Main View
This view is used for searching all possible sources.
First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
1
Acid-catalyzed rearrangements of flavans to novelbenzofuran ...

Jun 16, 2011 ... Pure compounds (either as the free phenols, the methyl ether, or the methyl ether-acetate derivatives) were isolated by a variety of ...

Treesearch

2
Acid-Catalyzed Degradation of Poly(2-butyl-1,3,6-trioxocane.
1985-10-21

... Abstract : Polyacetals, owing to the acid sensitivity of the acetal linkage, are attractive candidates for end uses in which acid sensitivity is a desirable ...

DTIC Science & Technology

3
Acid-Catalyzed Degradation of Poly(2-Butyl-1,3,6-Trioxocane)
1986-01-10

... Abstract : Polyacetals, owing to the acid sensitivity of the acetal linkage, are attractive candidates for end uses in which acid sensitivity is a desirable ...

DTIC Science & Technology

4
Trifluoromethanesulfonic acid catalyzed isomerization of kinetic enol derivatives to the thermodynamically favored isomers.
2011-06-09

Trifluoromethanesulfonic acid catalyzed isomerization of kinetic enol derivatives to the thermodynamically favored isomers was developed. Under the present conditions, kinetic enol phosphates, enol acetates and benzoates, and enol sulfonates were smoothly isomerized to produce the corresponding thermodynamically favored isomers in good ...

PubMed

5
Lewis acid catalyzed inverse-electron-demand Diels-Alder reaction of tropones.
2009-11-25

Lewis acid catalyzed inverse-electron-demand Diels-Alder reaction of tropone derivatives was developed. Up to 97% ee was obtained for the chiral dinucleus BINOL-aluminum complex catalyzed reaction between tropones and ketene diethyl acetal to give bicyclo[3.2.2] ring structures, which opens up a unique way of making chiral ...

PubMed

6
Highly stereoselective Br�nsted acid catalyzed synthesis of spirooxindole pyrans.
2011-05-18

A Br�nsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a ?-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry ...

PubMed

7
Investigation of acetic acid-catalyzed hydrothermal pretreatment on corn stover.
2010-03-01

Acetic acid (AA)-catalyzed liquid hot water (LHW) pretreatments on raw corn stover (RCS) were carried out at 195 degrees C at 15 min with the acetic acid concentrations between 0 and 400 g/kg RCS. After pretreatment, the liquor fractions and water-insoluble solids (WIS) were collected separately and tested in terms of the recoveries of glucan and xylan ...

PubMed

8
Acetate in hydrothermal solutions: Decomposition kinetics and metal complexation.
1992-01-01

Hydrothermal kinetics experiments indicate that acetate decomposes under achievable hydrothermal conditions dependant upon solution pH and the catalytic and/or oxidizing ability of mineral surfaces present. Surfaces studied thus far include quartz, calcit...

National Technical Information Service (NTIS)

9
Vinyl acetate formation in the reaction of acetylene with acetic acid catalyzed by zinc acetate supported on porous carbon spheres
2010-05-01

A kind of porous carbon spheres (PCS) was prepared by the carbonization of poly(vinylidene chloride) synthesized by suspension polymerization. Structure analyses revealed the existence of bumps and holes on the surface of PCS. The PCS, with the pore size between 0.8-1.2 nm, could be used as the support of zinc acetate because of the regular shape, high specific surface area, ...

NASA Astrophysics Data System (ADS)

10
Synthesis of cyclic acetals (ketals) from oleochemicals using a solvent free method

We have studied the reaction selectivities of acid catalyzed ring opening reactions of epoxidized methyl oleate (methyl 9,10-epoxy stearate; EMO), to form either acetal or branched ester products. We have produced: methyl 9-(2-butyl-2-methyl-5-octyl-1,3-dioxolan-4-yl) nonanoate (hexanone methyl st...

Technology Transfer Automated Retrieval System (TEKTRAN)

11
Convenient method for the production of 4-oxoalkanal dimethyl 1-acetals from carboxylic esters
1988-05-10

4-Oxoalkanal dimethyl 1-acetals are obtained with an overall yield of 60-85% by the action of 1-bromo-2-ethoxycyclopropyllithium on methyl carboxylates, acid-catalyzed methanolysis of the obtained 1-bromo-2-ethoxycyclopropyl ketones, and subsequent treatment of the reaction mass with zinc powder or triphenylphosphine.

Energy Citations Database

12
Thioglycosylation of 1,2-cis-glycosyl acetates: a long-standing overlooked issue in preparative carbohydrate chemistry.
2011-04-06

1,2-cis-Glycosyl acetates with the ?-configuration were revealed to be very unreactive towards Lewis acid catalyzed thioglycosylations. Optimal and cost-effective conditions for enabling this direct conversion is absent in the literature. Our studies have shown that elevating the reaction temperature with a catalytic amount of ...

