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1

MDEA\\/Piperazine as a solvent for CO 2 capture  

Microsoft Academic Search

The solvent blend methyldiethanolamine\\/piperazine (MDEA\\/PZ) has been investigated as an alternative for CO2 capture from coal-fired power plants. MDEA\\/PZ offers advantages over monoethanolamine (MEA) and MDEA alone because of its resistance to thermal and oxidative degradation at typical absorption\\/stripping conditions. We measured thermal degradation rates of MDEA and PZ of ?7±20 mmolal\\/day and ?9±5 mmolal\\/day, respectively, in a loaded 7 m MDEA\\/2 m PZ

Fred Closmann; Thu Nguyen; Gary T Rochelle

2009-01-01

2

A study on equilibrium solubility for carbon dioxide in methyldiethanolamine-piperazine-water solution  

SciTech Connect

Activated methyldiethanolamine (MDEA) technology has been frequently applied for the removal of acidic gases such as CO{sub 2} and H{sub 2}S from gas streams. Solubilities of CO{sub 2} in aqueous mixtures of methyldiethanolamine (MDEA) and piperazine (PZ) have been measured for temperatures and CO{sub 2} partial pressures ranging from 30 to 90 C and 13.16 to 935.3 kPa, respectively. A modified Deshmukh-Mather thermodynamic model is used to correlate the experimental data with the average deviation of 9.8%, in which the effect of salts on Henry's constant is taken into consideration. The results also indicate that the second-order dissociation reaction for piperazine can be neglected. A simple model is also given with the average deviation of 11.6%.

Liu, H.B.; Zhang, C.F.; Xu, G.W.

1999-10-01

3

Gas-liquid equilibrium in a CO{sub 2}-MDEA-H{sub 2}O system and the effect of piperazine on it  

SciTech Connect

Aqueous N-methyldiethanolamine (MDEA) solutions are widely used for removal of the acid gas (H{sub 2}S and CO{sub 2}) from natural gas synthesis and refinery gas streams. Solubility data of CO{sub 2} and vapor pressure of water in 3.04--4.28 kmol/m{sup 3} aqueous N-methyldiethanolamine (MDEA) solutions were obtained at temperatures ranging from 40 to 100 C and CO{sub 2} partial pressures ranging from 0.876 to 1,013 kPa. A thermodynamic model was proposed and used for predicting CO{sub 2} solubility and water vapor pressure. An enthalpy change of absorption of CO{sub 2} in 4.28 kmol/m{sup 3} MDEA solution was estimated. The effect of piperazine (PZ) concentration on CO{sub 2} loading in MDEA solutions was determined at piperazine concentration ranging from 0 to 0.515 kmol/m{sup 3}. The results show that piperazine is beneficial to the CO{sub 2} loading. The equilibrium partial pressure of piperazine in the PZ-MDEA-H{sub 2}O system was measured in an Ellis Cell. Results show that the PZ-MDEA-H{sub 2}O system is a typical negative deviation system, with the strength of deviation decreasing with MDEA solutions.

Xu, G.W.; Zhang, C.F.; Qin, S.J.; Gao, W.H.; Liu, H.B. [East China Univ. of Science and Technology, Shanghai (China). Research Inst. of Chemical Technology] [East China Univ. of Science and Technology, Shanghai (China). Research Inst. of Chemical Technology

1998-04-01

4

Desorption of COâ from MDEA and activated MDEA solutions  

Microsoft Academic Search

A packed column was used for investigating the desorption rate of COâ from aqueous methyldiethanolamine (MDEA) and activated MDEA solutions. Experiments were conducted within the temperature range 30--70 C, the concentration of MDEA was 4.28 kmol\\/m³, and the concentration of piperazine (PZ) was 0.10 kmol\\/m³ for aqueous activated MDEA solutions. Experimental data confirmed that the kinetics model of absorption COâ

Guo-Wen Xu; Cheng-Fang Zhang; Shu-Jun Qin; Bin-Chen Zhu

1995-01-01

5

Aerobic biodegradability of methyldiethanolamine (MDEA) used in natural gas sweetening plants in batch tests and continuous flow experiments  

Microsoft Academic Search

Mixtures of different amines including tertiary amines (methyldiethanolamine, MDEA) are commonly used for the removal of CO2 from gas mixtures or in gas sweetening processes for the extraction of CO2 and H2S. The absorber solutions used can be released into the industrial waste water due to continuous substitution of degraded MDEA, periodically cleaning processes or an accidental spill. In this

M. Fürhacker; A. Pressl; R. Allabashi

2003-01-01

6

Solubility of H 2S in (H 2O + piperazine) and in (H 2O + MDEA + piperazine)  

Microsoft Academic Search

New experimental results for the solubility of hydrogen sulfide in aqueous solutions of piperazine are presented for piperazine molalities up to 4mol\\/kg of water, temperatures between 313 and 393K, and pressures up to about 9MPa. Furthermore, the solubility of hydrogen sulfide was measured in about 2m MDEA + 2m piperazine aqueous solutions at 353K up to about 6MPa. Considering the

Jianzhong Xia; Álvaro Pérez-Salado Kamps; Gerd Maurer

2003-01-01

7

Desorption of CO{sub 2} from MDEA and activated MDEA solutions  

SciTech Connect

A packed column was used for investigating the desorption rate of CO{sub 2} from aqueous methyldiethanolamine (MDEA) and activated MDEA solutions. Experiments were conducted within the temperature range 30--70 C, the concentration of MDEA was 4.28 kmol/m{sup 3}, and the concentration of piperazine (PZ) was 0.10 kmol/m{sup 3} for aqueous activated MDEA solutions. Experimental data confirmed that the kinetics model of absorption CO{sub 2} into aqueous MDEA and activated MDEA solutions can be applicable to the situations in which desorption occurs, and the desorption rate of model predictions agree well with that of experimental determination.

Xu, G.W.; Zhang, C.F.; Qin, S.J.; Zhu, B.C. [East China Univ. of Science and Technology, Shanghai (China). Research Inst. of Inorganic Chemical Technology

1995-03-01

8

Gas-liquid equilibrium in a COâ-MDEA-HâO system and the effect of piperazine on it  

Microsoft Academic Search

Aqueous N-methyldiethanolamine (MDEA) solutions are widely used for removal of the acid gas (HâS and COâ) from natural gas synthesis and refinery gas streams. Solubility data of COâ and vapor pressure of water in 3.04--4.28 kmol\\/m³ aqueous N-methyldiethanolamine (MDEA) solutions were obtained at temperatures ranging from 40 to 100 C and COâ partial pressures ranging from 0.876 to 1,013 kPa.

Guo-Wen Xu; Cheng-Fang Zhang; Shu-Jun Qin; Wei-Hong Gao; Hua-Bin Liu

1998-01-01

9

Equilibrium solubilities of CO/sub 2/ and H/sub 2/S in diethanolamine (DEA) and methyldiethanolamine (MDEA) solutions  

SciTech Connect

The ability to predict equilibrium phase behavior in systems containing CO/sub 2/ and/or H/sub 2/S in alkanolamine solutions such as diethanolamine (DEA) and methyldiethanolamine (MDEA) is of vital importance for proper design and operation of acid gases treating systems. Literature data for the solubilities of CO/sub 2/ and/or H/sub 2/S in DEA and MDEA systems have been compiled and evaluated. Experimental measurements have also been made to confirm literature data and to expand the data base. A vapor-liquid equilibrium (VLE) model similar to the one developed by Kent and Eisenberg has been developed to correlate the data. The model gives the most accurate predictions when compared to other VLE models available for predicting equilibrium acid gas partial pressures over DEA and MDEA solutions.

Ho, A.S.; Equren, P.R. (Amoco Production Co., Tulsa, OK (US))

1988-01-01

10

Molecular dynamics simulation studies of absorption in piperazine activated MDEA solution.  

PubMed

Development of more efficient solvent solutions for removal of CO(2) from natural gas and flue gases is a major task, which contributes to improved design of process plants and leads to decreased costs for its removal. Understanding the mechanisms of CO(2) absorption as well as analysis of undesired simultaneous processes is crucially important in this regard. In this work, we have applied Molecular Dynamics (MD) to investigate the absorption of CO(2) from a binary mixture of CO(2) and CH(4) into aqueous piperazine activated MDEA solution. The MD simulations were performed at a constant temperature of 298 K for five different systems with a loading factor of 0.07 to provide insight into molecular distribution in the amine solution and to enhance understanding of absorption mechanisms on the molecular scale. Force field parameters that were missing from the OPLS-AA force field, as well as charge distribution of piperazine (PZ), protonated piperazine (PZH(+)), piperazine carbamate (PZCOO(-)) and MDEA were obtained by QM calculations. The results of our simulations emphasize the importance of piperazine and piperazine carbamate in accelerating the absorption process. For the first time, we have shown the undesirable trapping of CH(4) by the amine solution and revealed that amine groups are mainly responsible for both absorption of CO(2) and the undesired trapping of CH(4). PMID:21691636

Farmahini, Amir Hajiahmadi; Kvamme, Bjørn; Kuznetsova, Tatiana

2011-07-28

11

Thermodynamics of aqueous amines: excess molar heat capacities, volumes, and expansibilities of {water + methyldiethanolamine (MDEA)} and {water + 2-amino-2-methyl-1-propanol (AMP)}  

Microsoft Academic Search

The heat capacities of aqueous solutions of methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) were measured in a heat-flux differential scanning calorimeter at temperatures 278.15K?T? 368.15 K, to yield excess molar heat capacities Cp,mEover the whole mole fraction range. Densities of aqueous AMP were determined with a vibrating tube densimeter over the temperature range 293.15 K?T? 353.15 K, and used to derive

Peter R. Tremaine

2002-01-01

12

Selective removal of hydrogen sulfide from carbon dioxide containing gases with methyldiethanolamine (MDEA) aqueous solutions  

SciTech Connect

The kinetics of the chemical reactions between MDEA and H/sub 2/S can be regarded as instantaneous, since it is a proton-transfer reaction, and therefore these kinetics require no further investigation. The kinetics of the reaction between MDEA and CO/sub 2/ are more complicated and is studied here to clear the apparent contradiction in the literature (Barth et al., 1981; Blauwhoff et al., 1983). A base-catalyzed mechanism by MDEA is concluded with a kinetic equation which is first order in CO/sub 2/ and MDEA concentrations. The influence of ionic strength on these kinetics was studied, and it is concluded that a minor effect is indeed present. With the knowledge of the kinetics of these reactions, a model which describes the simultaneous absorption of H/sub 2/S and CO/sub 2/ in MDEA solutions is presented. This model can not only predict the simultaneous absorption of H/sub 2/S and CO/sub 2/ in the initial stage, but also predict an experimental observation of long time desorption of H/sub 2/S. Furthermore, this model provides analytical solutions of the mass transfer equations which take into account the interactions between the two chemical reactions. A special case, which is termed film effect, is taken into account in expanding the model into a design procedure. It is concluded that the film effect will be significant only at the lean end of the absorber. A linearized correction term is used to correct for this affect. Finally, the design procedures for both isothermal and adiabatic packed-bed absorbers are proposed on the basis of the simultaneous absorption model and the correction for film effect. No pilot plant data are included to check the calculation, because such data are not available in the open literature.

Yu, W.C.

1985-01-01

13

Predictions of the solubility of acid gases in monoethanolamine (MEA) and methyldiethanolamine (MDEA) solutions using the electrolyte-UNIQUAC model  

Microsoft Academic Search

A thermodynamic model was developed for representing vapor–liquid equilibria (VLE) of the CO2–H2S–MEA–MDEA–water system. The model accounts for chemical equilibria in the liquid phase and physical equilibria between the liquid and vapor phases. Activity coefficients are represented by the electrolyte-UNIQUAC equation. The present extension uses an ion-pair interaction approach and satisfies both the principles of like-ion repulsion and local electroneutrality.

Lupong Kaewsichan; Osama Al-Bofersen; Victor F. Yesavage; M. Sami Selim

2001-01-01

14

Simultaneous absorption of H/sub 2/S and CO/sub 2/ in aqueous MDEA. [Methyldiethanolamine  

SciTech Connect

In the simultaneous absorption of two gases in a reactive liquid, the rates of absorption of both gases are affected by their competition for the same reactive reagent. The case of absorption of two gases into a reactive liquid where one reacts under second order reaction kinetics while the other reacts instantaneously is of practical interest, since this case represents the absorption of CO/sub 2/ and H/sub 2/S into amine solutions. The rates of absorption were modeled according to the penetration theory. The model equations consisting of a system of nonlinear differential equations with a moving boundary were solved numerically. The theoretical model was applied to a description of the selective absorption of H/sub 2/S in diethanolamine solution in the presence of CO/sub 2/. The simultaneous absorption of H/sub 2/S and CO/sub 2/ gases into MDEA was studied experimentally using a stirred gas liquid absorber. This case was modeled theoretically assuming one of the gases CO/sub 2/ undergoes a second order reaction condition with the solution while the other gas, H/sub 2/S is entirely gas film controlled. The kinetics of the reaction between both gases and MDEA was studied. Unavailable physical properties such as diffusivities and solubilities of different species were measured experimentally using laminar jet apparatus.

Khalil, N.M.

1984-01-01

15

Thermodynamics of aqueous methyldiethanolamine (MDEA) and methyldiethanolammonium chloride (MDEAH +Cl ?) over a wide range of temperature and pressure: Apparent molar volumes, heat capacities, and isothermal compressibilities  

Microsoft Academic Search

Apparent molar volumes of aqueous methyldiethanolamine and its salt were determined with platinum vibrating tube densitometers over a range of temperatures from 283K?T?576K and at pressures from 0.1MPa to 20MPa. Apparent molar heat capacities were obtained using a Sodev Picker flow microcalorimeter at a pressure of 0.1MPa and within the temperature range of 283K?T?328K. Apparent molar adiabatic and isothermal compressibilities

B. Hawrylak; R. Palepu; Peter R. Tremaine

2006-01-01

16

Absorption of carbonyl sulfide in aqueous methyldiethanolamine  

SciTech Connect

The absorption of carbonyl sulfide in aqueous methyldiethanolamine (MDEA) was studied over a range of temperatures and MDEA concentrations. MDEA is commonly used for selective absorption of hydrogen sulfide in the presence of carbon dioxide. However, sulfur in the form of COS may also be present and it is necessary that estimates of absorption rates of this compound be made. The objective of this study is to determine the physiochemical properties needed to predict COS absorption rates in aqueous MDEA. Free gas solubility and the diffusivity of COS in MDEA solutions were measured over the temperature range 15 to 40{sup 0}C for MDEA concentrations up to 30 weight per cent using the nitrous oxide analogy method. Solubilities were measured volumetrically in an equilibrium cell and diffusivities were measured using a laminar liquid jet absorber. The kinetics of the reaction between COS and MDEA were studied by measuring absorption rates in a single wetted-sphere absorber.

Al-Ghawas, H.A.; Ruiz-Ibanez, G.; Sandall, O.C. (Dept. of Chemical and Nuclear Engineering, Univ. of California, Santa Barbara, CA (US))

1988-01-01

17

Heat capacity of aqueous monoethanolamine, diethanolamine, N-methyldiethanolamine, and N-methyldiethanolamine-based blends with carbon dioxide  

SciTech Connect

New data are reported on the heat capacity of CO{sub 2}-loaded, aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), and aqueous MDEA-based blends with MEA and DEA. The work reported here was motivated by the need to quantify the effect of acid gas loading on the important physical properties of gas-sweetening solvents.

Weiland, R.H.; Dingman, J.C.; Cronin, D.B. [Optimized Gas Treating, Inc., Houston, TX (United States)] [Optimized Gas Treating, Inc., Houston, TX (United States)

1997-09-01

18

SOLUBILITY OF NITROUS OXIDE IN AQUEOUS SOLUTIONS OF METHYLDIETHANOLAMINE, DIETHANOLAMINE AND MIXTURES OF METHYLDIETHANOLAMINE AND DIETHANOLAMINE  

Microsoft Academic Search

The solubility of nitrous oxide (N2O) in aqueous solutions of 0-50 mass % methyldiethanolamine (MDEA), 0-30 mass % diethanolamine (DEA), and 50 mass % total amine with DEA\\/MDEA weight ratios of 0.04413-0.5883 was measured over the temperature range 293-353 K and at N2O partial pressures near atmospheric. The solubility data from this work were found to be in fair agreement with

E. B. RINKER; O. C. SANDALL

1996-01-01

19

Cost efficient synthesis of bismuth aminoalkoxides from bismuth oxide: Molecular structure of [Bi 2(mdea) 2(mdeaH) 2](mdeaH 2) 2  

Microsoft Academic Search

Functional Bi alkoxides were prepared by reaction between the oxide and diols such as N-methyldiethanolamine (mdeaH2), diethanolamine (deaH2) and triethanolamine (teaH3) in refluxing toluene in high yields. Similar reactions with polyols without N-donor site lead to oxo species. The derivative obtained with N-methyldiethanolamine was characterised by X-ray diffraction as a dimer [Bi2(mdea)2(mdeaH)2] associated as chains through H-bonding with neutral diol

Jérome Le Bris; Liliane G. Hubert-Pfalzgraf; Stéphane Daniele; Jacqueline Vaissermann

2007-01-01

20

Effect of heat stable salts on MDEA solution corrosivity: Part 2  

Microsoft Academic Search

A comprehensive coupon corrosion testing program was undertaken to address the effect of various heat stable salts on methyldiethanolamine (MDEA) corrosivity to carbon steel and various stainless steels. Corrosion rates of carbon steel, 304SS, 316SS and 410SS liquid and vapor coupons towards MDEA, and MDEA containing various anions, at 180 F and 250 F, were measured in a reactor. Corrosion

P. C. Rooney; M. S. DuPart; T. R. Bacon

1997-01-01

21

Gas plant converts amine unit to MDEA-based solvent  

Microsoft Academic Search

This paper reports that methyldiethanolamine (MDEA) has successfully replaced monoethanolamine (MEA) solvent at one of Canada's largest gas processing plants. This acid gas treating solvent lowered costs associated with pumping horsepower, reboiler duty, solvent losses, corrosion and other gas processing problems. Not all operating conditions at a gas processing plant favor MDEA or MEA. In the Rimbey plant, originally designed

Mak

1992-01-01

22

Solubility of carbon dioxide in methyldiethanolamine + methanol + water  

SciTech Connect

Aqueous solutions of methyldiethanolamine (MDEA) are attractive solvents for the selective removal of H{sub 2}S from process stream containing CO{sub 2} and hydrocarbons. The solubility of CO{sub 2} in a mixed nonaqueous solvent of methyldiethanolamine MDEA and methanol has been measured at 40 C. The results are compared with the solubility of CO{sub 2} in pure methanol. The solubility of CO{sub 2} has also been obtained at 40 and 100 C in an aqueous mixed solvent consisting of methanol (40 mass %), MDEA (40 mass %), and water (20 mass %) at partial pressures of the acid gas up to 7.04 MPa. The solubility results are compared with the nonaqueous mixed solvent results and previously reported data for aqueous methyldiethanolamine.

Henni, A.; Mather, A.E. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical Engineering

1995-03-01

23

Diffusivity of nitrous oxide in N-methyldiethanolamine + diethanolamine + water  

Microsoft Academic Search

The tertiary amine N-methyldiethanolamine and the secondary amine diethanolamine are commonly used in the gas-treating industry as chemical solvents for the removal of acid gases such as COâ and HâS. The diffusion coefficients for nitrous oxide in aqueous solutions consisting of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) were measured over the temperature range 293--353 K for a total amine concentration of

E. B. Rinker; J. W. Russell; A. Tamimi; O. C. Sandall

1995-01-01

24

Diffusivity of nitrous oxide in N-methyldiethanolamine + diethanolamine + water  

SciTech Connect

The tertiary amine N-methyldiethanolamine and the secondary amine diethanolamine are commonly used in the gas-treating industry as chemical solvents for the removal of acid gases such as CO{sub 2} and H{sub 2}S. The diffusion coefficients for nitrous oxide in aqueous solutions consisting of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) were measured over the temperature range 293--353 K for a total amine concentration of 50 mass % and for the mass ratio of DEA to MDEA varying from 0.0441 to 0.588. The experimental diffusion coefficients were found to be relatively insensitive to the mass ratio of amines.

Rinker, E.B.; Russell, J.W.; Tamimi, A.; Sandall, O.C. [Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical Engineering

1995-05-01

25

Degradation of aqueous methyldiethanolamine by temperature and oxygen cycling  

Microsoft Academic Search

The primary degradation products identified in aqueous 7 molal (m) methyldiethanolamine (MDEA) loaded to 0.1 mol CO2\\/mol alkalinity and degraded in the Integrated Solvent Degradation Apparatus (ISDA) were diethanolamine (DEA), bicine and formate. DEA and bicine represented 43 and 9 % of the carbon loss, respectively, after the solvent was cycled for 167 hours. An MDEA loss of 8.8 mM\\/hr and a formate

Fred Closmann; Gary T. Rochelle

2011-01-01

26

Kinetics and modelling of carbon dioxide absorption into aqueous solutions of N-methyldiethanolamine  

Microsoft Academic Search

A wetted-sphere absorber was used to acquire kinetic data for the aqueous phase reaction between CO2 and N-methyldiethanolamine (MDEA). Data were obtained over the temperature range of 293–342 K for partial pressures of CO2 near atmospheric and for 10–30 mass% MDEA. The data are consistent with a mechanism in which MDEA catalyzes the hydrolysis of CO2. Three different mathematical models

Edward B. Rinker; S. Ashour Sami; Orville C. Sandall

1995-01-01

27

Solubility of CO{sub 2} in aqueous methyldiethanolamine solutions  

SciTech Connect

For 5.0, 20.5, 50.0, and 75.0 mass % methyldiethanolamine (MDEA) aqueous solutions, solubilities of CO{sub 2} were measured at 323.15, 348.15, and 373.15 K, respectively. Isothermal absorption capacities of CO{sub 2} as a function of MDEA concentration are presented. Lastly, the absorption enthalpy of CO{sub 2} in 50.0 mass % MDEA solution was calculated to be 54 kJ/mol CO{sub 2}.

Rho, S.W.; Yoo, K.P. [Sogang Univ., Seoul (Korea, Republic of). Dept. of Chemical Engineering] [Sogang Univ., Seoul (Korea, Republic of). Dept. of Chemical Engineering; Lee, J.S.; Nam, S.C.; Son, J.E.; Min, B.M. [Korea Inst. of Energy Research, Yusong, Taejon (Korea, Republic of). Energy and Environment Research Dept.] [Korea Inst. of Energy Research, Yusong, Taejon (Korea, Republic of). Energy and Environment Research Dept.

1997-11-01

28

Experimental investigation of the phase equilibria in the carbon dioxide-propane-3 M MDEA system  

Microsoft Academic Search

The treating of liquefied petroleum gas (LPG) to remove carbon dioxide and hydrogen sulfide using aqueous alkanolamine solutions is an important aspect of gas processing. One of the amines used in the natural gas industry is methyldiethanolamine (MDEA). Measurements of the phase equilibria in the carbon dioxide-propane-3 M MDEA system have been made at 25 and 40 C at pressures

Fang-Yuan Jou; Alan E. Mather; Frederick D. Otto; John J. Carroll

1995-01-01

29

Viscosity of aqueous solutions of n-methyldiethanolamine and of diethanolamine  

SciTech Connect

Aqueous solutions of alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), di-2-propanolamine (DIPA), and bis[2-(hydroxyamino)ethyl] ether (DGA) are good solvents for the removal of acid gases such as CO[sub 2] and H[sub 2]S from the gas streams of many processes in the natural gas, petroleum, ammonia synthesis, and some chemical industries. The viscosity of aqueous solutions of methyldiethanolamine (MDEA) and of diethanolamine (DEA) have been measured at five temperatures in the range 25--80 C throughout the whole concentration range. The viscosity has been correlated as a function of composition for use in industrial calculations.

Teng, T.T.; Maham, Y.; Hepler, L.G.; Mather, A.E. (Univ. of Alberta, Edmonton, Alberta (Canada))

1994-04-01

30

Modelling of carbon dioxide absorption in aqueous solutions of AMP and MDEA and their blends using Aspenplus  

Microsoft Academic Search

In this paper the results of an experimental investigation on the solubility of CO2 in methyldiethanolamine (MDEA), a tertiary amine, and 2-amino-2-methyl-1-propanol (AMP), a primary sterically hindered amine as well as their mixtures are presented. It is shown that AMP CO2 uptake is higher as compared to that of MDEA. The addition of AMP to MDEA enhances the CO2 loading

M. K. Aroua; M. Z. Haji-Sulaiman; K. Ramasamy

2002-01-01

31

Absorption of CO 2 in the aqueous solutions of functionalized ionic liquids and MDEA  

Microsoft Academic Search

Four ionic liquids (ILs)—tetramethylammonium glycinate (=[Gly]), tetraethylammonium glycinate ([N2222][Gly]), tetramethylammonium lysinate ([N1111][Lys]) and tetraethylammonium lysinate ([N2222][Lys]) were synthesized and mixed with water or N-methyldiethanolamine (MDEA) aqueous solutions to form a new type of solvents for the uptake of CO2. The solubility or absorption of CO2 in these IL+MDEA aqueous solutions was investigated over a wide range of IL concentrations (5–100%),

Zhang Feng; Fang Cheng-Gang; Wu You-Ting; Wang Yuan-Tao; Li Ai-Min; Zhang Zhi-Bing

2010-01-01

32

Modeling CO2 mass transfer in amine mixtures: PZ-AMP and PZ-MDEA.  

PubMed

The most common method of carbon dioxide (CO(2)) capture is the absorption of CO(2) into a falling thin film of an aqueous amine solution. Modeling of mass transfer during CO(2) absorption is an important way to gain insight and understanding about the underlying processes that are occurring. In this work a new software tool has been used to model CO(2) absorption into aqueous piperazine (PZ) and binary mixtures of PZ with 2-amino-2-methyl-1-propanol (AMP) or methyldiethanolamine (MDEA). The tool solves partial differential and simultaneous equations describing diffusion and chemical reaction automatically derived from reactions written using chemical notation. It has been demonstrated that by using reactions that are chemically plausible the mass transfer in binary mixtures can be fully described by combining the chemical reactions and their associated parameters determined for single amines. The observed enhanced mass transfer in binary mixtures can be explained through chemical interactions occurring in the mixture without need to resort to using additional reactions or unusual transport phenomena such as the "shuttle mechanism". PMID:21329341

Puxty, Graeme; Rowland, Robert

2011-03-15

33

Diffusivity of nitrous oxide in aqueous solutions of N-methyldiethanolamine and diethanolamine from 293 to 368 K  

Microsoft Academic Search

The diffusion coefficients for nitrous oxide in aqueous solutions of diethanolamine (DEA) and N-methyldiethanolamine (MDEA) were determined using a wetted-sphere absorber over the temperature range 293--368 K. The ranges of amine concentrations covered in the experiments were 10--30 mass % for DEA and 10--50 mass % for MDEA. The diffusion coefficients indicated a linear dependence on amine concentration, but the

A. Tamimi; E. B. Rinker; O. C. Sandall

1994-01-01

34

Removal process of CO 2 using MDEA aqueous solutions in a bubble column reactor  

Microsoft Academic Search

Present work analyses the behaviour and mass transfer of N-methyldiethanolamine (MDEA) in the removal process of carbon dioxide using a bubble column reactor (BCR) as gas–liquid contactor. The use of this type of equipment requires the interfacial area determination for the following mass transfer coefficient calculation based on absorption kinetics. In this work, a photographic method based on the bubble

José M. Navaza; Diego Gómez-Díaz; M La Rubia

2009-01-01

35

Operating costs cut 60% with amine switch. [Methyldiethanolamine and diethanolamine  

SciTech Connect

At the Waveland, Miss., facility of United Gas Pipe Line Co., a methyldiethanolamine (MDEA) unit was supplemented by a smaller diethanolamine (DEA) unit. With the units running in parallel, product gas specifications could be met. Each unit was treating about one-half the 30 MMscfd flow of sour gas. Natural gas, purchased from nearby producers, comes into the plant containing 40-60 ppm H/sub 2/S and 4.8% CO/sub 2/. Although the absorber of the MDEA unit was adequate to handle the gas flow and remove the H/sub 2/S to specification, the reboiler capacity was not sufficient to meet a 2% CO/sub 2/ specification. MDEA concentration was limited to less than 40% by potential corrosion problems. The DEA unit was more expensive to operate, requiring sweet processed gas as boiler fuel, and consumed twice as much electricity as the MDEA unit. The combined outlet gas from the two units met volume requirements and specifications. But the system presented operational problems. Repeated foaming occurred with the MDEA unit. Daily losses of solvent were as much as 250 gal. By closely monitoring the system, United Gas was able to reduce foaming significantly by minimizing contamination with liquid hydrocarbons which had been entering with the feed gas during line surges. Extra labor was required. Several approaches were investigated involving equipment modifications and new materials. As a result of the study, United Gas concluded that the system could be optimized and all incoming gas treated in one unit by switching solvent. Conventional MDEA was replaced by a specially formulated MDEA based solvent with low foaming tendency (Union Carbide Corp.'s Ucarsol HS Solvent 101). It could be used at a 50% concentration in aqueous solution without apparent corrosion.

Not Available

1984-01-09

36

Effect of heat stable salts on MDEA solution corrosivity: Part 2  

SciTech Connect

A comprehensive coupon corrosion testing program was undertaken to address the effect of various heat stable salts on methyldiethanolamine (MDEA) corrosivity to carbon steel and various stainless steels. Corrosion rates of carbon steel, 304SS, 316SS and 410SS liquid and vapor coupons towards MDEA, and MDEA containing various anions, at 180 F and 250 F, were measured in a reactor. Corrosion results of two refinery plant solutions before and after caustic neutralization were also performed. Based on these results, guidelines were determined for heat stable amine salt (HSAS) levels of oxalates, sulfates, formates, acetates and thiosulfates. In addition, caustic neutralization guidelines for MDEA heat stable salts were determined. Ongoing results include MDEA corrosivity with succinates, and malonates, glycolates, SO{sub 2} and ammonia.

Rooney, P.C.; DuPart, M.S.; Bacon, T.R. [Dow Chemical Co., Freeport, TX (United States)

1997-04-01

37

Selective removal of hydrogen sulphide by MDEA solutions  

SciTech Connect

When compared with primary or secondary amines, tertiary amines possess both ''thermodynamic'' and ''kinetic'' selectivity for removal of H/sub 2/S from mixtures of hydrogen sulphide and carbondioxide. One of these amines, methyl-diethanolamine, is used industrially as an aqueous solution, but the selectivity achieved may be less than that can be calculated by simply taking into account the alkalinity of the solution. Gas absorption experiments in the stirred cell confirmed that CO/sub 2/ reacts in aqueous MDEA solutions where the rate is proportional to the amine concentration. On the other hand, no reaction took place when a nonaqueous solution of MDEA in n-propanol was used. These results confirmed therefore that MDEA acted as a homogeneous catalyst for CO/sub 2/ hydrolysis.

