullery, Jody C.; Zhu, Jing; Tallman, Keri A.; Beavers, William N.; Porter, Ned A.; Marnett, Lawrence J.; Zhang, Bing; Liebler, Daniel C.

2014-01-01

Protein alkylation by reactive electrophiles contributes to chemical toxicities and oxidative stress, but the functional impact of alkylation damage across proteomes is poorly understood. We used Click chemistry and shotgun proteomics to profile the accumulation of proteome damage in human cells treated with lipid electrophile probes. Protein target profiles revealed three damage susceptibility classes, as well as proteins that were highly resistant to alkylation. Damage occurred selectively across functional protein interaction networks, with the most highly alkylation-susceptible proteins mapping to networks involved in cytoskeletal regulation. Proteins with lower damage susceptibility mapped to networks involved in protein synthesis and turnover and were alkylated only at electrophile concentrations that caused significant toxicity. Hierarchical susceptibility of proteome systems to alkylation may allow cells to survive sublethal damage while protecting critical cell functions. PMID:24429493

Alkylating agents for Waldenstrom's macroglobulinaemia.

PubMed

Yang, Kun; Tan, Jianlong; Wu, Taixiang

2009-01-21

Waldenstrom's macroglobulinaemia (WM) is an uncommon B-cell lymphoproliferative disorder characterized by bone marrow infiltration and production of monoclonal immunoglobulin. Uncertainty remains if alkylating agents, such as chlorambucil, melphalan or cyclophosphamide, are an effective form of management. To assess the effects and safety of the alkylating agents on Waldenstrom's macroglobulinaemia (WM). We searched the Cochrane Central Register of Controlled Trials (Issue 1, 2008), MEDLINE (1966 to 2008), EMBASE (1980 to 2008), the Chinese Biomedical Base (1982 to 2008) and reference lists of articles.We also handsearched relevant conference proceedings from 1990 to 2008. Randomised controlled trials (RCTs) comparing alkylating agents given concomitantly with radiotherapy, splenectomy, plasmapheresis, stem-cell transplantation in patients with a confirmed diagnosis of WM. Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We collected adverse effects information from the trials. One trial involving 92 participants with pretreated/relapsed WM compared the effect of fludarabine versus the combination of cyclophosphamide (the alkylating agent), doxorubicin and prednisone (CAP). Compared to CAP, the Hazard ratio (HR) for deaths of treatment with fludarabine was estimated to be 1.04, with a standard error of 0.30 (95% CI 0.58 to 1.48) and it indicated that the mean difference of median survival time was -4.00 months, and 16.00 months for response duration. The relative risks (RR) of response rate was 2.80 (95% CI 1.10 to 7.12). There were no statistically difference in overall survival rate and median survival months, while on the basis of response rate and response duration, fludarabine seemed to be superior to CAP for pretreated/relapsed patients with macroglobulinaemia. Although alkylating agents have been used for decades they have never actually been tested in a proper randomised trial. This

Sulfonated chitosan and dopamine based coatings for metallic implants in contact with blood.

PubMed

Campelo, Clayton S; Chevallier, Pascale; Vaz, Juliana M; Vieira, Rodrigo S; Mantovani, Diego

2017-03-01

Thrombosis and calcification constitute the main clinical problems when blood-interacting devices are implanted in the body. Coatings with thin polymer layers represent an acknowledged strategy to modulate interactions between the material surface and the blood environment. To ensure the implant success, at short-term the coating should limit platelets adhesion and delay the clot formation, and at long-term it should delay the calcification process. Sulfonated chitosan, if compared to native chitosan, shows the unique ability to reduce proteins adsorption, decrease thrombogenic properties and limit calcification. In this work, stainless steel surfaces, commonly used for cardiovascular applications, were coated with sulfonated chitosan, by using dopamine and PEG as anchors, and the effect of these grafted surfaces on platelet adhesion, clot formation as well as on calcification were investigated. Surface characterization techniques evidenced that the coating formation was successful, and the sulfonated chitosan grafted sample exhibited a higher roughness and hydrophilicity, if compared to native chitosan one. Moreover, sulfonated surface limited platelet activation and the process of clot formation, thus confirming its high biological performances in blood. Calcium deposits were also lower on the sulfonated chitosan sample compared to the chitosan one, thus showing that calcification was minimal in presence of sulfonate groups. In conclusion, this sulfonated-modified surface has potential to be as blood-interacting material. Copyright © 2016. Published by Elsevier B.V.

Antibacterial surface modified of novel nanocomposite sulfonated polyethersulfone/polyrhodanine membrane

NASA Astrophysics Data System (ADS)

Rostam, Abbas Babaei; Peyravi, Majid; Ghorbani, Mohsen; Jahanshahi, Mohsen

2018-01-01

In this study, sulfonated-polyethersulfone/polyrhodanine (SPES/PRh) membranes with antibacterial behavior were fabricated. Polyethersulfone (PES) sulfonation was performed to enhance its hydrophilicity and next polyrhodanine nanoparticles (PRhNPs) were synthesized along with the sulfonated PES (SPES) by polyrhodanine (PRh) in situ polymerization. The sulfonation step also helps making composite membrane due to development of probable bondings and polymers engagements. The constructed membranes characterization was performed by FTIR, FESEM, contact angle, 1H NMR, TGA and EDS analyses. SPES/PRh membrane had enhanced hydrophilicity and consequently better fluxes for aqueous solutions. The composite SPES/PRh membrane flux was improved to 139/78 L/m2 h comparing 58.21 L/m2 h for SPES one. Membrane operational performances, antibacterial and antibiofouling tests showed improved flux, better rejection and appropriate antibacterial and antibiofouling properties for SPES/PRh membrane. The 100% bacteria mortality for specified concentrations and appropriate inhibition zones up to 9 mm have been achieved. It is generally a suitable membrane to provide proper performance beside antibacterial and antibiofouling behavior.

Molecular and morphological characterization of midblock-sulfonated styrenic triblock copolymers

DOE PAGES

Mineart, Kenneth P.; Ryan, Justin J.; Lee, Byeongdu; ...

2017-01-11

Midblock-sulfonated triblock copolymers afford a desirable opportunity to generate network-forming amphiphilic materials that are suitable for use in a wide range of emerging technologies as fuel-cell, water-desalination, ion-exchange, photovoltaic, or electroactive membranes. Employing a previously reported synthetic strategy wherein poly( p- tert-butylstyrene) remains unreactive, we have selectively sulfonated the styrenic midblock of a poly( p- tert-butylstyrene- b-styrene- b- p- tert- butylstyrene) (TST) triblock copolymer to different extents. Comparison of the resulting sulfonated copolymers with results from our prior study provides favorable quantitative agreement and suggests that a shortened reaction time is advantageous. An ongoing challenge regarding the morphological development ofmore » charged block copolymers is the competition between microphase separation of the incompatible blocks and physical cross-linking of ionic clusters, with the latter often hindering the former. Here, we expose the sulfonated TST copolymers to solvent-vapor annealing to promote nanostructural refinement. Furthermore, the effect of such annealing on morphological characteristics, as well as on molecular free volume, is explored.« less

A Modular Flow Design for the meta‐Selective C−H Arylation of Anilines

PubMed Central

Gemoets, Hannes P. L.; Laudadio, Gabriele; Verstraete, Kirsten; Hessel, Volker

2017-01-01

Abstract Described herein is an effective and practical modular flow design for the meta‐selective C−H arylation of anilines. The design consists of four continuous‐flow modules (i.e., diaryliodonium salt synthesis, meta‐selective C−H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta‐arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances. PMID:28543979

Cu-Click Compatible Triazabutadienes To Expand the Scope of Aryl Diazonium Ion Chemistry.

PubMed

Cornali, Brandon M; Kimani, Flora W; Jewett, John C

2016-10-07

Triazabutadienes can be used to readily generate reactive aryl diazonium ions under mild, physiologically relevant conditions. These conditions are compatible with a range of functionalities that do not tolerate traditional aryl diazonium ion generation. To increase the utility of this aryl diazonium ion releasing chemistry an alkyne-containing triazabutadiene was synthesized. The copper-catalyzed azide-alkyne cycloaddition ("Cu-click") reaction was utilized to modify the alkyne-containing triazabutadiene and shown to be compatible with the nitrogen-rich triazabutadiene. One of the triazole products was tethered to a fluorophore, thus enabling the direct fluorescent labeling of a model protein.

Asymmetric Aryl Polyhedral Oligomeric SilSesquioxanes (ArPOSS) with Enhanced Solubility (Preprint)

DTIC Science & Technology

2011-03-23

by reaction of an aryl Grignard or lithium reagent with SiCl4 under reaction conditions s imilar to those previously reported [22]. The aryl...cooling to room temperature, this Grignard reagent w as added via canula to a SiCl 4 (25.1 g, 0.148 m ol) THF (70 mL) solution and stirred overnight

40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject to...

40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject to...

40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327) are...

40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327) are...

40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject to...

40 CFR 721.2420 - Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., alkyl sulfate salt. 721.2420 Section 721.2420 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2420 Alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt. (a... generically as an alkoxylated dialkyldiethylenetriamine, alkyl sulfate salt (PMN P-91-288) is subject to...

40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327) are...

40 CFR 721.2410 - Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., alkyl sulfate salts. 721.2410 Section 721.2410 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.2410 Alkoxylated alkyldiethylenetriamine, alkyl sulfate salts. (a... generically as alkoxylated dialkyldiethylenetriamine, alkyl sulfate salts (PMN P-94-325, 326, and 327) are...

Polymerization of Conducting Polymers Confined to Free Surfaces: A comparison of the Langmuir-Blodgett Polymerization of 3-Alkyl Pyrroles and 2- Alkyl Anilines

DTIC Science & Technology

1992-05-19

Confined to Free Surfaces: A Comparison of the Langmuir-Blodgett Polymerization of 3- Alkyl Pyrroles and 2- Alkyl Anilines Submitted for Publication in...Surfaces: A Comparison of the Langmuir Blodgett Polymerizations of 3- alkyl pyrroles and 2- alkyl anilines R. S. Duran and H.C. Zhou Dept. of Chemistry...polymerization reactions in more detail and compare them. To do this, the polymerization reactions were run under two conditions. In the first case

21 CFR 176.120 - Alkyl ketene dimers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... section. (a) The alkyl ketene dimers are manufactured by the dehydrohalogenation of the acyl halides derived from the fatty acids of animal or vegetable fats and oils. (b) The alkyl ketene dimers are used as...

Metal complexes of alkyl-aryl dithiocarbamates: Structural studies, anticancer potentials and applications as precursors for semiconductor nanocrystals

NASA Astrophysics Data System (ADS)

Andrew, Fartisincha P.; Ajibade, Peter A.

2018-03-01

Dithiocarbamates are versatile ligands able to stabilize wide range of metal ions in their various oxidation states with the partial double bond character of Csbnd N and Csbnd S of thioureide moiety. Variation of the substituents attached to the nitrogen atom of dithiocarbamate moiety generates various intermolecular interactions, which lead to different structural arrangement in the solid state. The presence of bulky substituents on the N atom obviates the supramolecular aggregation via secondary Msbnd S interactions whereas smaller substituents encourage such aggregation that results in their wide properties and applications. Over the past decades, the synthesis and structural studies of metal complexes of dithiocarbamates have received considerable attention as potential anticancer agents with various degree of DNA binding affinity and cytotoxicity and as single molecule precursors for the preparation of semiconductor nanocrystals. In this paper, we review the synthesis, structural studies, anticancer potency and the use of alkyl-phenyl dithiocarbamate complexes as precursors for the preparation of semiconductor nanocrystals. The properties of these compounds and activities are ascribed to be due to either the dithiocarbamate moieties, the nature or type of the substituents around the dithiocarbamate backbone and the central metal ions or combination of these factors.

Improvement of neutral oil quality in the production of sulfonate additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhurba, A.S.; Bludilin, V.M.; Antonov, V.N.