PubMed

13
Two-step synthesis of aza- and diazaindoles from chloroamino-N-heterocycles using ethoxyvinylborolane.
2010-01-01

An efficient two-step route to a broad range of aza- and diazaindoles was established, starting from chloroamino-N-heterocycles, without the need for protecting groups. The method involves an optimized Suzuki-Miyaura coupling with (2-ethoxyvinyl)borolane followed by acetic acid-catalyzed cyclization. PMID:19950955

PubMed

14
Summary of Activities: July 1968 to June 1969.
1969-01-01

Contents: Acid-catalyzed hydrolysis of isopropylidene acetals of some 2-pentuloses and 2-hexuloses; Improved preparation of 1,2:3,4-di-O-isopropylidene-D-erythro-pentulofuranose; Conformational analysis of heterocyclic compounds, p-dioxane-2,3-diol; Studi...

National Technical Information Service (NTIS)

15
Acid-Catalyzed Degradation of Poly(2-butyl-1,3,6-trioxocane.
1985-01-01

Polyacetals, owing to the acid sensitivity of the acetal linkage, are attractive candidates for end uses in which acid sensitivity is a desirable property, e.g. photo- or electron-resists. Many polysaccharides belong to this general class and owe many of ...

National Technical Information Service (NTIS)

16
ACID-CATALYZED HYDROGEN-DEUTERIUM EXCHANGE REACTIONS OF DEUTERATED ANISOLE, THIOANISOLE AND BENZENE
1961-01-01

The H-D exchange reactions of p-deuterated anisole and thioanisole and of mono-deuterated benzene were investigated in acetic acid containing sulfuric acid as catalyst. Anisole was found to react 30 to 40 times faster than thioanisole, and thioansole in turn reacts 50 times faster than benzene. (D.L.C.)

Energy Citations Database

17
Complex of vanadium (5+) with the dioxygen radical-anion in the catalyzed disproportionation of hydrogen peroxide
1986-02-01

This paper uses ESR and V 51 NMR spectroscopy to study possible intermediates in the disproportionation of H/sub 2/O/sub 2/ in 1-2% aqueous acetic acid in the presence of vanadium complexes. The intermediate formation of vanadium (5+) peroxo complexes was detected under conditions of the disproportionation of hydrogen peroxide in acetic ...

Energy Citations Database

18
Chiral Phosphoric Acid-Catalyzed Addition of Thiols to N-Acyl Imines: Access to Chiral N,S-Acetals.
2011-08-15

The first catalytic asymmetric method to prepare enantioenriched N,S-acetals using chiral BINOL phosphoric acids is reported. The reaction combines N-acyl imines with thiols to generate products in excellent yield and enantioselectivity. The addition reaction could also be achieved with an exceptional substrate to catalyst (S/C) molar ratio. Electron-rich and ...

PubMed

19
Mechanism of acid catalyzed reaction of amines with epoxides ...
1973-04-01

... Accession Number : ADD403994. Title : Mechanism of acid catalyzed reaction of amines with epoxides. Corporate Author ...

DTIC Science & Technology

20
7//-/ NASA ? '

that it is not simply a Lewis acid catalyzed decomposition by the aluminum ..... Lewis acid-catalyzed dispropor- tionation reaction mechanism (ref. 21). ...

NASA Website

First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
21
Acetate in hydrothermal solutions: Decomposition kinetics and metal complexation
1992-01-01

Hydrothermal kinetics experiments indicate that acetate decomposes under achievable hydrothermal conditions dependant upon solution pH and the catalytic and/or oxidizing ability of mineral surfaces present. Surfaces studied thus far include quartz, calcite, pyrite, Ca-montmorillonite, iron-bearing montmorillonite, magnetite, and ...

Energy Citations Database

22
Acetate in hydrothermal solutions: Decomposition kinetics and metal complexation
1992-04-01

Hydrothermal kinetics experiments indicate that acetate decomposes under achievable hydrothermal conditions dependant upon solution pH and the catalytic and/or oxidizing ability of mineral surfaces present. Surfaces studied thus far include quartz, calcite, pyrite, Ca-montmorillonite, iron-bearing montmorillonite, magnetite, and ...

Energy Citations Database

23
Rapid Conversion of Biomass and Carbon Dioxide into Fuel and Chemicals by Hydrothermal Reactions
2010-11-01

The presentation gives an overview of some recent advances in our research on hydrothermal conversion of biomasses, mainly including cellulose and lignocellulosic biomass, and carbon dioxide into chemicals, such as acetic acid, lactic acid and formic acid.

NASA Astrophysics Data System (ADS)

24
Delay-time stable chemically amplified deep-UV resist
1993-09-01

This paper describes a newly developed acetal-based positive tone deep UV photoresist called DX 46. The material consists of a 4-hydroxystyrene/4-hydroxy-3-methylstyrene copolymer, a polymeric dissolution inhibitor, and a bleachable diazo-photoactive compound. Each of the three compounds is specially designed to fit to each other for high performance sub-halfmicron resolution. ...