Alper, E.; Al-Ramadhan, A.

1987-01-01

38

Diffusivity of nitrous oxide in aqueous solutions of N-methyldiethanolamine and diethanolamine from 293 to 368 K  

SciTech Connect

The diffusion coefficients for nitrous oxide in aqueous solutions of diethanolamine (DEA) and N-methyldiethanolamine (MDEA) were determined using a wetted-sphere absorber over the temperature range 293--368 K. The ranges of amine concentrations covered in the experiments were 10--30 mass % for DEA and 10--50 mass % for MDEA. The diffusion coefficients indicated a linear dependence on amine concentration, but the temperature dependence was nonlinear. It was found that the diffusivity of N[sub 2]O in aqueous DEA is always less than that in aqueous MDEA under equivalent conditions of amine concentration and temperature.

Tamimi, A.; Rinker, E.B.; Sandall, O.C. (Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical and Nuclear Engineering)

1994-04-01

39

Vapor-liquid equilibria in the system ethanethiol + methyldiethanolamine + water in the presence of acid gases  

SciTech Connect

This investigation was carried out to determine the solubility of ethanethiol in a methyldiethanolamine (MDEA) solution. Measurements were made in the absence of acid gases, H{sub 2}H and CO{sub 2}, with individual acid gases present, and with mixtures of acid gases present. Experiments with an aqueous solution of 50 mass % MDEA were carried out at 40 and 70 C. The total pressure for most of the experiments was 6,890 kPa, which was maintained by methane. Partial pressures of ethanethiol ranged from 0.2 to 15 kPa.

Jou, F.Y.; Mather, A.E. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering] [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering; Schmidt, K.A.G.; Ng, H.J. [DB Robinson Research Ltd., Edmonton, Alberta (Canada)] [DB Robinson Research Ltd., Edmonton, Alberta (Canada)

1999-07-01

40

Selective absorption of H 2S from gas mixtures into aqueous solutions of blended amines of methyldiethanolamine and 2-tertiarybutylamino-2-ethoxyethanol in a packed column  

Microsoft Academic Search

In this work, an experimental investigation for selective absorption of H2S from gas-mixed streams into an aqueous blend of methyldiethanolamine (MDEA) and 2-tertiarybutylamino-2-ethoxyethanol (TBEE) in a packed column at atmospheric pressure and a constant liquid flowrate was performed. TBEE, a severe sterically hindered amine, was added into MDEA to form the blended amines. The effect of H2S loading of lean-solution,

Jian-Gang Lu; You-Fei Zheng; Du-Liang He

2006-01-01

41

Estimation of the CO absorption capacities in aqueous 2-(2-aminoethylamino)ethanol and its blends with MDEA and TEA in the presence of SO  

Microsoft Academic Search

A study of carbon dioxide (CO) and sulfur dioxide (SO)\\/CO mixtures absorption has been carried out in aqueous 2-(2-aminoethylamino)ethanol (AEE) solution and its blends with N-methyldiethanolamine (MDEA) and triethanolamine (TEA) to estimate the influence of SO, MDEA, and TEA on the CO absorption capacity of the AEE. The CO absorption loading has been estimated in 15 wt % AEE alone

D. Bonenfant; M. Minleault; R. Hausler

2007-01-01

42

Experimental investigation of the phase equilibria in the carbon dioxide-propane-3 M MDEA system  

SciTech Connect

The treating of liquefied petroleum gas (LPG) to remove carbon dioxide and hydrogen sulfide using aqueous alkanolamine solutions is an important aspect of gas processing. One of the amines used in the natural gas industry is methyldiethanolamine (MDEA). Measurements of the phase equilibria in the carbon dioxide-propane-3 M MDEA system have been made at 25 and 40 C at pressures up to 15.5 MPa. Vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria were determined. The vapor-liquid equilibrium data were compared with the model of Deshmukh and Mather.

Jou, F.Y.; Mather, A.E.; Otto, F.D.; Carroll, J.J. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical Engineering

1995-07-01

43

Viscosity, density, and surface tension of binary mixtures of water and N-methyldiethanolamine and water and diethanolamine and tertiary mixtures of these amines with water over the temperature range 20--100[degree]C  

SciTech Connect

Aqueous solutions of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) are widely used in the industrial treatment of acid gas streams containing H[sub 2]S and CO[sub 2]. The density and viscosity of aqueous solutions of N-methyldiethanolamine were measured over the temperature range 60--100 C. The density and viscosity of aqueous solutions of diethanolamine and diethanolamine + N-methyldiethanolamine were measured over the temperature range 20--100 C. The surface tension of aqueous solutions of the above mixtures was measured over the temperature range 20--80 C. The concentration ranges were 10--50 mass % N-methyldiethanolamine, 10--30 mass % diethanolamine, and 50 mass % total amine concentration with mass ratios of 0.0441--0.5883 (diethanolamine to N-methyldiethanolamine). The measured quantities were found to be in agreement with the literature where data were available.

Rinker, E.B.; Oelschlager, D.W.; Colussi, A.T.; Henry, K.R.; Sandall, O.C. (Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical and Nuclear Engineering)

1994-04-01

44

Simultaneous absorption of H2S and Co2 into aqueous methyldiethanolamine  

SciTech Connect

The tertiary amine methyldiethanolamine (MDEA) is finding increasing application as a chemical solvent for selective absorption of hydrogen sulfide from gases containing hydrogen sulfide and carbon dioxide. Gas streams of this type include some natural gases, synthetic gases from coal and heavy oil gasification and tail gases from sulfur plants. Selectivity for H2S is needed either to enrich Claus sulfur plant feed in H2S or to remove only H2S when CO2 removal is not necessary of economic. For the absorption of hydrogen sulfide into MDEA, the reaction which occurs can be considered to be instantaneous while carbon dioxide undergoes a second-order reaction with MDEA. In this work, the simultaneous absorption of two gases into a liquid containing a reactant with which both gases react is modelled using the film theory. Physical properties and kinetic rate parameters used in the model have been measured in the laboratory. The model is used to study the effect of process variables on the selectivity of MDEA for H2S over CO2. The simultaneous absorption of H2S and CO2 gases into aqueous MDEA is studied experimentally using a continuous stirred tank absorber. Experimental absorption rates are compared to predictions based on a multicomponent mass transfer model. The average deviations of the theoretical calculations from the experimental results are 10.2% and 12.9% for CO2 and H2S, respectively.

Haimour, N.; Bidarian, A.; Sandall, O.C.

1987-01-01

45

Kinetics of carbon dioxide absorption into mixed aqueous solutions of MDEA and MEA using a laminar jet apparatus and a numerically solved 2D absorption rate\\/kinetics model  

Microsoft Academic Search

New comprehensive numerically solved 1D and 2D absorption rate\\/kinetics models have been developed, for the first time, to interpret the experimental kinetic data obtained with a laminar jet apparatus for the absorption of carbon dioxide (CO2) in CO2 loaded mixed solutions of mixed amine system of methyldiethanolamine (MDEA) and monoethanolamine (MEA). Three MDEA\\/MEA weight ratios ranging from 27\\/03 to 23\\/07,

Mohamed Edali; Ahmed Aboudheir; Raphael Idem

2009-01-01

46

Gas plant converts amine unit to MDEA-based solvent  

SciTech Connect

This paper reports that methyldiethanolamine (MDEA) has successfully replaced monoethanolamine (MEA) solvent at one of Canada's largest gas processing plants. This acid gas treating solvent lowered costs associated with pumping horsepower, reboiler duty, solvent losses, corrosion and other gas processing problems. Not all operating conditions at a gas processing plant favor MDEA or MEA. In the Rimbey plant, originally designed to process sour gas, more sweet gas feed (per volume) called for considering advantages of the lesser-used MDEA. Gulf Canada Resources operates several major sour gas plants in Alberta. The Rimbey Plant was designed in 1960 to process 400 MMscfd of sour gas with 2% H[sub 2]S and 1.32% CO[sub 2]. The amine unit was designed to circulate 2,400 gpm of 20 wt% MEA solution. The single train amine plant has four gas conductors and two amine regenerators. The present raw inlet gas flowrate to the Rimbey Plant is about 312 MMscfd which is made up of three sources: 66 MMscfd of sour gas with 1.5% H[sub 2]S and 1.8% CO[sub 2]; 65 MMscfd of high CO[sub 2] gas with 400 ppmv H[sub 2]S and 3.9% CO[sub 2]; and 181 MMscfd of sweet gas with 2.2% CO[sub 2].

Mak, H.Y. (Gulf Canada Resources Ltd., Calgary, AB (Canada))

1992-10-01

47

A thermodynamic model of methyldiethanolamine-CO{sub 2}-H{sub 2}S-water  

SciTech Connect

Methyldiethanolamine (MDEA) is one of the favored alkanolamines in acid gas treating. It is receiving increased use due to its lower heat of reaction and lower corrosivity compared to the other amines. The electrolyte-nonrandom two-liquid model has been used to represent the thermodynamic behavior of the system: methyldiethanolamine-CO{sub 2}-H{sub 2}S-water. The Data Regression System (DRS) of Aspen Plus was used to regress parameters of the model to experimental data. pH and conductivity data were utilized to supplement vapor-liquid equilibria (VLE) data and improve confidence in model predictions at low acid gas loadings. Predictions for the mixed acid gas systems can be accurately made from the single acid gas parameter sets without the need to regress additional parameters. VLE data were fit well and the calculated heat absorption matches calorimetric data.

Posey, M.L.; Rochelle, G.T. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering] [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

1997-09-01

48

Densities and viscosities of solutions of monoethanolamine + N-Methyldiethanolamine + water and monoethanolamine + 2-amino-2-methyl-1-propanol + water  

SciTech Connect

The densities and viscosities of aqueous mixtures of monoethanolamine (MEA) with N-methyldiethanolamine (MDEA) and MEA with 2-amino-2-methyl-1-propanol (AMP) have been studied at temperatures from 30 to 80 C. For density measurements, four MEA + MDEA (a total of 20 mass %) + H[sub 2]O mixtures and eight MEA + AMP (20 and 30 mass %) + H[sub 2]O mixtures were studied. For viscosity measurements, ten MEA + MDEA + H[sub 2]O mixtures and eight MEA + AMP + H[sub 2]O mixtures were measured. A Redlich-Kister equation of the excess volume was applied to represent the density of the liquid mixtures. The equation of Grunberg and Nissan of liquid viscosity was used to correlate the viscosity data. Both density and viscosity calculations show satisfactory results.

Li, M.H.; Lie, Y.C. (Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering)

1994-07-01

49

Absorption of H{sub 2}S by an aqueous methyldiethanolamine solution at 296 and 343 K  

SciTech Connect

An apparatus developed to measure absorption kinetics of acid gases by amine solutions is described as well as the experimental procedures dealing with either the initial kinetics or kinetics for loaded solutions. Data obtained for H{sub 2}S absorption into a 50 mass % methyldiethanolamine (MDEA) aqueous solution with various initial H{sub 2}S loadings are reported for the following conditions: H{sub 2}S loadings from 0 to 0.44 mol H{sub 2}S per mol MDEA and two temperatures, 296 and 343 K. The H{sub 2}S experimental absorption rates have been used together with a model, based on mass transfer and involving an instantaneous reversible reaction, to determine the MDEA diffusion coefficient.

Pani, F.; Gaunand, A.; Richon, D.; Cadours, R.; Bouallou, C. [Ecole Nationale Superieure des Mines de Paris (France). Centre de Recherche in Procedes de Transformation de la Matiere] [Ecole Nationale Superieure des Mines de Paris (France). Centre de Recherche in Procedes de Transformation de la Matiere

1997-09-01

50

Vapor-liquid equilibrium of carbon dioxide in aqueous mixtures of monoethanolamine and methyldiethanolamine  

SciTech Connect

Aqueous solutions of alkanolamines are used to separate carbon dioxide and hydrogen sulfide from gas streams. Data for the distribution of carbon dioxide between the vapor and aqueous solutions of four mixtures of monoethanolamine (MEA) and methyldiethanolamine (MDEA) have been obtained at 25, 40, 80 and 120 C over a range of pressures from 100 kPa to 20 MPa. Partial pressures of CO[sub 2] ranged from 0.001 to 19,930 kPa. Enthalpies of reaction of CO[sub 2] in the solutions have been calculated from the solubility data.

Jou, F.Y.; Otto, F.D.; Mather, A.E. (Univ. of Alberta, Edmonton (Canada). Dept. of Chemical Engineering)

1994-08-01

51

Solubility of H/sub 2/S and CO/sub 2/ in aqueous methyldiethanolamine solutions  

SciTech Connect

The University of Alberta measured the solubilities of H/sub 2/S and CO/sub 2/ in 1.0, 2.0, and 4.28 kmol/m/sup 3/ aqueous solutions of methyldiethanolamine (MDEA) for temperature and acid-gas partial pressures ranging from 100/sup 0/ to 250/sup 0/F and 0.001 to 8600 kPa, respectively, used the procedure presented by Kent and Eisenberg to correlate the solubility data, and, calculated enthalpies of solution from the experimental results. Aqueous solutions of MDEA are attractive solvents for the selective removal of H/sub 2/S from process streams containing CO/sub 2/ and hydrocarbons.

Jou, F.Y.; Mather, A.E.; Otto, F.D.

1982-10-01

52

Diffusion coefficients significant in modeling the absorption rate of carbon dioxide into aqueous blends of N-methyldiethanolamine and diethanolamine and of hydrogen sulfide into aqueous N-methyldiethanolamine  

SciTech Connect

Absorption rates of gaseous CO{sub 2} into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H{sub 2}S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO{sub 2} and H{sub 2}S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} for the case of CO{sub 2} absorption and of bisulfide ion for the case of H{sub 2}S absorption from measured absorption rates. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1L3, and 2:3. H{sub 2}S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.

Adams, M.E.; Marshall, T.L.; Rowley, R.L. [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering] [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering

1998-07-01

53

Measurement of diffusion coefficients important in modeling the absorption rate of carbon dioxide into aqueous N-methyldiethanolamine  

SciTech Connect

Natural gas processors use amine treating processes to remove the acid gases H{sub 2}S and CO{sub 2} from gas streams. Absorption rates of gaseous CO{sub 2} into aqueous N-methyldiethanolamine (MDEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate and protonated MDEA ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. A numerical model was developed on the basis of these observations. The model was used to regress diffusion coefficients of bicarbonate and protonated amine, which must be equivalent by electroneutrality arguments, from measured absorption rates. Complete modeling of the absorption process also required data for the diffusion coefficient of MDEA in water. These were measured using a Taylor dispersion apparatus. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate and protonated MDEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % MDEA in water.

Rowley, R.L.; Adams, M.E.; Marshall, T.L.; Oscarson, J.L.; Wilding, W.V.; Anderson, D.J. [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering] [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering

1997-03-01

54

Design and operation of a selective sweetening plant using MDEA  

SciTech Connect

The Signalta Resources Forestburg Gas Plant was constructed during the winter of 1983 and placed on stream in April of 1984. A design outlet gas specification of 1/4 grain H/sub 2/S/100 scf was requested to ensure meeting the contract commitment of 1 grain/100 scf. The design gas flowrate was 30 MMSCFD containing 0.5% H/sub 2/S and 3% CO/sub 2/ at 415 psia and 70/sup 0/F. The overall plant is configured as shown in Figure 1. Inlet separation facilities are followed by a feed gas heater. The gas stream then flows through a filter separator followed by the amine contactor. Another filter separator is used as a sweet gas scrubber. After sweetening, the gas is routed to a dew point control refrigeration unit. Finally, a single stage of compression is required to boost the gas to 1200 psig maximum pipeline pressure. The sweetening chemical selected for the Forestburg Plant was methyldiethanolamine (MDEA). This was chosen due to its capability to remove H/sub 2/S and leave a portion of the CO/sub 2/ in the residue gas. At the time of plant commissioning it was one of the first operating MDEA facilities in Western Canada.

MacKenzie, D.H.; Chiraka-Parambil, F.; Daniels, C.A.; Bullin, J.A.

1986-01-01

55

Statistical factorial design analysis for parametric interaction and empirical correlations of CO 2 absorption performance in MEA and blended MEA\\/MDEA processes  

Microsoft Academic Search

A principle of statistical factorial design was applied to characterize behaviour of mass-transfer performance in the carbon dioxide (CO2) absorption process using monoethanolamine (MEA) and blended MEA\\/methyldiethanolamine (MDEA) solutions. Over a hundred experiments were carried out using a bench-scale absorber packed with structured packing. The absorption performance was analyzed in terms of overall mass-transfer coefficient (KGae). The results show that

Anothai Setameteekul; Adisorn Aroonwilas; Amornvadee Veawab

2008-01-01

56

Removal of carbon dioxide by absorption in mixed amines: modelling of absorption in aqueous MDEA\\/MEA and AMP\\/MEA solutions  

Microsoft Academic Search

This work presents an investigation of CO2 absorption into aqueous blends of methyldiethanolamine (MDEA) and monoethanolamine (MEA), as well as 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA). The combined mass transfer–reaction kinetics–equilibrium model to describe CO2 absorption into the amine blends has been developed according to Higbie's penetration theory following the work of Hagewiesche et al. (Chem. Eng. Sci. 50 (1995) 1071).

B. P. Mandal; M. Guha; A. K. Biswas; S. S. Bandyopadhyay

2001-01-01

57

Kinetics of the Absorption of CO{sub 2} in Aqueous Solutions of N-Methyldiethanolamine plus Triethylene Tetramine  

SciTech Connect

This work focuses on the development of a new solvent for CO{sub 2} capture. This new solvent is an aqueous solution with a blend of N-methyldiethanolamine (MDEA) and triethylene tetramine (TETA), an amine with four amino groups. CO{sub 2} absorption was investigated between 298 and 333 K using a Lewis cell with a constant interfacial area. Several concentrations of MDEA (17.5 and 40 wt %) and TETA (3 and 6 wt %) were assessed. The influence of the CO{sub 2} partial pressure on the absorption rate was pointed out. The addition of small amount of TETA leads to a high increase in the CO{sub 2} absorption rates. A numerical model based on the film theory was used to determine the rate coefficients between CO{sub 2} and TETA for the different solvents. The physicochemical parameters have a huge influence on the determination of the rate coefficients.

Amann, J.M.G.; Bouallou, C. [Centre Energetique et Procedes CEP, Paris (France)

2009-04-15

58

Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range 313--413 K at pressures up to 5 MPa  

SciTech Connect

Experimental results for the solubility of the single gases carbon dioxide and hydrogen sulfide in aqueous solutions of 2,2{prime}-methyliminodiethanol (N-methyldiethanolamine (MDEA)) at temperatures between 313 and 413 K and total pressures up to 5 MPa are reported. A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also used to compare the new experimental data with literature data.

Kuranov, G.; Smirnova, N.A. [St. Petersburg State Univ. (Russian Federation). Dept. of Chemistry] [St. Petersburg State Univ. (Russian Federation). Dept. of Chemistry; Rumpf, B.; Maurer, G. [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik] [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik

1996-06-01

59

Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range 313--413 K at pressures up to 5 MPa  

Microsoft Academic Search

Experimental results for the solubility of the single gases carbon dioxide and hydrogen sulfide in aqueous solutions of 2,2â²-methyliminodiethanol (N-methyldiethanolamine (MDEA)) at temperatures between 313 and 413 K and total pressures up to 5 MPa are reported. A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also

George Kuranov; N. A. Smirnova; B. Rumpf; Gerd Maurer

1996-01-01

60

Switch to MDEA raises capacity  

SciTech Connect

Canada's first plant conversion from DEA to MDEA is a success. Dome's North Caroline amine plant performs very smoothly after being debottlenecked to, at least, original design capacity. Performance data taken for the absorber at several amine flow rates compare with safe accuracy to values calculated by the TSWEET program that was used as the basis for conversion.

Daviet, G.R.; Bullin, J.A.; Donnelly, S.T.; Sundermann, R.

1984-05-01

61

Solubility and diffusivity of nitrous oxide in ternary mixtures of water, monoethanolamine, and N-methyldiethanolamine and solution densities and viscosities  

SciTech Connect

Recently, several researchers have suggested using aqueous mixtures of small amounts of monoethanolamine and much larger amounts of N-methyldiethanolamine for the absorption of CO{sub 2} and for the selective removal of H{sub 2}S from gas streams of mixtures of CO{sub 2} and H{sub 2}S. The densities and viscosities of aqueous N-methyldiethanolamine/monoethanolamine (MDEA/MEA) blends containing 30 and 40 mass % total amine with MEA concentrations of 5, 10, and 15 mass % of the total amine concentration were measured at temperatures of 303, 313, and 323 K. The diffusion coefficients and Henry`s law constants of N{sub 2}O in these solutions were also measured and were used to estimate the diffusion coefficients and Henry`s law constants of CO{sub 2} in these solutions according to the N{sub 2}O/CO{sub 2} analogy technique.

Hagewiesche, D.P.; Ashour, S.S.; Sandall, O.C. [Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical and Nuclear Engineering

1995-05-01

62

Correlation and prediction of the solubility of CO{sub 2} and H{sub 2}S in aqueous solution of methyldiethanolamine  

SciTech Connect

Aqueous alkanolamine solutions are frequently used for the removal of acidic gases, such as CO{sub 2} and H{sub 2}S, from industrial and natural gases. The simplified Clegg-Pitzer equations are used to correlate the solubility data for CO{sub 2} and H{sub 2}S over a wide range of solvent concentrations (12--50 wt % methyldiethanolamine (MDEA) aqueous solutions), temperature (25--120 C), partial pressure of acid gases (0.001--5,290 kPa), and acid gas loading (001--1.0 mol/mol) from different authors. The interaction parameters thus obtained can be used to predict the solubility data for the mixed acid gases in CO{sub 2}-H{sub 2}S-MDEA-H{sub 2}O systems without any additional adjustable parameters.

Li, Y.; Mather, A.E. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering] [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering

1997-07-01

63

Simulation of gas absorption with chemical reaction: The selective removal of hydrogen sulfide by aqueous methyldiethanolamine in packed columns  

SciTech Connect

The design of separation devices, particularly for solvent-based selective removal of H{sub 2}S from CO{sub 2}, requires an accurate mathematical model. Unfortunately, this requirement for high accuracy is often in conflict with the need for efficient computation. The addition of more and more complicated analyses, such as a move from Henry's law to a method incorporating gas and liquid activities for computing vapor liquid equilibria, may give a more accurate solution, but only at the cost of decreased computational efficiency. The efforts in this work have been directed toward two goals. The first was to develop an accurate mathematical model for the aqueous methyldiethanolamine (MDEA) system. The steady-state packed column model developed in this work has been tested with data from Schubert (1988) to verify its accuracy. The second goal was to modify the model to improve its computational efficiency. Areas such as vapor-liquid equilibrium calculations, flow hydrodynamics, and thermal effects were examined to determine what simplifications could be made, and how these simplifications affected both the accuracy and the efficiency of the model. The result of this effort is a mathematical model for multicomponent chemical absorption in a continuous contactor that balances computation efficiency with rigorous physical and chemical treatment. This model is useful not only for the analysis of the MDEA-H{sub 2}S-CO{sub 2} system, but the same framework also could be applied to other chemical absorption systems.

Lindner, J.R.

1988-01-01

64

Kinetics of CO{sub 2} desorption from highly concentrated and CO{sub 2}-loaded methyldiethanolamine aqueous solutions in the range 312--383 K  

SciTech Connect

Absorption by aqueous alkanolamine solutions is the dominant industrial process for acid gases removal, in particular CO{sub 2} and H{sub 2}S, from natural gas. Kinetics of CO{sub 2} desorption from CO{sub 2}-loaded methyldiethanolamine (MDEA) aqueous solutions were measured in the following conditions: 312--383 K, 25--50 wt% MDEA aqueous solutions, CO{sub 2} loadings from 5 to 85%. A thermoregulated constant interfacial area reaction cell was operated by measuring the pressure over the solution. Producing a very slight depression in the cell, the time-dependent equilibrium pressure recovery is accurately recorded during batch desorption. Kinetics are in agreement with a fast reaction regime of desorption according to the film theory. For CO{sub 2} loadings below 0.50 mol of gas/mol of amine, desorption rates are well predicted by using the kinetic constant and orders determined from absorption experiments for the reaction between CO{sub 2} and MDEA. Some discrepancies were pointed out for loadings above 0.50 mol of gas/mol of amine.

Cadours, R.; Bouallou, C.; Gaunand, A. [Ecole National Superieure des Mines de Paris (France). Centre de Recherche en Procedes de Transformation de la Matiere] [Ecole National Superieure des Mines de Paris (France). Centre de Recherche en Procedes de Transformation de la Matiere; Richon, D. [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France). Lab. de Thermodynamique des Equilibres entre Phases] [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France). Lab. de Thermodynamique des Equilibres entre Phases

1997-12-01

65

Solubility of carbon dioxide in aqueous solutions of 2-amino-2-methyl-1-propanol and N-methyldiethanolamine and their mixtures in the temperature range of 313 to 353 K and pressures up to 2.7 MPa  

SciTech Connect

The solubility of carbon dioxide in aqueous solutions containing 2-amino-2-methyl-1-propanol (AMP) was measured in the temperature range from 313 to 353 K at total pressures up to 2.7 MPa using an analytical method. A model taking into account chemical reactions in the liquid phase as well as physical interactions is used to correlate the new data. To test the predictive capability of the model, the solubility of carbon dioxide in an aqueous solution containing AMP and N-methyldiethanolamine (MDEA) was measured at 313 K. Experimental results are reported and compared to literature data and calculations.

Silkenbaeumer, D.; Lichtenthaler, R.N. [Univ. Heidelberg (Germany); Rumpf, B. [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik

1998-08-01

66

EXPERIMENTAL MEASUREMENTS OF FOAMING TENDENCIES IN AQUEOUS GAS SWEETENING SOLUTIONS CONTAINING MDEA OVER A TEMPERATURE RANGE OF 297–358 K AND A PRESSURE RANGE OF 101–500 KPA  

Microsoft Academic Search

This work presents experimental measurements of foaming tendencies and break times for 50 wt% aqueous solutions of MDEA in contact with nitrogen, methane, and ethane gases from atmospheric pressure to 500 kPa and temperatures from 297 to 358 K. The effect of various contaminants including methanol, HEP (1,4- bis-2-hydroxyethyl piperazine), hexane, and carboxylic acids ranging from formic to dodecanoic acid was investigated. Only

G. Yanicki; M. A. Trebble

2006-01-01

67

Lethal monointoxication by overdosage of MDEA  

Microsoft Academic Search

A 19-year-old man died after the intake of ten tablets of Ecstasy containing 3,4-methylenedioxy-N-ethylamphetamine (MDEA) as the main active ingredient. According to an eyewitness the symptoms of intoxication were strong sweating, sudden aggressiveness followed by hallucinations, subsequent failure of motoric coordination, severe spasms of arms and back, complete depression of the respiratory system, unconsciousness, and collapse. Resuscitation by an emergency

Wolfgang Weinmann; Michael Bohnert

1998-01-01

68

Experimental studies of selective acid gas removal: Absorption of hydrogen sulfide and carbon dioxide into aqueous methyldiethanolamine using packed columns  

SciTech Connect

The use of aqueous methyldiethanolamine (MDEA) for selective removal of hydrogen sulfide from acid gas streams has been studied in a 2 inch column packed with 1/4 inch ceramic Intalox saddles. The column was operated in a counter-current, steady state fashion. The feed gas composition varied between 1 and 5 mole % hydrogen sulfide and between 0 and 50 mole % carbon dioxide. In order to assist the development of packed column absorption models, the rate at which pure carbon dioxide absorbs into 2 M MDEA was measured as a function of pressure, liquid flow rate and packed bed length. The importance of end effects was carefully evaluated. In addition, draining and tracer methods were used to estimate the amount of static holdup present in the column. Using classical draining methods, as much as 50 % of the total holdup was found to be static. However, according to the step decrease in tracer method, less than 5 % of the total holdup was static. Since the step decrease in tracer method measures the amount of static holdup present in the bed under irrigated conditions, it seems likely that the draining method provides an unrealistic estimate of static holdup. Thus, although the notion of static holdup may be useful as a means of correlating mass transfer coefficients, the data indicate that very little static holdup exists in the column under irrigated conditions. Hence, in the absence of a mechanistically sound model, the choice of whether to use static holdup or dispersion as a means of accounting for deviations from plug flow in the liquid phase should be made on the basis of computational convenience.

Schubert, C.N.

1988-01-01

69

Operating data from a commercial MDEA gas treater  

Microsoft Academic Search

Methyl diethanolamine (MDEA) is a tertiary amine that has the capability to selectively remove HâS from natural gas while leaving the bulk of the COâ present in the residue gas stream. Known areas of application for MDEA plants include the enrichment of sulfur plant feed, recovery of HâS from sulfur plant tail gas, and treating of natural gas for selective

H. L. Ammons; D. M. Sitton

1981-01-01

70

CO/sub 2/ absorption into aqueous MDEA and MDEA/MEA solutions  

SciTech Connect

The rate of absorption of CO/sub 2/ into 2 molal MDEA was measured by following solution composition in a stirred-cell batch reactor. The conditions investigated were 9.5 - 62/sup 0/C at a nominal CO/sub 2/ pressure of 1 atm. The data were modelled with a combined mass transfer and equilibrium model which treated the reaction of CO/sub 2/ with MDEA as second order and reversible, rather than pseudo-first order. The resulting activation energy was 13.7 kcal/gmol, and the rate constant at 30.5/sup 0/C was 4.0 (Ms)/sup -1/. The assumption of pseudo-first order conditions was found to reduce the apparent activation energy to approximately 9 kcal/gmol. CO/sub 2/ absorption into 1.36 molal MDEA/0.61 molal MEA was studied at 31/sup 0/C. The experimental data were predicted better by a mass transfer model based on a shuttle mechanism than by one with two parallel reactions.

Critchfield, J.; Rochelle, G.T.

1987-01-01

71

Selective removal of hydrogen sulphide by MDEA solutions  

Microsoft Academic Search

When compared with primary or secondary amines, tertiary amines possess both ''thermodynamic'' and ''kinetic'' selectivity for removal of HâS from mixtures of hydrogen sulphide and carbondioxide. One of these amines, methyl-diethanolamine, is used industrially as an aqueous solution, but the selectivity achieved may be less than that can be calculated by simply taking into account the alkalinity of the solution.