This paper is concerned with improvement of neutral oil used as materials for sulfonation to produce additives for lubricating oils. In this article the authors analyze the basic reasons for the unsatisfactory quality of the neutral oil and attempt to define the ways in which the process technology can be improved so as to produce neutral oil with the required composition, at the same time raising the efficiency of utilization of the MSG-8 oil used as a feedstock for this process. Experimental results are presented which demonstrate the feasibility of sulfonating neutral oil in the high-speed mixer under near-optimal conditions.more » The yield of sulfonic acid approaches the theoretical yield. With the lowest contents of aromatic hydrocarbons in the original neutral oil, the aromatic hydrocarbons are almost completely converted to sulfonic acids. The yield of neutral oil is sufficiently high, and the residual content of aromatic hydrocarbons in the oil is no greater than 3%.« less

Stable trifluorostyrene containing compounds grafted to base polymers, and their use as polymer electrolyte membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhen-Yu; Roelofs, Mark Gerrit

2010-11-09

A fluorinated ion exchange polymer prepared by grafting at least one grafting monomer on to at least one base polymer, wherein the grafting monomer comprises structure 1a or 1b: wherein Z comprises S, SO.sub.2, or POR wherein R comprises a linear or branched perfluoroalkyl group of 1 to 14 carbon atoms optionally containing oxygen or chlorine, an alkyl group of 1 to 8 carbon atoms, an aryl group of 6 to 12 carbon atoms or a substituted aryl group of 6 to 12 carbon atoms; RF comprises a linear or branched perfluoroalkene group of 1 to 20 carbon atoms, optionallymore » containing oxygen or chlorine; Q is chosen from F, --OM, NH.sub.2, --N(M)SO.sub.2R.sup.2.sub.F, and C(M)(SO.sub.2R.sup.2.sub.F).sub.2, wherein M comprises H, an alkali cation, or ammonium; R.sup.2.sub.F groups comprises alkyl of 1 to 14 carbon atoms which may optionally include ether oxygens or aryl of 6 to 12 carbon atoms where the alkyl or aryl groups may be perfluorinated or partially fluorinated; and n is 1 or 2 for 1a, and n is 1, 2, or 3 for 1b. These ion exchange polymers are useful in preparing catalyst coated membranes and membrane electrode assemblies used in fuel cells.« less

Synthesis of benzo-fused 1-azabicyclo[m.n.0]alkanes via the Schmidt reaction: a formal synthesis of gephyrotoxin.

PubMed

Pearson, W H; Fang, W

2000-10-20

The intramolecular capture of benzocyclobutyl, benzocyclopentyl, and benzocyclohexyl carbocations 7 by azides produces spirocyclic aminodiazonium ions 8, which undergo 1,2-C-to-N rearrangement with loss of dinitrogen to produce benzo-fused iminium ions resulting from either aryl (9) or alkyl (10) migration to the electron-deficient nitrogen atom. Reduction of the iminium ions affords regioisomeric benzo-fused 1-azabicyclo[m.n.0]alkanes, e.g., benzopyrrolizidines, benzoindolizidines, benzoquinolizidines, or perhydrobenzo[f]pyrrolo[1,2-a]azepines in two regioisomeric versions, anilines (e.g., 11-14) and benzylic amines (e.g., 15-18), the result of aryl and alkyl migrations, respectively. Generally, aryl migration is preferred, despite modeling that shows that the lowest energy aminodiazonium ions are those where the departing dinitrogen is preferentially antiperiplanar to the migrating alkyl group rather than the aryl group. The utility of this methodology was illustrated by a formal synthesis of the alkaloid gephyrotoxin 4. A dependence on the efficiency and regioselectivity of the Schmidt reaction upon subtle changes in the structure of the cation precursor was observed, necessitating the exploration of a variety of substrates. Fortunately, these materials were easily made. Ultimately, the azido-alkene 81 bearing a 2-bromoethyl side-chain was useful for the Schmidt reaction, producing the known benzo-fused indolizidine 49, which had been transformed by Ito et al. into gephyrotoxin 4. The synthesis of 49 required nine steps (five purifications) from commercially available 4-methoxy-1-indanone 60 and proceeded in 22% overall yield.

A Concentration-Dependent Insulin Immobilization Behavior of Alkyl-Modified Silica Vesicles: The Impact of Alkyl Chain Length.

PubMed

Zhang, Jun; Zhang, Long; Lei, Chang; Huang, Xiaodan; Yang, Yannan; Yu, Chengzhong

2018-05-01

The insulin immobilization behaviors of silica vesicles (SV) before and after modification with hydrophobic alkyl -C 8 and -C 18 groups have been studied and correlated to the grafted alkyl chain length. In order to minimize the influence from the other structural parameters, monolayered -C 8 or -C 18 groups are grafted onto SV with controlled density. The insulin immobilization capacity of SV is dependent on the initial insulin concentrations (IIC). At high IIC (2.6-3.0 mg/mL), the trend of insulin immobilization capacity of SV is SV-OH > SV-C 8 > SV-C 18 , which is determined mainly by the surface area of SV. At medium IIC (0.6-1.9 mg/mL), the trend changes to SV-C 8 ≥ SV-C 18 > SV-OH as both the surface area and alkyl chain length contribute to the insulin immobilization. At an extremely low IIC, the hydrophobic-hydrophobic interaction between the alkyl group and insulin molecules plays the most significant role. Consequently, SV-C 18 with longer alkyl groups and the highest hydrophobicity show the best insulin enrichment performance compared to SV-C 8 and SV-OH, as evidenced by an insulin detection limit of 0.001 ng/mL in phosphate buffered saline (PBS) and 0.05 ng/mL in artficial urine determined by mass spectrometry (MS).

IONIC LIQUID-CATALYZED ALKYLATION OF ISOBUTANE WITH 2-BUTENE

EPA Science Inventory

A detailed study of the alkylation of isobutane with 2-butene in ionic liquid media has been conducted using 1-alkyl-3-methylimidazolium halides?aluminum chloride encompassing various alkyl groups (butyl-, hexyl-, and octyl-) and halides (Cl, Br, and I) on its cations and anions,...

Copolymers of fluorinated polydienes and sulfonated polystyrene

DOEpatents

Mays, Jimmy W [Knoxville, TN; Gido, Samuel P [Hadley, MA; Huang, Tianzi [Knoxville, TN; Hong, Kunlun [Knoxville, TN

2009-11-17

Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

Extended 3{beta}-alkyl steranes and 3-alkyl triaromatic steroids in crude oils and rock extracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahl, J.; Moldowan, J.M.; Summons, R.E.

1995-09-01

In oils and Precambian- to Miocene-age source rocks from varying depositional environments, we have conclusively identified several novel 3-alkyl sterane and triaromatic steroid series, including (1) 3{beta}-n-pentyl steranes, (2) 3{beta}-isopentyl steranes, (3) 3{beta}-n-hexyl steranes, (4) 3{beta}-n-hepatyl steranes, (5) 3,4-dimethyl steranes, (6) 3{beta}-butyl,4-methyl steranes, (7) triaromatic 3-n-pentyl steroids, and (8) triaromatic 3-isopentyl steroids. We have also tentatively identified additional homologs with 3-alkyl substituents as large as C{sub 11}. The relative abundances of these compounds vary substantially between samples, as indicated by (1) the ratio of 3{beta}-n-pentyl steranes to 3{beta}-isopentyl steranes and (2) the ratio of 3-n-pentyl triaromatic steroids to 3-isopentyl triaromaticmore » steroids. These data suggest possible utility for these parameters as tools for oil-source rock correlations and reconstruction of depositional environments. Although no 3-alkyl steroid natural products are currently known, several lines of evidence suggest that 3{beta}-alkyl steroids result from bacterial side-chain additions to diagenetic {delta}{sup 2}-sterenes.« less

Sulfonamidation of Aryl and Heteroaryl Halides through Photosensitized Nickel Catalysis.

PubMed

Kim, Taehoon; McCarver, Stefan J; Lee, Chulbom; MacMillan, David W C

2018-03-19

Herein we report a highly efficient method for nickel-catalyzed C-N bond formation between sulfonamides and aryl electrophiles. This technology provides generic access to a broad range of N-aryl and N-heteroaryl sulfonamide motifs, which are widely represented in drug discovery. Initial mechanistic studies suggest an energy-transfer mechanism wherein C-N bond reductive elimination occurs from a triplet excited Ni II complex. Late-stage sulfonamidation in the synthesis of a pharmacologically relevant structure is also demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A New Route to Azafluoranthene Natural Products via Direct Arylation

PubMed Central

Ponnala, Shashikanth; Harding, Wayne W.

2013-01-01

Microwave-assisted direct arylation was successfully employed in the synthesis of azafluoranthene alkaloids for the first time. Direct arylation reactions on a diverse set of phenyltetrahydroisoquinolines produces the indeno[1,2,3-ij]isoquinoline nucleus en route to a high yielding azafluoranthene synthesis. The method was used as a key step in the efficient preparation of the natural products rufescine and triclisine. As demonstrated herein, this synthetic approach should be generally applicable to the preparation of natural and un-natural azafluoranthene alkaloids as well as “azafluoranthene-like” isoquinoline alkaloids. PMID:23503080

Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta

PubMed Central

Lapadatescu, Carmen; Giniès, Christian; Le Quéré, Jean-Luc; Bonnarme, Pascal

2000-01-01

Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with l-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors (14C- and 13C-labelled l-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that l-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from l-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via β-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a β-oxidation degradation intermediate. To our knowledge, this is the first time that a β-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from l-phenylalanine is proposed. PMID:10742235

A transition-metal-free synthesis of arylcarboxyamides from aryl diazonium salts and isocyanides.

PubMed

Xia, Zhonghua; Zhu, Qiang

2013-08-16

A transition-metal-free carboxyamidation process, using aryl diazonium tetrafluoroborates and isocyanides under mild conditions, has been developed. This novel conversion was initiated by a base and solvent induced aryl radical, followed by radical addition to isocyanide and single electron transfer (SET) oxidation, affording the corresponding arylcarboxyamide upon hydration of the nitrilium intermediate.

Polyimide characterization studies - Effect of pendant alkyl groups

NASA Technical Reports Server (NTRS)

Jensen, B. J.; Young, P. R.

1984-01-01

The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.

Isomeric Detergent Comparison for Membrane Protein Stability: Importance of Inter-Alkyl-Chain Distance and Alkyl Chain Length

PubMed Central

Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S.; Du, Yang; Nielsen, Anne K.; Byrne, Bernadette; Kobilka, Brian K.; Loland, Claus J.; Guan, Lan

2017-01-01

Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C12 alkyl chain was most effective at maintaining solubility/stability of the membrane proteins. We propose that interplay between the hydrophile–lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane proteins. PMID:27981750

Arynes, diaryliodonium salts and azine N-oxides in transition metal-free electrophilic N-arylation

NASA Astrophysics Data System (ADS)

Bugaenko, D. I.; Karchava, A. V.; Yurovskaya, M. A.

2018-03-01

The main approach to the synthesis of aromatic and heteroaromatic amines is based on palladium- and copper-catalyzed N-arylation reactions. Although these methods are highly efficient and provide extensive opportunities for the synthesis of (het)arylamines with various structures and properties, they have some limitations related to the catalysts used and reaction conditions. This review addresses alternative approaches to N-(het)arylation that have been extensively developed in the past decade and are based on the use of arynes, diaryliodonium salts and azine N-oxides as electrophilic (het)arylating agents. Because of mild reaction conditions and no need for catalysts and strong bases, these N-(het)arylation methods are attractive for various synthetic applications and open up new possibilities for the preparation of valuable organic compounds inaccessible via traditional catalytic methods. The attention is focussed on publications of the last decade. The bibliography includes 112 references.

Use of Aryl Chlorides as Electrophiles in Pd-Catalyzed Alkene Difunctionalization Reactions

PubMed Central

Rosen, Brandon R.; Ney, Joshua E.; Wolfe, John P.

2010-01-01

The development of conditions that allow use of inexpensive aryl chlorides as electrophiles in Pd-catalyzed alkene carboamination and carboetherification reactions is described. A catalyst composed of Pd(OAc)2 and S-Phos minimizes N-arylation of the substrate and prevents formation of mixtures of regioisomeric products. A number of heterocycles, including pyrrolidines, isoxazolidines, tetrahydrofurans, and pyrazolidines, are efficiently generated with this method. PMID:20297834

Reusable copper-catalyzed cross-coupling reactions of aryl halides with organotins in inexpensive ionic liquids.

PubMed

Li, Jin-Heng; Tang, Bo-Xiao; Tao, Li-Ming; Xie, Ye-Xiang; Liang, Yun; Zhang, Man-Bo

2006-09-15

A combination of Cu2O nanoparticles with P(o-tol)3 shows highly catalytic activity for the Stille cross-coupling reaction. A series of copper catalysts and ligands were evaluated, and Cu2O nanoparticles combined with P(o-tol)3 provided the best results. In the presence of Cu2O nanoparticles and P(o-tol)3, a variety of aryl halides including aryl chlorides underwent the Stille reaction with organotins smoothly in moderate to excellent yields using inexpensive TBAB (n-Bu4NBr) as the medium. It is noteworthy that the Cu2O/P(o-tol)3/TBAB system can be recovered and reused at least three times without any loss of catalytic activity among the reactions of aryl iodides and activated aryl bromides.