NASA Astrophysics Data System (ADS)

25
By-products in the analysis of beta-muricholic acid in biological samples as methyl ester triacetate.
1989-06-01

By-products were formed on analysis of beta-muricholic acid (3 alpha, 6 beta, 7 beta-trihydroxy-5 beta-cholan-24-oic acid) in biological samples by a method involving acid-catalyzed solvolysis of sulfate esters in acetone-methanol, followed by perchloric acid-catalyzed acetylation with acetic anhydride-acetic acid. ...

PubMed

26
Hydrolyses of 2- and 4-fluoro N-heterocycles. 3. Nucleophilic catalysis by buffer bases in the general acid catalyzed hydrolysis of 4-fluoroquinaldine
1989-01-06

Pseudo-first-order rate constants and catalytic rate constants are reported for the buffer-catalyzed hydrolysis of 4-fluoroquinaldine (1) in carboxylic acid and phosphoric acid buffers. The buffer catalysis is consistent with specific acid, general base catalysis. Hydrolyses in 99% /sup 18/O-labeled acetate, indicate that the predominant catalytic mode for the ...

Energy Citations Database

27
Comparative study of abiogenesis of cysteine and other amino acids catalyzed by various metal ions.
1975-01-01

The present work pertains to the study of the influence of nickel, cobalt, thorium, vanadium, molybdate, ferrous ions on the formation of cysteine which is synthesized abiogenically together with other amino acids in sterilized aqueous mixtures of ammonium thiocyanate, formaldehyde, potassium dihydrogen phosphate, calcium acetate, and biological minerals after irradiating by ...

PubMed

28
A highly diastereoselective synthesis of ?-hydroxy-?-amino acid derivatives via a Lewis acid catalyzed three-component condensation reaction.
2010-11-01

A very efficient three-component synthesis of a series of syn ?-hydroxy-?-amino esters, obtained in high diastereoselection and yield, was realized starting from an aldehyde, benzylamine, and the ketene silyl acetals derived from Ley's lactones. The synthetic protocol was optimized and the above compounds were obtained without the isolation of intermediates. The origin of the ...

PubMed

29
"Plasmalogen-type" cyclic acetals: formation and conformation of the 1,3-dioxanes and 1,3-dioxolanes from 1-0-cis-alk-1'-enyl-sn-glycerols.
1972-09-01

Acid-catalyzed cyclization of 1-O-cis-alk-1'-enyl-sn-glycerol produced four structurally and geometrically isomeric long-chain cyclic acetals of glycerol. The isomers were isolated by adsorption and gas-liquid chromatography and were identified as cis-2-alkyl-5-hydroxy-1,3-dioxane (Ia), trans-2-alkyl-5-hydroxy-1,3-dioxane (IIa), ...

PubMed

30
Two Paired "Le Chatelier" Reactions
1995-07-01

We have created a two-week, two hour-per-week cyclic experiment, which pairs two reactions. These reactions, the acid catalyzed esterification to yield n-amyl acetate and the base catalyzed hydrolysis of n-amyl acetate are intended to serve as a first and last experiment respectively, of the second-semester ...

NASA Astrophysics Data System (ADS)

31
The continuous acid-catalyzed dehydration of alcohols in supercritical fluids: A new approach to the cleaner synthesis of acetals, ketals, and ethers with high selectivity
1999-11-24

This report describes a new a continuous method for forming ethers, acetals and ketals using solid acid catalysts, DELOXAN ASP or AMBERLYST 15, and supercritical fluid solvents. In the case of ether formation, the authors observe a high selectivity for linear alkyl ethers with little rearrangement to give branches ethers. Such rearrangement is common in conventional synthesis. ...

Energy Citations Database

32
Decomposition of peracetic acid catalyzed by vanadium complexes
1986-02-01

This paper studies the decomposition of peracetic acid (AcOOH) in acetic acid (AcOH) catalyzed by vanadium complexes. It is shown that peractic acid in acetic acid solutions of ammonium anadate decomposes with the predominant formation of 0/sub 2/ and small amounts of CO/sub 2/, the yield of which increases with increasing temperature and peracetic acid ...

Energy Citations Database

33
1,3-dioxolyl acetals as powerful crosslinkers of phenolic resin
1993-09-01

The principle of chemical amplification has proven to be successful for the design of highly sensitive, high resolution resist materials of both positive and negative tone, respectively. This paper discusses our new approach to a high resolution, aqueous base developable deep-UV negative tone resist. It is based on the acid catalyzed cleavage of ...