E. Alper; A. Al-Ramadhan

1987-01-01

72

SAM-modified microdisc electrode arrays (MDEAs) with functionalized carbon nanotubes  

Microsoft Academic Search

The construction of a novel voltammetric transducer employing mixed acid-chopped, oxidatively modified, single-walled carbon nanotubes (HOOC–SWNT–COOH) covalently coupled to alkane thiol self-assembled monolayers (SAMs) that were deposited onto gold microdisc electrode arrays (MDEA-Au) (1296 microdiscs, 100?m diameter each) has been demonstrated. The chemisorption of cysteamine (CA) and 11-amino-1-undecanethiol (11-AUT) SAMs onto the MDEAs resulted in MDEA-Au|CA and MDEA-Au|11-AUT, which when

Anthony Guiseppi-Elie; Abdur Rub Abdur Rahman; Nikhil K. Shukla

2010-01-01

73

Design considerations in the development and application of microdisc electrode arrays (MDEAs) for implantable biosensors.  

PubMed

The use of microlithographically fabricated Microdisc Electrode Arrays (MDEAs) in the development of implantable voltammetric biosensors necessitates design criteria that balances the overall footprint of the device with the advantages to be derived from large separation distances between non-interacting microdisc elements. Using the dynamic electroanalytical techniques of Multiple Scan Rate Cyclic Voltammetry (MSRCV) experiments with finite element simulations and Electrochemical Impedance Spectroscopy with equivalent circuit modeling, three unique MDEA designs; MDEA 050 (r = 25 microm, 5,184 discs), MDEA 100 (r = 50 microm, 1,296 discs) and MDEA 250 (r = 125 microm, 207 discs) of constant critical dimensions (center-to-center d/r = 4) and area (A = 0.1 cm(2)) were studied in 1.0 mM ferrocene monocarboxylic acid (FcCO(2)H) solution (in 0.1 M Tris/0.1 M KCl buffer, pH = 7.2). The critical disc-to-disc spacing (d/r) required to archive 67% of maximal current response was defined as optimal. Based on the predictive model, new MDEA designs; MDEA 001 (r = 0.5 microm, 127,324 discs), MDEA 002.5 (r = 1.25 microm, 20,372 discs), MDEA 005 (r = 2.5 microm, 5,093 discs), MDEA 010 (r = 5 microm, 1,273 discs), MDEA 015 (r = 7.5 microm, 566 discs), MDEA 020 (r = 10 microm, 318 discs) were simulated at 10 and 100 mV/s. The final disc count of each MDEA was dictated by the need to maintain a comparable electroactive area between the MDEAs, which was chosen to be 0.001 cm(2), which in turn was dictated by the need to generate sufficient electrochemical current to be comfortably measured by common electrochemical detectors. PMID:19165603

Rahman, Abdur Rub Abdur; Guiseppi-Elie, Anthony

2009-06-01

74

Fatal poisoning by MDMA (ecstasy) and MDEA: A case report  

Microsoft Academic Search

The first observation of lethal recreational use of MDMA (ecstasy) and MDEA in Italy is reported, together with extensive toxicological and histopathological documentation. Findings such as disseminated intravascular coagulation, rarely reported before, are colocated in the framework of the toxic syndrome for a better definition of criteria for forensic diagnosis.

Vittorio Fineschi; Alessandra Masti

1996-01-01

75

Novel Chromosomally Encoded Multidrug Efflux Transporter MdeA in Staphylococcus aureus  

Microsoft Academic Search

Antibiotic efflux is an important mechanism of resistance in pathogenic bacteria. Here we describe the identification and characterization of a novel chromosomally encoded multidrug resistance efflux protein in Staphylococcus aureus, MdeA (multidrug efflux A). MdeA was identified from screening an S. aureus open reading frame expression library for resistance to antibiotic compounds. When overexpressed, MdeA confers resistance on S. aureus

Jianzhong Huang; Paul W. O'Toole; Wei Shen; Heather Amrine-Madsen; Xinhe Jiang; Neethan Lobo; Leslie M. Palmer; LeRoy Voelker; Frank Fan; Michael N. Gwynn; Damien McDevitt

2004-01-01

76

Towards an implantable biochip for glucose and lactate monitoring using microdisc electrode arrays (MDEAs)  

Microsoft Academic Search

A complete electrochemical cell-on-a-chip that uses the MicroDisc Electrode Array (MDEA) working electrode (WE) design was\\u000a evaluated for eventual intramuscular implantation for the continuous amperometric monitoring of glucose and lactate in an\\u000a animal trauma model. The microfabricated ECC MDEA5037 comprises two discrete electrochemical cells-on-a-chip (ECCs), each\\u000a with a reference, counter, and MDEA working electrode. Each MDEA comprises 37 microdiscs (diameter?=?50 µm)

Abdur Rub Abdur Rahman; Gusphyl Justin; Anthony Guiseppi-Elie

2009-01-01

77

Operating data from a commercial MDEA gas treater  

SciTech Connect

Methyl diethanolamine (MDEA) is a tertiary amine that has the capability to selectively remove H/sub 2/S from natural gas while leaving the bulk of the CO/sub 2/ present in the residue gas stream. Known areas of application for MDEA plants include the enrichment of sulfur plant feed, recovery of H/sub 2/S from sulfur plant tail gas, and treating of natural gas for selective removal of H/sub 2/S. Goar and others have discussed the benefits associated with sulfur plant feed enrichment. This paper discusses the results taken from an operating MDEA gas treater that was designed to slip 50-60 percent of the CO/sub 2/ in the inlet feed to residue and still meet the specification of 1 grain/1-0 SCF H/sub 2/S. It is demonstrated that the H/sub 2/S in the residue gas did not change at any circulation rate until the stripping rate on the stripper dropped sufficiently low. CO/sub 2/ slippage decreased as the circulation rate increased. H/sub 2/S removal to less than 1 ppm in the residue gas is maintained at amine temperatures as high as 145/degree/F. CO/sub 2/ slippage decreased as amine temperature increased. 3 refs.

Ammons, H.L.; Sitton, D.M.

1981-01-01

78

21 CFR 520.2380f - Thiabendazole, piperazine phosphate powder.  

Code of Federal Regulations, 2013 CFR

... Thiabendazole, piperazine phosphate powder. 520.2380f Section 520.2380f... Thiabendazole, piperazine phosphate powder. (a) Specifications. Each ounce of water dispersible powder contains 6.67 grams of...

2013-04-01

79

Adam (MDMA) and Eve (MDEA) misuse: an immunohistochemical study on three fatal cases  

Microsoft Academic Search

Three fatal cases of MDMA\\/MDEA misuse have been examined. These referred to white males between 19 and 20 years of age, in which post-mortem toxicology showed the presence of MDMA (in one case), MDEA (in one case) and both (in one case). The clinical data were analysed and the histopathological findings were studied following immunohistochemical investigations. A complete immunohistochemical study

Vittorio Fineschi; Fabio Centini; Elena Mazzeo; Emanuela Turillazzi

1999-01-01

80

Simulation values prove out in DEA to MDEA switch  

SciTech Connect

After Dome's North Carolina plant was built in 1980, several new wells were completed and brought onstream. The new wells increased the CO/sub 2/ concentration in the feed to about 3.5%. The amine unit could not accomodate this large increase of CO/sub 2/. Since the amine unit could not tolerate any additional H/sub 2/S, the H/sub 2/S peak from the well caused the sales gas to exceed pipeline specifications and be automatically flared. Dome decided to debottleneck the plant to its original value and stabilize plant operation by converting the amine unit from DEA to MDEA.

Daviet, G.R.; Bullin, J.A.; Donnelly, S.T.; Sundermann, R.

1984-08-06

81

Reduced graphene oxide supported piperazine in aminocatalysis.  

PubMed

Reduced graphene oxide (rGO) has been used as a support for piperazine to provide a heterogeneous bifunctional organocatalyst (rGO-NH) that is able to efficiently promote vintage organic transformations such as Knoevenagel, Michael and aldol reactions. The obtained results suggest a significant role of the support in the course of these reactions. PMID:24796296

Rodrigo, Eduardo; García Alcubilla, Beatriz; Sainz, Raquel; Fierro, J L García; Ferritto, Rafael; Cid, M Belén

2014-06-14

82

Thermodynamics of protonation of amines in aqueous solutions at elevated temperatures  

Microsoft Academic Search

The dissociation constants, pKa, of monoethanolamine (MEA), N-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), 2(2-aminoethyl)etanolamine (AEEA), and piperazine (Pz) were measured by potentiometric titration over the temperature range (298.15 to 363.15)K. Enthalpies of protonation, ?Hp, were measured calorimetrically at temperatures from (298.15 to 393.15)K for MEA, MDEA, and AMP, and from (298.15 to 353.15)K for AEEA and Pz. In addition, the effect of

Inna Kim; Christian M. Jens; Andreas Grimstvedt; Hallvard F. Svendsen

2011-01-01

83

Converting to DEA/MDEA mix ups sweetening capacity  

SciTech Connect

Mixing amines can be the best method for increasing capacity or improving efficiency in an amine sweetening unit. In many cases, it may be possible simply to add a second amine to the existing solution on the fly, or as the unit is running. Union Pacific Resources` Bryan, Tex., gas plant provides one example. The plant was converted from diethanolamine (DEA) to a DEA/MDEA (methyl DEA) mixture after analysis by TSWEET, a process-simulation program. After conversion, CO{sub 2} levels in the sales gas fell to less than pipeline specifications. Data were taken for the absorber at a constant amine circulation of 120 gpm. A comparison of the performance data to the values calculated by the program proved the accuracy of TSWEET. The conversion and performance of the plant are described.

Spears, M.L. [Union Pacific Resources, Bryan, TX (United States); Hagan, K.M. [Union Pacific Resources, Ft. Worth, TX (United States); Bullin, J.A.; Michalik, C.J. [Bryan Research and Engineering, Bryan, TX (United States)

1996-08-12

84

Serotonergic Deficits and Impaired Passive-Avoidance Learning in Rats by MDEA  

Microsoft Academic Search

The serotonergic deficits induced by 3,4-methylenedioxyethamphetamine (MDEA, “eve”), were examined and compared with 3,4 methylenedioxymethamphetamine (MDMA, “ecstasy”). A single dose of MDEA (10, 20, or 40 mg\\/kg IP) induced a dose-related hyperthermia, but only the highest dose significantly reduced 5-HT content and 5-HT transporter density in the frontal cortex and in the hippocampus 7 days later. Long-term serotonergic deficits were

Meritxell Barrionuevo; Norberto Aguirre; Joaqu??n Del R??o; Berta Lasheras

2000-01-01

85

Solubility of hydrogen sulfide in aqueous mixtures of monoethanolamine with N-methyldiethanolamine  

SciTech Connect

Alkanolamine aqueous solutions are frequently used for the removal of acidic gases, such as CO[sub 2] and H[sub 2]S, from gas streams in the natural gas and synthetic ammonia industries and petroleum chemical plants. The solubilities of hydrogen sulfide in aqueous mixtures of monoethanolamine (MEA) with N-methyl-diethanolamine (MDEA) have been measured at 40, 60, 80, and 100C and at partial pressures of hydrogen sulfide ranging from 1.0 to 450 kPa. The mixtures of alkanolamines studied are 4.95 kmol/m[sup 3] MEA, 3.97 kmol/m[sup 3] MEA + 0.51 kmol/m[sup 3] MDEA, 2.0 kmol/m[sup 3] MEA + 1.54 kmol/m[sup 3] MDEA, and 2.57 kmol/m[sup 3] MDEA aqueous solutions. The solubilities of hydrogen sulfide in aqueous alkanolamine solutions are reported as functions of the partial pressure of hydrogen sulfide at the temperatures of 40-100C.

Meng Hui Li; Keh Perng Shen (Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering)

1993-01-01

86

Solubility of mixtures of hydrogen sulfide and carbon dioxide in aqueous N-methyldiethanolamine solutions  

Microsoft Academic Search

Aqueous solutions of alkanolamines are commonly used to strip acid gases (H[sub 2]S and CO[sub 2]) from streams contaminated with these components. The two most widely used amines are monoethanolamine (MEA) and diethanolamine (DEA). The solubilities of mixtures of hydrogen sulfide and carbon dioxide in a 35 wt% (3.04 kmol\\/m[sup 3]) aqueous solution of N-methyldiethanolamine at 40 and 100C have

Fang Yuan Jou; John J. Carroll; Alan E. Mather; Frederick D. Otto

1993-01-01

87

Simultaneous absorption of carbon dioxide and hydrogen sulfide with carbonyl sulfide contamination in aqueous methyldiethanolamine  

SciTech Connect

The primary objectives of the research were to: (1) obtain experimental data for simultaneous gas absorption systems to help formulate and test theoretical models of multicomponent mass transfer, and (2) develop the theoretical models which predict mass transfer rates from chemical reaction kinetics, system hydrodynamics and boundary conditions. To fulfill these objectives two-phase contact devices were designed and constructed. These were, a solubility of equilibrium apparatus, a laminar liquid jet apparatus, and a wetted-sphere apparatus. These devices were used to measure fundamental physiochemical properties of gases in liquids. The properties measured were the solubilities and diffusivities of N{sub 2}O, CO{sub 2}, and COS in aqueous MDEA. The reaction rate constants of the reactions between CO{sub 2} and MDEA and between COS and MDEA were also measured. In addition to these devices, a stirred tank absorber was used to obtain experimental data on multicomponent simultaneous absorption. A computer program was developed to solve the two-point boundary value problems generated by film theory. This research involved modeling and analyzing gas absorption systems with the chemical reactions taken as irreversible in one case and reversible in another. A parametric study of the case of reversible reactions revealed that for certain ranges of the parameter space the model predicted forced desorption. The program was tested against experimental data from two simultaneous absorption experiments. These were the simultaneous absorption of CO{sub 2}, COS, and N{sub 2} into aqueous MDEA and the simultaneous absorption of CO{sub 2}, H{sub 2}S, COS and N{sub 2} into aqueous MDEA. The program predictions of gas absorption rates were within 13% of the experimental values for the former experiment and within 9% for the latter.

Al-Ghawas, H.A.

1988-01-01

88

Carbon dioxide capture with concentrated, aqueous piperazine  

Microsoft Academic Search

Concentrated, aqueous piperazine (PZ) has been investigated as a novel amine solvent for carbon dioxide (CO2) absorption. The CO2 absorption rate of aqueous PZ is more than double that of 7m MEA and the amine volatility at 40°C ranges from 11 to 21ppm. Thermal degradation is negligible in concentrated, aqueous PZ up to a temperature of 150°C, a significant advantage

Stephanie A. Freeman; Ross Dugas; David H. Van Wagener; Thu Nguyen; Gary T. Rochelle

2010-01-01

89

Engineering of copper molybdates: Piperazine dictated pseudopolymorphs  

NASA Astrophysics Data System (ADS)

The hydrothermal syntheses, crystal structures and magnetic behavior of two compositionally different piperazine pillared copper molybdates, [{Cu( pip) 0.5}MoO 4] ( 1) and a hitherto unknown [Cu( pip)MoO 4] ( pip = piperazine) ( 2), are reported. Both 1 and 2 exhibit three-dimensional covalent frameworks constructed from bimetallic oxide layers pillared by piperazine; however, the {CuMoO 4} networks are quite distinct. The Cu-Mo-O layers in 1 are made of edge-shared {CuO 4N} square pyramidal pairs linked through {MoO 4} tetrahedra, in contrast to the sheets in 2 that are built of corner-sharing {MoO 4} tetrahedra and {CuO 3N 2} square pyramids. Self assembly of the two pseudopolymorphs, 1 and 2, is interpreted in terms of molecular recognition between reasonable soluble molecular species in the supramolecular reaction along the mechanistic approach proposed by Ramanan and Whittingham for rationalizing metal-organic framework structures. Crystal data: 1, Triclinic, space group P-1, a = 5.5765(8) Å, b = 6.8304(10) Å, c = 9.2379(14) Å, ? = 100.688(2)°, ? = 101.462(2)°, ? = 112.624(2)°, Z = 2; 2, Orthorhombic, space group Pbca, a = 11.3899(11) Å, b = 10.7726(10) Å, c = 13.2541(12) Å, Z = 8.

Pavani, Katikaneani; Singh, Monika; Ramanan, Arunachalam; Lofland, Samuel E.; Ramanujachary, Kandalam V.

2009-09-01

90

Towards an implantable biochip for glucose and lactate monitoring using microdisc electrode arrays (MDEAs).  

PubMed

A complete electrochemical cell-on-a-chip that uses the MicroDisc Electrode Array (MDEA) working electrode (WE) design was evaluated for eventual intramuscular implantation for the continuous amperometric monitoring of glucose and lactate in an animal trauma model. The microfabricated ECC MDEA5037 comprises two discrete electrochemical cells-on-a-chip (ECCs), each with a reference, counter, and MDEA working electrode. Each MDEA comprises 37 microdiscs (diameter = 50 microm) arranged in a Hexagonal Closed Packed (HCP) arrangement with a center to center distance (d) of 100 microm. Cyclic Voltammetry (CV) and Electrical Impendence Spectroscopy (EIS) reveals that this device scales in its interfacial properties with a corresponding MDEA 050 device that comprises 5,184 microdiscs. Parallel development of miniaturized mixed-signal integrated electronics for wireless reprogramming, data acquisition and communication addresses the key issues involved in developing measurement electronics, AD/DA processing, power management and telemetry for implantable amperometric biosensors. A generalized electronics platform based on the Texas Instruments TI NC01101 chip has been developed that may be readily applied to many types of biotransducers with minor modifications. PMID:18677565

Abdur Rahman, Abdur Rub; Justin, Gusphyl; Guiseppi-Elie, Anthony

2009-02-01

91

Solubility of hydrogen sulfide in aqueous mixtures of monoethanolamine with N-methyldiethanolamine  

Microsoft Academic Search

Alkanolamine aqueous solutions are frequently used for the removal of acidic gases, such as CO[sub 2] and H[sub 2]S, from gas streams in the natural gas and synthetic ammonia industries and petroleum chemical plants. The solubilities of hydrogen sulfide in aqueous mixtures of monoethanolamine (MEA) with N-methyl-diethanolamine (MDEA) have been measured at 40, 60, 80, and 100C and at partial

Meng Hui Li; Keh Perng Shen

1993-01-01

92

Solubility of mixtures of hydrogen sulfide and carbon dioxide in aqueous N-methyldiethanolamine solutions  

SciTech Connect

Aqueous solutions of alkanolamines are commonly used to strip acid gases (H[sub 2]S and CO[sub 2]) from streams contaminated with these components. The two most widely used amines are monoethanolamine (MEA) and diethanolamine (DEA). The solubilities of mixtures of hydrogen sulfide and carbon dioxide in a 35 wt% (3.04 kmol/m[sup 3]) aqueous solution of N-methyldiethanolamine at 40 and 100C have been measured. Partial pressures of the acid gases ranged from 0.006 to 101 kPa at 40C and from 4 to 530 kPa at 100C.

Jou, Fang Yuan; Carroll, J.J.; Mather, A.E.; Otto, F.D. (Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical Engineering)

1993-01-01

93

21 CFR 520.1804 - Piperazine phosphate capsules.  

Code of Federal Regulations, 2013 CFR

... â(1) Amount. 60 milligrams of piperazine phosphate monohydrate per pound of body weight.1 1 These conditions are NAS/NRC reviewed and deemed effective. Applications for these uses need not include effectiveness data as specified by §...

2013-04-01

94

Determination of MDMA, MDEA and MDA in urine by high performance liquid chromatography with fluorescence detection  

Microsoft Academic Search

This paper describes the development and validation of analytical methodology for the determination of the use of MDMA, MDEA and MDA in urine. After a simple liquid extraction, the analyses were carried out on a high performance liquid chromatography (HPLC) in an octadecyl column, with fluorescence detection. The mobile phase using a sodium dodecyl sulfate ion-pairing reagent allows good separation

José Luiz da Costa; Alice Aparecida da Matta Chasin

2004-01-01

95

Representation of CO 2 and H 2S solubility in aqueous MDEA solutions using an electrolyte equation of state  

Microsoft Academic Search

The electrolyte equation of state proposed by Fürst and Renon (1993, A.I.Ch.E. Journal, 39(2), 335–343) has been applied to the representation of CO2 and H2S solubility in MDEA aqueous solutions over a wide range of temperatures, MDEA concentrations and gas loadings. At low temperatures (298–313K), it has been shown that the gas solubility could be calculated using, as in the

Li Chunxi; W. Fürst

2000-01-01

96

Degradation of piperazine by Paracoccus sp. TOH isolated from activated sludge.  

PubMed

Piperazine is widely used as an intermediate in the manufacture of insecticides, rubber chemicals, corrosion inhibitors, and urethane. In this study, a highly effective piperazine-degrading bacteria strain, TOH, was isolated from the acclimated activated sludge of a pharmaceutical plant. This strain, identified as Paracoccus sp., utilises piperazine as the sole source of carbon, nitrogen and energy for growth. The optimal pH and temperature for the growth of TOH were 8.0 and 30°C, respectively. The effects of co-substrates and heavy metals on the degradation efficiency of piperazine were investigated. The results indicated that exogenously supplied glucose promoted the degradation of piperazine, while the addition of ammonium chloride slightly inhibited piperazine degradation. Metal ions such as Ni(2+) and Cd(2+) inhibited the degradation of piperazine, whereas Mg(2+) increased it. In addition, metabolic intermediates were identified by mass spectrometry, allowing a degradation pathway for piperazine to be proposed for the first time. PMID:23334008

Cai, Shu; Li, Xin; Cai, Tianming; He, Jian

2013-02-01

97

21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.  

Code of Federal Regulations, 2010 CFR

...Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520...FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1802...Piperazine-carbon disulfide complex oral dosage...

2009-04-01

98

Stimulation of Adventitious Rooting in Cuttings of Four Herbaceous Species by Piperazine  

Microsoft Academic Search

Piperazine, a chemical used as buffer component, greatly promoted adventitious root formation in cuttings of sunflower (Helianthus annuus L.), pea (Pisum sativum L.), mung bean (Vigna radiata L.) and to a lesser extent in bean (Phaseolus vulgaris L.) seedlings. Piperazine was more effective in acidic pH. The studies with piperazine analogues showed that any substantial modification of the structure caused

J.-H. Liu; E. C. Yeung; I. Mukherjee; D. M. Reid

1995-01-01

99

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Levamisole hydrochloride and piperazine dihydrochloride...FORM NEW ANIMAL DRUGS § 520.1242c Levamisole hydrochloride and piperazine dihydrochloride...contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine...

2009-04-01

100

The effect of corrosion product layers on the anodic and cathodic reactions of carbon steel in CO2-saturated mdea solutions at 100°C  

Microsoft Academic Search

The effects of corrosion-product layers on anodic dissolution and cathodic reduction were investigated under 4.5 MPa CO2 at 100°C using impedance, potentiodynamic polarization techniques and XRD analysis. Protective corrosion-product layers were formed on carbon steel in all MDEA solutions tested in this work. The composition of the layer depended on the MDEA concentration. In relatively concentrated MDEA solutions, the corrosion-product

X.-P Guo; Y Tomoe

1999-01-01

101

Heats of mixing of gaseous CO 2\\/CH 4 mixtures with aqueous solutions of methyldiethanolamine and diethanolamine  

Microsoft Academic Search

The heats of mixing of gaseous CO2\\/CH4 mixtures with aqueous solutions of methyldiethanolamine and diethanolamine have been determined using an isothermal flow calorimeter. Data were collected at 26.7, 76.7 and 126.7°C, at total pressures of 1.38, 3.45 and 6.90MPa, with aqueous amine concentrations of 20, 35 and 50wt%. The nominal partial pressure of CO2 in the gaseous feed stream was

John L Oscarson; Helga K Grimsrud; Sue E Gillespie

2000-01-01

102

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs)  

Microsoft Academic Search

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose,\\u000a pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices\\u000a for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and\\u000a the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant

Gusphyl Justin; Stephen Finley; Abdur Rub Abdur Rahman; Anthony Guiseppi-Elie

2009-01-01

103

Acute poisoning with amphetamines (MDEA) and heroin: Antagonistic effects between the two drugs  

Microsoft Academic Search

A case of oral ingestion of large doses of both the amphetamine-derivative 3,4-methylene dioxyethamphetamine (MDEA) and heroin is reported. Despite high serum levels of both drugs, the patient did not present with the classic signs and symptoms normally seen during intoxication with these drugs. The patient recovered after symptomatic treatment. The possibility that opposite pharmacological properties of the two drugs

P. G. Jorens; L. Heytens; H. E. Demey; S. Andries; G. A. Ricaurte; L. Bossaert; P. J. C. Schepens

1996-01-01

104

Design considerations in the development and application of microdisc electrode arrays (MDEAs) for implantable biosensors  

Microsoft Academic Search

The use of microlithographically fabricated Microdisc Electrode Arrays (MDEAs) in the development of implantable voltammetric\\u000a biosensors necessitates design criteria that balances the overall footprint of the device with the advantages to be derived\\u000a from large separation distances between non-interacting microdisc elements. Using the dynamic electroanalytical techniques\\u000a of Multiple Scan Rate Cyclic Voltammetry (MSRCV) experiments with finite element simulations and Electrochemical

Abdur Rub Abdur Rahman; Anthony Guiseppi-Elie

2009-01-01

105

Kinetics of absorption of CO{sub 2} in concentrated aqueous methyldiethanolamine solutions in the range 296 K to 343 K  

SciTech Connect

The kinetics of CO{sub 2} absorption by aqueous solutions of methyl diethanol amine (MDEA) were measured in the temperature range (296--343) K and MDEA concentration range (830--4,380) mol/m{sup 3} (10--50 mass %). A thermoregulated constant interfacial area Lewis-type cell was operated by recording the pressure drop during batch absorption. The kinetic results are in agreement with a fast regime of absorption according to film theory. MDEA depletion at the interface has a significant effect on the kinetics at the CO{sub 2} pressures (100 to 200 kPa) studied in this work, especially at low temperatures and low MDEA concentrations. Considering only the reaction between CO{sub 2} and MDEA, the CO{sub 2} absorption appears as a first-order reaction with respect to MDEA. The activation energy found for the reaction between CO{sub 2} and MDEA is 45 kJ/mol, but this value depends significantly (by about 10% in the worst case) on the vapor-liquid equilibrium data used.

Pani, F.; Gaunand, A.; Cadours, R.; Bouallou, C.; Richon, D. [Ecole Nationale Superieure des Mines de Paris (France). Centre de Recherche en Procedes de Transformation de la Matiere] [Ecole Nationale Superieure des Mines de Paris (France). Centre de Recherche en Procedes de Transformation de la Matiere

1997-03-01

106

The Piperazine Space in Isocyanide-based MCR Chemistry  

NASA Astrophysics Data System (ADS)

Piperazines and its congeners, (di)keto piperazines are valuable tools in drug discovery, providing a natural path for the process peptide > peptidomimetic > small molecule also called depeptisation. Moreover, they can provide molecular probes to understand molecular pathways for diseases of unmet medical need. However, in order to better understand the design of such value added compounds, the detailed understanding of scope and limitation of their synthesis as well as their 3D structures and associated physicochemical properties is indispensables. Isocyanide multicomponent reaction (MCR) chemistry provides a prime tool for entering the chemical space of (di)(keto)piperazines since not less then 20 different ways exist to access a diversity of related scaffolds.

Huang, Yijun; Khoury, Kareem; Dömling, Alexander

107

Aminoalcohols incorporating a piperazine ring: Synthesis, complexation of a hexadentate ligand and DNA cleavage capability of copper(II) complexes  

Microsoft Academic Search

The facility of aminoalcohol ligand synthesis via ring opening of cyclohexene oxide with polyamines including a piperazine ring is illustrated here with the syntheses and characterization of (2?-hydroxycyclohexyl)piperazine (1), bis(2?-hydroxycyclohexyl)-piperazine (2), 4-{(2?-hydroxycyclohexyl)-2?-aminoethyl)}piperazine (3), 1-(2?-hydroxycyclohexyl)-4-{(2?-hydroxycyclohexyl)-2?-aminoethyl)}piperazine (4), and 1,4-bis[(2?-hydroxycyclohexyl)-3?-aminopropyl]piperazine (5) described, along with an analogue of 4 in which a single –CH2–CH2– alkyl chain replaces the piperazine ring, 1,5-bis[(2?-hydroxycyclohexyl)amine]-3-azapentane (6). The viability

Brendan L. Griggs; Geoffrey A. Lawrance; Marcel Maeder; Mark J. Robertson; Peter Turner

2007-01-01

108

Thermodynamics of protonation of alkanolamines in aqueous solutions  

Microsoft Academic Search

The equilibrium constants, pKa, for protonation of monoethanolamine (MEA), N-methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propnol (AMP), 2(2-aminoethyl)etanol)amine (AEEA) and piperazine (Pz) have been measured by potentiometric titration at temperatures from 298.15 to 363.15 K. Enthalpies of protonation, ?Hp, for these amines were measured at 298.15 K in a reaction calorimeter and compared to those calculated from the experimental pKa values. The effect of the ionic

Inna Kim; Andreas Grimstvedt; Erik F. da Silva

2011-01-01

109

Part played by degradation products in the corrosion of gas sweetening plants using DEA and MDEA  

SciTech Connect

The experiments reported in this work are results of the most representative tests of the work done in Elf Aquitaine's Laboratories. The general conclusion is that degradation products of amines, DEA and MDEA, have no practical effect upon the corrosion rate of carbon steel. The reasons for this are different according as the products are basic or acid. Basic products, which are only slightly basic, cannot have a part in acid corrosion process. Some tests have even been performed to use this type of product as corrosion inhibitors. As for acid products, they play no part either, because of their low content in amine solutions. 27 references.

Blanc, C.; Grall, M.; Demarais, G.

1982-01-01

110

A status report on the investigation of the effects of antioxidants upon oxygen degradation of methyldiethanolamine  

SciTech Connect

Natural gas production is an important source of energy for the country. The gas directly from the gas fields is not suitable for consumption due to the presence of acidic impurities. The process of gas treating separates impurities such as carbon dioxide-(CO/sub 2/), hydrogen sulfide (H/sub 2/S), and sulfur dioxide (SO/sub 2/) from the gas stream. Industrial processes such as hydrogen manufacture and ammonia production also require acid gas removal systems. The oxygen degradation reactions of MDEA (Melhyl Diethanolamine) solutions were investigated. Several primary and secondary antioxidants were tested and found to be ineffective in the first series of batch reactor experiments at 195/sup 0/F and 50 psig O/sub 2/. This may be due to an excessively high oxygen pressure whereby the inhibitor reacted with the oxygen directly in a short period of time and thus the amine was not protected against degradation. Another possibility is that the severe experimental conditions may accelerate heat stable salts formation reactions at a constant rate. The current preliminary results are indicative that oxygen degradation reactions are quite complicated. Further studies are needed to determine the best antioxidants needed for amine sweetening systems.

Pundari, A.N.; Singh, M.; Bullin, J.A.