Catalytic ionic hydrogenation of ketones using tungsten or molybdenum organometallic species

DOEpatents

Voges, Mark; Bullock, R. Morris

2000-01-01

The present invention is a process for the catalytic hydrogenation of ketones and aldehydes to alcohols at low temperatures and pressures using organometallic molybdenum and tungsten complexes. The functional group is selected from groups represented by the formulas R(C.dbd.O)R' and R(C.dbd.O)H, wherein R and R' are selected from hydrogen or any alkyl or aryl group. The active catalyst for the process has the form: [CpM(CO).sub.2 (PR*.sub.3) L].sup.+ A.sup.-, where Cp=.eta..sup.5 -R.sup..tangle-solidup..sub.m C.sub.5 H.sub.5-m and R.sup..tangle-solidup. represents an alkyl group or a halogen (F, Cl, Br, I) or R.sup..tangle-solidup. =OR' (where R'=H, an alkyl group or an aryl group) or R.sup..tangle-solidup. =CO.sub.2 R' (where R'=H, an alkyl group or an aryl group) and m=0 to 5; M represents a molybdenum atom or a tungsten atom; R*.sub.3 represents three hydrocarbon groups selected from a cyclohexyl group (C.sub.6 H.sub.11), a methyl group (CH.sub.3), and a phenyl group (C.sub.6 H.sub.5) and all three R* groups can be the same or different or two of the three groups can be the same; L represents a ligand; and A.sup.- represents an anion. In another embodiment, one, two or three of the R* groups can be an OR*.

Synthesis of Quaternary Carbon Stereogenic Centers through Enantioselective Cu-Catalyzed Allylic Substitutions with Vinylaluminum Reagents

PubMed Central

Gao, Fang; McGrath, Kevin P.; Lee, Yunmi; Hoveyda, Amir H.

2010-01-01

Catalytic enantioselective allylic substitution (EAS) reactions, which involve the use of alkyl- or aryl-substituted vinylaluminum reagents and afford 1,4-dienes containing a quaternary carbon stereogenic center at their C-3 site, are disclosed. The C–C bond forming transformations are promoted by 0.5–2.5 mol % of sulfonate bearing chiral bidentate N-heterocyclic carbene (NHC) complexes, furnishing the desired products efficiently (66–97% yield of isolated products) and in high site- (>98% SN2′) and enantioselectivity [up to 99:1 enantiomer ratio (er)]. To the best of our knowledge, the present report puts forward the first cases of allylic substitution reactions that result in the generation of all-carbon quaternary stereogenic centers through the addition of a vinyl unit. The aryl- and vinyl-substituted vinylaluminum reagents, which cannot be prepared in high efficiency through direct reaction with diisobutylaluminum hydride, are accessed through a recently introduced Ni-catalyzed reaction of the corresponding terminal alkynes with the same inexpensive metal-hydride agent. Sequential Ni-catalyzed hydrometallations and Cu-catalyzed C–C bond forming reactions allow for efficient and selective synthesis of a range of enantiomerically enriched EAS products, which cannot cannot be accessed by previously disclosed strategies (due to inefficient vinylmetal synthesis or low reactivity and/or selectivity with Si-substituted derivatives). The utility of the protocols developed is demonstrated through a concise enantioselective synthesis of natural product bakuchiol. PMID:20860365

A Convenient Approach to Synthesizing Peptide C-Terminal N-Alkyl Amides

PubMed Central

Fang, Wei-Jie; Yakovleva, Tatyana; Aldrich, Jane V.

2014-01-01

Peptide C-terminal N-alkyl amides have gained more attention over the past decade due to their biological properties, including improved pharmacokinetic and pharmacodynamic profiles. However, the synthesis of this type of peptide on solid phase by current available methods can be challenging. Here we report a convenient method to synthesize peptide C-terminal N-alkyl amides using the well-known Fukuyama N-alkylation reaction on a standard resin commonly used for the synthesis of peptide C-terminal primary amides, the PAL-PEG-PS (Peptide Amide Linker-polyethylene glycol-polystyrene) resin. The alkylation and oNBS deprotection were conducted under basic conditions and were therefore compatible with this acid labile resin. The alkylation reaction was very efficient on this resin with a number of different alkyl iodides or bromides, and the synthesis of model enkephalin N-alkyl amide analogs using this method gave consistently high yields and purities, demonstrating the applicability of this methodology. The synthesis of N-alkyl amides was more difficult on a Rink amide resin, especially the coupling of the first amino acid to the N-alkyl amine, resulting in lower yields for loading the first amino acid onto the resin. This method can be widely applied in the synthesis of peptide N-alkyl amides. PMID:22252422

Spectral study and protein labeling of inclusion complex between dye and calixarene sulfonate.

PubMed

Fei, Xuening; Zhang, Yong; Zhu, Sen; Liu, Lijuan; Yu, Lu

2013-05-01

The host-guest inclusion complex of calix[6]arene sulfonate (SCA6) with thiazole orange (TO) formed in aqueous solution was studied. Absorption and fluorescence techniques were used for the analysis of this inclusion complex. The addition of calixarene sulfonate leads to a decrease in both absorption and fluorescence intensity of the dye, indicating that the inclusion complex was formed. Simultaneously, the inclusion phenomenon of another cyanine dye, Cy3, with calixarene sulfonate was investigated. The stability constant of the two complexes was determined, and the results were compared. The water solubility of TO dye was increased in the presence of calixarene sulfonate, and further protein labeling experiments suggested that this TO-SCA6 complex can act as a fluorescent probe for labeling of biomolecules.

A Modular Flow Design for the meta-Selective C-H Arylation of Anilines.

PubMed

Gemoets, Hannes P L; Laudadio, Gabriele; Verstraete, Kirsten; Hessel, Volker; Noël, Timothy

2017-06-12

Described herein is an effective and practical modular flow design for the meta-selective C-H arylation of anilines. The design consists of four continuous-flow modules (i.e., diaryliodonium salt synthesis, meta-selective C-H arylation, inline copper extraction, and aniline deprotection) which can be operated either individually or consecutively to provide direct access to meta-arylated anilines. With a total residence time of 1 hour, the desired product could be obtained in high yield and excellent purity without the need for column chromatography, and the residual copper content meets the standards for parenterally administered pharmaceutical substances. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Synthesis of aryl azides and vinyl azides via proline-promoted CuI-catalyzed coupling reactions.

PubMed

Zhu, Wei; Ma, Dawei

2004-04-07

The coupling reaction of aryl halides or vinyl iodide with sodium azide under catalysis of CuI/L-proline works at relatively low temperature to provide aryl azides or vinyl azides in good to excellent yields.

Two-step sulfonation process for the conversion of polymer fibers to carbon fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barton, Bryan E.; Patton, Jasson T.; Hukkanen, Eric J.

Disclosed herein are processes for preparing carbon fibers, comprising: sulfonating a polymer fiber with a sulfonating agent that is fuming sulfuric acid, sulfuric acid, chlorosulfonic acid, or a combination thereof; treating the sulfonated polymer with a heated solvent, wherein the temperature of the heated solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 501-3000.degree. C. Carbon fibers prepared according to these methods are also disclosed herein.

Synthesis and Characterization of Polymers for Fuel Cells Application

NASA Technical Reports Server (NTRS)

Tytko, Stephen F.

2003-01-01

The goal of this summer research is to prepare Polymer Exchange Membranes (PEM s) for fuel cell application. Several high temperature polymers such as polybenzimidazoles and polyether ketones were known to possess good high temperature stability and had been investigated by post-sulfonation to yield sulfonated polymers. The research project will involve two approaches: 1. Synthesis of polybenzimidazoles and then react with alkyl sultonse to attach an aliphatic sulfonic groups. 2. Synthesis of monomers containing sulfonic acid units either on a aromatic ring or on an aliphatic chain and then polymerize the monomers to form high molecular weight sulfonate polymers.

Design, synthesis, and characterization of lightly sulfonated multigraft acrylate-based copolymer superelastomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misichronis, Konstantinos; Wang, Weiyu; Cheng, Shiwang

2018-01-29

Multigraft copolymer superelastomers consisting of a poly(n-butyl acrylate) backbone and polystyrene side chains were synthesized and the viscoelastic properties of the non-sulfonated and sulfonated final materials were investigated using extensional rheology (SER3). The non-linear viscoelastic experiments revealed significantly increased true stresses (up to 10 times higher) after sulfonating only 2–3% of the copolymer while the materials maintained high elongation (<700%). The linear viscoelastic experiments showed that the storage and loss modulus are increased by sulfonation and that the copolymers can be readily tuned and further improved by increasing the number of branching points and the molecular weight of the backbone.more » Here, in this way, we show that by tuning not only the molecular characteristics of the multigraft copolymers but also their architecture and chemical interaction, we can acquire thermoplastic superelastomer materials with desired viscoelastic properties.« less

40 CFR 721.10677 - Alkyl phosphonate (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10677 Alkyl phosphonate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl phosphonate (PMN P-12-584...

An Efficient Process for Pd-Catalyzed C–N Cross-Coupling Reactions of Aryl Iodides: Insight Into Controlling Factors

PubMed Central

Fors, Brett P.; Davis, Nicole R.; Buchwald, Stephen L.

2009-01-01

An investigation into Pd-catalyzed C–N cross-coupling reactions of aryl iodides is described. NaI is shown to have a significant inhibitory effect on these processes. By switching to a solvent system in which the iodide byproduct was insoluble, reactions of aryl iodides were accomplished with the same efficiencies as aryl chlorides and bromides. Using catalyst systems based on certain biarylphosphine ligands, aryl iodides were successfully reacted with an array of primary and secondary amines in high yields. Lastly, reactions of heteroarylamines and heteroaryliodides were also conducted in high yields. PMID:19348431

40 CFR 721.10704 - Aryl-substituted alkane.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aryl-substituted alkane. 721.10704 Section 721.10704 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES..., Authorization, and Restriction of Chemicals in the European Union) without submitting all final reports and the...

PREPARATION OF ALKYL PYROPHOSPHATE EXTRACTANTS

DOEpatents

Levine, C.A.; Skiens, W.E.; Moore, G.R.

1960-08-01

A process for providing superior solvent extractants for metal recovery processes is given wherein the extractant comprises an alkyl pyrophosphoric acid ester dissolved in an organic solvent diluent. Finely divided solid P/sub 2/O/ sub 5/ is slurried in an organic solvent-diluent selected from organic solvents such as kerosene, benzene, chlorobenzene, toluene, etc. An alcohol selected from the higher alcohols having 4 to 17 carbon atoms. e.g.. hexanol-1. heptanol-3, octanol-1. 2.6-dimethyl-heptanol-4, and decanol-1, is rapidly added to the P/sub 2/O/sub 5/ slurry in the amount of about 2 moles of alcohol to 1 mole of P/sub 2/ O/sub 5/. The temperature is maintained below about 110 deg C during the course of the P/sub 2/O/sub 5/-alcohol reaction. An alkyl pyrophosphate extractant compound is formed as a consequence of the reaction process. The alkyl pyrophosphate solvent-diluent extractant phase is useful in solvent extraction metal recovery processes.

Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: relevance of their surface active properties and of the type of emulsifier.

PubMed

González, María J; Medina, Isabel; Maldonado, Olivia S; Lucas, Ricardo; Morales, Juan C

2015-09-15

The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaerobic Aryl Reductive Dehalogenation of Halobenzoates by Cell Extracts of “Desulfomonile tiedjei”

PubMed Central

DeWeerd, Kim A.; Suflita, Joseph M.

1990-01-01

We studied the transformation of halogenated benzoates by cell extracts of a dehalogenating anaerobe, “Desulfomonile tiedjei.” We found that cell extracts possessed aryl reductive dehalogenation activity. The activity was heat labile and dependent on the addition of reduced methyl viologen, but not on that of reduced NAD, NADP, flavin mononucleotide, flavin adenine dinucleotide, desulfoviridin, cytochrome c3, or benzyl viologen. Dehalogenation activity in extracts was stimulated by formate, CO, or H2, but not by pyruvate plus coenzyme A or by dithionite. The pH and temperature optima for aryl dehalogenation were 8.2 and 35°C, respectively. The rate of dehalogenation was proportional to the amount of protein in the assay mixture. The substrate specificity of aryl dehalogenation activity for various aromatic compounds in “D. tiedjei” cell extracts was identical to that of whole cells, except differences were observed in the relative rates of halobenzoate transformation. Dehalogenation was 10-fold greater in “D. tiedjei” extracts prepared from cells cultured in the presence of 3-chlorobenzoate, suggesting that the activity was inducible. Aryl reductive dehalogenation in extracts was inhibited by sulfite, sulfide, and thiosulfate, but not sulfate. Experiments with combinations of substrates suggested that cell extracts dehalogenated 3-iodobenzoate more readily than either 3,5-dichlorobenzoate or 3-chlorobenzoate. Dehalogenation activity was found to be membrane associated. This is the first report characterizing aryl dehalogenation activity in cell extracts of an obligate anaerobe. PMID:16348308

Camphyl-based α-diimine palladium complexes: highly efficient precatalysts for direct arylation of thiazoles in open-air.