NASA Astrophysics Data System (ADS)

34
Accretion Reactions of Glyoxal, Methylglyoxal, and Amines in Evaporating Cloud Droplets
2007-05-01

Glyoxal and methyl glyoxal (G+MG) are secondary pollutants produced by the atmospheric oxidation of aromatic compounds, isoprene and terpenes. They are known to partition efficiently into tropospheric water droplets, reaching micromolar concentrations. While G+MG hydrates are quite unreactive, we show that cloud droplet evaporation triggers accretion acid-catalyzed reactions ...

NASA Astrophysics Data System (ADS)

35
Acid catalyzed polymerization of monomethylol urea.
1973-04-01

... Abstract : NMR spectra of monomethylol urea and acid catalyzed solutions of ... be composed of residues of compound 2-keto-5-carboxyamide-1,3,-5 ...

DTIC Science & Technology

36
Primary and secondary kinetic isotope effects in the acid-catalyzed dehydration of 1,1'-diadamantylmethylcarbinol in aqueous acetic acid
1981-01-16

The sulfuric acid catalyzed dehydration of 1,1'-diadamantyl-methylcarbinol in anhydrous acetic acid proceeds exclusively to 1,1'-bis(1-adamantyl)ethylene. The secondary deuterium isotope effect of 1.32 found for this reaction shows that carbonium ion formation from the protonated alcohol is rate determining. In the ...

Energy Citations Database

37
Controlling hydrothermal reaction pathways to improve acetic acid production from carbohydrate biomass.
2005-03-15

A two-step hydrothermal process to improve the production of acetic acid was discussed. The first step was to accelerate the formation of 5-hydroxymethyl-2-furaldehyde (HMF), 2-furaldehyde (2-FA), and lactic acid (LA), and the second step was to further convert the furans (HMF, 2-FA) and LA produced in the first step to acetic acid by ...

PubMed

38
Versatile acetylation of carbohydrate substrates with bench-top sulfonic acids and application to one-pot syntheses of peracetylated thioglycosides.
2008-01-26

Inexpensive and readily available sulfonic acids, p-toluenesulfonic acid, and sulfuric acid are versatile and efficient catalysts for the peracetylation of a broad spectrum of carbohydrate substrates in good yield and in a practical time frame. Three appealing features in sulfonic acid-catalyzed acetylation of free sugars were explored including (1) suppression of furanosyl ...

PubMed

39
THE CATALYSIS OF THE H$sub 2$-D$sub 2$O EXCHANGE BY AQUEOUS BUFFER SOLUTIONS
1958-01-01

The exchange between molecular hydrogen and D/sub 2/O is known to be eatalyzed by hydroxide ion and follows the rate law/sup 3/d(P/sub HD/)/dt lambda k(P/sub H2/)(OH/sup -/). The exchange has been investigated at lower pH values in the temperature range ll0 to 190 deg using borate, phosphate, glycine, succinate and acetate buffers. The same rate law is obeyed ...

Energy Citations Database

40
Kinetics and mechanism of acid catalyzed oxidation of phenol and substituted phenols by isoquinolinium bromochromate
2010-12-01

Oxidation of phenols by isoquinolinium bromochromate (IQBC) in aqueous acetic acid leads to the formation of corresponding quinones. The reaction is first order with respect to both phenol and IQBC and catalysed by hydrogen ion. The rate of oxidation decreases with increase in dielectric constant of solvent indicating ion-dipole interaction. The rate of oxidation decreases ...

NASA Astrophysics Data System (ADS)

First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
41
Fluoro artemisinins: difluoromethylene ketones.
2001-11-16

The reactions of the ring-contracted aldehydes, derived from anhydrodihydroartemisinin, with gem-difluoroenoxysilanes in the presence of BF(3).Et(2)O afforded the corresponding difluoromethylene ketol adducts in good yields. Similar Lewis acid catalyzed reactions of dihydroartemisinin acetate with the difluoroenoxysilanes provided the ...

PubMed

42
Efficient synthesis of 1,3,5-trisubstituted (pyrrol-2-yl)acetic acid esters via dual nucleophilic reactions of sulfonamides or carbamate with 4-trimethyl-siloxy-(5E)-hexen-2-ynoates: Lewis acid catalyzed SN1 and intramolecular Michael addition.
2006-08-17

[reaction: see text] Carbamates or sulfonamides have proven to regioselectively attack 2-propynyl-allyl hybrid cations, generated by the action of TMSOTf on 4-(trimethylsioxy)hex-5-en-2-ynoates, to afford conjugated 6-aminohex-4-en-2-ynoates in which an intramolecular amino-Michael reaction took place, leading to pyrrole frameworks. In particular, the sulfonamides gave 1-sulfonylpyrroles in one ...

PubMed

43
The keto- and imine-epoxide rearrangements in the formation of substituted tetrahydrofurans and piperidines: Synthesis of ([+-])-teneraic acid; approahces to ([+-])-nemorensic acid and (+)-desoxoprosopinine
1992-01-01

Previous work by Wasserman and co-workers showed that 2,7-dioxabicyclo-[2.21]heptanes can be formed via a thermal of Lewis acid-catalyzed rearrangement of 3,4-epoxy ketones. The author utilized this keto-epoxide rearrangement in the approach to the synthesis of nemorensic acid. A novel reaction of Grignard reagents with bicyclic acetals was developed ...