1987-01-01

111

CO/sub 2/ desorption from DEA and DEA-promoted MDEA  

SciTech Connect

CO/sub 2/ desorption rates were measured in 2 M diethanolamine and 2 M diethanolamine-promoted methyldiethanolamine solutions at 25{sup 0}C. CO/sub 2/ vapor pressure equilibria were estimated through extrapolation of the measured rates. The estimated vapor pressures were used to calculate apparent rate constants, and the resulting rate constants were interpreted as a function of CO/sub 2/ loading. The rate constants derived from the low driving force desorption experiments were compared with values obtained from high driving force, irreversible absorption experiments. In the absorption work, the effect of varied driving force on the resulting apparent rate constant was studied. The experimental results confirm that the absorption experiments were not affected by diffusion constraints. The agreement between the apparent rate constants determined from the absorption and desorption techniques was found to be very good.

Critchfield, J.E.; Rochelle, G.T. (Dept. of Chemical Engineering, The Univ. of Texas at Austin (US))

1988-01-01

112

Gene cloning and characterization of MdeA, a novel multidrug efflux pump in Streptococcus mutans.  

PubMed

Multidrug resistance, especially multidrug efflux mechanisms that extrude structurally unrelated cytotoxic compounds from the cell by multidrug transporters, is a serious problem and one of the main reasons for the failure of therapeutic treatment of infections by pathogenic microorganisms as well as of cancer cells. Streptococcus mutans is considered one of the primary causative agents of dental caries and periodontal disease, which comprise the most common oral diseases. A fragment of chromosomal DNA from S. mutans KCTC3065 was cloned using Escherichia coli KAM32 as host cells lacking major multidrug efflux pumps. Although E. coli KAM32 cells were very sensitive to many antimicrobial agents, the transformed cells harboring a recombinant plasmid became resistant to several structurally unrelated antimicrobial agents such as tetracycline, kanamycin, rhodamin 6G, ampicillin, acriflavine, ethidium bromide, and tetraphenylphosphonium chloride. This suggested that the cloned DNA fragment carries a gene encoding a multidrug efflux pump. Among 49 of the multidrug-resistant transformants, we report the functional gene cloning and characterization of the function of one multidrug efflux pump, namely MdeA from S. mutans, which was expressed in E. coli KAM32. Judging from the structural and biochemical properties, we concluded that MdeA is the first cloned and characterized multidrug efflux pump using the proton motive force as the energy for efflux drugs. PMID:23462018

Kim, Do Kyun; Kim, Kyoung Hoon; Cho, Eun Ji; Joo, Seoung-Je; Chung, Jung-Min; Son, Byoung Yil; Yum, Jong Hwa; Kim, Young-Man; Kwon, Hyun-Ju; Kim, Byung-Woo; Kim, Tae Hoon; Lee, Eun-Woo

2013-03-01

113

Degradation of aqueous piperazine in carbon dioxide capture  

Microsoft Academic Search

Concentrated, aqueous piperazine (PZ) is a novel solvent for carbon dioxide (CO2) capture by absorption\\/stripping. One of the major advantages of PZ is its resistance to thermal degradation and oxidation.At 135 and 150°C, 8m PZ is up to two orders of magnitude more resistant to thermal degradation than 7m monoethanolamine (MEA). After 18 weeks at 150°C, only 6.3% of the

Stephanie A. Freeman; Jason Davis; Gary T. Rochelle

2010-01-01

114

Probing of different conformations of piperazine using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Piperazine exists in a number of energetically close structural conformations, and here, we investigated the dependence of their relative abundance on the surrounding conditions by using Raman and SERS spectroscopy in pure solid, aqueous solution and Ag hydrosol. The experimental results were interpreted by DFT calculations using B3LYP functional with aug-cc-pvdz/LANL2DZ basis sets. In the chair form of piperazine, which is more stable than the skewed boat by ?8 kcal mol-1, the two N-H bonds can remain equatorial or axial, leading to three different conformations, eq-eq, eq-ax and ax-ax. The calculated Raman spectrum of the lowest energy eq-eq conformation corresponds well with the experimental spectrum in pure solid, indicating eq-eq to be predominant. But, the contribution of the eq-ax conformation was found to be maximum in aqueous solution. The SERS spectrum revealed that eq-ax conformation was preferably adopted as piperazine was adsorbed vertically through its axial N-atom over silver nanoparticle surface.

SenGupta, Sumana; Maiti, Nandita; Chadha, Ridhima; Kapoor, Sudhir

2014-06-01

115

Ecstasy (MDMA, MDA, MDEA, MBDB) consumption, seizures, related offences, prices, dosage levels and deaths in the UK (1994–2003)  

Microsoft Academic Search

In the last decade, a global trend of escalating ecstasy (MDMA, MDA, MDEA, MBDB) use was observed. Mentions on medical death certificates, last year's ecstasy use, number of drug offenders, seizures, prices and dosage levels figures were used for this descriptive and correlational study. Figures (1994ñ2003) were taken from the UK General Mortality Registers, from the Home Office Statistical Bulletins,

Fabrizio Schifano; John Corkery; Paolo Deluca; Adenekan Oyefeso; A. Hamid Ghodse

2006-01-01

116

Fast LC-MS/MS method for the determination of amphetamine, methamphetamine, MDA, MDMA, MDEA, MBDB and PMA in urine.  

PubMed

A fast method was designed for the simultaneous determination of amphetamine (A), methamphetamine (MA), PMA, MDA, MDMA, MDEA and MBDB in urine. The drugs were analysed by LC (ESI)-MS/MS, after a simple liquid-liquid extraction in the presence of the deuterated analogues. Reverse phase separation on an Atlantis dC18 Intelligent Speed column was achieved in less than 4 min under gradient conditions, and the total run time was 8 min. The method was fully validated, including linearity (1-1000 ng/mL for A, MDMA, MDEA and MBDB; 2-1000 ng/mL for MDA and PMA; 1-200 ng/mL for MA; r2>0.99 for all compounds), recovery (>80%), within-day and between-day precision and accuracy (CV and MRE<12.7% for intermediate level and ULOQ, and <17.2% for LLOQ), limit of detection (0.2 ng/mL for MDMA, MDEA and MBDB; 0.5 ng/mL for A, MA and PMA; 1 ng/mL for MDA) and quantitation (1 ng/mL for A, MA, MDMA, MDEA and MBDB; 2 ng/mL for MDA and PMA) and relative ion intensities. No matrix effect was observed. The procedure proved to be sensitive, specific and rapid, and was applied to real forensic cases. PMID:17097252

Concheiro, Marta; Simões, Susana Maria dos Santos Sadler; Quintela, Oscar; de Castro, Ana; Dias, Mário João Rodrigues; Cruz, Angelines; López-Rivadulla, Manuel

2007-08-24

117

The degradation mechanism of wastewater containing MDEA using UV\\/H2O2 advanced oxidation process  

Microsoft Academic Search

Alkanolamines such as MEA, DEA, MDEA and DIPA in aqueous solutions is frequently used for scrubbing carbon dioxide from natural gas. High quantity of alkanolamine appears in the wastewater during cleaning and maintenance as well as shutdown of the absorption and desorption columns. The alkanolamines waste is toxic to the environment and this wastewater cannot be treated in the conventional

Sabtanti Harimurti; Abul Aziz Omar; Anisa Ur Rahmah; Thanpalan Murugesan

2011-01-01

118

Sensitive Gas Chromatography-Mass Spectrometry Method for Simultaneous Measurement of MDEA, MDMA, and Metabolites HMA, MDA, and HMMA in Human Urine  

Microsoft Academic Search

Background: A sensitive gas chromatography-mass spectrometry method was developed and validated for the simultaneous measurement of MDEA, MDMA, and its metabolites, 3,4-methylenedioxy-N-ethylamphet- amine (MDEA), 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy), and its metabolites, 4-hydroxy-3- methoxyamphetamine (HMA), 3,4-methylenedioxyam- phetamine (MDA), and 4-hydroxy-3-methoxyamphet- amine (HMMA) in human urine. Methods: We hydrolyzed 1 mL urine, fortified with MDMA-d5, MDA-d5, and MDEA-d6, with 100 Lo f

Stephane O. Pirnay; Tsadik T. Abraham; Marilyn A. Huestis

119

5-Methyl-3,3-bis-(4-methyl-piperazin-1-yl)-1-[2-(4-methyl-piperazin-1-yl)eth-yl]indolin-2-one  

PubMed Central

In the title compound, C26H43N7O, each piperazine ring adopts a chair conformation. Two 1-methyl­piperazine rings bond to one Csp 3 of the pyrrole ring via the piperazine N atoms, while the third one links to the N atom of the indolin-2-one unit through a flexible ethyl group with an almost syn conformation. In the crystal, mol­ecules are connected through methyl­ene–carbonyl C—H?O inter­actions into an infinite chain along the c axis. The almost parallel arrays are stacked, forming a three-dimensional framework.

Lin, Hui-Hui; Zheng, Xiao-Lin; Cao, Sheng-Li

2012-01-01

120

5-Methyl-3,3-bis-(4-methyl-piperazin-1-yl)-1-[2-(4-methyl-piperazin-1-yl)eth-yl]indolin-2-one.  

PubMed

In the title compound, C(26)H(43)N(7)O, each piperazine ring adopts a chair conformation. Two 1-methyl-piperazine rings bond to one Csp(3) of the pyrrole ring via the piperazine N atoms, while the third one links to the N atom of the indolin-2-one unit through a flexible ethyl group with an almost syn conformation. In the crystal, mol-ecules are connected through methyl-ene-carbonyl C-H?O inter-actions into an infinite chain along the c axis. The almost parallel arrays are stacked, forming a three-dimensional framework. PMID:22719620

Lin, Hui-Hui; Zheng, Xiao-Lin; Cao, Sheng-Li

2012-06-01

121

Solubility of carbon dioxide in aqueous mixtures of alkanolamines  

Microsoft Academic Search

The solubility of CO[sub 2] in water + N-methyldiethanolamine + monoethanolamine (MDEA + MEA) and water + N-methyldiethanolamine + diethanolamine (MDEA + DEA) are reported at two compositions of 3.4 M MDEA + 0.8 M MEA or DEA and 2.1 M MDEA + 2.1 M MEA or DEA at temperatures from 70 to 180 C and CO[sub 2] partial pressures

Olukayode Fatai Dawodu; Axel Meisen

1994-01-01

122

Effects of MDMA, MDA and MDEA on blood pressure, heart rate, locomotor activity and body temperature in the rat involve ?-adrenoceptors  

PubMed Central

The effects of injection of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and N-ethyl-3,4-methylenedioxyamphetamine (MDEA) (all 20?mg?kg?1) on blood pressure, heart rate, core body temperature and locomotor activity in conscious rats were investigated using radiotelemetry. MDMA and MDA produced a prolonged increase in both systolic and diastolic pressures, with MDA causing the most marked rise. MDEA produced a transient but nonsignificant fall in diastolic pressure. The pressor response produced by MDA was accompanied by bradycardia. All three amphetamine derivatives caused an initial hypothermic response; however, MDA also produced a subsequent hyperthermia, and the speed of recovery from hypothermia was MDA>MDMA>MDEA. The ?2A-adrenoceptor antagonist 2-((4,5-dihydro-1H-imidazol-2-yl)methyl)-2,3-dihydro-1-methyl-1H-isoindole (BRL 44408) (1?mg?kg?1) prolonged the hypothermic response to MDMA. Only MDA induced locomotor activity when given alone, but in the presence of BRL 44408, MDMA produced increased locomotor activity. The order of potency for producing isometric contractions of rat aorta (?1D) and vas deferens (?1A) was MDA>MDMA>MDEA, with MDEA acting as an ?1-adrenoceptor antagonist with a pKB of 4.79±0.12 (n=4) in aorta. The order of potency for prejunctional inhibition of stimulation-evoked contractions in rat vas deferens (?2A-adrenoceptor mediated) was MDA>MDMA>MDEA. Blood pressure actions of the three amphetamine derivatives may be at least partly due to ?1-adrenoceptor agonism or antagonism. The reversal of the hypothermic actions are at least partly due to ?2A-adrenoceptor agonism since the hypothermic response was more prolonged with MDEA which exhibits low ?2A-adrenoceptor potency, and effects of MDMA after ?2A-adrenoceptor antagonism were similar to those of MDEA.

Bexis, Sotiria; Docherty, James R

2006-01-01

123

1,4-Bis(2-diazo-acet-yl)piperazine  

PubMed Central

The asymmetric unit of the title compound, C8H10N6O2, contains one-half mol­ecule, which is completed by a crystallographic center of symmetry. The piperazine ring adopts a chair conformation. In the crystal, weak C—H?O inter­actions link the mol­ecules into layers parallel to the bc plane. The crystal packing also exhibits short N?N contacts of 3.0467?(16)?Å between the terminal diazo N atoms from neighbouring mol­ecules.

Kaupang, Asmund; Gorbitz, Carl Henrik; Bonge-Hansen, Tore

2013-01-01

124

Modeling of CO 2 solubility and carbamate concentration in DEA, MDEA and their mixtures using the Deshmukh–Mather model  

Microsoft Academic Search

The equilibrium of CO2 and carbamate concentration data for the absorption of CO2 in aqueous solutions of single and mixed amines was analyzed using the Deshmukh–Mather model. Data on CO2 loading in aqueous solutions of DEA and MDEA and their mixtures at various temperature (303–323K) and CO2 partial pressure (0.09–100kPa) together with carbamate concentrations in case of DEA and its

A. Benamor; M. K. Aroua

2005-01-01

125

Fast LC–MS\\/MS method for the determination of amphetamine, methamphetamine, MDA, MDMA, MDEA, MBDB and PMA in urine  

Microsoft Academic Search

A fast method was designed for the simultaneous determination of amphetamine (A), methamphetamine (MA), PMA, MDA, MDMA, MDEA and MBDB in urine. The drugs were analysed by LC (ESI)–MS\\/MS, after a simple liquid–liquid extraction in the presence of the deuterated analogues. Reverse phase separation on an Atlantis dC18 Intelligent Speed column was achieved in less than 4min under gradient conditions,

Marta Concheiro; Susana Maria dos Santos Sadler Simões; Óscar Quintela; Ana de Castro; Mário João Rodrigues Dias; Angelines Cruz; Manuel López-Rivadulla

2007-01-01

126

Determination of MDMA, MDA, MDEA and MBDB in oral fluid using high performance liquid chromatography with native fluorescence detection  

Microsoft Academic Search

This paper describes the analytical methodology for the determination of MDMA, MDA, MDEA and MBDB in oral fluid. After a liquid–liquid extraction, the analysis was carried out by high performance liquid chromatography (HPLC), with fluorescence detection. The detector wavelength was fixed at 285nm for excitation and 320nm for emission. The mobile phase, a mixture of phosphate buffer (pH=5) and acetonitrile

Marta Concheiro; Ana de Castro; Oscar Quintela; Manuel López-Rivadulla; Angelines Cruz

2005-01-01

127

Determination of the metabolites of the new designer drugs bk-MBDB and bk-MDEA in human urine.  

PubMed

This is the first report on identifying the specific metabolites of the new designer drugs 2-methylamino-1-(3,4-methylenedioxyphenyl)butan-1-one (bk-MBDB) and 2-ethylamino-1-(3,4-methylenedioxyphenyl)propan-1-one (bk-MDEA) in human urine using synthesized standards. Based on GC/MS and LC/MS, we identified N-dealkylation, demethylenation followed by O-methylation, and beta-ketone reduction as their major metabolic pathways. The quantitative analyses by LC/MS revealed that both demethylenation followed by O-methylation and beta-ketone reduction were superior to N-dealkylation and that both bk-MBDB and bk-MDEA were mainly metabolized into their corresponding 4-hydroxy-3-methoxy metabolites (4-OH-3MeO metabolites). After hydrolysis, the concentrations of 4-OH-3MeO metabolites and 3-hydroxy-4-methoxy metabolites of both bk-MBDB and bk-MDEA dramatically increased, suggesting that the metabolites mainly exist as their conjugates. PMID:19406592

Zaitsu, Kei; Katagi, Munehiro; Kamata, Hiroe T; Kamata, Tooru; Shima, Noriaki; Miki, Akihiro; Tsuchihashi, Hitoshi; Mori, Yasushige

2009-07-01

128

Heteroleptic titanium(IV) catecholato/piperazine systems and their anti-cancer properties.  

PubMed

In this paper we report the synthesis and full characterisation of a range of Ti(IV)-catecholato systems complexed to piperazine or homopiperazine salan ligands. The steric/electronic environment of the catecholate moiety has been varied and the effect this has on cytotoxicity discussed. It was observed that the 7-membered homopiperazine complexes are more stable to hydrolysis than their piperazine cousins in biological media. In general the homopiperazine complexes show higher cytotoxicity than the piperazine complexes, with the most cytotoxic complex exhibiting IC50 (?M) values of 3 ± 0.5 ?M (HT-29) and 4 ± 1 ?M (OVCAR). PMID:24201896

Hancock, Stuart L; Gati, Rachel; Mahon, Mary F; Tshuva, Edit Y; Jones, Matthew D

2014-01-21

129

21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.  

Code of Federal Regulations, 2013 CFR

...piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status. The conditions of use are NAS/NRC reviewed and found effective. Applications for these uses need not include...

2013-04-01

130

GC-MS studies on side chain regioisomers related to substituted methylenedioxyphenethylamines: MDEA, MDMMA, and MBDB.  

PubMed

Three regioisomeric 3,4-methylenedioxyphenethylamines having the same molecular weight and major mass spectral fragments of equal mass have been reported as drugs of abuse in forensic studies in recent years. These compounds are 3,4-methylenedioxy-N-ethylamphetamine (MDEA), 3,4-methylenedioxy-N,N-dimethylamphetamine (MDMMA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB). A series of seven additional side chain regioisomers have mass spectra essentially equivalent to the three controlled drug substances, all have molecular weight of 207 and major fragment ions in their electron ionization mass spectra at m/z 72 and 135/136. The trifluoroacetyl, pentafluoropropionyl, and heptafluorobutryl derivatives of the primary and secondary regioisomeric amines were evaluated in GC-MS studies. The mass spectra for these derivatives were significantly individualized, and the resulting unique fragment ions allowed for specific side chain identification. The trifluoroacetyl and heptafluorobutryl derivatives provided more specific fragment ions for molecular individualization among these regioisomeric substances. These perfluoroacyl derivatives showed reasonable resolution on the polar stationary phase Rtx-200. PMID:20875234

Awad, Tamer; Belal, Tarek; Maher, Hadir M; DeRuiter, Jack; Clark, C Randall

2010-10-01

131

Pharmacological profiles of aminoindanes, piperazines, and pipradrol derivatives.  

PubMed

Aminoindanes, piperazines, and pipradrol derivatives are novel psychoactive substances found in "Ecstasy" tablets as replacements for 3,4-methylenedioxymethamphetamine (MDMA) or substances sold as "ivory wave." The pharmacology of these MDMA- and methylphenidate-like substances is poorly known. We characterized the pharmacology of the aminoindanes 5,6-methylenedioxy-2-aminoindane (MDAI), 5-iodoaminoindane (5-IAI), and 2-aminoindane (2-AI), the piperazines meta-chlorophenylpiperazine (m-CPP), trifluoromethylphenylpiperazine (TFMPP), and 1-benzylpiperazine (BZP), and the pipradrol derivatives desoxypipradrol (2-diphenylmethylpiperidine [2-DPMP]), diphenylprolinol (diphenyl-2-pyrrolidinemethanol [D2PM]), and methylphenidate. We investigated norepinephrine (NE), dopamine (DA), and serotonin (5-hydroxytryptamine [5-HT]) uptake inhibition using human embryonic kidney 293 (HEK 293) cells that express the respective human monoamine transporters (NET, DAT, and SERT). We also evaluated the drug-induced efflux of NE, DA, and 5-HT from monoamine-preloaded cells and the binding affinity to monoamine transporters and receptors, including trace amine-associated receptor 1 (TAAR1). 5-IAI and MDAI preferentially inhibited the SERT and NET and released 5-HT. 2-AI interacted with the NET. BZP blocked the NET and released DA. m-CPP and TFMPP interacted with the SERT and serotonergic receptors. The pipradrol derivatives were potent and selective catecholamine transporter blockers without substrate releasing properties. BZP, D2PM, and 2-DPMP lacked serotonergic activity and TAAR1 binding, in contrast to the aminoindanes and phenylpiperazines. In summary, all of the substances were monoamine transporter inhibitors, but marked differences were found in their DAT vs. SERT inhibition profiles, release properties, and receptor interactions. The pharmacological profiles of D2PM and 2-DPMP likely predict a high abuse liability. PMID:24486525

Simmler, Linda D; Rickli, Anna; Schramm, York; Hoener, Marius C; Liechti, Matthias E

2014-03-15

132

Determination of the metabolites of the new designer drugs bk-MBDB and bk-MDEA in human urine  

Microsoft Academic Search

This is the first report on identifying the specific metabolites of the new designer drugs 2-methylamino-1-(3,4-methylenedioxyphenyl)butan-1-one (bk-MBDB) and 2-ethylamino-1-(3,4-methylenedioxyphenyl)propan-1-one (bk-MDEA) in human urine using synthesized standards. Based on GC\\/MS and LC\\/MS, we identified N-dealkylation, demethylenation followed by O-methylation, and ?-ketone reduction as their major metabolic pathways. The quantitative analyses by LC\\/MS revealed that both demethylenation followed by O-methylation and ?-ketone

Kei Zaitsu; Munehiro Katagi; Hiroe T. Kamata; Tooru Kamata; Noriaki Shima; Akihiro Miki; Hitoshi Tsuchihashi; Yasushige Mori

2009-01-01

133

Piperazine designer drugs induce toxicity in cardiomyoblast h9c2 cells through mitochondrial impairment.  

PubMed

Abuse of synthetic drugs is widespread among young people worldwide. In this context, piperazine derived drugs recently appeared in the recreational drug market. Clinical studies and case-reports describe sympathomimetic effects including hypertension, tachycardia, and increased heart rate. Our aim was to investigate the cytotoxicity of N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl) piperazine (TFMPP), 1-(4-methoxyphenyl) piperazine (MeOPP), and 1-(3,4-methylenedioxybenzyl) piperazine (MDBP) in the H9c2 rat cardiac cell line. Complete cytotoxicity curves were obtained at a 0-20mM concentration range after 24h incubations with each drug. The EC50 values (?M) were 343.9, 59.6, 570.1, and 702.5 for BZP, TFMPP, MeOPP, and MDBP, respectively. There was no change in oxidative stress markers. However, a decrease in total GSH content was noted for MDBP, probably due to metabolic conjugation reactions. All drugs caused significant decreases in intracellular ATP, accompanied by increased intracellular calcium levels and a decrease in mitochondrial membrane potential that seems to involve the mitochondrial permeability transition pore. The cell death mode revealed early apoptotic cells and high number of cells undergoing secondary necrosis. Among the tested drugs, TFMPP seems to be the most potent cytotoxic compound. Overall, piperazine designer drugs are potentially cardiotoxic and support concerns on risks associated with the intake of these drugs. PMID:24968061

Arbo, Marcelo Dutra; Silva, Renata; Barbosa, Daniel José; da Silva, Diana Dias; Rossato, Luciana Grazziotin; Bastos, Maria de Lourdes; Carmo, Helena

2014-08-17

134

Characterization of tunable piperidine and piperazine carbamates as inhibitors of endocannabinoid hydrolases  

PubMed Central

Monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH) are two enzymes from the serine hydrolase superfamily that degrade the endocannabinoids 2-arachidonoylglycerol and anandamide, respectively. We have recently discovered that MAGL and FAAH are both inhibited by carbamates bearing an N-piperidine/piperazine group. Piperidine/piperazine carbamates show excellent in vivo activity, raising brain endocannabinoid levels and producing CB1-dependent behavioral effects in mice, suggesting that they represent a promising class of inhibitors for studying the endogenous functions of MAGL and FAAH. Herein, we disclose a full account of the syntheses, structure-activity relationships, and inhibitory activities of piperidine/piperazine carbamates against members of the serine hydrolase family. These scaffolds can be tuned for MAGL-selective or dual MAGL-FAAH inhibition by the attachment of an appropriately substituted bisarylcarbinol or aryloxybenzyl moiety, respectively, on the piperidine/piperazine ring. Modifications to the piperidine/piperazine ring ablated inhibitory activity, suggesting a strict requirement for a six-member ring to maintain potency.

Long, Jonathan Z.; Jin, Xin; Adibekian, Alexander; Li, Weiwei; Cravatt, Benjamin F.

2010-01-01

135

The acute effect in rats of 3,4-methylenedioxyethamphetamine (MDEA, "eve") on body temperature and long term degeneration of 5-HT neurones in brain: a comparison with MDMA ("ecstasy").  

PubMed

Administration of a single dose of the recreationally used drug 3,4-methylenedioxyethamphetamine (MDEA or "eve") to Dark Agouti rats resulted in an acute dose-dependent hyperthermic response. The peak effect and duration of hyperthermia of a dose of MDEA of 35 mg/kg intraperitoneally was similar to a dose of 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") of 15 mg/kg intraperitoneally. Seven days later this dose of MDMA produced a marked (approximately 50%) loss of 5-HT and its metabolite 5-HIAA in cortex, hippocampus and striatum and a similar loss of [3H]-paroxetine binding in cortex: these losses reflecting the MDMA-induced neurotoxic degeneration of 5-HT nerve endings. In contrast, administration of MDEA (15, 25 or 35 mg/kg), even at the highest dose, produced only a 20% loss in cortex and hippocampus and no decrease in striatum. The neurotoxic effect of MDEA was only weakly dose-dependent. Neither MDEA (35 mg/kg) nor MDMA (15 mg/kg) altered striatal dopamine content 7 days later. MDEA appeared to have about half the potency of MDMA in inducing acute hyperthermia and 25% of the potency in inducing degeneration of cerebral 5-HT neurones. However since higher doses of MDEA (compared to MDMA) are probably necessary to induce mood changing effects, these data do not support any contention that this compound is a "safer" recreational drug than MDMA in terms of either acute toxicity or long term neurodegeneration. PMID:10401727

Colado, M I; Granados, R; O'Shea, E; Esteban, B; Green, A R

1999-06-01

136

Molecular Pacman: folding, inclusion, and X-ray structures of tri- and tetraamino piperazine cyclophanes.  

PubMed

Reaction of piperazine and 1,3-bis(bromomethyl)-2-nitrobenzene under high-dilution conditions yields cyclic trimeric trinitro, tetrameric tetranitro, and pentameric pentanitro piperazine cyclophanes. Reduction of the nitro groups with SnCl(2) under acidic conditions produces the corresponding triamino and tetraamino piperazine cyclophanes. The solution studies of both nitro and amino piperazine cyclophanes at 30 degrees C by (1)H NMR spectroscopy shows symmetrical structures owing to the fast conformational exchange, whereas the low temperature studies of the tetraamino piperazine cyclophane reveals interesting dynamic behavior that indicates additional intramolecular interactions. Careful crystallizations of the trimeric trinitro and triamino and the tetrameric tetraamino cyclophanes resulted in crystals suitable for X-ray diffraction studies. In the crystalline state the amino-functionalized cyclophanes manifest an extraordinary circular intramolecular hydrogen-bonding network that leads to a fixed 3D structure. Hydrogen bonding in the triamino trimer leads to orientation of all three of the amino groups on the same side of the macrocycle, namely, the rcc conformation, whereas the tetraamino tetramer folds into a more compact shell-like conformation. During the crystallization process one acetonitrile guest is enclosed into the cavity of the tetraamino cyclophane, which gives a crystalline inclusion complex with remarkable resemblance to the famous Pacman motif. The folding, which mimics the behavior of some cyclic peptides and pyrroles, is induced by intramolecular hydrogen bonding from the amino groups to the tertiary amine groups of the piperazines. The cavity of the tetraamino tetramer is markedly smaller than in the corresponding, but nonfolded, tetranitro tetramer and the guest/host volume ratio (packing coefficient) for the acetonitrile and the cavity is approximately 50 %, which indicates a good size match for acetonitrile inclusion. PMID:18288653

Raatikainen, Kari; Huuskonen, Juhani; Kolehmainen, Erkki; Rissanen, Kari

2008-01-01

137

New metal phosphonates containing coordination piperazine or pyridyl groups  

NASA Astrophysics Data System (ADS)

Reactions of transition metal(II) salts with three aminophosphonic acids, 1-[(H 2O 3PCH 2) 2NCH 2CH 2-]-piperazine-4-CH 2PO 3H 2 (H 6L 1), 3-pyridyl-CH 2N(CH 2PO 3H 2) 2 (H 4L 2) and 4-pyridyl-CH 2N(CH 2PO 3H 2) 2 (H 4L 3) afforded three new metal phosphonates, namely, Cu(H 4L 1)·2H 2O (1), Co(H 3L 2) 2·H 2O (2) and [Co(H 2L 3)(H 2O)]·H 2O (3). The structure of compound 1 features a 1D chain in which the CuN 2O 3 and CPO 3 polyhedra are interconnected by bridging phosphonate ligands to form 1D chains. Compound 2 has a layered structure. The cobalt(II) ions in the octahedral coordination geometries and {CPO 3} tetrahedra are interconnected into an inorganic chain via -N(CH 2PO 3H) 2 moieties, and adjacent chains are further bridged by the coordination pyridyl groups of H 3L 2 into a 2D layer. The structure of compound 3 features a 2D double layered structure, in which the Co(II) ions are interconnected by bridging phosphonate groups into a 1D chain along b-axis. Neighboring chains are interconnected by coordination pyridyl groups into a double layer perpendicular to the c-axis.

Song, Jun-Ling; Mao, Jiang-Gao

2005-11-01

138

1-Phenyl-piperazine-1,4-diium tetra-chlorido-cobalt(II)  

PubMed Central

In the title mol­ecular salt, (C10H16N2)[CoCl4], the piperazine ring of the phenyl­piperazine dication adopts a chair conformation and the phenyl ring occupies an equatorial orientation. In the tetra­chlorido­cobaltate(II) dianion, the Co—Cl bond lengths for the chloride ions not accepting hydrogen bonds are significantly shorter than those for the chloride ions accepting such bonds. In the crystal, the components are linked by N—H?Cl hydrogen bonds, generating [001] chains.

Dhieb, Abdelhamid Chiheb; Janzen, Daron E.; Rzaigui, Mohamed; Smirani Sta, Wajda

2014-01-01

139

The study on organic nitrates, part V. New derivatives of piperazine potential NO donors.  