PubMed

Chen, Fu-Min; Lu, Dong-Dong; Hu, Li-Qun; Huang, Ju; Liu, Feng-Shou

2017-07-21

Based on the strategy of the development of phosphine-free palladium-catalyzed direct C-H arylation, a series of camphyl-based α-diimine palladium complexes bearing sterically bulky substituents were synthesized and characterized. The palladium complexes were applied for the cross-coupling of thiazole derivatives with aryl bromides. The effect of the sterically bulky substituent on the N-aryl moiety as well as the reaction conditions was screened. Under the optimal protocols, a wide range of aryl bromides can be smoothly coupled with thiazoles in good to excellent yields in the presence of a low palladium loading of 0.2 mol% under open-air conditions.

Anhydrous state proton and lithium ion conducting solid polymer electrolytes based on sulfonated bisphenol-A-poly(arylene ethers)

NASA Astrophysics Data System (ADS)

Guha Thakurta, Soma

Sulfonated polymer based solid polymer electrolytes (SPEs) have received considerable interest in recent years because of their wide variety of applications particularly in fuel cells, batteries, supercapacitors, and electrochromic devices. The present research was focused on three interrelated subtopics. First, two different bisphenol-A-poly(arylene ethers), polyetherimide (PEI) and polysulfone (PSU) were sulfonated by a post sulfonation method to various degrees of sulfonation, and their thermal and mechanical properties were examined. The effects of poly(arylene ether) chemical structure, reaction time, concentration, and types of sulfonating agents on sulfonation reaction were investigated. It was found that deactivation of bisphenol A unit caused by the electron withdrawing imide, retarded the sulfonation of PEI compared to PSU. Sulfonation conducted with a high concentration of sulfonating agent and/or prolonged reaction time exhibited evidence of degradation at the isopropylidene unit. The degradation occurred through the same mechanistic pathway with the two different sulfonating agents, chlorosulfonic acid (CSA) and trimethylsilyl chlorosulfonate (TMSCS). The degradation was faster with CSA than its silyl ester, TMSCS, and was evident even at low acid concentration. Second, novel anhydrous proton conducting solid polymer electrolytes (SPEs) were prepared by the incorporation of 1H-1,2,4-triazole (Taz) as a proton solvent in sulfonated polyetherimide (SPEI) matrix. The size, shape, and state of dispersion (crystal morphology) of triazole crystals in SPEI were examined as a function of degree of sulfonation and triazole concentration. Increasing sulfonic acid content caused reduction of triazole crystallite size, hence the depression of melting temperature and their uniform distribution throughout the sulfonated polymer matrix. The increased rate of structure diffusion within the smaller size crystals due to the improved molecular mobility contributed

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: A Review

PubMed Central

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-01-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical, and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter, or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article. PMID:29755967

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: a Review

NASA Astrophysics Data System (ADS)

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-04-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article.

Structure of aryl O -demethylase offers molecular insight into a catalytic tyrosine-dependent mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohler, Amanda C.; Mills, Matthew J. L.; Adams, Paul D.

Some strains of soil and marine bacteria have evolved intricate metabolic pathways for using environmentally derived aromatics as a carbon source. Many of these metabolic pathways go through intermediates such as vanillate, 3-O-methylgallate, and syringate. Demethylation of these compounds is essential for downstream aryl modification, ring opening, and subsequent assimilation of these compounds into the tricarboxylic acid (TCA) cycle, and, correspondingly, there are a variety of associated aryl demethylase systems that vary in complexity. Intriguingly, only a basic understanding of the least complex system, the tetrahydrofolate-dependent aryl demethylase LigM from Sphingomonas paucimobilis, a bacterial strain that metabolizes lignin-derived aromatics, wasmore » previously available. LigM-catalyzed demethylation enables further modification and rin g opening of the single-ring aromatics vanillate and 3-Omethylgallate, which are common byproducts of biofuel production. We characterize aryl O-demethylation by LigM and report its 1.81-Å crystal structure, revealing a unique demethylase fold and a canonical folate-binding domain. Structural homology and geometry optimization calculations enabled the identification of LigM's tetrahydrofolate-binding site and protein-folate interactions. Computationally guided mutagenesis and kinetic analyses allowed the identification of the enzyme's aryl-binding site location and determination of its unique, catalytic tyrosine-dependent reaction mechanism. This work defines LigM as a distinct demethylase, both structurally and functionally, and provides insight into demethylation and its reaction requirements. Our results afford the mechanistic details required for efficient utilization of LigM as a tool for aryl O-demethylation and as a component of synthetic biology efforts to valorize previously underused aromatic compounds.« less

Structure of aryl O -demethylase offers molecular insight into a catalytic tyrosine-dependent mechanism

DOE PAGES

Kohler, Amanda C.; Mills, Matthew J. L.; Adams, Paul D.; ...

2017-04-03

Some strains of soil and marine bacteria have evolved intricate metabolic pathways for using environmentally derived aromatics as a carbon source. Many of these metabolic pathways go through intermediates such as vanillate, 3-O-methylgallate, and syringate. Demethylation of these compounds is essential for downstream aryl modification, ring opening, and subsequent assimilation of these compounds into the tricarboxylic acid (TCA) cycle, and, correspondingly, there are a variety of associated aryl demethylase systems that vary in complexity. Intriguingly, only a basic understanding of the least complex system, the tetrahydrofolate-dependent aryl demethylase LigM from Sphingomonas paucimobilis, a bacterial strain that metabolizes lignin-derived aromatics, wasmore » previously available. LigM-catalyzed demethylation enables further modification and rin g opening of the single-ring aromatics vanillate and 3-Omethylgallate, which are common byproducts of biofuel production. We characterize aryl O-demethylation by LigM and report its 1.81-Å crystal structure, revealing a unique demethylase fold and a canonical folate-binding domain. Structural homology and geometry optimization calculations enabled the identification of LigM's tetrahydrofolate-binding site and protein-folate interactions. Computationally guided mutagenesis and kinetic analyses allowed the identification of the enzyme's aryl-binding site location and determination of its unique, catalytic tyrosine-dependent reaction mechanism. This work defines LigM as a distinct demethylase, both structurally and functionally, and provides insight into demethylation and its reaction requirements. Our results afford the mechanistic details required for efficient utilization of LigM as a tool for aryl O-demethylation and as a component of synthetic biology efforts to valorize previously underused aromatic compounds.« less

Effect of the C-2 hydroxyl group on the mesomorphism of alkyl glycosides: synthesis and thermotropic behavior of alkyl 2-deoxy-D-arabino-hexopyranosides.

PubMed

Singh, Madan Kumar; Jayaraman, Narayanaswamy; Rao, D S Shankar; Prasad, S Krishna

2008-10-01

A homologous series of alkyl 2-deoxy-alpha-d-arabino-hexopyranosides and alkyl 2-deoxy-beta-d-arabino-hexopyranosides were synthesized, upon glycosylation of 1-alkanols (from C8 to C18 alkanols) with ethyl 2-deoxy-3,4,6-tri-O-acetyl-1-thio-d-arabino-hexopyranoside, followed by a deprotection. The thermotropic behavior of these new types of alkyl glycosides was investigated. It was observed that the beta-anomers of these alkyl glycosides, bearing nonyl to tetradecyl alkyl chain are mesomorphic, exhibiting monotropic smectic A phase. In contrast, the alpha-anomers are all non-mesomorphic. An effort to identify the liquid crystalline behavior of binary mixtures of the alpha- and beta-anomers was undertaken and it was found that mixtures containing equimolar amounts of the anomers exhibited mesomorphic behavior. A fine balance of the hydrophilic and hydrophobic components within the molecule is also found to be important for the alkyl 2-deoxy glycosides to form the mesophase.

Direct N-alkylation of unprotected amino acids with alcohols

PubMed Central

Yan, Tao; Feringa, Ben L.; Barta, Katalin

2017-01-01

N-alkyl amino acids find widespread application as highly valuable, renewable building blocks. However, traditional synthesis methodologies to obtain these suffer from serious limitations, providing a major challenge to develop sustainable alternatives. We report the first powerful catalytic strategy for the direct N-alkylation of unprotected α-amino acids with alcohols. This method is highly selective, produces water as the only side product leading to a simple purification procedure, and a variety of α-amino acids are mono- or di-N-alkylated, in most cases with excellent retention of optical purity. The hydrophobicity of the products is tunable, and even simple peptides are selectively alkylated. An iron-catalyzed route to mono-N-alkyl amino acids using renewable fatty alcohols is also described that represents an ideal green transformation for obtaining fully bio-based surfactants. PMID:29226249

Isomeric Detergent Comparison for Membrane Protein Stability: Importance of Inter-Alkyl-Chain Distance and Alkyl Chain Length.

PubMed

Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S; Du, Yang; Nielsen, Anne K; Byrne, Bernadette; Kobilka, Brian K; Loland, Claus J; Guan, Lan; Chae, Pil Seok

2016-12-14

Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C 12 alkyl chain was most effective at maintaining solubility/stability of the membrane proteins. We propose that interplay between the hydrophile-lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane proteins. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Salvage of failed protein targets by reductive alkylation.

PubMed

Tan, Kemin; Kim, Youngchang; Hatzos-Skintges, Catherine; Chang, Changsoo; Cuff, Marianne; Chhor, Gekleng; Osipiuk, Jerzy; Michalska, Karolina; Nocek, Boguslaw; An, Hao; Babnigg, Gyorgy; Bigelow, Lance; Joachimiak, Grazyna; Li, Hui; Mack, Jamey; Makowska-Grzyska, Magdalena; Maltseva, Natalia; Mulligan, Rory; Tesar, Christine; Zhou, Min; Joachimiak, Andrzej

2014-01-01

The growth of diffraction-quality single crystals is of primary importance in protein X-ray crystallography. Chemical modification of proteins can alter their surface properties and crystallization behavior. The Midwest Center for Structural Genomics (MCSG) has previously reported how reductive methylation of lysine residues in proteins can improve crystallization of unique proteins that initially failed to produce diffraction-quality crystals. Recently, this approach has been expanded to include ethylation and isopropylation in the MCSG protein crystallization pipeline. Applying standard methods, 180 unique proteins were alkylated and screened using standard crystallization procedures. Crystal structures of 12 new proteins were determined, including the first ethylated and the first isopropylated protein structures. In a few cases, the structures of native and methylated or ethylated states were obtained and the impact of reductive alkylation of lysine residues was assessed. Reductive methylation tends to be more efficient and produces the most alkylated protein structures. Structures of methylated proteins typically have higher resolution limits. A number of well-ordered alkylated lysine residues have been identified, which make both intermolecular and intramolecular contacts. The previous report is updated and complemented with the following new data; a description of a detailed alkylation protocol with results, structural features, and roles of alkylated lysine residues in protein crystals. These contribute to improved crystallization properties of some proteins.

Salvage of Failed Protein Targets by Reductive Alkylation

PubMed Central

Tan, Kemin; Kim, Youngchang; Hatzos-Skintges, Catherine; Chang, Changsoo; Cuff, Marianne; Chhor, Gekleng; Osipiuk, Jerzy; Michalska, Karolina; Nocek, Boguslaw; An, Hao; Babnigg, Gyorgy; Bigelow, Lance; Joachimiak, Grazyna; Li, Hui; Mack, Jamey; Makowska-Grzyska, Magdalena; Maltseva, Natalia; Mulligan, Rory; Tesar, Christine; Zhou, Min; Joachimiak, Andrzej

2014-01-01

The growth of diffraction-quality single crystals is of primary importance in protein X-ray crystallography. Chemical modification of proteins can alter their surface properties and crystallization behavior. The Midwest Center for Structural Genomics (MCSG) has previously reported how reductive methylation of lysine residues in proteins can improve crystallization of unique proteins that initially failed to produce diffraction-quality crystals. Recently, this approach has been expanded to include ethylation and isopropylation in the MCSG protein crystallization pipeline. Applying standard methods, 180 unique proteins were alkylated and screened using standard crystallization procedures. Crystal structures of 12 new proteins were determined, including the first ethylated and the first isopropylated protein structures. In a few cases, the structures of native and methylated or ethylated states were obtained and the impact of reductive alkylation of lysine residues was assessed. Reductive methylation tends to be more efficient and produces the most alkylated protein structures. Structures of methylated proteins typically have higher resolution limits. A number of well-ordered alkylated lysine residues have been identified, which make both intermolecular and intramolecular contacts. The previous report is updated and complemented with the following new data; a description of a detailed alkylation protocol with results, structural features, and roles of alkylated lysine residues in protein crystals. These contribute to improved crystallization properties of some proteins. PMID:24590719

Synthesis of substituted pyrazines

DOEpatents

Pagoria, Philip F.; Zhang, Mao Xi

2016-10-04

A method for synthesizing a pyrazine-containing material according to one embodiment includes contacting an iminodiacetonitrile derivative with a base and a reagent selected from a group consisting of hydroxylamine, a hydroxylamine salt, an aliphatic primary amine, a secondary amine, an aryl-substituted alkylamine a heteroaryl-substituted alkyl amine, an alcohol, an alkanolamine and an aryl alcoholamine. Additional methods and several reaction products are presented. ##STR00001##

Anticancer activity and anti-inflammatory studies of 5-aryl-1,4-benzodiazepine derivatives.