Energy Citations Database

44
Acidity, catalytic activity, and deactivation of H-gallosilicate (MFI) in propane aromatization: Influence of hydrothermal pretreatments
1996-02-01

Effect of various hydrothermal pretreatments [at different temperatures (400-800{degrees}C) and concentrations of steam (13-80 mol%) or with liquid water at 150{degrees}C under autogenous pressure] to H-gallosilicate (MFI) zeolite (bulk Si/Ga = 33 and Na/Ga = 0.1) on its acidity/acid strength distribution (determined by chemisorption and step-wise thermal desorption of ...

Energy Citations Database

45
Base hydrolysis and hydrothermal processing of PBX-9404 explosive
1994-12-31

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, we examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. We also examine products from the subsequent ...

Energy Citations Database

46
Base hydrolysis and hydrothermal processing of PBX-9404
1994-11-01

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, the authors examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. They also examined products from ...

DOE Information Bridge

47
Partial oxidation of 4-tert-butyltoluene catalyzed by homogeneous cobalt and cerium acetate catalysts in the Br-/H2O2/acetic acid system: insights into selectivity and mechanism.
2007-01-01

The partial oxidation of 4-tert-butyltoluene to 4-tert-butylbenzaldehyde by hydrogen peroxide in glacial acetic acid, catalyzed by bromide ions in combination with cobalt(II) acetate or cerium(III) acetate, has been studied in detail. Based on the observed differences in reaction rates and ...

PubMed

48
A mild hydrothermal route to fix carbon dioxide to simple carboxylic acids.
2010-02-19

The reduction of carbon dioxide (CO(2)) under mild hydrothermal conditions was carried out in the presence of iron nanoparticles. In this reaction system, the iron nanoparticles not only act as the reducing agent but also catalyze the reduction of CO(2) to form formic acid and acetic acid. PMID:20104858

PubMed

49
Abrasion-resistant solgel antireflective films with a high laser-induced damage threshold for inertial confinement fusion
2005-09-01

To prepare abrasion-resistant antireflective (AR) films for inertial confinement fusion, four solgel routes have been investigated on polysiloxane-modified and polyvinylalcohol- (PVA-) modified SiO{sub 2} sols. As confirmed with a transmissive electron microscope, different fractal structure characteristics of the modified SiO{sub 2} particles are disclosed by small-angle x-ray scattering ...

Energy Citations Database

50
Abrasion-resistant solgel antireflective films with a high laser-induced damage threshold for inertial confinement fusion
2005-09-01

To prepare abrasion-resistant antireflective (AR) films for inertial confinement fusion, four solgel routes have been investigated on polysiloxane-modified and polyvinylalcohol- (PVA-) modified SiO2 sols. As confirmed with a transmissive electron microscope, different fractal structure characteristics of the modified SiO2 particles are disclosed by small-angle x-ray scattering technology. And it ...

NASA Astrophysics Data System (ADS)

51
TiCl(4)-Promoted Cyclization Reactions of Aminoacetals and Ethenetricarboxylates Leading to Nitrogen-Containing Heterocycles.
2011-07-08

Lewis acid-catalyzed cyclization of aminoacetals 2 and triethyl ethenetricarboxylate (1a) has been examined. The reaction of 3-aminopropionaldehyde diethyl acetal (2a) and 1a in the presence of 1 equiv of TiCl(4) at room temperature gave 4-ethoxypiperidine-2,3,3-tricarboxylate 3a in 92% yield with a 2,4-diastereomer ratio of 1:1. The reaction in the ...

PubMed

52
New C(3v)-symmetrical tribenzotriquinacenes bearing extended and oxy-functionalised alkyl groups at their benzhydrylic bridgeheads.
2010-09-27

A series of tribenzotriquinacene derivatives bearing three oxy-functionalised alkyl groups at the benzhydrylic bridgeheads (C-4b, C-8b and C-12b) have been synthesised. The 4b,8b,12b-triallyl derivative was used to generate the corresponding TBTQ-tris-acetaldehyde and TBTQ-tris(acetic acid), in which the functional groups stretch out from the convex rigid molecular surface. ...

PubMed

53
Kinetic hydrogen isotope effects in the concerted mechanism for the hydrolysis of acetals, ketals, and ortho esters
1978-10-25

The hydrolysis of many ortho esters, and some acetals and ketals, is general acid catalyzed, and in some examples these generate linear Bronsted plots over substantial ranges of catalyst acidity. This suggests that the reaction coordinate is primarily a reorganization of heavy atoms since proton transfer from one oxygen to another has ...