PubMed

We have obtained a series of non-symmetrical 1,4-disubstituted derivatives of piperazine, with the structure of organic nitrates, as potential NO donors. These compounds were obtained from respective hydroxyl derivatives of piperazine in an esterification reaction by fuming nitric acid. The obtained nitrates were tested in-vitro by reaction with a sulfhydryl compound. The structure of the most active nitrate and its hydroxyl analogue was used for the calculation of geometrical optimization with the determination of 3D-QSAR by a semi-empirical method PM3 using HyperChem 4.5. PMID:11902813

Korzycka, Lucyna

2002-03-01

140

Theoretical study of differential enthalpy of absorption of CO2 with MEA and MDEA as a function of temperature.  

PubMed

Temperature dependent correlations for enthalpy of deprotonation, carbamate formation, and heat of absorption of the overall reaction between aqueous MEA and MDEA and gaseous CO2 are calculated on the basis of computational chemistry based ln K values input to the Gibbs-Helmholtz equation. Temperature dependency of reaction equilibrium constants for deprotonation and carbamate formation reactions is calculated with the SM8T continuum solvation model coupled with density functional theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. Calculated reaction equilibrium constants and enthalpies of individual reactions and overall heat of absorption are compared against experimental data in the temperature range 273.15-373 K. Temperature dependent correlations for different reaction equilibrium constants and enthalpies of reactions are given. These correlated results can be used in thermodynamic models such as UNIQUAC and NRTL for better understanding of post-combustion CO2 capture solvent chemistry. PMID:23855311

Gupta, Mayuri; da Silva, Eirik F; Hartono, Ardi; Svendsen, Hallvard F

2013-08-15

141

Differences in binding affinities of MDA, MDMA, MDEA, Amphetamine, Methamphetamine, and their deuterated analogues to solid-phase extraction cartridges.  

PubMed

This study evaluated the potential for partial separation of drugs from their deuterated internal standards using Cerex(®) Polycrom™ CLIN II solid-phase extraction (SPE) cartridges. After elution from the column and derivatization, gas chromatography-mass spectrometry results showed that the target compound eluted from the SPE cartridge prior to its deuterated form. This elution separation effect was greater for 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (MAMP) than for the other drugs studied. When the drugs were eluted in 0.5 mL increments from a 50 mg sorbent bed, no drug appeared in the first fraction. The drug to internal standard ratios (expected value 1.00) for subsequent fractions collected were 1.30, 1.07, and 0.83 for MDA/MDA-d(5); 1.65, 1.18, 0.67, and 0.56 for MDMA/MDMAd(5); and 1.37, 1.18, and 0.95 for MDEA/MDEA-d(6). For d-AMP and d-MAMP, the expected ratio was 0.40. The subsequent ratios were 0.63, 0.46, 0.35, and 0.34 for d-AMP/d-AMP-d(11); and 1.00, 0.59, 0.25, and 0.18 for d-MAMP/d-MAMP-d(14). The affinity of d-MAMPd(14) was shown to be greater than that of d-MAMP-d(5), and deuteration at the propyl end of the molecule was shown to increase binding more than deuteration on the phenyl group. PMID:21219698

Romberg, R W; Ntamack, A G; Blacik, L J; Kazarian, C M; Snyder, J Jacob; Welsh, E R

2011-01-01

142

Integration of enabling methods for the automated flow preparation of piperazine-2-carboxamide.  

PubMed

Here we describe the use of a new open-source software package and a Raspberry Pi(®) computer for the simultaneous control of multiple flow chemistry devices and its application to a machine-assisted, multi-step flow preparation of pyrazine-2-carboxamide - a component of Rifater(®), used in the treatment of tuberculosis - and its reduced derivative piperazine-2-carboxamide. PMID:24778715

Ingham, Richard J; Battilocchio, Claudio; Hawkins, Joel M; Ley, Steven V

2014-01-01

143

Stereoselective synthesis of polysubstituted piperazines and oxopiperazines. Useful building blocks in medicinal chemistry.  

PubMed

Many pharmaceutical agents include piperazines or oxopiperazines as part of their core structures. The presence of substituents on these heterocycles has a significant influence on the biological activity, thus the search for efficient routes to control the substitution at different ring positions might have a crucial impact, especially to promote the use of such scaffolds in SAR studies. Many research groups have been engaged in the stereoselective synthesis of polysubstituted piperazines and oxopiperazines and in the majority of cases the stereochemistry of the final compounds is dependent on the starting material configuration. In the present minireview we have summarized some of the most significant approaches towards the stereoselective synthesis and functionalization of substituted piperazines and oxopiperazines, with a particular focus on our own contributions mainly based on readily available natural amino-acids as "chiral pool" starting materials. An efficient and scalable route to orthogonally protected 2-oxopiperazines has been developed using the corresponding diamines as key intermediates: diastereoselective elaboration of the resulting heterocycles was possible by metalation and reaction with electrophiles, leading to anti 3,5-disubstituted-oxopiperazines, in agreement with the model for a conventional 1,3-asymmetric induction. Both piperazines and tetrahydropyrazines could be prepared via LiAlH4-mediated reduction of 2-oxopiperazines, depending on reaction conditions. Finally, the diastereoselective synthesis of cyclopropane- containing analogs 2,5-diaza-bicyclo[4.1.0]heptanes was demonstrated by application of the classic Simmons-Smith reaction on enantiomerically enriched dihydro-2H-pyrazines. PMID:24758427

Mordini, Alessandro; Reginato, Gianna; Calamante, Massimo; Zani, Lorenzo

2014-01-01

144

Synthesis and Chemistry of Some Furazano- and Furoxano(3,4-b)piperazines.  

National Technical Information Service (NTIS)

A series of N,N'-disubstituted furazano- and furoxano (3,4-B) piperazines have been syntheiszed from N,N'-disubstituted 2,3-piperazinedione dioximes by base-promoted dehydration and by basic potassium ferricyanide oxidation, respectively. The N,N'-disubst...

R. L. Willer D. W. Moore

1985-01-01

145

Pilot plant studies of the COâ capture performance of aqueous MEA and mixed MEA\\/MDEA solvents at the University of Regina COâ capture technology development plant and the Boundary Dam COâ capture demonstration  

Microsoft Academic Search

Evaluations of the benefits of using a mixed MEA\\/MDEA solvent for COâ capture in terms of the heat requirement for solvent regeneration, lean and rich loadings, COâ production, and solvent stability were performed by comparing the performance of aqueous 5 kmol\\/m³ MEA with that of an aqueous 4:1 molar ratio MEA\\/MDEA blend of 5 kmol\\/ml total amine concentration as a

R. Idem; M. Wilson; P. Tontiwachwuthikul; A. Chakma; A. Veawab; A. Aroonwilas; D. Gelowitz

2006-01-01

146

Development and Validation of a Disk Solid Phase Extraction and Gas Chromatography-Mass Spectrometry Method for MDMA, MDA, HMMA, HMA, MDEA, Methamphetamine and Amphetamine in Sweat  

PubMed Central

We describe the development and validation of a method for the simultaneous quantification of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3-hydroxy-4-methoxymethamphetamine (HMMA), 3-hydroxy-4-methoxyamphetamine (HMA), 3,4-methylenedioxyethylamphetamine (MDEA), methamphetamine (MAMP) and amphetamine (AMP) in sweat. Drugs were eluted from PharmChek™ sweat patches with sodium acetate buffer, extracted with disk solid phase extraction and analyzed using GC/MS-EI with selected ion monitoring. Limits of quantification (LOQ) for MDMA, MDEA, MAMP and AMP were 2.5 ng/patch, and 5 ng/patch for MDA, HMA and HMMA. This fully validated procedure was more sensitive than previously published analytical methods and permitted the simultaneous analysis of multiple amphetamine analogs in human sweat.

De Martinis, Bruno S.; Barnes, Allan J.; Scheidweiler, Karl B.; Huestis, Marilyn A.

2009-01-01

147

GC–MS and GC–IRD analysis of ring and side chain regioisomers of ethoxyphenethylamines related to the controlled substances MDEA, MDMMA and MBDB  

Microsoft Academic Search

Three regioisomeric 3, 4-methylenedioxyphenethylamines having the same molecular weight and major mass spectral fragments of equal mass have been reported as drugs of abuse in recent years. These compounds are 3,4-methylenedioxy-N-ethylamphetamine (MDEA), 3,4-methylenedioxy-N,N-dimethylamphetamine (MDMMA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB). Ring substituted ethoxy phenethylamines having the same side chain are compounds with an isobaric relationship to these controlled drug substances, all have molecular

Abdullah M. Al-Hossaini; Tamer Awad; Jack DeRuiter; C. Randall Clark

2010-01-01

148

Development of a validated method for the simultaneous determination of amphetamine, methamphetamine and methylenedioxyamphetamines (MDA, MDMA, MDEA) in serum by GC-MS after derivatisation with perfluorooctanoyl chloride  

Microsoft Academic Search

A rapid and simple method for the simultaneous detection and quantitation of amphetamine, methamphetamine, methylenedioxyamphetamine\\u000a (MDA), methylenedioxymethamphetamine (MDMA) and methylenedioxyethylamphetamine (MDEA) in human serum was developed and fully\\u000a validated. Serum samples were extracted with cyclohexane, derivatised with perfluorooctanoyl chloride without prior evaporation\\u000a of the solvent and analysed with gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode (SIM). For

Folker Westphal; Cornelia Franzelius; Jon Schäfer; Hans Werner Schütz; Gertrud Rochholz

2007-01-01

149

Modelling selective H 2S absorption and desorption in an aqueous MDEA-solution using a rate-based non-equilibrium approach  

Microsoft Academic Search

A rate-based algorithm was used to yield a predictive tool for MDEA gas scrubbing processes. The model adopts the two-film theory, assuming that thermodynamic equilibrium exists only at the gas–liquid interphase, but not in the boundary layers, where temperature and concentration gradients are present. Correspondingly chemical equilibrium among the reacting species in the liquid phase is assumed for the bulk

Markus Bolhàr-Nordenkampf; Anton Friedl; Ulrich Koss; Thomas Tork

2004-01-01

150

Development and validation of a disk solid phase extraction and gas chromatography–mass spectrometry method for MDMA, MDA, HMMA, HMA, MDEA, methamphetamine and amphetamine in sweat  

Microsoft Academic Search

We describe the development and validation of a method for the simultaneous quantification of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3-hydroxy-4-methoxymethamphetamine (HMMA), 3-hydroxy-4-methoxyamphetamine (HMA), 3,4-methylenedioxyethylamphetamine (MDEA), methamphetamine (MAMP) and amphetamine (AMP) in sweat. Drugs were eluted from PharmChek™ sweat patches with sodium acetate buffer, extracted with disk solid phase extraction and analyzed using GC\\/MS-EI with selected ion monitoring. Limits of quantification (LOQ)

Bruno S. De Martinis; Allan J. Barnes; Karl B. Scheidweiler; Marilyn A. Huestis

2007-01-01

151

Two-Dimensional Gas Chromatography\\/ Electron-Impact Mass Spectrometry with Cryofocusing for Simultaneous Quantification of MDMA, MDA, HMMA, HMA, and MDEA in Human Plasma  

Microsoft Academic Search

BACKGROUND: 3,4-Methylenedioxymethamphetamine (MDMA, or Ecstasy) is a popular recreational drug. Analysis of MDMA and metabolites in human plasma, particularly in pharmacokinetic studies, requires low limits of quantification. Two-dimensional GC\\/MS with cryofocusing is a chromatographic technique rec- ognized for its increased selectivity and resolution. METHODS: This method simultaneously quantifies 3,4- methylenedioxyethylamphetamine (MDEA), MDMA, and its metabolites, 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and

Erin A. Kolbrich; Ross H. Lowe; Marilyn A. Huestis

152

Imidazole piperazines: SAR and development of a potent class of cyclin-dependent kinase inhibitors with a novel binding mode  

Microsoft Academic Search

A piperazine series of cyclin-dependent kinase (CDK) inhibitors have been identified. The compounds exhibit excellent physiochemical properties and a novel binding mode, whereby a bridging interaction via a water molecule with Asp 86 of CDK2, leads to selectivity for the CDK family of enzymes over other kinases. Piperazines 2e and 2i were subsequently shown to inhibit tumour growth when dosed

M. Raymond V. Finlay; David G. Acton; David M. Andrews; Andrew J. Barker; Michael Dennis; Eric Fisher; Mark A. Graham; Clive P. Green; David W. Heaton; Galith Karoutchi; Sarah A. Loddick; Rémy Morgentin; Andrew Roberts; Julie A. Tucker; Hazel M. Weir

2008-01-01

153

Enantioselective synthesis of C2-functionalized, N-protected morpholines and orthogonally N,N?-protected piperazines via organocatalysis  

PubMed Central

In this Letter, we describe a novel three-step, one-pot procedure for the enantioselective synthesis of N-benzyl protected morpholines and orthogonally N,N?-protected piperazines with chiral alkyl groups installed at the C2 position of each heterocyclic core via organocatalysis. This methodology allows for the rapid preparation of functionalized morpholines and piperazines that are not readily accessible through any other chemistry in good to excellent % ee (55–98% ee).

O'Reilly, Matthew C.; Lindsley, Craig W.

2012-01-01

154

Investigations on the stereoselectivity of the phase II metabolism of the 3,4-methylenedioxyethylamphetamine (MDEA) metabolites 3,4-dihydroxyethylamphetamine (DHEA) and 4-hydroxy-3-methoxyethylamphetamine (HMEA).  

PubMed

Different elimination was reported for the two enantiomers of the designer drug 3,4-methylenedioxyethylamphetamine (MDEA) in vivo. In the present work, the enantioselectivity of glucuronidation and sulfation of the MDEA phase I metabolites 3,4-dihydroxyethylamphetamine (DHEA) and 4-hydroxy-3-methoxyethylamphetamine (HMEA) was investigated. First, glucuronide standards were synthesized using rat liver microsomes. Incubations were performed with recombinant human UDP-glucuronyltransferases (UGT) and pooled human liver microsomes (pHLM) for glucuronidation and using recombinant human sulfotransferases (SULT) and pooled human liver cytosol (pHLC) for sulfation. Product formation experiments were performed by quantification of the phase II metabolites using liquid chromatography-high-resolution mass spectrometry. Additionally, substrate depletion experiments were conducted by gas chromatography-mass spectrometry after chiral derivatization for sulfation. UGT2B7, 2B15, and 2B17 were involved in glucuronidation of HMEA and SULT1A1 and SULT1A3 and SULT1A3 and SULT1E1 in the sulfation of DHEA and HMEA, respectively. SULTs provided much higher affinity, whereas UGTs showed higher capacities. Marked stereoselectivity could be observed for UGT2B15, UGT2B17, and pHLM toward S-HMEA, for SULT1A3 and pHLC toward S-DHEA and for SULT1A3 and pHLC toward R-HMEA. In conclusion, the phase II metabolism might also contribute to the observed different pharmacokinetic properties of MDEA. PMID:22564759

Schwaninger, Andrea E; Meyer, Markus R; Zapp, Josef; Maurer, Hans H

2012-07-01

155

[Study of new blended chemical absorbents to absorb CO2].  

PubMed

Three kinds of blended absorbents were investigated on bench-scale experimental bench according to absorption rate and regeneration grade to select a reasonable additive concentration. The results show that, among methyldiethanolamine (MDEA) and piperazine (PZ) mixtures, comparing MDEA : PZ = 1 : 0.4 (m : m) with MDEA : PZ = 1 : 0.2 (m : m), the absorption rate is increased by about 70% at 0.2 mol x mol(-1). When regeneration lasting for 40 min, regeneration grade of blended absorbents with PZ concentration of 0.2, 0.4, and 0.8 is decreased to 83.06%, 77.77% and 76.67% respectively while 91.04% for PZ concentration of 0. MDEA : PZ = 1 : 0.4(m : m) is a suitable ratio for MDEA/PZ mixtures as absorption and regeneration properties of the blended absorbents are all improved. The aqueous blends with 10% primary amines and 2% tertiary amines could keep high CO2 absorption rate, and lower regeneration energy consumption. Adding 2% 2-Amino-2-methyl-1-propanol (AMP) to 10% diethanolamine (DEA), the blended amine solvents have an advantage in absorption and regeneration properties over other DEA/AMP mixtures. Blended solvents, which consist of a mixture of primary amines with a small amount of tertiary amines, have the highest absorption rate among the three. And mixed absorbents of secondary amines and a small amount of sterically hindered amines have the best regeneration property. To combine absorption and regeneration properties, blends with medium activator addition to tertiary amines are competitive. PMID:18290495

Wang, Jin-Lian; Fang, Meng-Xiang; Yan, Shui-Ping; Luo, Zhong-Yang; Cen, Ke-Fa

2007-11-01

156

Cancer Cell Cytotoxicities of 1-(4-Substitutedbenzoyl)-4-(4-chlorobenzhydryl)piperazine Derivatives  

PubMed Central

A series of novel 1-(4-substitutedbenzoyl)-4-(4-chlorobenzhydryl)piperazine derivatives 5a–g was designed by a nucleophilic substitution reaction of 1-(4-chlorobenzhydryl)piperazine with various benzoyl chlorides and characterized by elemental analyses, IR and 1H nuclear magnetic resonance spectra. Cytotoxicity of the compounds was demonstrated on cancer cell lines from liver (HUH7, FOCUS, MAHLAVU, HEPG2, HEP3B), breast (MCF7, BT20, T47D, CAMA-1), colon (HCT-116), gastric (KATO-3) and endometrial (MFE-296) cancer cell lines. Time-dependent cytotoxicity analysis of compound 5a indicated the long-term in situ stability of this compound. All compounds showed significant cell growth inhibitory activity on the selected cancer cell lines.

Yarim, Mine; Koksal, Meric; Durmaz, Irem; Atalay, Rengul

2012-01-01

157

Synthesis and evaluation of 1-(quinoliloxypropyl)-4-aryl piperazines for atypical antipsychotic effect.  

PubMed

A series of 1-(quinoliloxypropyl)-4-aryl-piperazines has been synthesized and the target compounds evaluated for atypical antipsychotic activity in apomorphine induced mesh climbing and stereotypic behaviour in mice. The 8-hydroxyquinoline ether derivative 14 has emerged as an important lead compound showing a potential atypical antipsychotic profile. Employing appropriate physicochemical properties, the similarity of the compounds was assessed with respect to some atypical antipsychotic drugs as clozapine, ketanserine, ziprasidone and risperidone. PMID:19398330

Bali, Alka; Malhotra, Sarika; Dhir, Himjyoti; Kumar, Anil; Sharma, Ajay

2009-06-01

158

Kinetics of base hydrolysis of ?-amino acid esters catalyzed by palladium(II) piperazine complex  

Microsoft Academic Search

The kinetics of base hydrolysis of glycine, histidine, and methionine methyl esters in the presence of [Pd(pip)(H2O)2]2+ complex, where pip is piperazine, is studied in aqueous solutions, at T = 25°C, and I = 0.1 mol dm?3. The rate of ester hydrolysis for glycine methyl ester is studied at different temperature and dioxane\\/water solutions of\\u000a different compositions. The kinetic data

Azza A. Shoukry; Mohamed M. Shoukry; Mohamed N. Hafez

2010-01-01

159

Benzothiophene piperazine and piperidine urea inhibitors of fatty acid amide hydrolase (FAAH)  

PubMed Central

The synthesis and structure–activity relationships (SAR) of a series of benzothiophene piperazine and piperidine urea FAAH inhibitors is described. These compounds inhibit FAAH by covalently modifying the enzyme’s active site serine nucleophile. Activity-based protein profiling (ABPP) revealed that these urea inhibitors were completely selective for FAAH relative to other mammalian serine hydrolases. Several compounds showed in vivo activity in a rat complete Freund’s adjuvant (CFA) model of inflammatory pain.

Johnson, Douglas S.; Ahn, Kay; Kesten, Suzanne; Lazerwith, Scott E.; Song, Yuntao; Morris, Mark; Fay, Lorraine; Gregory, Tracy; Stiff, Cory; Dunbar, James B.; Liimatta, Marya; Beidler, David; Smith, Sarah; Nomanbhoy, Tyzoon K.; Cravatt, Benjamin F.

2011-01-01

160

Tri-chlorido-(1-ethyl-piperazin-1-ium)cobalt(II)  

PubMed Central

In the title complex, [Co(C6H15N2)Cl3], the Co2+ ion is coordinated in a distorted tetra­hedral fashion by three chloride ions and one N atom of the piperazine ring; the ring adopts a chair conformation with the N—Co and N—CEt bonds in equatorial orientations. In the crystal, mol­ecules are connected by N—H?Cl hydrogen bonds, generating (10-1) sheets.

Dhieb, Abdelhamid Chiheb; Janzen, Daron E.; Rzaigui, Mohamed; Smirani Sta, Wajda

2014-01-01

161

1-Methyl-piperazine-1,4-diium tetra-chloridozincate hemihydrate  

PubMed Central

The crystal structure of the title compound, (C5H14N2)[ZnCl4]·0.5H2O, is built up from discrete 1-methyl­piperazine­diium cations with chair conformation, tetrahedral tetrachloridozincate anions and uncoordinated solvent water mol­ecules linked together by three types of inter­molecular hydrogen bonds, viz. N—H?Cl, N—H?O and O—H?Cl.

Walha, Sondra; Naili, Houcine; Yahyaoui, Samia; Mhiri, Tahar

2011-01-01

162

Piperazine sulfonamide BACE1 inhibitors: Design, synthesis, and in vivo characterization  

SciTech Connect

With collaboration between chemistry, X-ray crystallography, and molecular modeling, we designed and synthesized a series of novel piperazine sulfonamide BACE1 inhibitors. Iterative exploration of the non-prime side and S2{prime} sub-pocket of the enzyme culminated in identification of an analog that potently lowers peripheral A{beta}{sub 40} in transgenic mice with a single subcutaneous dose.

Cumming, Jared; Babu, Suresh; Huang, Ying; Carrol, Carolyn; Chen, Xia; Favreau, Leonard; Greenlee, William; Guo, Tao; Kennedy, Matthew; Kuvelkar, Reshma; Le, Thuy; Li, Guoqing; McHugh, Nansie; Orth, Peter; Ozgur, Lynne; Parker, Eric; Saionz, Kurt; Stamford, Andrew; Strickland, Corey; Tadesse, Dawit; Voigta, Johannes; Zhang, Lili; Zhang, Qi (Ligand); (Merck)

2010-08-17

163

Melanocortin subtype-4 receptor agonists containing a piperazine core with substituted aryl sulfonamides  

Microsoft Academic Search

The biological activity for a set of melanocortin-4 receptor (MC4R) agonists containing a piperazine core with an ortho-substituted aryl sulfonamide is described. Compounds from this set had binding and functional activities at MC4R less than 30nM. The most selective compound in this series was >25,000-fold more potent at MC4R than MC3R, and 490-fold more potent at MC4R than MC5R. This

Christopher Fotsch; Nianhe Han; Premilla Arasasingham; Yunxin Bo; Michelle Carmouche; Ning Chen; James Davis; Martin H. Goldberg; Clarence Hale; Feng-Yin Hsieh; Michael G. Kelly; Qingyian Liu; Mark H. Norman; Duncan M. Smith; Markian Stec; Nuria Tamayo; Ning Xi; Shimin Xu; Anthony W. Bannon; James W. Baumgartner

2005-01-01

164

4-(2-Azaniumyl-eth-yl)piperazin-1-ium bis(perchlorate)  

PubMed Central

In the title compound, C6H17N3 2+·2ClO4 ?, the piperazine ring adopts a chair conformation with the ethyl­ammonium fragment occupying an equatorial position. In the crystal, the dications and perchlorate anions are linked through N—H?O hydrogen bonding and weak C—H?O hydrogen bonding into a three-dimensional supra­molecular network.

Reisi, Mohammad Reza; Saleh Salga, Muhammad; Khaledi, Hamid; Mohd Ali, Hapipah

2011-01-01

165

trans-2,5-Di-methyl-piperazine-1,4-diium dinitrate  

PubMed Central

In the structure of the title salt, C6H16N2 2+·2NO3 ?, the cations are connected to the anions through bifurcated N—H?(O,O) and weak C—H?O hydrogen bonds, generating corrugated layers parallel to the (100) plane. The organic cation is centrosymmetric and the diprotonated piperazine ring adopts a chair conformation, with the methyl groups occupying equatorial positions.

Gatfaoui, Sofian; Roisnel, Thierry; Dhaouadi, Hassouna; Marouani, Houda

2014-01-01

166

Multimetallic assemblies using piperazine-based dithiocarbamate building blocks.  

PubMed

Treatment of cis-[RuCl2(dppm)2] (dppm = bis(diphenylphosphino)methane) with dithiocarbamates, NaS2CNR2 (R = Me, Et) and [H2NC5H10][S2CNC5H10], yields cations [Ru(S2CNR2)2(dppm)2](+) and [Ru(S2CNC5H10)2(dppm)2](+), respectively. The zwitterions S2CNC4H8NHR (R = Me, Et) react with the same metal complex in the presence of base to yield [Ru(S2CNC4H8NR)(dppm)2](+). Piperazine or 2,6-dimethylpiperazine reacts with carbon disulfide to give the zwitterionic dithiocarbamate salts H2NC4H6(R2-3,5)NCS2 (R = H; R = Me), which form the complexes [Ru(S2CNC4H6(R2-3,5)NH2)(dppm)2](2+) on reaction with cis-[RuCl2(dppm)2]. Sequential treatment of [Ru(S2CNC4H8NH2)(dppm)2](2+) with triethylamine and carbon disulfide forms the versatile metalla-dithiocarbamate complex [Ru(S2CNC4H8NCS2)(dppm)2] which reacts readily with cis-[RuCl2(dppm)2] to yield [{Ru(dppm)2}2(S2CNC4H8NCS2)]. Reaction of [Ru(S2CNC4H8NCS2)(dppm)2] with [Os(CH=CHC6H4Me-4)Cl(CO)(BTD)(PPh3)2] (BTD = 2,1,3-benzothiadiazole), [Pd(C6H4CH2NMe2)Cl]2, [PtCl2(PEt3)2], and [NiCl2(dppp)] (dppp = 1,3-bis(diphenylphosphino)propane) results in the heterobimetallic complexes [(dppm)2Ru(S2CNC4H8NCS2)ML(n))](m+) (ML(n) = Os(CH=CHC6H4Me-4)(CO)(PPh3)2](+), m = 1; ML(n) = Pd(C,N-C6H4CH2NMe2), m = 1; ML(n) = Pt(PEt3)2, m = 2; ML(n) = Ni(dppp), m = 2). Reaction of [NiCl2(dppp)] with H2NC4H8NCS2 yields the structurally characterized compound, [Ni(S2CNC4H8NH2)(dppp)](2+), which reacts with base, CS2, and cis-[RuCl2(dppm)2] to provide an alternative route to [(dppm)2Ru(S2CNC4H8NCS2)Ni(dppp)](+). A further metalla-dithiocarbamate based on cobalt, [CpCo(S2CNC4H8NH2)(PPh3)](2+), is formed by treatment of CpCoI2(CO) with S2CNC4H8NH2 followed by PPh3. Further reaction with NEt3, CS2, and cis-[RuCl2(dppm)2] yields [(Ph3P)CpCo(S2CNC4H8NCS2)Ru(dppm)2](2+). Heterotrimetallic species of the form [{(dppm)2Ru(S2CNC4H8NCS2)}2M](2+) result from the reaction of [Ru(S2CNC4H8NCS2)(dppm)2] and M(OAc)2 (where M = Ni, Cu, Zn). Reaction of [Ru(S2CNC4H8NCS2)(dppm)2] with Co(acac)3 and LaCl3 results in the formation of the compounds [{(dppm)2Ru(S2CNC4H8NCS2)}3Co](3+) and [{(dppm)2Ru(S2CNC4H8NCS2)}3La](3+), respectively. The electrochemical behavior of selected examples is also reported. PMID:18811147

Wilton-Ely, James D E T; Solanki, Dina; Knight, Edward R; Holt, Katherine B; Thompson, Amber L; Hogarth, Graeme

2008-10-20

167

Binding of the Amphetamine-like 1-Phenyl-piperazine to Monoamine Transporters  

PubMed Central

The human serotonin transporter (hSERT), the human dopamine transporter (hDAT), and the human norepinephrine transporter (hNET) facilitate the active uptake of the neurotransmitters serotonin, dopamine, and norepinephrine from the synaptic cleft. Drugs of abuse such as MDMA (streetname “ecstasy”) and certain 1-phenyl-piperazine (PP) analogs such as 1-(3-chlorophenyl)-piperazine (mCPP) elicit their stimulatory effect by elevating the synaptic concentration of serotonin by blocking or reversing the normal transport activity of hSERT. Recent data suggest that certain analogs of PP may be able to counteract the addictive effect of cocaine. Little is still known about the precise mechanism by which MDMA and PP analogs function at hSERT, hDAT, and hNET and even less is known about the specific protein–ligand interactions. In this study, we provide a comprehensive biochemical examination of a repertoire of PP analogs in hSERT, hDAT, and hNET. Combined with induced fit docking models and molecular dynamics simulations of PP and 1-(3-hydroxyphenyl)-piperazine (3-OH-PP) bound to hSERT and hDAT, we present detailed molecular insight into the promiscuous binding of PP analogs in the monoamine transporters. We find that PP analogs inhibit uptake as well as induce release in all three monoamine transporters. We also find that the selectivity of the PP analogs can be adjusted by carefully selecting substituents on the PP skeleton.

2012-01-01

168

Is the conformational flexibility of piperazine derivatives important to inhibit HIV-1 replication?  

PubMed

The conserved binding site of HIV-1 gp120 envelope protein, an essential component in the viral entry process, provides an attractive antiviral target. The structural similarities between two piperazine derivatives: PMS-601, showing a dual activity for anti-PAF and anti-HIV activity, and BMS-378806, known to inhibit HIV-1 gp120, motivated us to merge important structural features of the two compounds. Novel piperazine derivatives were synthesized and evaluated in vitro concerning their ability to inhibit HIV-1 replication in in vitro infected lymphocytes. We described an approach that combines molecular docking, molecular dynamics, MM-PBSA calculations and conformational analysis to rationally predict piperazine derivatives binding mode with HIV-1 gp120. We also inquired about the conformational adaptability of the molecules, upon complex formation, and its importance to their respective inhibitory activity. The analysis suggested that the impact of the flexibility of these molecules revealed to be more important, in the context of drug design, than it has generally been assumed. These new insights at the atomic level might be useful to design inhibitors with improved antiviral activity. PMID:23748247

Teixeira, Cátia; Serradji, Nawal; Amroune, Souad; Storck, Karen; Rogez-Kreuz, Christine; Clayette, Pascal; Barbault, Florent; Maurel, François

2013-07-01

169

GC-MS studies on the regioisomeric methoxy-methyl-phenethylamines related to MDEA, MDMMA, and MBDB.  