PubMed

Sandra, Cortez-Maya; Eduardo, Cortes Cortes; Simon, Hernandez-Ortega; Teresa, Ramirez Apan; Antonio, Nieto Camacho; Lijanova, Irina V; Marcos, Martinez-Garcia

2012-07-01

A series of 5-aryl-1,4-benzodiazepines with chloro- or fluoro-substituents in the second ring have been synthesized and their anti-inflammatory, myeloperoxidase and anticancer properties studied. The synthesized compounds showed potential anti-inflammatory and anticancer activities, which were enhanced in the presence of a chloro-substituent in the second ring of the 5-aryl-1,4- benzodiazepine.

Synthesis and biological screening of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyls as possible anti-tubercular and antimicrobial agents.

PubMed

Abhale, Yogita K; Sasane, Amit V; Chavan, Abhijit P; Deshmukh, Keshav K; Kotapalli, Sudha Sravanti; Ummanni, Ramesh; Sayyad, Sadikali F; Mhaske, Pravin C

2015-04-13

A series of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyl derivatives, 25-64 were synthesized and evaluated for inhibitory activity against Mycobacterium smegmatis MC(2) 155 strain and antimicrobial activities against four pathogenic bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Among them, compounds 40, 49, 50, and 54 exhibited moderate to good inhibition on the growth of the bacteria Mycobacterium smegmatis at the concentration of 30 μM. Compounds 26, 40, 44, 54 and 56 exhibited moderate to good antibacterial activity. Compound 5-(2'-(4-fluorobenzyl)thiazol-4'-yl)-2-(4-fluorophenyl)-4-methyl-thiazole (54) exhibited both antitubercular as well as antimicrobial activity against all tested strains. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Balancing repair and tolerance of DNA damage caused by alkylating agents.

PubMed

Fu, Dragony; Calvo, Jennifer A; Samson, Leona D

2012-01-12

Alkylating agents constitute a major class of frontline chemotherapeutic drugs that inflict cytotoxic DNA damage as their main mode of action, in addition to collateral mutagenic damage. Numerous cellular pathways, including direct DNA damage reversal, base excision repair (BER) and mismatch repair (MMR), respond to alkylation damage to defend against alkylation-induced cell death or mutation. However, maintaining a proper balance of activity both within and between these pathways is crucial for a favourable response of an organism to alkylating agents. Furthermore, the response of an individual to alkylating agents can vary considerably from tissue to tissue and from person to person, pointing to genetic and epigenetic mechanisms that modulate alkylating agent toxicity.

Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations.

PubMed

Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim A

2013-10-01

Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of α-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of α-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, α,α-disubstituted α-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed.

Aryl Ketone Synthesis via Tandem Orthoplatinated Triarylphosphite-Catalyzed Addition Reactions of Arylboronic Acids with Aldehydes Followed by Oxidation

PubMed Central

Liao, Yuan-Xi; Hu, Qiao-Sheng

2010-01-01

Tandem orthoplatinated triarylphosphite-catalyzed addition reactions of arylboronic acids with aldehydes followed by oxidation to yield aryl ketones is described. 3-Pentanone was identified as a suitable oxidant for the tandem aryl ketone formation reaction. By using microwave energy, aryl ketones were obtained in high yields with the catalyst loading as low as 0.01%. PMID:20849092

Aryl-substituted aminobenzimidazoles targeting the hepatitis C virus internal ribosome entry site

PubMed Central

Ding, Kejia; Wang, Annie; Boerneke, Mark A.; Dibrov, Sergey M.; Hermann, Thomas

2014-01-01

We describe the exploration of N1-aryl-substituted benzimidazoles as ligands for the hepatitis C virus (HCV) internal ribosome entry site (IRES) RNA. The design of the compounds was guided by the co-crystal structure of a benzimidazole viral translation inhibitor in complex with the RNA target. Structure-binding activity relationships of aryl-substituted benzimidazole ligands were established that were consistent with the crystal structure of the translation inhibitor complex. PMID:24856063

Water Soluble Phosphane-Gold(I) Complexes. Applications as Recyclable Catalysts in a Three-component Coupling Reaction and as Antimicrobial and Anticancer Agents

PubMed Central

Elie, Benelita T.; Levine, Chaya; Ubarretxena-Belandia, Iban; Varela-Ramírez, Armando; Aguilera, Renato J.; Ovalle, Rafael; Contel, María

2013-01-01

Water-soluble compounds of the type [AuCl(PR3)] with alkyl-bis-(m-sulfonated-phenyl)-(mC6H4SO3Na)2 and dialkyl-(m-sulfonated-phenyl)-(mC6H4SO3Na) (R = nBu, Cp) phosphanes have been prepared. Dialkyl-phosphane compounds generate water-soluble nanoparticles of 10-15 nm radius when dissolved in water. These air-stable complexes have been evaluated as catalysts in the synthesis of propargylamines via a three-component coupling reaction of aldehydes, amines and alkynes in water. The antimicrobial activity of the new complexes against Gram-positive and Gram-negative bacteria and yeast has been evaluated. The new compounds display moderate to high antibacterial activity. The more lipophilic compounds are also potent against fungi. Their cytotoxic properties have been analyzed in vitro utilizing human Jurkat T-cell acute lymphoblastic leukemia cells. Compounds with dialkyl-(m-sulfonated-phenyl)-(mC6H4SO3Na) phosphanes displayed moderate to high cytotoxicity on this cell line. Death cell mechanism occurs mainly by early apoptosis. The catalytic/biological activity of the previously described compound with commercial m-trisulfonated-triphenylphosphine [AuCl(TPPTS)] (6) has been also evaluated to compare the effects of the higher basicity and lipophilicity of the alkyl- and di-alkyl-(m-sulfonated-phenyl) phosphanes on these new compounds. PMID:23524957

The evolution of aryl hydrocarbon signaling proteins: diversity of ARNT isoforms among fish species.

PubMed

Powell, W H; Hahn, M E

2000-01-01

The aryl hydrocarbon receptor nuclear translocator (ARNT) mediates aryl hydrocarbon signaling and toxicity by dimerizing with the ligand-activated aryl hydrocarbon receptor (AHR), forming a complex that binds specific DNA elements and alters transcription of target genes. Two genes encode different forms of ARNT in rodents: ARNT1, which is widely expressed, and ARNT2, which exhibits a very restricted expression pattern. In an effort to characterize aryl hydrocarbon signaling mechanisms in fishes, we previously isolated an ARNT cDNA from Fundulus heteroclitus and discovered that this species expresses ARNT2 ubiquitously. This situation differs not only from mammals, but also from rainbow trout, which expresses a divergent ARNT gene that we hypothesized was peculiar to salmonids (rtARNTa/b). In this communication, we examine the ARNT sequences of multiple fish species, including a newly isolated cDNA from scup (Stenotomus chrysops). Our phylogenetic analysis demonstrates that zebrafish ARNT, like the Fundulus protein, is an ARNT2. Contrary to expectations, the scup ARNT is closely related to the rainbow trout protein, demonstrating that the existence of this ARNT isoform predates the divergence of salmonids from the other teleosts. Thus, different species of fish express distinct and highly conserved isoforms of ARNT. The number, type, and expression pattern of ARNT proteins may contribute to interspecies differences in aryl hydrocarbon toxicity, possibly through distinct interactions with additional PAS-family proteins.

Identification of alkyl carbazoles and alkyl benzocarbazoles in Brazilian petroleum derivatives.

PubMed

Oliveira, Eniz Conceição; Vaz de Campos, Maria Cecília; Rodrigues, Maria Regina Alves; Pérez, Valéria Flores; Melecchi, Maria Inês Soares; Vale, Maria Goreti Rodrigues; Zini, Cláudia Alcaraz; Caramão, Elina Bastos

2006-02-10

Carbozoles are important compounds in crude oils, as they may be used as geochemical tracers, being the major type of nitrogen compounds in petroleum. At the same time, they are regarded as undesirable due to the problems they may cause in the refining process, such as catalyst poisoning, corrosion, gum or color formation in final products. As separation and identification of carbazoles are challenging goals, this work presents a chromatographic method, made of a pre-fractionation on neutral alumina followed by the separation and identification of two classes of carbazoles using FeCl(3)/Chromossorb W and gas chromatograph with mass spectrometer (GC/MS) (SIM-single ion monitoring mode) analysis. For the first time, a series of alkyl carbazoles and alkyl benzocarbazoles were identified in heavy gas oil (HGO) and atmospheric residue of distillation (ARD) obtained from Brazilian petroleum.

Oxidative coupling of sp 2 and sp 3 carbon-hydrogen bonds to construct dihydrobenzofurans.

PubMed

Shi, Jiang-Ling; Wang, Ding; Zhang, Xi-Sha; Li, Xiao-Lei; Chen, Yu-Qin; Li, Yu-Xue; Shi, Zhang-Jie

2017-08-10

Metal-catalyzed cross-couplings provide powerful, concise, and accurate methods to construct carbon-carbon bonds from organohalides and organometallic reagents. Recent developments extended cross-couplings to reactions where one of the two partners connects with an aryl or alkyl carbon-hydrogen bond. From an economic and environmental point of view, oxidative couplings between two carbon-hydrogen bonds would be ideal. Oxidative coupling between phenyl and "inert" alkyl carbon-hydrogen bonds still awaits realization. It is very difficult to develop successful strategies for oxidative coupling of two carbon-hydrogen bonds owning different chemical properties. This article provides a solution to this challenge in a convenient preparation of dihydrobenzofurans from substituted phenyl alkyl ethers. For the phenyl carbon-hydrogen bond activation, our choice falls on the carboxylic acid fragment to form the palladacycle as a key intermediate. Through careful manipulation of an additional ligand, the second "inert" alkyl carbon-hydrogen bond activation takes place to facilitate the formation of structurally diversified dihydrobenzofurans.Cross-dehydrogenative coupling is finding increasing application in synthesis, but coupling two chemically distinct sites remains a challenge. Here, the authors report an oxidative coupling between sp 2 and sp 3 carbons by sequentially activating the more active aryl site followed by the alkyl position.

Synthesis and characterization of sulfonated poly ether ether ketone (sPEEK) membranes for low temperature fuel cells

NASA Astrophysics Data System (ADS)

Ali, Mawlood Maajal; Rizvi, S. J. A.; Azam, Ameer

2018-05-01

Poly ether ether ketone (PEEK) was sulfonated with 1.0 M sulphuric acid for varying durations to have various degrees of sulfonation (DS) from 43 to 55%. The FT-IR spectra confirmed the successful sulfonation of PEEK. The sulfonated PEEK (sPEEK) membranes were prepared by a solvent casting method using dimethylacetamide (DMAc) as solvent and upon drying the membranes were characterized. The DS% and ion exchange capacity (IEC) were determined by a back titration method. The IEC and DS of sPEEK was found to increase with the increment of sulfonation reaction time. Water uptake also increased with increase in the DS. The Thermogravimetric (TGA) curves revealed poor thermal stability of sPEEK. The proton conductivity of sPEEK membrane was found to considerably better with degree of sulfonation for fuel cell application.

40 CFR 721.10548 - Mixed alkyl phosphate esters alkoxylated (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed alkyl phosphate esters... Specific Chemical Substances § 721.10548 Mixed alkyl phosphate esters alkoxylated (generic). (a) Chemical... as mixed alkyl phosphate esters alkoxylated (PMN P-04-624) is subject to reporting under this section...