Energy Citations Database

54
Base hydrolysis and supercritical water oxidation of PBX-9404
1994-11-09

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, the authors examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. The authors also examine products ...

DOE Information Bridge

55
Synthesis and catalytic properties of crystalline, microporous vanadium silicates with MEL structure
1992-09-01

A thermally stable, vanadium-containing silicate with the MEL structure has been prepared by hydrothermal crystallization. XRD and framework IR spectra of samples with three different Si/V ratios suggest the presence of V ions in framework positions wherein the concentration of SiOH groups is likely to be high. ESR spectra of the as-synthesized and reduced samples indicate ...

Energy Citations Database

56
An XAS study of zinc speciation in aqueous acetate solutions at 25-200 �C
2010-07-01

Solutions of zinc(II) acetate in acetic acid/sodium acetate buffer solutions of varying concentration were examined by X-ray absorption spectroscopy (XAS) at temperatures between 25 and 200 �C. The influence on speciation by increasing the ratio of available acetate to Zn concentration was marked, and followed a ...

NASA Astrophysics Data System (ADS)

57
A new process for producing calcium acetate from vegetable wastes for use as an environmentally friendly deicer.
2010-05-18

A new process for producing calcium acetate, a non-corrosive deicer, is proposed. The process consists of a two-step continuous-flow hydrothermal conversion of vegetable wastes into acetic acid and the production of calcium acetate, followed by the separation and condensation of the product. The experiments for ...

PubMed

58
Acetic acid and lithium chloride effects on hydrothermal carbonization of lignocellulosic biomass.
2011-02-13

As a renewable non-food resource, lignocellulosic biomass has great potential as an energy source or feedstock for further conversion. However, challenges exist with supply logistics of this geographically scattered and perishable resource. Hydrothermal carbonization treats any kind of biomass in 200 to 260�C compressed water under an inert atmosphere to produce a ...

PubMed

59
Synthesis of N,N-disubstituted phosphoramidates via a Lewis acid-catalyzed phosphorimidate rearrangement.
2008-04-18

A Lewis acid-catalyzed rearrangement of phosphorimidates allows a direct, high-yielding transformation of azides with commercially available phosphites into secondary phosphoramidates. PMID:18566729

PubMed

60
Lewis acid catalyzed indole synthesis via intramolecular nucleophilic attack of phenyldiazoacetates to iminium ions.
2009-12-01

Lewis acids catalyze the cyclization of methyl phenyldiazoacetates with an ortho-imino group, prepared from o-aminophenylacetic acid, to give 2,3-substituted indoles in quantitative yields. PMID:19904905

PubMed

First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
61
Lewis Acid-Catalyzed Indole Synthesis via Intramolecular Nucleophilic Attack of Phenyldiazoacetates to Iminium Ions
2009-12-04

Lewis acids catalyze the cyclization of methyl phenyldiazoacetates with an ortho-imino group, prepared from o-aminophenylacetic acid, to give 2,3-substituted indoles in quantitative yields.

PubMed Central

62
Acid-catalyzed regioselective sulfetherification of alkenols and stereoselective rearrangement of tetrahydrofuran to tetrahydropyran.
2011-03-01

An efficient acid-catalyzed sulfetherification of various unsaturated alcohols with sulfenamides to form tetrahydrofurans and tetrahydropyrans regioselectively is described. Mechanistic studies have shown that the tetrahydrofurans can stereoselectively rearrange to the corresponding tetrahydropyrans. PMID:21361303

PubMed

63
Acid catalyzed reactions of alpha and beta styryl azides

Title: Acid catalyzed reactions of alpha and beta styryl azides. Online Source: Click to View PDF File [PDF Size: 427 KB]. Author: Boyer, J. H.; Krueger, ...

NASA Website

64
Fluorescence Quenching of Methoxybenzyl Alcohols by the ...

... Title : Fluorescence Quenching of Methoxybenzyl Alcohols by the Hydronium Ion in Aqueous Solution: Acid-Catalyzed Formation of Methoxybenzyl ...

DTIC Science & Technology

65
Aromatic Substitution. 43. Perfluorinated Resinsulfonic Acid ...
1978-06-19

... Accession Number : ADA095669. Title : Aromatic Substitution. 43. Perfluorinated Resinsulfonic Acid Catalyzed Nitration of Aromatics,. ...

DTIC Science & Technology

66
A FUNCTION OF HYDROXYL POSITION IN LINEAR ...
1970-05-01

... There is some evidence to suggest thatsecondary alcohols tend to dehydrate more rapidly than primary alcoholsduring acid catalyzed esterification ...

DTIC Science & Technology

67
Theoretical analysis of kinetic isotope effects on proton transfer reactions between substituted alpha-methoxystyrenes and substituted acetic acids.
2009-10-01

Primary kinetic isotope effects (KIEs) on a series of carboxylic acid-catalyzed protonation reactions of aryl-substituted alpha-methoxystyrenes (X-1) to form oxocarbenium ions have been computed using the second-order Kleinert variational perturbation theory (KP2) in the framework of Feynman path integrals (PI) along with the potential energy surface obtained at the ...