PubMed

Three regioisomeric 3,4-methylenedioxyphenethylamines having the same molecular weight and major mass spectral fragments of equal mass have been reported as drugs of abuse in forensic studies in recent years. These compounds are 3,4-methylenedioxy-N-ethylamphetamine (MDEA), 3,4-methylenedioxy-N-N-dimethylamphetamine (MDMMA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB). The mass spectra of the regioisomers (4-methoxy-3-methyl and 4-methoxy-2-methyl-phenethylamines) are essentially equivalent to the three compounds reported as drugs of abuse. This project focused on the synthesis, mass spectral characterization, and chromatographic analysis of these six regioisomeric methoxy methyl phenethylamines. Additionally, the mass spectral and chromatographic properties of these compounds will be compared to the isobaric 2,3- and 3,4-methylenedioxyphenethyl-amines of the same side chain. The six regioisomeric methoxy-methyl-phenethylamines were synthesized from commercially available starting materials. Side chain differentiation by mass spectrometry was possible after the formation of the perfluoroacyl derivatives, pentafluoropropionylamides (PFPA) and heptafluorobutrylamides (HFBA). Gas chromatographic separation on Rtx-1 was successful at resolving the perfluoroacyl derivatives of the 4-methoxy-3-methyl phenethylamines from those of the 4-methoxy-2-methyl phenethylamines. The 4-methoxy-3-methyl-phenethylamine derivatives eluted before the 4-methoxy-2-methyl-phenethylamine derivatives as both the PFPA and HFBA derivatives. PMID:19007498

Thigpen, Ashley; Awad, Tamer; Deruiter, Jack; Clark, C Randall

2008-01-01

170

4-aryl piperazine and piperidine amides as novel mGluR5 positive allosteric modulators.  

PubMed

Positive allosteric modulation of metabotropic glutamate receptor 5 (mGluR5) is regarded as a potential novel treatment for schizophrenic patients. Herein we report the synthesis and SAR of 4-aryl piperazine and piperidine amides as potent mGluR5 positive allosteric modulators (PAMs). Several analogs have excellent activity and desired drug-like properties. Compound 2b was further characterized as a PAM using several in vitro experiments, and produced robust activity in several preclinical animal models. PMID:21067920

Xiong, Hui; Brugel, Todd A; Balestra, Michael; Brown, Dean G; Brush, Kelly A; Hightower, Caprice; Hinkley, Lindsay; Hoesch, Valerie; Kang, James; Koether, Gerard M; McCauley, John P; McLaren, Francis M; Panko, Laura M; Simpson, Thomas R; Smith, Reed W; Woods, James M; Brockel, Becky; Chhajlani, Vijay; Gadient, Reto A; Spear, Nathan; Sygowski, Linda A; Zhang, Minli; Arora, Jalaj; Breysse, Nathalie; Wilson, Julie M; Isaac, Methvin; Slassi, Abdelmalik; King, Megan M

2010-12-15

171

1-Methyl-piperazine-1,4-dium bis-(hydrogen oxalate)  

PubMed Central

In the crystal structure of the title compound, C5H14N2 2+·2HC2O4 ?, the two crystallographically independent hydrogen oxalate anions are linked by strong inter­molecular O—H?O hydrogen bonds, forming two independent corrugated chains parallel to the b axis. These chains are further connected by N—H?O and C—H?O hydrogen bonds originating from the organic cations, forming a three-dimensional network. The diprotonated piperazine ring adopts a chair conformation, with the methyl group occupying an equatorial position.

Essid, Manel; Marouani, Houda; Rzaigui, Mohamed

2014-01-01

172

Melanocortin subtype-4 receptor agonists containing a piperazine core with substituted aryl sulfonamides.  

PubMed

The biological activity for a set of melanocortin-4 receptor (MC4R) agonists containing a piperazine core with an ortho-substituted aryl sulfonamide is described. Compounds from this set had binding and functional activities at MC4R less than 30 nM. The most selective compound in this series was >25,000-fold more potent at MC4R than MC3R, and 490-fold more potent at MC4R than MC5R. This compound also reduced food intake after oral dosing at 25, 50, and 100 mg kg(-1) in fasted mice. PMID:15745810

Fotsch, Christopher; Han, Nianhe; Arasasingham, Premilla; Bo, Yunxin; Carmouche, Michelle; Chen, Ning; Davis, James; Goldberg, Martin H; Hale, Clarence; Hsieh, Feng-Yin; Kelly, Michael G; Liu, Qingyian; Norman, Mark H; Smith, Duncan M; Stec, Markian; Tamayo, Nuria; Xi, Ning; Xu, Shimin; Bannon, Anthony W; Baumgartner, James W

2005-03-15

173

Synthesis and antimalarial evaluation of new 1,4-bis(3-aminopropyl)piperazine derivatives.  

PubMed

Synthesis and evaluation of the activity of a new family of 1,4-bis(3-aminopropyl)piperazine derivatives against a chloroquine-resistant strain of Plasmodium falciparum, and as inhibitors of beta-hematin formation, are described. The highest antimalarial activities were obtained for compounds displaying the highest predicted vacuolar accumulation ratios and the best potencies as inhibitors of beta-hematin formation. The most potent compound displayed an activity 3-fold better than chloroquine for a comparable selectivity index upon MRC-5 cells. Therefore, in this series, the replacement of the 7-chloroquinoline group can constitute a strong rationale for further investigation. PMID:14552779

Ryckebusch, Adina; Deprez-Poulain, Rébecca; Debreu-Fontaine, Marie-Ange; Vandaele, Richard; Mouray, Elisabeth; Grellier, Philippe; Sergheraert, Christian

2003-11-01

174

4-(Furan-2-carbon-yl)piperazin-1-ium 3,5-di-nitro-benzoate.  

PubMed

In the cation of the title salt, C9H13N2O2 (+)·C7H3N2O6 (-), the piperazine ring adopts a slightly distorted chair conformation. Twofold rotational disorder is exhibited by the furan ring in a 0.430?(4):0.570?(4) ratio. In the crystal, N-H?O hydrogen bonds link the ions into chains along [010]. Additional weak C-H?O inter-actions are observed, leading to a supra-molecular layer parallel to (011). PMID:24940274

Kavitha, Channappa N; Kaur, Manpreet; Jasinski, Jerry P; Butcher, Ray J; Yathirajan, H S

2014-06-01

175

4-(Furan-2-carbon-yl)piperazin-1-ium 3,5-di-nitro-benzoate  

PubMed Central

In the cation of the title salt, C9H13N2O2 +·C7H3N2O6 ?, the piperazine ring adopts a slightly distorted chair conformation. Twofold rotational disorder is exhibited by the furan ring in a 0.430?(4):0.570?(4) ratio. In the crystal, N—H?O hydrogen bonds link the ions into chains along [010]. Additional weak C—H?O inter­actions are observed, leading to a supra­molecular layer parallel to (011).

Kavitha, Channappa N.; Kaur, Manpreet; Jasinski, Jerry P.; Butcher, Ray J.; Yathirajan, H.S.

2014-01-01

176

Synthesis, properties and structural characterization of 4-(2-ammonioethyl)piperazin-1-ium tetrasulfidotungstate hemihydrate and 1-ethylpiperazinediium tetrasulfidotungstate  

Microsoft Academic Search

The reaction of ammonium tetrasulfidotungstate with 2-piperazin-1-ylethanamine or 1-ethylpiperazine results in the formation of 4-(2-ammonioethyl)piperazin-1-ium tetrasulfidotungstate hemihydrate (C6H17N3)[WS4]·½H2O 1 or 1-ethylpiperazinediium tetrasulfidotungstate (C6H16N2)[WS4] 2. The hemihydrate 1 can be dehydrated to the anhydrous compound (C6H17N3)[WS4] 1a, which can be rehydrated to 1. Both 1 and 2 decompose to amorphous carbon containing tungsten disulphide. Compound 1 crystallizes in the centrosymmetric monoclinic

Bikshandarkoil R. Srinivasan; Ashish R. Naik; Sunder N. Dhuri; Christian Näther; Wolfgang Bensch

2009-01-01

177

2-[2-(4-Methyl-piperazin-1-yl)eth-yl]iso-indoline-1,3-dione  

PubMed Central

In the title compound, C15H19N3O2, the piperazine ring adopts a chair conformation, with its N—C bonds in pseudo-equatorial orientations. The dihedral angle between the C atoms of the piperazine ring and the phthalamide ring system (r.m.s. deviaiton = 0.008?Å) is 89.30?(8)°. In the crystal, mol­ecules are linked by C—H?O hydrogen bonds, generating a three-dimensional network and aromatic ?–? inter­actions also occur [centroid–centroid distances = 3.556?(1)–3.716?(1)?Å].

Zhou, Mi; Shao, Ying; Xia, Yong-an; Liu, Xiao-Long; Sun, Xiao-Qiang

2014-01-01

178

Advanced Amine Solvent Formulations and Process Integration for Near-Term CO2 Capture Success  

SciTech Connect

This Phase I SBIR project investigated the economic and technical feasibility of advanced amine scrubbing systems for post-combustion CO2 capture at coal-fired power plants. Numerous combinations of advanced solvent formulations and process configurations were screened for energy requirements, and three cases were selected for detailed analysis: a monoethanolamine (MEA) base case and two “advanced” cases: an MEA/Piperazine (PZ) case, and a methyldiethanolamine (MDEA) / PZ case. The MEA/PZ and MDEA/PZ cases employed an advanced “double matrix” stripper configuration. The basis for calculations was a model plant with a gross capacity of 500 MWe. Results indicated that CO2 capture increased the base cost of electricity from 5 cents/kWh to 10.7 c/kWh for the MEA base case, 10.1 c/kWh for the MEA / PZ double matrix, and 9.7 c/kWh for the MDEA / PZ double matrix. The corresponding cost per metric tonne CO2 avoided was 67.20 $/tonne CO2, 60.19 $/tonne CO2, and 55.05 $/tonne CO2, respectively. Derated capacities, including base plant auxiliary load of 29 MWe, were 339 MWe for the base case, 356 MWe for the MEA/PZ double matrix, and 378 MWe for the MDEA / PZ double matrix. When compared to the base case, systems employing advanced solvent formulations and process configurations were estimated to reduce reboiler steam requirements by 20 to 44%, to reduce derating due to CO2 capture by 13 to 30%, and to reduce the cost of CO2 avoided by 10 to 18%. These results demonstrate the potential for significant improvements in the overall economics of CO2 capture via advanced solvent formulations and process configurations.

Fisher, Kevin S.; Searcy, Katherine; Rochelle, Gary T.; Ziaii, Sepideh; Schubert, Craig

2007-06-28

179

GC-MS and GC-IRD analysis of ring and side chain regioisomers of ethoxyphenethylamines related to the controlled substances MDEA, MDMMA and MBDB.  

PubMed

Three regioisomeric 3, 4-methylenedioxyphenethylamines having the same molecular weight and major mass spectral fragments of equal mass have been reported as drugs of abuse in recent years. These compounds are 3,4-methylenedioxy-N-ethylamphetamine (MDEA), 3,4-methylenedioxy-N,N-dimethylamphetamine (MDMMA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB). Ring substituted ethoxy phenethylamines having the same side chain are compounds with an isobaric relationship to these controlled drug substances, all have molecular weight of 207 and major fragment ions in their electron ionization mass spectra at m/z 72 and 135/136. The three methylenedioxyphenethylamines were resolved from the ethoxyphenethylamines by capillary gas chromatography using an Rxi-50 stationary phase. The trifluoroacetyl, pentafluoropropionyl and heptafluorobutryl derivatives of the secondary amines were evaluated in GC-MS studies. The mass spectra for these derivatives were significantly individualized and the resulting unique fragment ions allowed for specific side chain identification. The perfluoroacyl derivatives showed reasonable resolution on a non-polar stationary phase such as Rtx-1. GC-IRD studies provided structure-IR spectra relationships used for the discrimination of the three target drugs (MDEA, MDMMA and MBDB) from the other nine ring substituted ethoxyphenethylamine regioisomers. PMID:20427137

Al-Hossaini, Abdullah M; Awad, Tamer; DeRuiter, Jack; Clark, C Randall

2010-07-15

180

Kinetics of N-nitrosopiperazine formation from nitrite and piperazine in CO2 capture.  

PubMed

Piperazine (PZ) is an efficient amine for carbon capture systems, but it can form N-nitrosopiperazine (MNPZ), a carcinogen, from nitrogen oxides (NO(x)) in flue gas from coal or natural gas combustion. The reaction of nitrite with PZ was studied in 0.1 to 5 mol/dm(3) PZ with 0.001 to 0.8 mol CO2/mol PZ at 50 to 135 °C. The reaction forming MNPZ is first order in nitrite, piperazine carbamate species, and hydronium ion. The activation energy is 84 ± 2 kJ/mol with a rate constant of 8.5 × 10(3) ± 1.4 × 10(3) dm(6) mol(-2) s(-1) at 100 °C. The proposed mechanism involves protonation of the carbamate species, nucleophilic attack of the carbamic acid, and formation of bicarbonate and MNPZ. These kinetics and mechanism will be useful in identifying inhibitors and other strategies to reduce nitrosamine accumulation in CO2 capture by scrubbing with PZ or other amines. PMID:23438967

Goldman, Mark J; Fine, Nathan A; Rochelle, Gary T

2013-04-01

181

Synthesis, pharmacological evaluation, and ?1 receptor interaction analysis of hydroxyethyl substituted piperazines.  

PubMed

Starting from (S)- or (R)-aspartate, three synthetic strategies were explored to prepare hydroxyethyl substituted piperazines with different substituents at the N-atoms. ? receptor affinity was recorded using receptor material from both animal and human origin. ?1 affinities determined with guinea pig brain and human RPMI 8226 tumor cell lines differed slightly but showed the same tendency. (S)-2-[4-(Cyclohexylmethyl)-1-(naphthalene-2-ylmethyl)piperazin-2-yl]ethanol (7c) revealed the highest affinity at human ?1 receptors (Ki = 6.8 nM). The potent ?1 receptor ligand 7c was able to inhibit selectively the growth of three human tumor cell lines with IC50 values in the low micromolar range. The reduced growth of the RPMI-8226 cell line was caused by apoptosis. The interaction of 7c with the ?1 receptor was analyzed in detail using the 3D homology model of the ?1 receptor. The calculated free binding energies of all hydroxyethylpiperazines nicely correlate with their recorded affinities toward the human ?1 receptor. PMID:24617836

Weber, Frauke; Brune, Stefanie; Korpis, Katharina; Bednarski, Patrick J; Laurini, Erik; Dal Col, Valentina; Pricl, Sabrina; Schepmann, Dirk; Wünsch, Bernhard

2014-04-10

182

Chiral separation and quantification of R\\/ S-amphetamine, R\\/ S-methamphetamine, R\\/ S-MDA, R\\/ S-MDMA, and R\\/ S-MDEA in whole blood by GC-EI-MS  

Microsoft Academic Search

The enantioselective composition of the amphetamines is of interest, as the enantiomers show differences in their pharmacological effects and several methods for chiral separation of amphetamines have been described. Only a few methods have used whole blood as matrix and none of these separates both classic amphetamines (amphetamine and methamphetamine) and designer amphetamines (MDA, MDMA and MDEA). The aim of

Louise Bang Rasmussen; Kristine Høje Olsen; Sys Stybe Johansen

2006-01-01

183

Synthesis and SAR of piperazine amides as novel c-jun N-terminal kinase (JNK) inhibitors  

SciTech Connect

A novel series of c-jun N-terminal kinase (JNK) inhibitors were designed and developed from a high-throughput-screening hit. Through the optimization of the piperazine amide 1, several potent compounds were discovered. The X-ray crystal structure of 4g showed a unique binding mode different from other well known JNK3 inhibitors.

Shin, Youseung; Chen, Weiming; Habel, Jeff; Duckett, Derek; Ling, Yuan Yuan; Koenig, Marcel; He, Yuanjun; Vojkovsky, Tomas; LoGrasso, Philip; Kamenecka, Theodore M.; (Scripps)

2009-09-14

184

Design, Synthesis and Biological Evaluation of Novel Piperazine Derivatives as CCR5 Antagonists  

PubMed Central

By using a fragment-assembly strategy and bioisosteric-replacement principle, a series of novel piperazine derivatives were designed, synthesized, and evaluated for their cellular target-effector fusion activities and in vitro antiviral activities against HIV-1. Preliminary structure-activity relationships (SARs) of target compounds were concluded in this study, and five compounds were found to exhibited medium to potent CCR5 fusion activities with IC50 values in low micromolar level. Among evaluated compounds, 23 h was found to be a CCR5 antagonist with an IC50 value of 6.29 µM and an anti-HIV-1 inhibitor with an IC50 value of 0.44 µM.

Liu, Tao; Weng, Zhiyong; Dong, Xiaowu; Chen, Linjie; Ma, Ling; Cen, Shan; Zhou, Naiming; Hu, Yongzhou

2013-01-01

185

Synthesis and antiproliferative evaluation of piperazine-1-carbothiohydrazide derivatives of indolin-2-one.  

PubMed

By varying the substituents (R(1)) at the indolin-2-one scaffold, a series of indolin-2-one derivatives bearing 4-phenylpiperazine-1-carbothiohydrazide moiety at the C3-position were synthesized and evaluated for their antiproliferative activity against three human cancer cell lines. We further selected the 5-chloroindolin-2-one moiety for the extension to another series of compounds by varying the substituents (R(2)) at the phenyl group connected with the piperazine ring. Among all the compounds synthesized, 6d and 6l were most potent with IC50 values of 3.59 and 5.58 ?M, respectively against A549 lung cancer cells, while 5f and 6l possessed IC50 values of 3.49 and 4.57 ?M, respectively against HCT-116 colon cancer cells which were comparable to that of Sunitinib, an indolin-2-one derivative in cancer therapy. PMID:23602441

Lin, Hui-Hui; Wu, Wei-Yao; Cao, Sheng-Li; Liao, Ji; Ma, Li; Gao, Man; Li, Zhong-Feng; Xu, Xingzhi

2013-06-01

186

Inhibition of adenovirus replication by a trisubstituted piperazin-2-one derivative.  

PubMed

The number of disseminated adenovirus (Ad) infections continues to increase mostly due to the growing use of immunosuppressive treatments. Recipients of solid organ or hematopoietic stem cell transplants, mainly in pediatric units, exhibit a high morbidity and mortality due to these infections. Unfortunately, there are no Ad-specific antiviral drugs currently approved for medical use. To address this situation, we used high-throughput screening (HTS) of synthetic small molecule libraries to identify compounds that restrict Ad infection. Among the more than 25,000 compounds screened, we identified a hit compound that significantly inhibited Ad infection. The compound (15D8) is a trisubstituted piperazin-2-one derivative that showed substantial antiviral activity with little or no cytotoxicity at low micromolar concentrations. Compound 15D8 selectively inhibits Ad DNA replication in the nucleus, providing a potential candidate for the development of a new class of antiviral compounds to treat Ad infections. PMID:24907427

Sanchez-Cespedes, Javier; Moyer, Crystal L; Whitby, Landon R; Boger, Dale L; Nemerow, Glen R

2014-08-01

187

Syntheses of aminated poly(vinyl chloride)s using methyl piperazine for the development of pH-selective membranes  

Microsoft Academic Search

Fifty-seven copolymers of poly(vinyl chloride-vinyl methyl piperazine) were prepared from the reaction of poly(vinyl chloride) (PVC) and 1-methyl piperazine (Me-PIP) either with dimethyl sulfoxide (DMSO) or without any aprotic solvent. Reaction temperatures, times and concentrations were varied from 23 to 45°C, from 1 to 35 days, and from 0.125 to 1.0 mol. eq. of Me-PIP, respectively. Nitrogen (N) analyses, electromotive

John Q Whitley; Robert P Kusy

1998-01-01

188

Design, synthesis and antitubercular evaluation of novel series of N-[4-(piperazin-1-yl)phenyl]cinnamamide derivatives.  

PubMed

The analogs of N-[4-(piperazin-1-yl)phenyl]cinnamamide were designed and synthesized by molecular hybridization approach in which part C of the designed molecule was linked through amide and carbamate functionality that improves the physicochemical properties and govern the pharmacokinetic and pharmacodynamic behavior. The systematic modification was done around the Part C to explore the structure activity relationship of antitubercular cinnamamide. All 52 compounds were evaluated for its antitubercular activity against Mycobacterium tuberculosis (M. tb) using Resazurin microtitre plate assay (REMA). Compound 11 g with trifluoromethyl substitution exhibited good antitubercular activity of 3.125 ?g/ml. The synthesized N-[4-(piperazin-1-yl)phenyl]cinnamamide derivatives showed promising activity against M. tb. PMID:24530490

Patel, Kavitkumar N; Telvekar, Vikas N

2014-03-21

189

Synthesis and crystal structure from X-ray powder diffraction data of two zirconium diphosphonates containing piperazine groups.  

PubMed

Two new zirconium aminophosphonates have been obtained by reaction of Zr(IV) with piperazine-N,N'-bis(methylenephosphonate) building blocks. Their crystal structure has been determined ab initio from X-ray powder diffraction data collected with a conventional diffractometer. Although prepared in similar conditions, their composition and crystal structure is markedly different. Compound 1, of formula Zr(2)H(4)[(O(3)PCH(2))(2)N(2)C(4)H(8)](3)·9H(2)O, has a three-dimensional structure (trigonal, space group R3 (No. 148), a = 19.9400(9) Å, c = 9.5728(6) Å, Z = 3), made of infinite inorganic chains of ZrO(6) octahedra and PO(3)C tetrahedra, running along the c-axis direction, connected by piperazine groups in the ab plane, and generating channels running along the c axis. Compound 2, of formula ZrF(2)(O(3)PCH(2))(2)(NH)(2)C(4)H(8), has a pillared-layered structure (monoclinic, space group P2(1)/c (No. 14), a = 8.7148(2) Å, b = 8.1731(1) Å, c = 9.0134(2) Å, ? = 105.175(1)° Z = 2) in which inorganic layers, made of the connectivity of Zr octahedra and P tetrahedra, are covalently connected by piperazine groups, that act as pillars. The effect of the various synthesis parameters is discussed. A probable structure directing parameter seems to be the pH value of the starting precipitation solution, that can influence the protonation of N atoms of piperazine moiety. PMID:20863075

Taddei, Marco; Costantino, Ferdinando; Vivani, Riccardo

2010-10-18

190

Piperazine-like compounds: a new group of designer drugs-of-abuse on the European market  

Microsoft Academic Search

1-Aryl-piperazine compounds are, depending on their substituents, selective for certain serotonin receptors and together with their easy availability and their so-called legal status, this group of psychoactive compounds are potential designer drugs-of-abuse. Internet in that respect is an important source of information and distribution facilities. Because this development may have consequences for the interpretation of future clinical and forensic toxicological

Douwe de Boer; Ingrid J Bosman; Elöd Hidvégi; Carmo Manzoni; András A Benkö; Lourenço J. A. L dos Reys; Robert A. A Maes

2001-01-01

191

(Z)-1-Di-phenyl-methyl-4-(3-phenyl-prop-2-en-yl)piperazine  

PubMed Central

In the title compound, C26H28N2, the piperazine group adopts a chair conformation with the exocyclic N—C bonds in equatorial orientations. The dihedral angle between the geminal benzene rings is 80.46?(12)° and the C=C—C—N torsion angle is 145.9?(2)°. In the crystal, weak C—H?? inter­actions link the mol­ecules into [100] chains.

Shivaprakash, S.; Chandrasekara Reddy, G.; Jasinski, Jerry P.

2014-01-01

192

(Z)-1-Di-phenyl-methyl-4-(3-phenyl-prop-2-en-yl)piperazine.  

PubMed

In the title compound, C26H28N2, the piperazine group adopts a chair conformation with the exocyclic N-C bonds in equatorial orientations. The dihedral angle between the geminal benzene rings is 80.46?(12)° and the C=C-C-N torsion angle is 145.9?(2)°. In the crystal, weak C-H?? inter-actions link the mol-ecules into [100] chains. PMID:24860379

Shivaprakash, S; Chandrasekara Reddy, G; Jasinski, Jerry P

2014-05-01

193

Covalent inhibitors of fatty acid amide hydrolase (FAAH): A rationale for the activity of piperidine and piperazine aryl ureas  

PubMed Central

Recently, covalent drugs have attracted great interest in the drug discovery community, with successful examples that have demonstrated their therapeutic effects. Here, we focus on the covalent inhibition of the fatty acid amide hydrolase (FAAH), which is a promising strategy in the treatment of pain and inflammation. Among the most recent and potent FAAH inhibitors (FAAHi), there are the cyclic piperidine/piperazine aryl ureas. FAAH hydrolyzes efficiently the amide bond of these compounds, forming a covalent enzyme-inhibitor adduct. To rationalize this experimental evidence, we performed an extensive computational analysis centered on the piperidine-based PF750 (1) and the piperazine-based JNJ1661010 (2), two potent lead compounds used to generating covalent inhibitors as clinical candidates. We found that FAAH induces a distortion of the amide bond of the piperidine/piperazine aryl ureas. QM/MM ?ELUMO-HOMO energies indicate that the observed enzyme-induced distortion of the amide bond favors the formation of a covalent FAAH- inhibitor adduct. These findings could help in the rational structure-based design of novel covalent FAAHi.

Palermo, Giulia; Branduardi, Davide; Masetti, Matteo; Lodola, Alessio; Mor, Marco; Piomelli, Daniele; Cavalli, Andrea; De Vivo, Marco

2013-01-01

194

New Urea and Thiourea Derivatives of Piperazine Doped with Febuxostat: Synthesis and Evaluation of Anti-TMV and Antimicrobial Activities  

PubMed Central

A series of new 4-(5-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-2-carbonyl)-N-(substituted phenyl)piperazine-1-carboxamides 8(a–e)/carbothioamides 8(f–j) were accomplished for biological interest by the simple addition of active functionalized arylisocyanates 7(a–e)/arylisothiocyanates 7(f–j) with 2-isobutoxy-5-(4-methyl-2-(piperazine-1-carbonyl)thiazol-5-yl)benzonitrile (4). Compound 4 was synthesized in high yields (94%) by the condensation reaction of febuxostat (1) with piperazine using a selective reagent such as propylphosphonic anhydride (T3P). Antiviral activity against Tobacco mosaic virus (TMV) and antimicrobial activity of the synthesized compounds were evaluated. Biological data revealed that 4-nitrophenyl substituted urea 8d, and 3-bromophenyl substituted thiourea 8f exhibited promising antiviral activities. Moreover, 4-fluorophenyl substituted urea 8a, 4-nitrophenyl substituted urea 8d, 3-bromophenyl substituted thiourea 8f, and 2,4-dichlorophenyl substituted thiourea 8j exhibited potent antimicrobial activity.

Krishna Reddy, Reddivari Chenna; Rasheed, Syed; Subba Rao, Devineni; Adam, Shaik; Raju, Chamarthi Naga

2013-01-01

195

New urea and thiourea derivatives of piperazine doped with febuxostat: synthesis and evaluation of anti-TMV and antimicrobial activities.  

PubMed

A series of new 4-(5-(3-cyano-4-isobutoxyphenyl)-4-methylthiazole-2-carbonyl)-N-(substituted phenyl)piperazine-1-carboxamides 8(a-e)/carbothioamides 8(f-j) were accomplished for biological interest by the simple addition of active functionalized arylisocyanates 7(a-e)/arylisothiocyanates 7(f-j) with 2-isobutoxy-5-(4-methyl-2-(piperazine-1-carbonyl)thiazol-5-yl)benzonitrile (4). Compound 4 was synthesized in high yields (94%) by the condensation reaction of febuxostat (1) with piperazine using a selective reagent such as propylphosphonic anhydride (T3P). Antiviral activity against Tobacco mosaic virus (TMV) and antimicrobial activity of the synthesized compounds were evaluated. Biological data revealed that 4-nitrophenyl substituted urea 8d, and 3-bromophenyl substituted thiourea 8f exhibited promising antiviral activities. Moreover, 4-fluorophenyl substituted urea 8a, 4-nitrophenyl substituted urea 8d, 3-bromophenyl substituted thiourea 8f, and 2,4-dichlorophenyl substituted thiourea 8j exhibited potent antimicrobial activity. PMID:24453889

Krishna Reddy, Reddivari Chenna; Rasheed, Syed; Subba Rao, Devineni; Adam, Shaik; Venkata Rami Reddy, Yellala; Raju, Chamarthi Naga

2013-01-01

196

Drug Testing in Blood: Validated Negative-Ion Chemical Ionization Gas Chromatographic-Mass Spectrometric Assay for Enantioselective Measurement of the Designer Drugs MDEA, MDMA, and MDA and Its Application to Samples from a Controlled Study with MDMA  

Microsoft Academic Search

Background: The enantiomers of the designer drugs 3,4-methylenedioxyamphetamine (MDA), 3,4-methyl- enedioxymethamphetamine (MDMA), and 3,4-methyl- enedioxyethylamphetamine (MDEA) differ in their pharmacologic and toxicologic potency. The aim of this study was to develop an assay for measuring these enantiomers in small plasma volumes and to analyze samples from a controlled study with MDMA. Methods: The analytes were extracted from <0.2 mL of

Frank T. Peters; Nele Samyn; Caroline T. J. Lamers; Wim J. Riedel; Thomas Kraemer; Gert de Boeck; Hans H. Maurer

197

Network formation and photoluminescence in copper(I) halide complexes with substituted piperazine ligands.  

PubMed

The synthesis, X-ray structures and photophysics of ten complexes of CuX (X = I or Br) with bridging N-substituted and N,N'-disubstituted piperazines (Pip) are presented. Depending on the steric demand of the Pip substituents, the complexes fall into four categories: (CuX)(4)(Pip)(2), which are networks of linked Cu(4)X(4) cubane units, (CuX)(2)(Pip), which are chains of linked Cu(2)X(2) rhombs, and (CuX)(2)(Pip)(2) or (CuX)(4)(Pip)(4), which are simple rhomboid dimers and cubane tetramers. A combination of spectroscopic studies and DFT calculations was used to investigate the luminescence of the products. The results suggest that the relatively high energy emission seen in dimers is due to cluster-centred (XMLT/metal-centred) excitations for the aliphatic amines and MLCT (d ??*) for aromatic amines, and low energy emission seen in the tetramers is the result of cluster-centred transitions. The (CuI)(2)(Pip) complexes act as sensor materials, undergoing irreversible reaction with aliphatic and aromatic amines (Nu) in the vapour state, irreversibly producing cubanes (CuI)(4)Nu(4), with corresponding production of long wavelength emission. PMID:22859067

Safko, Jason P; Kuperstock, Jacob E; McCullough, Shannon M; Noviello, Andrew M; Li, Xiaobo; Killarney, James P; Murphy, Caitlin; Patterson, Howard H; Bayse, Craig A; Pike, Robert D

2012-10-14

198

A chemical genetic approach identifies piperazine antipsychotics as promoters of CNS neurite growth on inhibitory substrates  

PubMed Central

Injury to the central nervous system (CNS) can result in lifelong loss of function due in part to the regenerative failure of CNS neurons. Inhibitory proteins derived from myelin and the astroglial scar are major barriers for the successful regeneration of injured CNS neurons. Previously, we described the identification of a novel compound, F05, which promotes neurite growth from neurons challenged with inhibitory substrates in vitro, and promotes axonal regeneration in vivo (Usher et al., 2010). To identify additional regeneration-promoting compounds, we used F05-induced gene expression profiles to query the Broad Institute Connectivity Map, a gene expression database of cells treated with >1,300 compounds. Despite no shared chemical similarity, F05-induced changes in gene expression were remarkably similar to those seen with a group of piperazine phenothiazine antipsychotics (PhAPs). In contrast to antipsychotics of other structural classes, PhAPs promoted neurite growth of CNS neurons challenged with two different glial derived inhibitory substrates. Our pharmacological studies suggest a mechanism whereby PhAPs promote growth through antagonism of calmodulin signaling, independent of dopamine receptor antagonism. These findings shed light on mechanisms underlying neurite-inhibitory signaling, and suggest that clinically approved antipsychotic compounds may be repurposed for use in CNS injured patients.