40 CFR 721.10548 - Mixed alkyl phosphate esters alkoxylated (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed alkyl phosphate esters... Specific Chemical Substances § 721.10548 Mixed alkyl phosphate esters alkoxylated (generic). (a) Chemical... as mixed alkyl phosphate esters alkoxylated (PMN P-04-624) is subject to reporting under this section...

Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

PubMed Central

Das, Gautam; Yoon, Hyon Hee

2015-01-01

An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 (μA · cm−2·mM−1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM) with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity) after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. PMID:26346240

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... derivatives, sulfonated, po-tas-sium salts. 721.1225 Section 721.1225 Protection of Environment ENVIRONMENTAL... derivatives, sulfonated, po-tas-sium salts. (a) Chemical substances and significant new uses subject to..., sulfonated, potassium salts (PMN P-89-711) is subject to reporting under this section for the significant new...

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... derivatives, sulfonated, po-tas-sium salts. 721.1225 Section 721.1225 Protection of Environment ENVIRONMENTAL... derivatives, sulfonated, po-tas-sium salts. (a) Chemical substances and significant new uses subject to..., sulfonated, potassium salts (PMN P-89-711) is subject to reporting under this section for the significant new...

40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

40 CFR 721.5380 - Mixed alkyl phenolic novolak resin (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed alkyl phenolic novolak resin... Specific Chemical Substances § 721.5380 Mixed alkyl phenolic novolak resin (generic). (a) Chemical... as mixed alkyl phenolic novolak resin (PMN P-98-718) is subject to reporting under this section for...

40 CFR 721.10493 - Tris-alkyl-alkoxy melamine polymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Tris-alkyl-alkoxy melamine polymer... Specific Chemical Substances § 721.10493 Tris-alkyl-alkoxy melamine polymer (generic). (a) Chemical... as tris-alkyl-alkoxy melamine polymer (PMN P-05-417) is subject to reporting under this section for...

40 CFR 721.10493 - Tris-alkyl-alkoxy melamine polymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Tris-alkyl-alkoxy melamine polymer... Specific Chemical Substances § 721.10493 Tris-alkyl-alkoxy melamine polymer (generic). (a) Chemical... as tris-alkyl-alkoxy melamine polymer (PMN P-05-417) is subject to reporting under this section for...

Selective alkylation of T–T mismatched DNA using vinyldiaminotriazine–acridine conjugate

PubMed Central

Onizuka, Kazumitsu; Usami, Akira; Yamaoki, Yudai; Kobayashi, Tomohito; Hazemi, Madoka E; Chikuni, Tomoko; Sato, Norihiro; Sasaki, Kaname; Katahira, Masato

2018-01-01

Abstract The alkylation of the specific higher-order nucleic acid structures is of great significance in order to control its function and gene expression. In this report, we have described the T–T mismatch selective alkylation with a vinyldiaminotriazine (VDAT)–acridine conjugate. The alkylation selectively proceeded at the N3 position of thymidine on the T–T mismatch. Interestingly, the alkylated thymidine induced base flipping of the complementary base in the duplex. In a model experiment for the alkylation of the CTG repeats DNA which causes myotonic dystrophy type 1 (DM1), the observed reaction rate for one alkylation increased in proportion to the number of T–T mismatches. In addition, we showed that primer extension reactions with DNA polymerase and transcription with RNA polymerase were stopped by the alkylation. The alkylation of the repeat DNA will efficiently work for the inhibition of replication and transcription reactions. These functions of the VDAT–acridine conjugate would be useful as a new biochemical tool for the study of CTG repeats and may provide a new strategy for the molecular therapy of DM1. PMID:29309639

Copper/amino acid catalyzed cross-couplings of aryl and vinyl halides with nucleophiles.

PubMed

Ma, Dawei; Cai, Qian

2008-11-18

Copper-assisted Ullmann-type coupling reactions are valuable transformations for organic synthesis. Researchers have extensively applied these reactions in both academic and industrial settings. However, two important issues, the high reaction temperatures (normally above 150 degrees C) and the stoichiometric amounts of copper necessary, have greatly limited the reaction scope. To solve these problems, we and other groups have recently explored the use of special ligands to promote these coupling reactions. We first showed that the structure of alpha-amino acids can accelerate Cu-assisted Ullmann reactions, leading to the coupling reactions of aryl halides and alpha-amino acids at 80-90 degrees C. In response to these encouraging results, we also discovered that an l-proline ligand facilitated the following transformations: (1) coupling of aryl halides with primary amines, cyclic secondary amines, and N-containing heterocycles at 40-90 degrees C; (2) coupling of aryl halides with sulfinic acid salts at 80-95 degrees C; (3) azidation of aryl halides and vinyl halides with sodium azide at 40-95 degrees C; (4) coupling of aryl halides with activated methylene compounds at 25-50 degrees C. In addition, we found that N,N-dimethylglycine as a ligand facilitated Cu-catalyzed biaryl ether formation at 90 degrees C. Moreover, Sonogashira reactions worked in the absence of palladium and phosphine ligands, forming enamides from vinyl halides and amides at temperatures ranging from ambient temperature up to 80 degrees C. Furthermore, we discovered that an ortho-amide group can accelerate some Ullmann-type reactions. This functional group in combination with other ligand effects allowed for aryl amination or biaryl ether formation at ambient temperature. The coupling between aryl halides and activated methylene compounds even proceeded at -45 degrees C to enantioselectively form a quaternary carbon center. Taking advantage of these results, we developed several novel approaches

Subcellular Localization of Rice Leaf Aryl Acylamidase Activity 1

PubMed Central

Gaynor, John J.; Still, Cecil C.

1983-01-01

The intracellular localization of aryl acylamidase (aryl-acylamide amidohydrolase, EC 3.5.1.13) in rice (Oryza sativa L. var Starbonnet) leaves was investigated. The enzyme hydrolyzes and detoxifies the herbicide propanil (3,4-dichloropropionanilide) thereby accounting for immunity of the rice plant to herbicidal action. Fractionation of mesophyll protoplasts by differential centrifugation yielded the highest specific activity of amidase in the crude mitochondrial fraction. Further separation of density gradients of the silica sol Percoll also indicated that this enzyme was mitochondrial. By the use of biochemical markers, the purified mitochondrial fraction was shown to be substantially free of contamination from nuclei, chloroplasts, golgi, and plasma membranes. Subfractionation of the purified mitochondria suggests that this enzyme is located on the outer membrane. PMID:16662987

Enhanced interfacial properties of carbon fiber composites via aryl diazonium reaction “on water”

NASA Astrophysics Data System (ADS)

Wang, Yuwei; Meng, Linghui; Fan, Liquan; Ma, Lichun; Qi, Meiwei; Yu, Jiali; Huang, Yudong

2014-10-01

Polyacrylonitrile-based carbon fibers were functionalized with phenyl amine group via aryl diazonium reaction "on water" to improve their interfacial bonding with resin matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were employed to characterize ordered degree, functional groups, chemical states and morphology of carbon fiber surface, respectively. The results showed that phenyl amine groups were grafted on the fiber surface successfully. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 73%, while the tensile strength was down very slightly. Hence aryl diazonium reaction "on water" could be a facile green platform to functionalize carbon fibers for many interesting applications.

Alkyl chitosan film-high strength, functional biomaterials.

PubMed

Lu, Li; Xing, Cao; Xin, Shen; Shitao, Yu; Feng, Su; Shiwei, Liu; Fusheng, Liu; Congxia, Xie

2017-11-01

Biofilm with strong tensile strength is a topic item in the area of tissue engineering, medicine engineering, and so forth. Here we introduced an alkyl chitosan film with strong tensile strength and its possibility for an absorbable anticoagulation material in vivo was tested in the series of blood test, such as dynamic coagulation time, plasma recalcification time and hemolysis. Alkyl chitosan film was a better biomaterial than traditional chitosan film in the anticoagulation, tissue compatibility and cell compatibility. The unique trait of alkyl chitosan film may be for its greater contact angle and hydrophobicity ability to reduce the adsorption capacity for the blood component and the activity of fibrinolytic enzymes, enhance the antibacterial capacity than chitosan film. Moreover, none of chitosan film or butyl chitosan film exhibited quick inflammation or other disadvantage and degraded quickly by implanted test. Therefore, Alkyl chitosan film is of prospective properties as an implantable, absorbable agent for tissue heals, and this material need further research. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3034-3041, 2017. © 2017 Wiley Periodicals, Inc.

Detection and identification of alkylating agents by using a bioinspired "chemical nose".

PubMed

Hertzog-Ronen, Carmit; Borzin, Elena; Gerchikov, Yulia; Tessler, Nir; Eichen, Yoav

2009-10-12

Alkylating agents are simple and reactive molecules that are commonly used in many and diverse fields such as organic synthesis, medicine, and agriculture. Some highly reactive alkylating species are also being used as blister chemical-warfare agents. The detection and identification of alkylating agents is not a trivial issue because of their high reactivity and simple structure. Herein, we report on a new multispot luminescence-based approach to the detection and identification of alkylating agents. In order to demonstrate the potential of the approach, seven pi-conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1-7, were adsorbed onto a solid support and exposed to vapors of alkylators 8-15. The alkylation-induced color-shift patterns of the seven-spot array allow clear discrimination of the different alkylators. The spots are sensitive to minute concentrations of alkylators and, because the detection is based on the formation of new covalent bonds, these spots saturate at about 50 ppb.

Synthesis of Secondary Aromatic Amides via Pd-Catalyzed Aminocarbonylation of Aryl Halides Using Carbamoylsilane as an Amide Source.

PubMed

Tong, Wenting; Cao, Pei; Liu, Yanhong; Chen, Jianxin

2017-11-03

Using N-methoxymethyl-N-organylcarbamoyl(trimethyl)silanes as secondary amides source, the direct transformation of aryl halides into the corresponding secondary aromatic amides via palladium-catalyzed aminocarbonylation is described. The reactions tolerated a broad range of functional groups on the aryl ring except big steric hindrance of substituent. The types and the relative position of substituents on the aryl ring impact the coupling efficiency.

Behavioral difficulties in 7-year old children in relation to developmental exposure to perfluorinated alkyl substances.

PubMed

Oulhote, Youssef; Steuerwald, Ulrike; Debes, Frodi; Weihe, Pal; Grandjean, Philippe

2016-12-01

Perfluorinated alkyl substances (PFAS) are suspected endocrine disruptors that are highly persistent and neurotoxic in animals. Human epidemiological studies of exposure-related deviations of children's behaviors are sparse. We assessed the associations between prenatal, 5- and 7-year PFAS exposures and behavioral problem scores in 7-year Faroese children. Concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonic acid (PFHxS) were measured in maternal serum and in serum from children at ages 5 and 7years (n=539, 508, and 491, respectively). We used multivariable regressions and structural equations models to estimate the covariate-adjusted associations between serum-PFAS concentrations and behavioral difficulties, as assessed by the strengths and difficulties questionnaire (SDQ) at age 7. Serum-PFOS and PFHxS concentrations declined over time, whereas PFOA, PFNA, and PFDA tended to increase. No associations were observed between prenatal PFAS concentrations and SDQ scores. However, a two-fold increase in 5-year serum-PFOA, PFNA, and PFDA concentrations was associated with increases in total SDQ scores by 1.03 (95% CI: 0.11, 1.95), 0.72 (95% CI: 0.07, 1.38) and 0.78 points (95% CI: 0.01, 1.55), respectively. For SDQ subscales, significant associations were found in regard to hyperactivity, peer relationship, and conduct problems, as well as internalizing and externalizing problems and autism screening composite scores. Cross-sectional analyses at age 7years showed possible sex-dimorphic associations between PFAS concentrations and SDQ scores, where girls had consistently positive associations with SDQ scores whereas boys exhibited a pattern of negative or null associations. Higher serum PFAS concentrations at ages 5- and 7-years, but not prenatally, were associated with parent-reported behavioral problems at age 7. Copyright © 2016 Elsevier Ltd

Behavioral difficulties in 7-year old children in relation to developmental exposure to perfluorinated alkyl substances

PubMed Central

Oulhote, Youssef; Steuerwald, Ulrike; Debes, Frodi; Weihe, Pal; Grandjean, Philippe