PubMed

68
Theoretical Analysis of Kinetic Isotope Effects on Proton Transfer Reactions between Substituted ?-Methoxystyrenes and Substituted Acetic Acids
2009-10-07

Primary kinetic isotope effects (KIEs) on a series of carboxylic acid-catalyzed protonation reactions of aryl-substituted ?-methoxystyrenes (X-1) to form oxocarbenium ions have been computed using the Kleinert variational second-order perturbation theory (KP2) in the framework of Feynman path integrals (PI) along with the potential energy surface obtained at the ...

PubMed Central

69
Lewis acid or Br�nsted acid catalyzed reactions of vinylidene cyclopropanes with activated carbon-nitrogen, nitrogen-nitrogen, and iodine-nitrogen double-bond-containing compounds.
2009-01-01

Lewis acid or Br�nsted acid catalyzed reactions of vinylidene cyclopropanes (VDCPs), 1, with activated carbon-nitrogen, nitrogen-nitrogen, and iodine-nitrogen double-bond-containing compounds have been thoroughly investigated. We found that pyrrolidine and 1,2,3,4-tetrahydroquinoline derivatives can be formed in good yields in the reactions of VDCPs 1 ...

PubMed

70
Sulfonic acid resin-catalyzed addition of phenols, carboxylic acids, and water to olefins: Model reactions for catalytic upgrading of bio-oil.
2010-01-25

Acid-catalyzed 1-octene reactions with phenol and mixtures of phenol with water, acetic acid and 1-butanol were studied as partial bio-oil upgrading models. Bio-oil from fast biomass pyrolysis has poor fuel properties due to the presence of substantial amounts of water, carboxylic acid, phenolic derivatives and other hydroxyl-containing compounds. ...

PubMed

71
Atmospheric Environment 40 (2006) 6863�6878 Acid-catalyzed reactions of hexanal on sulfuric acid particles

Atmospheric Environment 40 (2006) 6863�6878 Acid-catalyzed reactions of hexanal on sulfuric acid are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe

E-print Network

72
Production of acetic acid by hydrothermal two-step process of vegetable wastes for use as a road deicer
2008-07-01

This study aimed to produce acetic acid from vegetable wastes by a new hydrothermal two-step process. A continuous flow reaction system with a maximum treatment capacity of 2 kg/h of dry biomass developed by us was used. Five kinds of vegetables of carrots, white radish, chinese cabbage, cabbage and potato were selected as the representation of vegetable ...

NASA Astrophysics Data System (ADS)

73
Production of Formic Acid and Acetic Acid by Hydrothermal Oxidation of Alkali Lignin
2010-11-01

The production of formic acid and acetic acid by hydrothermal oxidation of alkali lignin, a kind of biomasses, was investigated using a batch reactor with H2O2 oxidant. Experiments were performed over a wide range of conditions with temperature varying from 260 to 320� C, oxygen supply varying from 60% to 120%, and reaction time varying from 30 to 150 s. ...

NASA Astrophysics Data System (ADS)

74
[Resistance to levomycetin and activity of several enzymes in Escherichia coli and the agent of plague].
1976-01-01

The authors compared the activity of acetyl-CoA-synthetase and of the enzymes belonging to the group of asparaginic acid in levomycetin sensitive and resistant strains of Y. pestis and E. coli. There were revealed marked differences in the activity of aspartase, fumarase, synthetase and desamidase of L-asparagin, and also of the enzyme activated by acetate in the E. coli ...

PubMed

75
Water-soluble oligomer formation from acid-catalyzed reactions of levoglucosan in proxies of atmospheric aqueous aerosols.
2006-08-15

Herein is reported the first laboratory observation of the oligomerization of levoglucosan studied under atmospherically relevant conditions. Oligomers up to 1458 Da (9-mer) were measured by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. A rational mechanism is proposed based on both the acid-catalyzed cationic ring-opening of levoglucosan and nucleophilic attack of ...

PubMed

76
Studies directed toward the synthesis of the A-ring of taxol
1992-01-01

Taxol 1, a novel anticancer agent, isolated from Taxus brevifolia, is a member of the class of taxane diterpenes. Since its isolation and characterization many groups around the world using varied approaches have made significant contributions toward the assembly of the taxane framework and ultimately to taxol itself. The focus of this investigation was directed towards making a fully ...

Energy Citations Database

77
Stereoselective Synthesis of 2-C-Branched (Acetylmethyl) Oligosaccharides and Glycoconjugates: Lewis Acid-Catalyzed Glycosylation from 1,2-Cyclopropaneacetylated Sugars.
2011-01-19

1,2-Cyclopropaneacetylated sugars as glycosyl donors reacted with a series of glycosyl acceptors (monosaccharides, amino acids, and other alcohols) in the presence of Lewis acid to produce oligosaccharides and glycoconjugates containing 2-C-acetylmethylsugars. Galactosyl donor gave good to excellent ?-selectivities with TMSOTf as a catalyst, whereas galactosyl donor offered moderate to good ...