Johnstone, AL; Reierson, GW; Smith, RP; Goldberg, JL; Lemmon, VP; Bixby, JL

2012-01-01

199

Corrosion in CO{sub 2} capture process using blended monoethanolamine and piperazine  

SciTech Connect

This work explores the promise of aqueous solutions of blended monoethanolamine (MEA) and piperazine (PZ) as a cost-effective solvent for carbon dioxide (CO{sub 2}) capture, from industrial flue gas streams with respect to corrosion, which is regarded as one of the, most severe operational problems in typical CO{sub 2} capture plants. Electrochemical corrosion experiments were carried out using the potentiodynamic polarization technique for corrosion measurements. The results show that the blended MEA/PZ solutions are more corrosive than the MEA solutions. The corrosion rate of carbon steel increases with concentration of PZ, total amine concentration, CO{sub 2} loading of solution, solution temperature, and the presence of heat stable salts. Among the tested heat-stable salts, formate is the most corrosive salt, followed by acetate, oxalate, and thiosulfate in the absence of oxygen (O{sub 2}), while acetate is the most corrosive salt followed by formate, oxalate, and thiosulfate in the presence of O{sub 2}.

Nainar, M.; Veawab, A. [University of Regina, Regina, SK (Canada). Faculty of Engineering

2009-10-15

200

Charge-transfer complexes of 1-(2-aminoethyl) piperazine with ?- and ?-acceptors  

NASA Astrophysics Data System (ADS)

The solid charge-transfer (CT) molecular complexes formed in the reaction of 1-(2-aminoethyl) piperazine (AEPIP) with the ?-acceptor iodine and ?-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodi-methane (TCNQ), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCHD) and 2,3,5,6-tetrachloro-1,4-benzoquinone (CHL) were studied in chloroform at 25 °C. The products were investigated through electronic and infrared spectra as well as elemental analysis. The obtained results showed that the formed solid CT-complexes have the formulas [(AEPIP) I] +I5-, [(AEPIP)(DDQ) 2], [(AEPIP)(TCNQ) 2], [(AEPIP) 2(TBCHD) 3] and [(AEPIP)(CHL)] which are in full agreement with the known reaction stoichiometries in solution as well as the elemental analysis measurements. The formation constant KCT, molar extinction coefficient ?CT, free energy change ? G0 and CT energy ECT have been calculated for the CT-complexes [(AEPIP)(DDQ) 2], [(AEPIP)(TCNQ) 2] and [(AEPIP)(CHL)] as well.

Mostafa, Adel; Bazzi, Hassan S.

2010-11-01

201

Dimethyl phenyl piperazine iodide (DMPP) induces glioma regression by inhibiting angiogenesis.  

PubMed

1,1-Dimethyl-4-phenyl piperazine iodide (DMPP) is a synthetic nicotinic acetylcholine receptor (nAChR) agonist that could reduce airway inflammation. In this study, we demonstrated that DMPP could dramatically inhibit glioma size maintained on the chick embryonic chorioallantoic membrane (CAM). We first performed MTT and BrdU incorporation experiments on U87 glioma cells in vitro to understand the mechanism involved. We established that DMPP did not significantly affect U87 cell proliferation and survival. We speculated that DMPP directly caused the tumor to regress by affecting the vasculature in and around the implanted tumor on our chick CAM model. Hence, we conducted detailed analysis of DMPP's inhibitory effects on angiogenesis. Three vasculogenesis and angiogenesis in vivo models were used in the study which included (1) early chick blood islands formation, (2) chick yolk-sac membrane (YSW) and (3) CAM models. The results revealed that DMPP directly suppressed all developmental stages involved in vasculogenesis and angiogenesis - possibly by acting through Ang-1 and HIF-2? signaling. In sum, our results show that DMPP could induce glioma regression grown on CAM by inhibiting vasculogenesis and angiogenesis. PMID:24162003

He, Yan-Qing; Li, Yan; Wang, Xiao-Yu; He, Xiao-Dong; Jun, Li; Chuai, Manli; Lee, Kenneth Ka Ho; Wang, Ju; Wang, Li-Jing; Yang, Xuesong

2014-01-15

202

Decomposition of Nitrosamines in CO2 Capture by Aqueous Piperazine or Monoethanolamine.  

PubMed

Amine scrubbing is an efficient method for carbon capture and sequestration, but secondary amines present in all amine solvents can form carcinogenic nitrosamines. Decomposition kinetics for n-nitrosopiperazine (MNPZ), nitrosodiethanolamine (NDELA), and nitroso-(2-hydroxyethyl) glycine (NHeGly) were measured over a range of temperature, base concentration, base strength, and CO2 loading pertinent to amine scrubbing. MNPZ and NDELA decomposition is first order in the nitrosamine, half order in base concentration, and base-catalyzed with a Brønsted slope of ? = 0.5. The activation energy is 94, 106, and 112 kJ/mol for MNPZ, NDELA, and NHeGly, respectively. MNPZ readily decomposes at 150 °C in 5 M piperazine, making thermal decomposition an important mechanism for MNPZ control. However, NHeGly and NDELA are too stable at 120 °C in 7 M monoethanolamine (MEA) for thermal decomposition to be important. Base treatment during reclaiming could rapidly and selectively decompose NHeGly and NDELA to mitigate nitrosamine accumulation in MEA. PMID:24730662

Fine, Nathan A; Nielsen, Paul T; Rochelle, Gary T

2014-05-20

203

Quantum Chemical Studies on Solvents for Post-Combustion Carbon Dioxide Capture: Calculation of pKa and Carbamate Stability of Disubstituted Piperazines.  

PubMed

Piperazine is a widely studied solvent for post-combustion carbon dioxide capture. To investigate the possibilities of further improving this process, the electronic and steric effects of ?CH3 , ?CH2 F, ?CH2 OH, ?CH2 NH2 , ?COCH3 , and ?CN groups of 2,5-disubstituted piperazines on the pKa and carbamate stability towards hydrolysis are investigated by quantum chemical methods. For the calculations, B3LYP, M11L, and spin-component-scaled MP2 (SCS-MP2) methods are used and coupled with the SMD solvation model. The experimental pKa values of piperazine, 2-methylpiperazine, and 2,5-dimethylpiperazine agree well with the calculated values. The present study indicates that substitution of ?CH3 , ?CH2 NH2 , and ?CH2 OH groups on the 2- and 5-positions of piperazine has a positive impact on the CO2 absorption capacity by reducing the carbamate stability towards hydrolysis. Furthermore, their higher boiling points, relative to piperazine itself, will lead to a reduction of volatility-related losses. PMID:24782140

Gangarapu, Satesh; Wierda, Gerben J; Marcelis, Antonius T M; Zuilhof, Han

2014-06-23

204

Solubility of carbon dioxide in aqueous mixtures of alkanolamines  

SciTech Connect

The solubility of CO[sub 2] in water + N-methyldiethanolamine + monoethanolamine (MDEA + MEA) and water + N-methyldiethanolamine + diethanolamine (MDEA + DEA) are reported at two compositions of 3.4 M MDEA + 0.8 M MEA or DEA and 2.1 M MDEA + 2.1 M MEA or DEA at temperatures from 70 to 180 C and CO[sub 2] partial pressures from 100 to 3,850 kPa. The solubility of CO[sub 2] in the blends decreased with an increase in temperature but increased with an increase in CO[sub 2] partial pressure. At low partial pressures of CO[sub 2] and the same total amine concentration, the equilibrium CO[sub 2] loadings were in the order MDEA + MEA > MDEA + DEA > MDEA. However, at high CO[sub 2] partial pressures, the equilibrium CO[sub 2] loadings in the MDEA solutions were higher than those of the MDEA + MEA and MDEA + DEA blends of equal molar strengths due to the stoichiometric loading limitations of MEA and DEA. The nonadditivity of the equilibrium loadings for single amine systems highlights the need for independent measurements on amine blends.

Dawodu, O.F.; Meisen, A. (Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Chemical Engineering)

1994-07-01

205

Effect of the Piperazine Unit and Metal-Binding Site Position on the Solubility and Anti-Proliferative Activity of Ruthenium(II)- and Osmium(II)- Arene Complexes of Isomeric Indolo[3,2-c]quinoline--Piperazine Hybrids  

PubMed Central

In this study, the indoloquinoline backbone and piperazine were combined to prepare indoloquinoline–piperazine hybrids and their ruthenium- and osmium-arene complexes in an effort to generate novel antitumor agents with improved aqueous solubility. In addition, the position of the metal-binding unit was varied, and the effect of these structural alterations on the aqueous solubility and antiproliferative activity of their ruthenium- and osmium-arene complexes was studied. The indoloquinoline–piperazine hybrids L1–3 were prepared in situ and isolated as six ruthenium and osmium complexes [(?6-p-cymene)M(L1–3)Cl]Cl, where L1 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-2-N-amine, M = Ru ([1a]Cl), Os ([1b]Cl), L2 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-4-N-amine, M = Ru ([2a]Cl), Os ([2b]Cl), L3 = 6-(4-methylpiperazin-1-yl)-N-(pyridin-2-yl-methylene)-11H-indolo[3,2-c]quinolin-8-N-amine, M = Ru ([3a]Cl), Os ([3b]Cl). The compounds were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy, ESI mass spectrometry, IR and UV–vis spectroscopy, and single-crystal X-ray diffraction. The antiproliferative activity of the isomeric ruthenium and osmium complexes [1a,b]Cl–[3a,b]Cl was examined in vitro and showed the importance of the position of the metal-binding site for their cytotoxicity. Those complexes containing the metal-binding site located at the position 4 of the indoloquinoline scaffold ([2a]Cl and [2b]Cl) demonstrated the most potent antiproliferative activity. The results provide important insight into the structure–activity relationships of ruthenium- and osmium-arene complexes with indoloquinoline–piperazine hybrid ligands. These studies can be further utilized for the design and development of more potent chemotherapeutic agents.

2014-01-01

206

Control of water molecule aggregations in copper 1,4-cyclohexanedicarboxylate coordination polymers containing pyridyl-piperazine type ligands  

NASA Astrophysics Data System (ADS)

A series of layered divalent copper coordination polymers containing 1,4-cyclohexanedicarboxylate and long-spanning pyridyl-piperazine type ligands exhibits greatly different co-crystallized water molecule aggregations depending on the specific ligands used. Both [Cu(t-14cdc)(4-bpmp)]n (1, t-14cdc = trans-1,4-cyclohexanedicarboxylate, 4-bpmp = bis(4-pyridylmethyl)piperazine) and {[Cu(t-14cdc)(4-bpfp)(H2O)2]·6H2O}n (2, 4-bpfp = bis(4-pyridylformyl)piperazine) possess 2D (4,4) coordination polymer grids. However 1 lacks any co-crystallized water and has pinched grid apertures, while 2 manifests infinite water tapes with T6(2)4(2) classification and rectangular grid apertures. {[Cu2(c-14cdc)2(4-bpmp)]·2H2O}n (3, c-14cdc = cis-1,4-cyclohexanedicarboxylate) has [Cu2(c-14cdc)]2 ribbons with paddlewheel dimeric units linked into 2D slabs by 4-bpmp tethers, along with isolated water molecule pairs. In contrast, {[Cu2(c-14cdc)2(4-bpfp)]·10H2O}n (4) shows a very similar underlying coordination polymer topology but entrains unique decameric water molecule clusters. The minor product {[Cu2(c-14cdcH)2(t-1,4-cdc)(4-bpfp)2(H2O)2]·2H2O}n (5) was isolated along with 4; this compound underwent some in situ cis to trans cyclohexane-dicarboxylate ligand isomerization and exhibits a ladder polymer motif.

Qiblawi, Sultan H.; LaDuca, Robert L.

2014-01-01

207

Effect of piperazine (diethylenediamine) on the moulting, proteome expression and pyrophosphatase activity of Ascaris suum lung-stage larvae.  

PubMed

Piperazine (diethylenediamine) is an anthelmintic widely used against animal and bird ascariasis. In this study, we show that treatment with piperazine blocks Ascaris suum larval moulting and development processes and affects larval proteome expression profiles. A. suum lung-stage L3 (LL3) obtained from an infected rabbit's lungs were cultured in RPMI medium in the presence of increasing concentrations of piperazine sulfate (Pzes). Our results showed that Pzes potently inhibited moulting of A. suum LL3 in a dose-dependent manner and that moulting was completely blocked (100%) at 50mM concentrations. We then examined the changes in A. suum LL3 proteome expression patterns following Pzes exposure using two-dimensional (2D) electrophoresis. Pzes exposure inhibited expression of at least 16 major protein spots in unmoulted LL3 out of more than 200 visible protein spots resolved on 2D gels prepared from moulted larvae (i.e., lung-stage L4). Pzes exposure also inhibited expression of 13 immunogenic protein spots in unmoulted LL3. More importantly, Pzes exposure inhibited activity of a moulting-specific enzyme, inorganic pyrophosphatase of A. suum (AsPPase), by 26%. Expression of native AsPPase was also reduced following Pzes exposure as detected by immunoblotting and immunofluorescent staining. Transmission electron microscopy showed that Pzes interfered with growth and ecdysis of the cuticle and caused damage to gut tissues of the larvae. Our results suggest that A. suum LL3 may become a suitable model to screening new-class anthelmintics with antimoulting functions and that A. suum LL3-Pzes may serve as a useful tool for identification of moulting-specific potential proteins in Ascaris roundworms. PMID:16987490

Islam, M Khyrul; Miyoshi, Takeharu; Yamada, Manabu; Alim, M Abdul; Huang, Xiaohong; Motobu, Maki; Tsuji, Naotoshi

2006-10-01

208

Synthesis and antiproliferative effect of novel 4-thiazolidinone-, pyridine- and piperazine-based conjugates on human leukemic cells.  

PubMed

The present work reveals the synthesis and antiproliferative effect of a series of 2, 3 disubstituted 4-thiazolidinone analogues on human leukemic cells. The chemical structures of newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR and mass spectral analysis. Compound methyl 3-methoxy-4-(4-oxo-3-(5-(piperazin-1-yl)pyridin-2-yl)thiazolidin-2-yl)benzoate (5) displayed potent activity (IC509.71, 15.24 and 19.29 ?M) against Nalm6, K562, Jurkat cells. Cell cycle analysis and mitochondrial membrane potential further confirmed that compound 5 is cytotoxic and able to induce cell death. PMID:24852281

Sharath Kumar, Kothanahally S; Hanumappa, Ananda; Hegde, Mahesh; Narasimhamurthy, Kereyagalahally H; Raghavan, Sathees C; Rangappa, Kanchugarakoppal S

2014-06-23

209

Tri- and tetraurea piperazine cyclophanes: synthesis and complexation studies of preorganized and folded receptor molecules.  

PubMed

A series of symmetrical tri- and tetrameric N-ethyl- and N-phenylurea-functionalized cyclophanes have been prepared in nearly quantitative yields (86-99?%) from the corresponding tri- and tetraamino-functionalized piperazine cyclophanes and ethyl or phenyl isocyanates. Their conformational and complexation properties have been studied by single-crystal X-ray diffraction, variable-temperature NMR spectroscopy, and ESI-MS analysis. The rigid 27-membered trimeric cyclophane skeleton assisted by a seam of intramolecular hydrogen bonds results in a preorganized ditopic recognition site with an all-syn conformation of the urea moieties that, complemented by a lipophilic cavity of the cyclophane, binds molecular and ionic guests as well as ion pairs. The all-syn conformation persists in acidic conditions and the triprotonated triurea cyclophane binds an unprecedented anion pair, H(2)PO(4)(-)???HPO(4)(2-), in the solid state. The tetra-N-ethylurea cyclophane is less rigid and demonstrates an induced-fit recognition of diisopropyl ether in the solid state. The guest was encapsulated within the lipophilic interior of a quasicapsule, formed by intramolecular hydrogen-bond-driven folding of the 36-membered cyclophane skeleton. In the gas phase, the essential role of the urea moieties in the binding was demonstrated by the formation of monomeric 1:1 complexes with K(+), TMA(+), and TMP(+) as well as the ion-pair complexes [KI+K](+), [TMABr+TMA](+) and [TMPBr+TMP](+). In the positive-mode ESI-MS analysis, ion-pair binding was found to be more pronounced with the larger tetraurea cyclophanes. In the negative mode, owing to the large size of the binding site, a general binding preference towards larger anions, such as the iodide, over smaller anions, such as the fluoride, was observed. PMID:21077059

Raatikainen, Kari; Beyeh, N Kodiah; Rissanen, Kari

2010-12-27

210

4-(4-Methyl-piperazin-1-yl)-3-(5-phenyl-1,3,4-oxadiazol-2-yl)-7-(trifluoro-meth-yl)quinoline  

PubMed Central

In the title compound, C23H20F3N5O, the piperazine ring adopts a chair conformation. The quinoline ring makes dihedral angles of 56.61?(11), 49.94?(12) and 42.58?(14)° with the piperazine ring, the 1,3,4-oxadiazole ring and the benzene ring, respectively. An intra­molecular C—H?O hydrogen bond generates an S(7) ring motif. In the crystal, mol­ecules are linked into infinite chains along the b axis by C—H?N hydrogen bonds.

Fun, Hoong-Kun; Arshad, Suhana; Garudachari, B.; Isloor, Arun M.; Satyanarayan, M. N.

2011-01-01

211

Design, synthesis, and structure-activity relationship study of bicyclic piperazine analogs of indole-3-carboxamides as novel cannabinoid CB1 receptor agonists.  

PubMed

Bicyclic piperazine derivatives were synthesized as conformationally constrained analogs of N-alkyl piperazines and were found to be potent CB1 receptor agonists. The CB1 receptor agonist activity was dependent upon the absolute configuration of the chiral center of the bicyclic ring system. Although the conformational constraint did not protect the compounds from metabolism by N-dealkylation, several bicyclic analogs were found to be more potent than the unconstrained lead compound. Compound 8b demonstrated potent antinociceptive activity in vivo. PMID:21074434

Moir, Elizabeth M; Yoshiizumi, Kazuya; Cairns, Jim; Cowley, Phillip; Ferguson, Morag; Jeremiah, Fiona; Kiyoi, Takao; Morphy, Richard; Tierney, Jason; Wishart, Grant; York, Mark; Baker, James; Cottney, Jean E; Houghton, Andrea K; McPhail, Petula; Osprey, Andrew; Walker, Glenn; Adam, Julia M

2010-12-15

212

Synthesis and Structural Characterization of Two New Schiff Bases incorporating a Piperazine Skeleton, and their Reactions with Copper(II) Perchlorate  

Microsoft Academic Search

The synthesis of Schiff bases N,N??bis(4?dodecyloxy?benzylidene?N?propyl)?piperazine (2) and N,N??bis?[4?(4??octyloxy?benzoic)?ester?benzylidene?N?propyl]?piperazine (6) in a multistep process is reported. The intermediates as well as the products were characterized by elemental analysis, melting point and IR, H and C?NMR spectroscopy. The complex formation of these Schiff bases with copper(II) perchlorate resulted in disruption of the imino bond and yielded N,N??bis(3?aminopropyl)piperazineperchloratocopper(II) perchlorate, Cu(L)(ClO4)2, where L

Liliana Cseh; Ramona Tudose; Otilia Costisor; Ingo Pantenburg; Gerd Meyer; Wolfgang Linert

2008-01-01

213

Expedite protocol for construction of chiral regioselectively N-protected monosubstituted piperazine, 1,4-diazepane, and 1,4-diazocane building blocks.  

PubMed

This paper describes the first study of solution-phase synthesis of chiral monosubstituted piperazine building blocks from nosylamide-activated aziridines. The protocol, involving aminolysis of the starting aziridines with omega-amino alcohols and subsequent Fukuyama-Mitsunobu cyclization, offers the advantage of mild conditions as well as short reaction times, and it leads to optically pure N-Boc- or N-Ns-protected piperazines. This four-step sequence, requiring only a single final chromatographic purification, was extended to include novel diazepane and diazocane derivatives. PMID:19518106

Crestey, François; Witt, Matthias; Jaroszewski, Jerzy W; Franzyk, Henrik

2009-08-01

214

Acid gas treating by aqueous alkanolamines. Annual report, January-December 1993  

SciTech Connect

The objective of the work is to investigate the simultaneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed thus far, density, viscosity, gas diffusivity, gas solubility, surface tension, and amine solution vapor pressure have been measured for aqueous MDEA, DEA, and MDEA/DEA mixtures over the temperature range 20 to 100 deg. C and for concentrations up to 50 weight %. A mathematical model, based on the penetration theory, for the simultaneous absorption (desorption) of CO2 and H2S into (from) aqueous solutions of MDEA and DEA has been developed.

Sandall, O.C.; Rinker, E.B.; Ashour, S.

1993-12-01

215

Acid gas treating by aqueous alkanolamines. Annual report, July-December 1992  

SciTech Connect

The objective of the work is to investigate the simultaneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed thus far models have been developed for single gas (either H2S or CO2) absorption into a single amine solution (MDEA or DEA). Density and viscosity measurements have been made for aqueous MDEA, DEA and MDEA/DEA mixtures over the temperature range 20 to 100 C and for concentrations up to 50 weight %.

Sandall, O.C.; Rinker, E.B.; Tamimi, A.; Davis, R.A.; Oelschlager, D.W.

1992-12-01

216

7-O-[4-methyl piperazine-1-(2-acetyl)]-2H-1-benzopyran-2-one: a novel antifilarial lead compound.  

PubMed

In preliminary studies we found that benzopyrones (coumarins), which are known to exert many biological activities including anti-inflammatory effect, possess promising macrofilaricidal action as well. In order to explore the possibility of combining such a macrofilaricidal activity with the microfilaricidal potential of the known piperazine pharmacophore, we synthesized a series of compounds and evaluated their antifilarial effect. In the present study, one of these compounds, 7-O-[4-methyl piperazine-1-(2-acetyl)]-2H-1-benzopyran-2-one (2), which has shown promising macrofilaricidal action against rodent filariid Litomosoides carinii in cotton rats, was evaluated against infection with Brugia malayi in Mastomys coucha and jird (Meriones unguiculatus). In the B. malayi-M. coucha system, the compound at a dose of 300 mg/kg, oral (p.o.) x5 days showed 53.6% adulticidal and 46.0% microfilaricidal activity along with 46.3% sterilization effect on the female worms. In addition, the compound interfered with the establishment of infective larvae (L(3))-induced infection to an extent of 50% at the same dose level. At 1 microM concentration it inhibited protease activity of B. malayi to 82%. The compound thus provides a novel lead for further synthesis and development of antifilarial agents with macrofilaricidal, microfilaricidal, female-sterilizing and possible larvicidal efficacy. PMID:12826297

Tripathi, R P; Tiwari, V K; Misra-Bhattacharya, S; Tyagi, K; Srivastava, V M L; Murthy, P K

2003-07-01

217

Regioisomeric bromodimethoxy benzyl piperazines related to the designer substance 4-bromo-2,5-dimethoxybenzylpiperazine: GC-MS and FTIR analysis.  

PubMed

A series of seven regioisomeric bromodimethoxy benzyl piperazines including the designer benzylpiperazine (4-bromo-2,5-dimethoxybenzylpiperazine) were synthesized and their analytical profiles evaluated using GC-MS and FT-IR. The mass spectra for the seven regioisomeric bromodimethoxy benzyl piperazines are almost identical with only the two 2,3-dimethoxy isomers showing one unique major fragment ion at m/z 214/216. Thus, mass spectrometry alone does not provide for the confirmation of identity of any one of the seven compounds to the exclusion of the other isomers. Perfluoroacylation of the secondary amine nitrogen for each of the seven regioisomers gave mass spectra showing some differences in the relative abundance of fragment ions without the appearance of any unique fragments for specific confirmation of structure. Attenuated total reflection infrared spectroscopy provides direct confirmatory data for differentiation between the seven regioisomeric aromatic ring substituted bromodimethoxy benzyl piperazines. Mixtures of the seven piperazine PFP derivatives were successfully resolved via capillary gas chromatography using a relatively polar stationary phase composed of 100% trifluoropropyl methyl polysiloxane. PMID:24819165

Abdel-Hay, Karim M; DeRuiter, Jack; Clark, C Randall

2014-07-01

218

Quantification of piperazine phosphate in human plasma by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry employing precolumn derivatization with dansyl chloride.  

PubMed

This paper describes a novel method that combines dansyl chloride (DNS-CL) derivatization with high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) for the sensitive and selective determination of piperazine phosphate in human plasma. After addition of ondansetron hydrochloride as internal standard (IS), piperazine phosphate was derivatized and then extracted with ethyl acetate. After being evaporated and reconstituted, the sample was analyzed using LC-ESI/MS/MS. Separation was achieved using an Agilent ZORBAX SB-C(18) (150 mm x 2.1 mm I.D., 3.5 microm) column and isocratic elution with 10 mM ammonium acetate solution (pH 3.0)-methanol (50: 50, v/v). Detection was performed on a triple-quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operating in positive ion and selected reaction monitoring (SRM) mode with the precursor to product ion transitions m/z 320-->171 for DNS-CL-piperazine phosphate and m/z 294-->170 for the IS. The method was fully validated for its selectivity, sensitivity, linearity, precision, accuracy, recovery, matrix effect and stability. The coefficient (r) of piperazine phosphate with a linear range of 0.1-15 microg mL(-1) was 0.9974-0.9995. The limit of detection and lower limit of quantification in human plasma were 0.01 and 0.1 microg mL(-1), respectively. The validated LC-ESI/MS/MS method has been successfully applied to a bioequivalence study of piperazine phosphate trochiscus in Chinese healthy male volunteers. PMID:20226930

Lin, Hui; Tian, Yuan; Zhang, Zunjian; Wu, Lili; Chen, Yun

2010-04-01

219

Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt  

PubMed Central

Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR), p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution powder X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid?pyridine heterosynthon and N—H?O catemer hydrogen bonds involving the amide group. The acid?amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl?carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24?h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM–PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine salt of acemetacin exhibits superior stability, faster dissolution rate and is able to overcome the hydration tendency of the reference drug.

Sanphui, Palash; Bolla, Geetha; Nangia, Ashwini; Chernyshev, Vladimir

2014-01-01

220

Poly[[{?3-2-[4-(2-hy-droxy-eth-yl)piperazin-1-yl]ethane-sulfonato}-silver(I)] trihydrate  

PubMed Central

Ethane­sulfonic acid-based buffers like 2-[4-(2-hy­droxy­eth­yl)­piperazin-1-yl]ethane­sulfonic acid (HEPES) are commonly used in biological experiments because of their ability to act as non-coordinating ligands towards metal ions. However, recent work has shown that some of these buffers may in fact coordinate metal ions. The title complex, {[Ag(C8H17N2O4S)]·3H2O}n, is a metal–organic framework formed from HEPES and a silver(I) ion. In this polymeric complex, each Ag atom is primarily coordinated by two N atoms in a distorted linear geometry. Weaker secondary bonding inter­actions from the hy­droxy and sulfate O atoms of HEPES complete a distorted seesaw geometry. The crystal structure is stabilized by O—H?O hydrogen-bonding interactions.

Bilinovich, Stephanie M.; Panzner, Matthew J.; Youngs, Wiley J.; Leeper, Thomas C.

2011-01-01

221

Bis(1-methyl-piperazine-1,4-diium) di-?-bromido-bis-[tetra-bromido-bismuthate(III)] dihydrate  

PubMed Central

In the title hydrated salt, (C5H14N2)2[Bi2Br10]·2H2O, the com­plete [Bi2Br10]4? biocta­hedron is generated by crystallographic inversion symmetry. The diprotonated piperazine ring adopts a chair conformation, with the methyl group occupying an equatorial position. In the crystal, the tetra­anions and water mol­ecules are linked by O—H?Br and O—H?(Br,Br) hydrogen bonds to generate [100] chains. The chains are crosslinked by N—H?Br, N—H?O and C—H?Br hydrogen bonds originating from the piperazinediium dications, thereby forming a three-dimensional network.

Essid, Manel; Roisnel, Thierry; Marouani, Houda

2014-01-01

222

(4-Methyl-piperazin-1-yl)(2,3,4-tri-meth-oxy-benzyl-idene)amine.  

PubMed

In the title compound, C15H23N3O3, the piperazine ring is in a slightly distorted chair conformation and is twisted from the mean plane of the benzene ring making a dihedral angle of 14.94?(6)°. The 4-meth-oxy substituent is almost co-planar with the benzene ring [C-C-O-C torsion angle = 5.4?(1)°], while the meth-oxy groups at positions 2 and 3 [C-C-O-C torsion angles of 122.6?(4) and -66.1?(4)°, respectively] are twisted away from the mean plane of the benzene ring in anti-clinical and synclinical conformations, respectively. No classical hydrogen bonds or any weak inter-molecular inter-actions are observed in the crystal structure. PMID:24826188

Kavitha, Channappa N; Jasinski, Jerry P; Kaur, Manpreet; Yathirajan, H S

2014-04-01

223

(4-Methyl-piperazin-1-yl)(2,3,4-tri-meth-oxy-benzyl-idene)amine  

PubMed Central

In the title compound, C15H23N3O3, the piperazine ring is in a slightly distorted chair conformation and is twisted from the mean plane of the benzene ring making a dihedral angle of 14.94?(6)°. The 4-meth­oxy substituent is almost co-planar with the benzene ring [C—C—O—C torsion angle = 5.4?(1)°], while the meth­oxy groups at positions 2 and 3 [C—C—O—C torsion angles of 122.6?(4) and ?66.1?(4)°, respectively] are twisted away from the mean plane of the benzene ring in anti­clinical and synclinical conformations, respectively. No classical hydrogen bonds or any weak inter­molecular inter­actions are observed in the crystal structure.