2016-01-01

Background Perfluorinated alkyl substances (PFAS) are suspected endocrine disruptors that are highly persistent and neurotoxic in animals. Human epidemiological studies of exposure-related deviations of children’s behaviors are sparse. We assessed the associations between prenatal, 5- and 7-year PFAS exposures and behavioral problem scores in 7-year Faroese children. Methods Concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonic acid (PFHxS) were measured in maternal serum and in serum from children at ages 5 and 7 years (n=539, 508, and 491, respectively). We used multivariable regressions and structural equations models to estimate the covariate-adjusted associations between serum-PFAS concentrations and behavioral difficulties, as assessed by the strengths and difficulties questionnaire (SDQ) at age 7. Results Serum-PFOS and PFHxS concentrations declined over time, whereas PFOA, PFNA, and PFDA tended to increase. No associations were observed between prenatal PFAS concentrations and SDQ scores. However, a two-fold increase in 5-year serum-PFOA, PFNA, and PFDA concentrations was associated with increases in total SDQ scores by 1.03 (95% CI: 0.11, 1.95), 0.72 (95% CI: 0.07, 1.38) and 0.78 points (95% CI: 0.01, 1.55), respectively. For SDQ subscales, significant associations were found in regard to hyperactivity, peer relationship, and conduct problems, as well as internalizing and externalizing problems and autism screening composite scores. Cross-sectional analyses at age 7 years showed possible sex-dimorphic associations between PFAS concentrations and SDQ scores, where girls had consistently positive associations with SDQ scores whereas boys exhibited a pattern of negative or null associations. Conclusions Higher serum PFAS concentrations at ages 5- and 7-years, but not prenatally, were associated with parent-reported behavioral problems

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

PubMed Central

Mebrahtu, Fanuel M; Manana, Mandlenkosi M; Madumo, Kagiso; Sokamisa, Mokela S

2015-01-01

Summary 1-C and 2-C-branched carbohydrates are present as substructures in a number of biologically important compounds. Although the synthesis of such carbohydrate derivatives is extensively studied, the synthesis of 1,2-cis-2-C-branched C-, S-, and N-glycosides is less explored. In this article a synthetic strategy for the synthesis of 1,2-cis-2-C-branched-aryl-C-glucosides is reported via a hydrogenolytic desulfurization of suitably orientated carbohydrate based hemithioacetals. 1,2-cis-2-Hydroxymethyl and 2-carbaldehyde of aryl-C-glucosides have been synthesized using the current strategy in very good yields. The 2-carbaldehyde-aryl-C-glucosides have been identified as suitable substrates for the stereospecific preparation of 2,3-unsaturated-aryl-C-glycosides (Ferrier products). PMID:26124859

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

NASA Technical Reports Server (NTRS)

Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

1997-01-01

Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

Structure-biocompatibility and transfection activity relationships of cationic polyaspartamides with (dialkylamino)alkyl and alkyl or hydroxyalkyl side groups.

PubMed

Salakhieva, Diana; Shevchenko, Vesta; Németh, Csaba; Gyarmati, Benjámin; Szilágyi, András; Abdullin, Timur

2017-01-30

A series of 14 cationic derivatives of poly(aspartic acid) i.e. cationic polyaspartamides with different (dialkylamino)alkyl and alkyl or hydroxyalkyl side groups was synthesized by nucleophilic addition on polysuccinimide. The resulting polyaspartamides have moderate amphiphilic properties. Relationships between the structure and ratio of side groups and in vitro properties of polyaspartamides, including their cytotoxic and membrane-damaging activity towards human cell lines, primary skin fibroblasts and erythrocytes, were established and discussed. Cationic polyaspartamides vary in their DNA-binding, condensing and nuclease-protecting characteristics depending on the concentration ratio of (dialkylamino)alkyl and alkyl or hydroxyalkyl side groups. Effective cell transfection was achieved upon polyaspartamide-mediated plasmid DNA delivery in serum-free medium in the presence of chloroquine. Effect of serum proteins adsorption onto polyaspartamide based polyplexes, and the role of concentration of polyplexes in culture medium in their colloidal stability and transfection process were demonstrated. Synthesized polyaspartamides are biocompatible and long-acting gene carriers, which are applied to cells after dilution and without washing, thus providing transfection level comparable to that of commercial transfection reagent. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanisms of chemoresistance to alkylating agents in malignant glioma.

PubMed

Sarkaria, Jann N; Kitange, Gaspar J; James, C David; Plummer, Ruth; Calvert, Hilary; Weller, Michael; Wick, Wolfgang

2008-05-15

Intrinsic or acquired chemoresistance to alkylating agents is a major cause of treatment failure in patients with malignant brain tumors. Alkylating agents, the mainstay of treatment for brain tumors, damage the DNA and induce apoptosis, but the cytotoxic activity of these agents is dependent on DNA repair pathways. For example, O6-methylguanine DNA adducts can cause double-strand breaks, but this is dependent on a functional mismatch repair pathway. Thus, tumor cell lines deficient in mismatch repair are resistant to alkylating agents. Perhaps the most important mechanism of resistance to alkylating agents is the DNA repair enzyme O6-methylguanine methyltransferase, which can eliminate the cytotoxic O6-methylguanine DNA adduct before it causes harm. Another mechanism of resistance to alkylating agents is the base excision repair (BER) pathway. Consequently, efforts are ongoing to develop effective inhibitors of BER. Poly(ADP-ribose)polymerase plays a pivotal role in BER and is an important therapeutic target. Developing effective strategies to overcome chemoresistance requires the identification of reliable preclinical models that recapitulate human disease and which can be used to facilitate drug development. This article describes the diverse mechanisms of chemoresistance operating in malignant glioma and efforts to develop reliable preclinical models and novel pharmacologic approaches to overcome resistance to alkylating agents.

Alcohols as alkylating agents in heteroarene C-H functionalization

NASA Astrophysics Data System (ADS)

Jin, Jian; MacMillan, David W. C.

2015-09-01

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of `spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

Alcohols as alkylating agents in heteroarene C-H functionalization.

PubMed

Jin, Jian; MacMillan, David W C

2015-09-03

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of 'spin-centre shift', during which an alcohol C-O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based alkylation methods require the use of stoichiometric oxidants, increased temperatures or peroxides, a mild protocol using simple and abundant alkylating agents would have considerable use in the synthesis of diversely functionalized pharmacophores. Here we describe the development of a dual catalytic alkylation of heteroarenes, using alcohols as mild alkylating reagents. This method represents the first, to our knowledge, broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer catalysis. The value of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone.

Vinyl Sulfones as Antiparasitic Agents and a Structural Basis for Drug Design*

PubMed Central

Kerr, Iain D.; Lee, Ji H.; Farady, Christopher J.; Marion, Rachael; Rickert, Mathias; Sajid, Mohammed; Pandey, Kailash C.; Caffrey, Conor R.; Legac, Jennifer; Hansell, Elizabeth; McKerrow, James H.; Craik, Charles S.; Rosenthal, Philip J.; Brinen, Linda S.

2009-01-01

Cysteine proteases of the papain superfamily are implicated in a number of cellular processes and are important virulence factors in the pathogenesis of parasitic disease. These enzymes have therefore emerged as promising targets for antiparasitic drugs. We report the crystal structures of three major parasite cysteine proteases, cruzain, falcipain-3, and the first reported structure of rhodesain, in complex with a class of potent, small molecule, cysteine protease inhibitors, the vinyl sulfones. These data, in conjunction with comparative inhibition kinetics, provide insight into the molecular mechanisms that drive cysteine protease inhibition by vinyl sulfones, the binding specificity of these important proteases and the potential of vinyl sulfones as antiparasitic drugs. PMID:19620707

N,N-Diethylurea-Catalyzed Amidation between Electron-Defficient Aryl Azides and Phenylacetaldehydes

PubMed Central

Xie, Sheng; Ramström, Olof; Yan, Mingdi

2015-01-01

Urea structures, of which N,N-diethylurea (DEU) proved to be the most efficient, were discovered to catalyze amidation reactions between electron-defficient aryl azides and phenylacetaldehydes. Experimental data support 1,3-dipolar cycloaddition between DEU-activated enols and electrophilic phenyl azides, especially perfluoroaryl azides, followed by rearrangement of the triazoline intermediate. The activation of the aldehyde under near-neutral conditions was of special importance in inhibiting dehydration/aromatization of the triazoline intermediate, thus promoting the rearrangement to form aryl amides. PMID:25616121

40 CFR 721.10711 - Alkyl substituted catechol (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10711 Alkyl substituted catechol (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as alkyl...

40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

Code of Federal Regulations, 2010 CFR

2010-07-01

... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this section...

40 CFR 721.840 - Alkyl substituted diaromatic hydrocarbons.

Code of Federal Regulations, 2011 CFR

2011-07-01

... hydrocarbons. 721.840 Section 721.840 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.840 Alkyl substituted diaromatic hydrocarbons. (a) Chemical substance... alkyl substituted di-aro-matic hydrocarbons (PMN P-91-710) is subject to reporting under this section...

Effect of alkyl chain length on the rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imides.

PubMed

Gangamallaiah, V; Dutt, G B

2013-10-10

Rotational diffusion of a nonpolar solute 9-phenylanthracene (9-PA) and a cationic solute rhodamine 110 (R110) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl) bis(trifluoromethylsulfonyl)imides to understand the influence of alkyl chain length on solute rotation. In this study, reorientation times (τr) have been measured as a function of viscosity (η) by varying the temperature (T) of the solvents. These results have been analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory along with the ones obtained for the same solutes in 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides (Gangamallaiah and Dutt, J. Phys. Chem. B 2012, 116, 12819-12825). It has been noticed that the data for 9-PA and R110 follows the relation τr = A(η/T)(n) with A being the ratio of hydrodynamic volume of the solute to the Boltzmann constant and n = 1 as envisaged by the SED theory. However, upon increasing the alkyl chain length from methyl to octadecyl significant deviations from the SED theory have been observed especially from the octyl derivative onward. From methyl to octadecyl derivatives, the value of A decreases by a factor of 3 for both the solutes and n by a factor of 1.4 and 1.6 for 9-PA and R110, respectively. These observations have been rationalized by taking into consideration the organized structure of the ionic liquids, whose influence appears to be pronounced when the number of carbon atoms in the alkyl chain attached to the imidazolium cation exceeds eight.

Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

PubMed

Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

2015-01-01

A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithium perchlorate-nitromethane-promoted alkylation of anilines with arylmethanols.

PubMed

Zhou, Jun; Mao, Hai-Feng; Wang, Lu; Zou, Jian-Ping; Zhang, Wei

2011-11-01

A new application of lithium perchlorate-nitromethane (LPNM) for the formation of aromatic C-N and C-C bonds is introduced. LPNM-promoted reactions of anilines with diarylmethanols selectively generate N-alkylated anilines or mono and double Friedel-Crafts alkylation products under different conditions by changing the reaction time, reaction temperature, and the ratio of the reactants. This method does not require the use of transition metal catalysts to prepare alkylated aniline derivatives.

Compositions for labeling .beta.-amyloid plaques and neurofibrillary tangles

DOEpatents

Barrio, Jorge R [Agoura Hills, CA; Petric, Andrej [Ljubljana, SI; Satyamurthy, Nagichettiar [Los Angeles, CA; Small, Gary W [Los Angeles, CA; Cole, Gregory M [Santa Monica, CA; Huang, Sung-Cheng [Sherman Oaks, CA

2008-03-11

Compositions useful for labeling .beta.-amyloid plaques and neurofibrillary tangles are provided. The compositions comprises compounds of formula (I): ##STR00001## wherein R.sub.1 is selected from the group consisting of --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C.dbd.C(CN).sub.2-alkyl, --C.dbd.C(CN).sub.2-alkylenyl-R.sub.4, ##STR00002## wherein R.sub.4 is a radical selected from the group consisting of alkyl, substituted alkyl, aryl and substituted aryl; R.sub.5 is a radical selected from the group consisting of --NH.sub.2, --OH, --SH, --NH-alkyl, --NHR.sub.4, --NH-alkylenyl-R.sub.4, --O-alkyl, --O-alkylenyl-R.sub.4, --S-alkyl, and --S-alkylenyl-R.sub.4; R.sub.6 is a radical selected from the group consisting of --CN, --COOH, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)-halogen, --C(O)NH-alkyl, --C(O)NH-alkylenyl-R.sub.4 and --C(O)NH.sub.2; R.sub.7 is a radical selected from the group consisting of O, NH, and S; and R.sub.8 is N, O or S; and R.sub.2 is selected from the group consisting of alkyl and alkylenyl-R.sub.10 and R.sub.3 is alkylenyl-R.sub.10, wherein R.sub.10 is selected from the group consisting of --OH, --OTs, halogen, spiperone, spiperone ketal, and spiperone-3-yl, or R.sub.2 and R.sub.3 together form a heterocyclic ring, optionally substituted with at least one radical selected from the group consisting of alkyl, alkoxy, OH, OTs, halogen, alkyl-R.sub.10, carbonyl, spiperone, spiperone ketal and spiperone-3-yl, and further wherein one or more of the hydrogen, halogen or carbon atoms are optionally replaced with a radiolabel.