PubMed

78
Qualitative analysis of products formed during the acid catalyzed liquefaction of bagasse in ethylene glycol.
2006-12-08

Bagasse was liquefied in ethylene glycol (EG) catalyzed by sulfuric acid at 190 degrees C under atmospheric pressure. The compositions of the crude products obtained were analyzed after separating them into three fractions: a water-soluble fraction, an acetone-soluble fraction and a residue. With infrared, gel permeation chromatography and elemental analyses, the residue mainly included ...

PubMed

79
Protective group-free syntheses of (�)-frontalin, (�)-endo-brevicomin, (�)-exo-brevicomin, and (�)-3,4-dehydro-exo-brevicomin: racemic pheromones with a 6,8-dioxabicyclo[3.2.1]octane ring.
2011-05-20

Protective group-free syntheses of four racemic pheromones with a 6,8-dioxabicyclo[3.2.1]octane ring were achieved in five or six steps from commercially available (�)-3-butyn-2-ol (6) and 2-alkenyl halides or 2-alken-1-ol by employing Lewis acid-catalyzed acetalization of ?, ?-epoxy ketones as the key reaction. (�)-Frontalin (1) was prepared in a 25% ...

PubMed

80
Positive- and negative-tone water-processable photoresists: a progress report
1998-06-01

This paper presents the progress we have made toward the development of fully water processable, negative and positive tone I-line resist systems. The negative tone system is based on styrene copolymers bearing pendant ammonium sulfonate groups and vicinal diol functionalities. The salt provides the means of rendering the polymer water soluble. The diol undergoes an acid ...

NASA Astrophysics Data System (ADS)

First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
First Page Previous Page 1 2 3 4 5 Next Page Last Page
 
81
Mild synthesis of disaccharidic 2,3-enopyranosyl cyanides and 2-C-2-deoxy pyranosyl cyanides with Hg(CN)(2)/HgBr(2)/TMSCN.
2002-11-01

Lewis acid-catalyzed dimerization of mono- and disaccharidic per-O-acetylated glycals gave di- and tetrasaccharidic O-acetylated C-glycosides, respectively. 2,3-Enopyranosyl cyanides were obtained from per-O-acetylated glycals by a new, mild anomeric S(N)'-acetoxy displacement with Hg(CN)(2)/HgBr(2)/TMSCN. Per-O-acetylated 2-C-2-deoxy-pyranoses were converted into pyranosyl ...

PubMed

82
Heterogeneous Chemistry of Carbonyls and Alcohols With Sulfuric Acid: Implications for Secondary Organic Aerosol Formation
2006-12-01

Recent environmental chamber studies have suggested that acid-catalyzed particle-phase reactions of organic carbonyls lead to multifold increases in secondary organic aerosol (SOA) mass and acid-catalyzed reactions between alcohols and aldehydes in the condensed phase lead to the formation of hemiacetals and acetals, also enhancing secondary organic aerosol growth. The ...

NASA Astrophysics Data System (ADS)

83
Cu(I)-carbenoid- and Ag(I)-Lewis acid-catalyzed asymmetric intermolecular insertion of alpha-diazo compounds into N-H bonds.
2004-09-28

Chiral Cu(I)-bisoxazoline- and Cu(I)-PN-complexes were found to catalyze the intermolecular insertion of alpha-diazo compounds into N-H bonds. The insertion reactions proceed with enantioselectivities of up to 28% ee for the different alpha-diazo acetates into one of the N-H bonds of different amines. Analogous chiral Ag(I) complexes were found to give higher ...

PubMed

84
Chemical aspects of silicon-containing bilayer resists
1999-05-01

We have prepare several novel silicon-containing polymers containing both low Ea and high Ea protecting groups, and we have evaluated these materials at both 193 nm. Low Ea acetal-containing polymers were prepared by reacting poly(4-vinylphenol) with novel silyl enol ethers. The ease of protecting group cleavage in these materials is manifested in the immediate formation of a ...

NASA Astrophysics Data System (ADS)

85
Multiple-anion nonvolatile acetal (MANA) resists
2001-08-01

New acetal or ketal blocking reagents were investigated for use in e-beam lithography and compared with the performance of ethyl vinyl either (EVE). Three blocking groups, (alpha) -Angelicalactone (AL), 6-methylene-5,6-benzo-1,4- dioxane (MBD), and MANA50 (an undisclosed blocking group used to show the potential of this chemistry) were reacted with poly(p-hydroxystyrene) (PHS) ...

NASA Astrophysics Data System (ADS)

First Page Previous Page 1 2 3 4 5 Next Page Last Page