Chiral Brønsted Base-Promoted Nitroalkane Alkylation: Enantioselective Synthesis of sec-Alkyl-3-Substituted Indoles

PubMed Central

Dobish, Mark C.; Johnston, Jeffrey N.

2010-01-01

A Brønsted base-catalyzed reaction of nitroalkanes with alkyl electrophiles provides indole heterocycles substituted at C3 bearing a sec-alkyl group with good enantioselectivity (up to 90% ee). Denitration by hydrogenolysis provides a product with equally high ee. An indolenine intermediate is implicated in the addition step, and surprisingly, water cosolvent was found to have a beneficial effect in this step, leading to a one-pot protocol for elimination/enantioselective addition using PBAM, a bis(amidine) chiral nonracemic base. PMID:21090654

Protein resistance of surfaces modified with oligo(ethylene glycol) aryl diazonium derivatives.

PubMed

Fairman, Callie; Ginges, Joshua Z; Lowe, Stuart B; Gooding, J Justin

2013-07-22

Anti-fouling surfaces are of great importance for reducing background interference in biosensor signals. Oligo(ethylene glycol) (OEG) moieties are commonly used to confer protein resistance on gold, silicon and carbon surfaces. Herein, we report the modification of surfaces using electrochemical deposition of OEG aryl diazonium salts. Using electrochemical and contact angle measurements, the ligand packing density is found to be loose, which supports the findings of the fluorescent protein labelling that aryl diazonium OEGs confer resistance to nonspecific adsorption of proteins albeit lower than alkane thiol-terminated OEGs. In addition to protein resistance, aryl diazonium attachment chemistry results in stable modification. In common with OEG species on gold electrodes, OEGs with distal hydroxyl moieties do confer superior protein resistance to those with a distal methoxy group. This is especially the case for longer derivatives where superior coiling of the OEG chains is possible. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphology and Proton Transport in Sulfonated Block Copolymer and Mesoporous Polymer Electrolyte Membranes

NASA Astrophysics Data System (ADS)

Chen, Chelsea; Wong, David; Beers, Keith; Balsara, Nitash

2013-03-01

In an effort to understand the fundamentals of proton transport in polymer electrolyte membranes (PEMs), we have developed a series of poly(styrene-b-ethylene-b-styrene) (SES) membranes. The SES membranes were subsequently sulfonated to yield proton conducting S-SES membranes. We examine the effects of sulfonation level, temperature and thermal history on the morphology of S-SES membranes in both dry and hydrated states. The effects of these parameters on water uptake and proton transport characteristics of the membranes are also examined. Furthermore, building upon the strategy we deployed in sulfonating the SES membranes, we fabricated mesoporous S-SES membranes, with pores lined up with the proton conducting channels. These membranes have three distinct phases: structural block, proton-conducting block, and void. We examine the effects of pore size, domain structure and sulfonation level on water uptake and proton conductivity of the mesoporous PEMs at different temperatures. This work is funded by Department of Energy.

Laccase-catalyzed α-arylation of benzoylacetonitrile with substituted hydroquinones

DOE PAGES

Cannatelli, Mark D.; Ragauskas, Arthur J.

2014-09-03

This article investigates a green method for α-arylation of a primary nitrile. Compounds possessing a benzylic nitrile have shown to exhibit biological activity. Laccases (benzenediol:oxygen oxidoreductase EC 1.10.3.2) were used as the catalysts to perform the cross-coupling reaction between benzoylacetonitrile and substituted hydroquinones. The corresponding 2-substituted 3-oxo-3-phenylpropanenitriles where synthesized in moderate to excellent yields in pH 7.0 buffered water under mild conditions. The substituent on the hydroquinone had a significant impact on product yields and regioselectivity of reaction. The use of laccases, which require O 2 as their only co-substrate and produce H 2O as their only by-product, to performmore » this transformation is an environmentally benign method for α-arylation of primary nitriles.« less

Sleep-inducing N-alkyl-5-[m-(trifluoromethyl)phenyl]-5-hydroxy-2-pyrrolidinones and N-alkyl-3-(trifluoromethyl)cinnamamides.

PubMed

Houlihan, W J; Gogerty, J H; Ryan, E A; Schmitt, G

1985-01-01

A series of N-alkyl-3-[m-(trifluoromethyl)phenyl]-5-hydroxy-2-pyrrolidinones and N-alkyl-3-(trifluoromethyl)-cinnamamides were prepared and screened in a series of tests designed to detect potential sleep inducers. The more active members of the series were evaluated for their ability to induce sleep in Cebus monkeys. The most active compound, N-methyl-5-[m-(trifluoromethyl)phenyl]-5-hydroxy-2-pyrrolidinone, was equal to methaqualone.

Synthesis and characterization of chitosan alkyl urea.

PubMed

Wang, Jing; Jiang, Ji-Zhou; Chen, Wei; Bai, Zheng-Wu

2016-07-10

Chitosan is a versatile material employed for various purposes in many fields including the development of chiral stationary phases for enantioseparation. Chitosan alkyl urea is a kind of intermediate used to prepare enantioseparation materials. In order to synthesize the intermediates, in the present work, a new way to prepare chitosan alkyl urea has been established: chitosan was first reacted with methyl chloroformate yielding N-methoxyformylated chitosan, which was then converted to chitosan alkyl urea through amine-ester exchange reaction. With a large excess of methyl chloroformate and primary amine of low stereohindrance, the amino group in chitosan could be almost completely converted to ureido group. The as-prepared chitosan alkyl urea derivatives were characterized by IR, (1)H NMR, (13)C NMR,(1)H-(1)H COSY and (1)H-(13)C HSQC NMR spectra. The chemical shifts of hydrogen and carbon atoms of glucose unit were assigned. It was found that the degree of substitution was obviously lower if cyclopropyl amine, aniline, tert-butyl amine and diethyl amine were used as reactants for the amine-ester exchange reaction. The reason was explained with the aid of theoretical calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Alcohols as alkylating agents in heteroarene C–H functionalization

PubMed Central

Jin, Jian; MacMillan, David W. C.

2015-01-01

Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage1. One of the core principles that underlies DNA biosynthesis is the radical-mediated elimnation of H2O to deoxygenate ribonucleotides, an example of ‘spin-center shift’ (SCS)2, during which an alcohol C–O bond is cleaved, resulting in a carbon-centered radical intermediate. While SCS is a well-understood biochemical process, it is underutilized by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylations using alcohols as radical precursors. Considering traditional radical-based alkylation methods require the use of stoichiometric oxidants, elevated temperatures, or peroxides3–7, the development of a mild protocol using simple and abundant alkylating agents would have significant utility in the synthesis of diversely functionalized pharmacophores. In this manuscript, we describe the successful execution of this idea via the development of a dual catalytic alkylation of heteroarenes using alcohols as mild alkylating reagents. This method represents the first broadly applicable use of unactivated alcohols as latent alkylating reagents, achieved via the successful merger of photoredox and hydrogen atom transfer (HAT) catalysis. The utility of this multi-catalytic protocol has been demonstrated through the late-stage functionalization of the medicinal agents, fasudil and milrinone. PMID:26308895

Effect of additives on the performance and morphology of sulfonated copoly (phthalazinone biphenyl ether sulfone) composite nanofiltration membranes☆

NASA Astrophysics Data System (ADS)

Guan, Shanshan; Zhang, Shouhai; Liu, Peng; Zhang, Guozhen; Jian, Xigao

2014-03-01

Sulfonated copoly (phthalazinone biphenyl ether sulfone) (SPPBES) composite nanofiltration membranes were fabricated by adding low molecular weight additives into SPPBES coating solutions during a dip coating process. Three selected additives: glycol, glycerol and hydroquinone were used in this work. The effect of additives on the membrane performance was studied and discussed in terms of rejection and permeation flux. Among all the composite membranes, the membrane prepared with glycol as an additive achieved the highest Na2SO4 rejection, and the membrane fabricated with glycerol as an additive exhibited the highest flux. The salts rejection of SPPBES composite membranes increased in the following order MgCl2 < NaCl ≤ MgSO4 < Na2SO4. The morphologies of the SPPBES composite membranes were characterized by SEM, it was found that the membrane prepared with hydroquinone showed a rough membrane surface. Composite membrane fabricated with glycol or glycerol as the additive showed very good chemical stability.

Methods for labeling .beta.-amyloid plaques and neurofibrillary tangles

DOEpatents

Barrio, Jorge R.; Petric, Andrej; Satyamurthy, Nagichettiar; Small, Gary W.; Cole, Gregory M.; Huang, Sung-Cheng

2003-12-09

A method for labeling .beta.-amyloid plaques and neurofibrillary tangles in vivo and in vitro, comprises contacting a compound of formula (I): ##STR1## with mammalian tissue. In formula (I), R.sub.1 is selected from the group consisting of --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C.dbd.C(CN).sub.2 -alkyl, --C.dbd.C(CN).sub.2 -alkylenyl-R.sub.4, ##STR2## R.sub.4 is a radical selected from the group consisting of alkyl, substituted alkyl, aryl and substituted aryl; R.sub.5 is a radical selected from the group consisting of --NH.sub.2, --OH, --SH, --NH-alkyl, --NHR.sub.4, --NH-alkylenyl-R.sub.4, --O-alkyl, --O-alkylenyl-R.sub.4, --S-alkyl, and --S-alkylenyl-R.sub.4 ; R.sub.6 is a radical selected from the group consisting of --CN, --COOH, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)-halogen, --C(O)NH, --C(O)NH-alkyl, --C(O)NH-alkylenyl-R.sub.4 ; R.sub.7 is a radical selected from the group consisting of O, NH, and S; and R.sub.8 is N, O or S. R.sub.2 and R.sub.3 are each independently selected from the group consisting of alkyl and alkylenyl-R.sub.10, wherein R.sub.10 is selected from the group consisting of --OH, --OTs, halogen, spiperone, spiperone ketal and spiperone-3-yl. Alternatively, R.sub.2 and R.sub.3 together form a heterocyclic ring, optionally substituted with at least one radical selected from the group consisting of alkyl, alkoxy, OH, OTs, halogen, alkylenyl-R.sub.10, carbonyl, spiperone, spiperone ketal and spiperone-3-yl. In the compounds of formula (I), one or more of the hydrogen, halogen or carbon atoms can, optionally, be replaced with a radiolabel.

Methods for labeling .beta.-amyloid plaques and neurofibrillary tangles

DOEpatents

Barrio, Jorge R.; Petric, Andrej; Satyamurthy, Nagichettiar; Small, Gary W.; Cole, Gregory M.; Huang, Sung-Cheng

2001-01-01

A method for labeling .beta.-amyloid plaques and neurofibrillary tangles in vivo and in vitro, comprises contacting a compound of formula (I): ##STR1## with mammalian tissue. In formula (I), R.sub.1 is selected from the group consisting of --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C.dbd.C(CN).sub.2 -alkyl, --C.dbd.C(CN).sub.2 -alkylenyl-R.sub.4 , ##STR2## R.sub.4 is a radical selected from the group consisting of alkyl, substituted alkyl, aryl and substituted aryl; R.sub.5, is a radical selected from the group consisting of --NH.sub.2, --OH, --SH, --NH-alkyl, --NHR.sub.4, --NH-alkylenyl-R.sub.4, --O-alkyl, --O-alkylenyl-R.sub.4, --S-alkyl, and --S-alkylenyl-R.sub.4 ; R.sub.6 is a radical selected from the group consisting of --CN, --COOH, --C(O)O-alkyl, --C(O)O-alkylenyl-R.sub.4, --C(O)-alkyl, --C(O)-alkylenyl-R.sub.4, --C(O)-halogen, --C(O)NH , --C(O)NH-alkyl, --C(O)NH-alkylenyl-R.sub.4 ; R.sub.7 is a radical selected from the group consisting of O, NH, and S; and R.sub.8 is N, O or S. R.sub.2 and R.sub.3 are each independently selected from the group consisting of alkyl and alkylenyl-R.sub.10, wherein R.sub.10 is selected from the group consisting of --OH, --OTs, halogen, spiperone, spiperone ketal and spiperone-3-yl. Alternatively, R.sub.2 and R.sub.3 together form a heterocyclic ring, optionally substituted with at least one radical selected from the group consisting of alkyl, alkoxy, OH, OTs, halogen, alkylenyl-R.sub.10, carbonyl, spiperone, spiperone ketal and spiperone-3-yl. In the compounds of formula (I), one or more of the hydrogen, halogen or carbon atoms can, optionally, be replaced with a radiolabel.

Detection of Alkylating Agents using Electrical and Mechanical Means