Kavitha, Channappa N.; Jasinski, Jerry P.; Kaur, Manpreet; Yathirajan, H.S.

2014-01-01

224

Design, syntheses, and characterization of piperazine based chemokine receptor CCR5 antagonists as anti prostate cancer agents.  

PubMed

Chemokine receptor CCR5 plays an important role in the pro-inflammatory environment that aids in the proliferation of prostate cancer cells. Previously, a series of CCR5 antagonists containing a piperidine ring core skeleton were designed based upon the proposed CCR5 antagonist pharmacophore from molecular modeling studies. The developed CCR5 antagonists were able to antagonize CCR5 at a micromolar level and inhibit the proliferation of metastatic prostate cancer cell lines. In order to further explore the structure-activity-relationship of the pharmacophore identified, the molecular scaffold was expanded to contain a piperazine ring as the core. A number of compounds that were synthesized showed promising anti prostate cancer activity and reasonable cytotoxicity profiles based on the biological characterization. PMID:24731275

Arnatt, Christopher K; Adams, Joanna L; Zhang, Zhu; Haney, Kendra M; Li, Guo; Zhang, Yan

2014-05-15

225

Structure–activity relationships in platelet-activating factor. Part 13: Synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 or pure antiretroviral activity  

Microsoft Academic Search

HIV-1 infection of the brain and PAF neurotoxicity are implicated in AIDS dementia complex. We previously reported that a trisubstituted piperazine derivative is able to diminish both HIV-1 replication in monocyte-derived macrophages and PAF-induced platelet aggregation. We report in this work new compounds obtained by modifying its piperazine substituents. The structure–activity relationship study shows that a better dual activity or

Nawal Serradji; Okkacha Bensaid; Marc Martin; Wafa Sallem; Nathalie Dereuddre-Bosquet; Houcine Benmehdi; Catherine Redeuilh; Aazdine Lamouri; Georges Dive; Pascal Clayette; Françoise Heymans

2006-01-01

226

Structure-activity relationships in platelet-activating factor. Part 13: synthesis and biological evaluation of piperazine derivatives with dual anti-PAF and anti-HIV-1 or pure antiretroviral activity.  

PubMed

HIV-1 infection of the brain and PAF neurotoxicity are implicated in AIDS dementia complex. We previously reported that a trisubstituted piperazine derivative is able to diminish both HIV-1 replication in monocyte-derived macrophages and PAF-induced platelet aggregation. We report in this work new compounds obtained by modifying its piperazine substituents. The structure-activity relationship study shows that a better dual activity or even pure antiretroviral compounds can be obtained in this series. PMID:16893650

Serradji, Nawal; Bensaid, Okkacha; Martin, Marc; Sallem, Wafa; Dereuddre-Bosquet, Nathalie; Benmehdi, Houcine; Redeuilh, Catherine; Lamouri, Aazdine; Dive, Georges; Clayette, Pascal; Heymans, Françoise

2006-12-01

227

3-(Adamantan-1-yl)-1-[(4-benzyl-piperazin-1-yl)meth-yl]-4-ethyl-1H-1,2,4-triazole-5(4H)-thione  

PubMed Central

In the title compound, C26H37N5S, the piperazine ring adopts a chair conformation with the exocyclic N—C bonds in pseudo-equatorial orientations. The piperazine ring (all atoms) subtends dihedral angles of 79.47?(9) and 73.07?(9)° with the triazole and benzene rings, respectively, resulting in an approximate U-shape for the mol­ecule. No significant inter­molecular inter­actions are observed in the crystal.

Al-Abdullah, Ebtehal S.; Al-Tuwaijri, Hanaa M.; El-Emam, Ali A.; Chidan Kumar, C. S.; Fun, Hoong-Kun

2013-01-01

228

Experimental determination of hydrogen sulfide solubility data in aqueous alkanolamine solutions  

Microsoft Academic Search

A computer-operated static apparatus for the measurement of gas solubility data by the synthetic method was used for the experimental determination of hydrogen sulfide solubility data in aqueous N-methyldiethanolamine (MDEA), diethanolamine (DEA) solutions and aqueous solution of a mixture of MDEA\\/DEA. For these systems, measurements at 313 and 373K and pressures up to about 1.3MPa were performed. The experimental data

Réda Sidi-Boumedine; Sven Horstmann; Kai Fischer; Elise Provost; Walter Fürst; Jürgen Gmehling

2004-01-01

229

Synthesis and evaluation of 1-benzhydryl-sulfonyl-piperazine derivatives as inhibitors of tumor growth and tumor angiogenesis of mouse ehrlich ascites tumor in vivo.  

PubMed

A series of novel 1-benzhydryl-sulfonyl-piperazine derivatives 3(a-e) were synthesized by nucleophilic substitution reaction of 1-benzhydryl-piperazine with different sulfonyl chlorides and were characterized by 1H NMR, LC/MS, FTIR and elemental analysis. In the present study, the compounds 3(a-e) exhibited in vivo inhibition of Ehrlich ascites tumor (EAT) cell growth and increased the Median Survival Time (MST) and %ILS of EAT bearing mice. Further treatment of derivatives in vivo resulted in reduction of EAT cell number and ascites formation. The efficacy of the derivatives to inhibit the angiogenesis in vivo was evaluated in tumor bearing mice peritoneum and chorio allantoic membrane (CAM) model. The compounds suppressed the blood vessel formation in vivo in mice peritoneum and in CAM. Among the compounds studied, 3e demonstrated highest tumor inhibitory and anti-angiogenic effects against mouse tumor. However, this phenomenon needs detailed investigation. PMID:18782043

Kumar, C S Ananda; Chandru, H; Sharada, A C; Thimmegowda, N R; Prasad, S B Benaka; Kumar, M Karuna; Rangappa, K S

2008-09-01

230

5-(Adamantan-1-yl)-3-[(4-benzyl-piperazin-1-yl)meth-yl]-1,3,4-oxadiazole-2(3H)-thione  

PubMed Central

The mol­ecule of the title compound, C24H32N4OS, is a functionalized 1,3,4-oxadiazole-2-thione with substituted piperazine and adamantanyl substituents attached at the 3- and 5-positions, respectively, of the oxadiazole spacer with an approximately C-shaped conformation. In the crystal, mol­ecules form dimers via C—H?S inter­action. The piperazine ring has a chair conformation; the substituents S, methyl­ene C and adamantane C of the essentially planar oxadiazole ring are approximately in the same plane, with distances of ?0.046?(2), ?0.085?(5) and 0.003?(4)?Å, respectively. The dihedral angle between the planes of the phenyl and oxadiazole rings is 31.3?(3)°.

El-Emam, Ali A.; El-Brollosy, Nasser R.; Attia, Mohamed I.; Said-Abdelbaky, Mohammed; Garcia-Granda, Santiago

2012-01-01

231

HEAT OF DISSOLUTION MEASUREMENTS FOR CO2 IN MIXED ALKANOLAMINE SOLVENTS  

SciTech Connect

The main objective of this project is to measure heat of dissolution of CO{sub 2} in carefully selected mixed alkanolamine solvent systems, and provide such directly measured data that might be used for efficient design of CO{sub 2} capture processes, or for better understanding of thermodynamics of CO{sub 2}-alkanolamine systems. Carbon dioxide is one of the major greenhouse gases, and the need for stabilization of its composition in earth's atmosphere is vital for the future of mankind. Although technologies are available for capture and storage of CO{sub 2}, these technologies are far too expensive for economical commercialization. Reduction of cost would require research for refinement of the technology. For more economical CO{sub 2} capture and regeneration, there is a need for development of more efficient solvent systems. In this project we will extend the thermodynamic database by measuring heat of solution data of CO{sub 2} in mixed solvents made of MEA (monoethanolamine), MDEA (methyldiethanolamine), piperazine, and water. Mixed solvents of different compositions will be selected and in each case data will be measured at temperatures 40 and 80 C and various partial pressures of CO{sub 2}. At the end of the project, observations, conclusions, and recommendations will be derived for the choice of mixed solvents for efficient CO{sub 2} capture with potential for commercialization.

Vinayak N. Kabadi

2004-11-15

232

HEAT OF DISSOLUTION MEASUREMENTS FOR CO2 IN MIXED ALKANOLAMINE SOLVENTS  

SciTech Connect

The main objective of this project is to measure heat of dissolution of CO{sub 2} in carefully selected mixed alkanolamine solvent systems, and provide such directly measured data that might be used for efficient design of CO{sub 2} capture processes, or for better understanding of thermodynamics of CO{sub 2}-alkanolamine systems. Carbon dioxide is one of the major greenhouse gases, and the need for stabilization of its composition in earth's atmosphere is vital for the future of mankind. Although technologies are available for capture and storage of CO{sub 2}, these technologies are far too expensive for economical commercialization. Reduction of cost would require research for refinement of the technology. For more economical CO{sub 2} capture and regeneration, there is a need for development of more efficient solvent systems. In this project we will extend the thermodynamic database by measuring heat of solution data of CO{sub 2} in mixed solvents made of MEA (monoethanolamine), MDEA (methyldiethanolamine), piperazine, and water. Mixed solvents of different compositions will be selected and in each case data will be measured at temperatures 40 and 80C and various partial pressures of CO{sub 2}. At the end of the project, observations, conclusions, and recommendations will be derived for the choice of mixed solvents for efficient CO{sub 2} capture with potential for commercialization.

Vinayak N. Kabadi

2005-05-23

233

Heat of Dissolution Measurements for CO2 in Mixed Alkanolamine Solvents  

SciTech Connect

The main objective of this project is to measure heat of dissolution of CO{sub 2} in carefully selected mixed alkanolamine solvent systems, and provide such directly measured data that might be used for efficient design of CO{sub 2} capture processes, or for better understanding of thermodynamics of CO{sub 2}-alkanolamine systems. Carbon dioxide is one of the major greenhouse gases, and the need for stabilization of its composition in earth's atmosphere is vital for the future of mankind. Although technologies are available for capture and storage of CO{sub 2}, these technologies are far too expensive for economical commercialization. Reduction of cost would require research for refinement of the technology. For more economical CO{sub 2} capture and regeneration, there is a need for development of more efficient solvent systems. In this project we will extend the thermodynamic database by measuring heat of solution data of CO{sub 2} in mixed solvents made of MEA (monoethanolamine), MDEA (methyldiethanolamine), piperazine, and water. Mixed solvents of different compositions will be selected and in each case data will be measured at temperatures 40 and 80C and various partial pressures of CO{sub 2}. At the end of the project, observations, conclusions, and recommendations will be derived for the choice of mixed solvents for efficient CO{sub 2} capture with potential for commercialization.

Vinayak N. Kabadi

2006-05-29

234

Effects of repeated administration of the monoamine oxidase inhibitor phenelzine on the discriminability of d-lysergic acid diethylamide (LSD) and 1-(m-trifluoromethylphenyl) piperazine (TFMPP)  

Microsoft Academic Search

Rats trained to discriminate d-lysergic acid diethylamide (LSD; 0.08 mg\\/kg) or 1-(m-trifluoromethylphenyl) piperazine (TFMPP; 0.8 mg\\/kg) were treated with the monoamine oxidase inhibitor (MAOI) phenelzine (10 mg\\/kg\\/day) for 7 days. After a 24 h “washout” period, they were challenged with the training drug (and dose) or saline, during extinction test sessions. Following 0.08 mg\\/kg LSD, LSD-trained rats responded primarily on

Kathryn A. Cunningham; Brenda A. Carroll; James B. Appel

1986-01-01

235

Design, synthesis and biological evaluation of 3-[4-(7-chloro-quinolin-4-yl)-piperazin-1-yl]-propionic acid hydrazones as antiprotozoal agents.  

PubMed

N-Acylhydrazones derived from 7-chloro-4-piperazin-1-yl-quinoline were synthesized and biologically evaluated for blood-stage of Plasmodium falciparum and Entamoeba histolytica trophozoites. N-Acylhydrazone F12 was found to inhibit the P. falciparum growth as well as its life cycle with good selectivity, which was achieved by inhibiting hematin formation. Compound F24 showed better IC50 value than the amoebicidal drug metronidazole. PMID:24530492

Inam, Afreen; Siddiqui, Shadab Miyan; Macedo, Taís Soares; Moreira, Diogo Rodrigo Magalhaes; Leite, Ana Cristina Lima; Soares, Milena Botelho Pereira; Azam, Amir

2014-03-21

236

Temperature- and pH-responsive nanoparticles of biocompatible polyurethanes for doxorubicin delivery.  

PubMed

A series of temperature- and pH-responsive polyurethanes based on hexamethylene diisocyanate (HDI) and 4,4'-diphenylmethane diisocyanate (MDI) were synthesized by a coupling reaction with bis-1,4-(hydroxyethyl) piperazine (HEP), N-methyldiethanolamine (MDEA) and N-butyldiethanolamine (BDEA), respectively. The chemical structure, molecular weight, thermal property and crystallization properties were characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) spectroscopy. The resulting polyurethanes were then used to prepare nanoparticles either by direct dispersion method or dialysis method. Their pH and temperature responsibilities were evaluated by optical transmittance and size measurement in aqueous media. Interestingly, HDI-based and MDI-based polyurethanes exhibited different pH and temperature responsive properties. Nanoparticles based on HDI-HEP and HDI-MDEA were temperature-responsive, while MDI-based biomaterials were not. All of them showed pH-sensitive behavior. The possible responsive mechanism was investigated by (1)H NMR spectroscopy. The cytotoxicity of the polyurethanes was evaluated using methylthiazoletetrazolium (MTT) assay in vitro. It was shown that the HDI-based polyurethanes were non-toxic, and could be applied to doxorubicin (DOX) encapsulation. The experimental results indicated that DOX could be efficiently encapsulated into polyurethane nanoparticles and uptaken by Huh-7 cells. The loaded DOX molecules could be released from the drug-loaded polyurethane nanoparticles upon pH and temperature changes, responsively. PMID:23262421

Wang, Anning; Gao, Hui; Sun, Yanfang; Sun, Yu-long; Yang, Ying-Wei; Wu, Guolin; Wang, Yinong; Fan, Yunge; Ma, Jianbiao

2013-01-30

237

Design, synthesis, and structure-affinity relationships of regioisomeric N-benzyl alkyl ether piperazine derivatives as sigma-1 receptor ligands.  

PubMed

A series of N-(benzofuran-2-ylmethyl)-N'-benzylpiperazines bearing alkyl or fluoroalkyl aryl ethers were synthesized and evaluated at various central nervous system receptors. Examination of in vitro sigma1 {[3H]+-pentazocine} and sigma2 ([3H]DTG) receptor binding profiles of piperazines 11-13 and 25-36 revealed several highly potent and sigma1 selective ligands, notably, N-(benzofuran-2-ylmethyl)-N'-(4'-methoxybenzyl)piperazine (13, Ki=2.7 nM, sigma2/sigma1=38) and N-(benzofuran-2-ylmethyl)-N'-(4'-(2''-fluoroethoxy)benzyl)piperazine (30, Ki=2.6 nM, sigma2/sigma1=187). Structural features for optimal sigma1 receptor affinity and selectivity over the sigma2 receptor were identified. On the basis of its favorable log D value, 13 was selected as a candidate for the development of a sigma1 receptor positron emission tomography radiotracer. [11C]13 showed high uptake in the brain and other sigma receptor-rich organs of a Papio hamadryas baboon. The in vivo evaluation of [11C]13 indicates that this radiotracer is a suitable candidate for imaging the sigma1 receptor in neurodegenerative processes. PMID:20662542

Moussa, Iman A; Banister, Samuel D; Beinat, Corinne; Giboureau, Nicolas; Reynolds, Aaron J; Kassiou, Michael

2010-08-26

238

Apoptosis of human Burkitt's lymphoma cells induced by 2-N,N-diethylaminocarbonyloxymethyl-1-diphenylmethyl-4-(3,4,5-trimethoxybenzoyl) piperazine hydrochloride (PMS-1077).  

PubMed

Piperazine is one of the heterocycles which are associated with diverse pharmacological activities. 2-N,N-Diethylaminocarbonyloxymethyl-1-diphenylmethyl-4-(3,4,5-trimethoxybenzoyl) piperazine hydrochloride (PMS-1077) is a trisubstituted piperazine which contains a trimethoxybenzene ring and a benzhydrylpiperazine fragment, both of which can induce cell proliferation regression by different mechanisms. We have therefore examined the effects of PMS-1077 on Human Burkitt's lymphoma cells (Raji). The viability of Raji cells was determined by MTT assay and also assessed by trypan blue dye exclusion method. The results demonstrate that PMS-1077 can suppress the proliferation of Raji cells in a dose- and timedependent manner, while inhibit colony formation ability of Raji cells merely in a dose-dependent manner in vitro. Meanwhile, morphological changes were observed using fluorescence microscope. Flow cytometric analysis through PI stains showed that PMS-1077 blocked the growth of Raji cells in the G(0)/G(1) period, and induced apoptosis of Raji cells after 48 h of incubation. Cell apoptosis induced by PMS-1077 was further confirmed by staining with Annexin-V FITC and PI. Preliminary study by molecular docking suggests that PMS-1077 may inhibit tubulin polymerization. More experiments are in progress in our laboratory to reveal the mode of action of PMS-1077 in the induction of apoptosis of Raji cells. PMID:20162401

Wang, Wen-di; Xu, Xi-ming; Chen, Ying; Jiang, Peng; Dong, Chang-zhi; Wang, Qin

2009-12-01

239

Investigation on the inclusion interaction of 4-sulfonatocalix[n]arenes with 1-(4-nitrophenyl)piperazine.  

PubMed

The inclusion behaviors of 4-Sulfonatocalix[n]arenes (SCXn) (n=4, 6, 8) with 1-(4-nitrophenyl)piperazine (NPP) were investigated by UV spectroscopy and fluorescence spectroscopy at different pH values (pH=3.05, 6.50, 8.40). The UV absorption and fluorescence intensity of NPP remarkably increased in presence of SCXn revealing formation of the inclusion complexes between NPP and SCXn. Moreover, the formation constants (K) of inclusion complexes were also determined by the non-linear fitting method, and the obtained data showed that the formation constants decreasedgradually with the increasing of the pH value. When the pH value was 3.05, the formation constant of NPP with SCX8 reached a maximum of 1.7×10(7)Lmol(-1). The stoichiometric ratio was verified to be 1:1 by the continuous variation method. Meanwhile FT-IR and DSC analysis also indicated that NPP could form the inclusion complex with SCXn. In order to explore the inclusion mechanism of NPP with SCXn, (1)H NMR and molecular modeling studies were carried out and experimental results showed that the part of benzene ring of NPP penetrated into the hydrophobic cavity of SCXn. PMID:24858345

Zhang, Yongbin; Chao, Jianbin; Zhao, Shuhui; Xu, Penghao; Wang, Hongfang; Guo, Zhiqiang; Liu, Diansheng

2014-11-11

240

A novel piperazine derivative potently induces caspase-dependent apoptosis of cancer cells via inhibition of multiple cancer signaling pathways  

PubMed Central

Despite rapid progress in anticancer drug development and improvement in clinical outcomes, the survival rate for many types of cancer is still unacceptably low. Therefore, it is crucial to discover novel anticancer drugs to both prevent and treat the disease. In recent years, the advent of combinatorial chemistry allows the design and parallel synthesis of millions of small compounds that have drug-like properties. In vitro high throughput screening of such compound libraries has allowed the identification of many new drug candidates that may be further evaluated for their efficacy and mechanism of action. The overall objective of this study was to identify small molecule compounds as candidates for anti-cancer drug development. We first used cell proliferation and cytotoxicity assays to identify compounds exhibiting anti-cancer activity in vitro in a leukemia cell line (K562). Six top compounds selected from the initial screening of a library of 2,560 compounds were further evaluated in multiple cancer cell lines to rank the drug candidates. The top candidate was further investigated to elucidate the molecular mechanism underlying its anticancer activity. Our studies suggest that this piperazine derivative effectively (GI50 = 0.06-0.16 ?M) inhibits cancer cell proliferation and induces caspase-dependent apoptosis via inhibiting multiple cancer signaling pathways including the PI3K/AKT, the Src family kinases and the BCR-ABL pathways.

She, Edward X; Hao, Zhonglin

2013-01-01

241

Growth, nonlinear optical, thermal, dielectric and laser damage threshold studies of semiorganic crystal: monohydrate piperazine hydrogen phosphate.  

PubMed

Monohydrate piperazine hydrogen phosphate (MPHP), a semi organic nonlinear optical material has been synthesized and single crystals were grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction study on grown crystal reveals that they belong to monoclinic crystal system with space group P2(1)/c; (a=6.39Å; b=12.22Å; c=11.16Å; ?=97.14°; V=864Å(3)). The structural perfection of the grown crystal was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. FTIR spectrum confirms the presence of the functional groups in synthesized material. UV-Vis spectrum indicates that the crystal is transparent in the entire visible region with a lower cut off wavelength of 387 nm. The variation of dielectric properties of the grown crystal with respect to frequency has been investigated at different temperatures. Thermal analysis carried out on the MPHP crystal shows that the crystal is stable up to 135°C. Relative powder second harmonic generation efficiency tested by Kurtz-Perry powder technique, which was about 0.638 times that of Potassium dihydrogen phosphate. PMID:23220681

Krishnan, P; Gayathri, K; Bhagavannarayana, G; Gunasekaran, S; Anbalagan, G

2013-02-01

242

Acid Gas Treating by Aqueous Alkanolamines. Annual Report, January-December 1993.  

National Technical Information Service (NTIS)

The objective of the work is to investigate the simultaneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed thus far, density, visco...

O. C. Sandall E. B. Rinker S. Ashour

1993-01-01

243

Acid Gas Treating by Aqueous Alkanolamines. Annual Report, January-December 1994.  

National Technical Information Service (NTIS)

The objective of this work is to investigate the simulateneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed this year the authors ...

O. C. Sandall E. B. Rinker S. Ashour

1994-01-01

244

HS process: an advanced process for selective H/sub 2/S  

SciTech Connect

Union Carbide's HS process offers improved efficiency in both H/sub 2/S removal and system costs while remaining flexible to diverse gas-conditioning requirements. The process combines three principal elements - an MDEA (methyldiethanolamine) solvent, a multistaged contactor design, and a special selective contactor tray. Prototype pilot-plant operations have demonstrated the superior performance of the HS process over existing methods.

Sigmund, P.W.; Butwell, K.F.; Wussler, A.J.

1981-01-01

245

Simultaneous removal of water and hydrogen sulphide from natural gas.  

National Technical Information Service (NTIS)

The thesis relates to the development of a process for the simultaneous removal of water and H2S from natural gas. The new process is based on the use of TEG (triethylene glycol) and MDEA (methyldiethanolamine). Some absorption of CO2 must also be expecte...

D. Eimer

1994-01-01

246

Physical solubility of carbon dioxide in aqueous alkanolamines via nitrous oxide analogy  

Microsoft Academic Search

In the petrochemical and natural gas industry, the removal of carbon dioxide and hydrogen sulfide from process gas streams is commonly achieved by reacting these impurities with aqueous alkanolamines. Van Krevelen coefficients for protonated monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA), the carbamates of MEA and DEA, and the bicarbonate ion have been determined experimentally from measurements of the solubility

Gregory J. Browning; Ralph H. Weiland

1994-01-01

247

Interactions of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas with dopamine D2 and 5-hydroxytryptamine 5HT(1A) receptors.  

PubMed

It is suggested that the ratio of dopamine D(2) to 5-hydroxytryptamine 5-HT(1A) activity is an important parameter that determines the efficiency of antipsychotic drugs. Here we present the synthesis of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas and their structure-activity relationship studies on dopamine D(2) and 5-hydrohytryptamine 5-HT(1A) receptors. It was shown that ligand selectivity and affinity strongly depends on their topology and the presence of a pyridyl group in the head of molecules. Molecular modeling studies using homology modeling and docking simulation revealed a rational explanation for the ligand behavior. The observed binding modes and receptor-ligand interactions provided us with a clue for optimizing the optimal selectivity towards 5-HT(1A) receptors. PMID:22607670

Sukalovic, Vladimir; Ignjatovic, Djurdjica; Tovilovic, Gordana; Andric, Deana; Shakib, Kaveh; Kostic-Rajacic, Sladjana; Soskic, Vukic

2012-06-15

248

Pilot plant studies of the CO{sub 2} capture performance of aqueous MEA and mixed MEA/MDEA solvents at the University of Regina CO{sub 2} capture technology development plant and the Boundary Dam CO{sub 2} capture demonstration  

SciTech Connect

Evaluations of the benefits of using a mixed MEA/MDEA solvent for CO{sub 2} capture in terms of the heat requirement for solvent regeneration, lean and rich loadings, CO{sub 2} production, and solvent stability were performed by comparing the performance of aqueous 5 kmol/m{sup 3} MEA with that of an aqueous 4:1 molar ratio MEA/MDEA blend of 5 kmol/ml total amine concentration as a function of the operating time. The tests were performed using two pilot CO{sub 2} capture plants of the International Test Centre for CO{sub 2} Capture (ITC), which provided two different sources and compositions of flue gas. The University of Regina CO{sub 2} plant (UR unit) processes flue gas from the combustion of natural gas while the Boundary Dam CO{sub 2} plant (BD unit) processes flue gas from a coal-fired electric power station. The results show that a huge heat-duty reduction can be achieved by using a mixed MEA/MDEA solution instead of a single MEA solution in an industrial environment of a CO{sub 2} capture plant. However, this benefit is dependent on whether the chemical stability of the solvent can be maintained.

Idem, R.; Wilson, M.; Tontiwachwuthikul, P.; Chakma, A.; Veawab, A.; Aroonwilas, A.; Gelowitz, D. [University of Regina, Regina, SK (Canada). Faculty of Engineering

2006-04-12

249

Discriminating octahedral transition metal ions: highly selective tripodal tris-(2,2'-bipyridine) functionalized piperazine cyclophane receptor for Cu2+ ions.  

PubMed

New tripodal transition metal ion receptors, tris(5-ethoxycarbonyl-2,2'-bipyridine) and tris(5-carboxylate-2,2'-bipyridine) substituted 27-membered trimeric piperazine cyclophanes 5 and 7 as well as tetra(5-ethoxycarbonyl-2,2'-bipyridine) substituted 36-membered tetrameric piperazine cyclophane 6, have been prepared and their transition metal ion complexing properties studied in solution by UV-vis spectroscopy and in the solid state by single-crystal X-ray diffraction. The crystal structures of [H(3)5(3+)·Fe(2+)]·4(ClO(4)(-))·CF(3)COO(-) (V), [H(3)7(2+)·Fe(2+)]·2(SO(4)(2-)) (VII) and the reference complex [tris(5,5'-bis(ethoxycarbonyl)-2,2'-bipyridine)Fe(II) perchlorate] (I) showed that the robust piperazine cyclophane is an optimal platform in preorganizing the 2,2'-bipy moieties to form a very fixed octahedral coordination site. In an acidic water solution, the highly preorganized structure of 5 gives a [5·Fe(2+)] complex, the stability of which is comparable with the classical tris(2,2'-bipy) Fe(2+)-complex but it is a significant 3.7 logK units more stable than the non-preorganized tetrameric analog [6·Fe(2+)]. Detailed studies with other similar divalent octahedral transition metal cations showed that the restricted octahedral coordination in complexes of 5 results in an unusual selectivity. The selectivity order [Zn(2+)

Raatikainen, Kari; Huuskonen, Juhani; Rissanen, Kari

2011-06-01

250

Assembly and photocatalysis of two novel 3D Anderson-type polyoxometalate-based metal-organic frameworks constructed from isomeric bis(pyridylformyl)piperazine ligands.  

PubMed

Two novel Anderson-type polyoxometalates (POMs)-based metal-organic frameworks (MOFs), namely, H{Cu2(?2-OH)2L(1)[CrMo6(OH)6O18]}·4H2O (), {Cu2L(2)[CrMo(VI)5Mo(V)(OH)6O18](H2O)4}·4H2O () (L(1) = N,N'-bis(3-pyridinecarboxamide)-piperazine, L(2) = N,N'-bis(4-pyridinecarboxamide)-piperazine), are hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). In complex , the hexadentate [CrMo6(OH)6O18](3-) polyoxoanion bridges the Cu(II) ions to generate a 2D Cu-POM inorganic layer, which is further extended by the ?2-bridging L(1) ligands (via ligation of pyridyl nitrogen atoms) to form a 3D MOF with a 4,6-connected {4(4)·6(10)·8}{4(4)·6(2)} topology. Complex is also a 3D POM-based MOF exhibiting a {4(2)·8(4)} topology, which is constructed from the quadridentate [CrMo(VI)5Mo(V)(OH)6O18](4-) polyoxoanions and ?4-bridging L(2) ligands (via ligation of pyridyl nitrogen and carbonyl oxygen atoms). The different coordination modes of POM polyanions and the isomeric bis(pyridylformyl)piperazine ligands play key roles in the construction of the title complexes. In addition, the photocatalytic activities of the title complexes on the degradation of methylene blue (MB) under UV, visible light and sunlight irradiation have been investigated in detail. PMID:24958084

Wang, Xiuli; Chang, Zhihan; Lin, Hongyan; Tian, Aixiang; Liu, Guocheng; Zhang, Juwen

2014-07-22

251

Acid gas treating by aqueous alkanolamines. Annual report, January-December 1994  

SciTech Connect

The objective of this work is to investigate the simulateneous absorption or desorption of CO2 and H2S into and from a mixed aqueous amine solvent consisting of methyldiethanolamine (MDEA) and diethanolamine (DEA). In work completed this year the authors have measured the density, viscosity and surface tension of pure MDEA and DEA over a range in temperatures. The diffusivity of N2O was measured in aqueous blends of MDEA and DEA at 50 wt% total amine for various ratios of DEA to MDEA over the temperature range 20 to 80 deg. C. A theoretically-based model has been developed for the correlation of the physical solubility of N2O in aqueous amine solutions. A penetration theory type model which was developed to describe acid gas absorption in aqueous amine solutions was used to carry out a sensitivity analysis for the various parameters affecting the rate of absorption of CO2 in MDEA solutions.

Sandall, O.C.; Rinker, E.B.; Ashour, S.

1994-12-01

252

2-Methyl-4-(4-methyl-piperazin-1-yl)-10H-thieno[2,3-b][1,5]benzodiazepine (olanzapine) propan-2-ol disolvate  

PubMed Central

In the title solvate, C17H20N4S·2C3H8O, pairs of olanzapine mol­ecules related by a centre of inversion stack along the a axis, forming columns, which are packed parallel to each other along the b axis, forming a sheet arrangement. The columns within these sheets are hydrogen bonded to each other through the propan-2-ol solvent mol­ecules. The diazepine ring of the olanzapine exists in a puckered conformation with the thiophene and phenyl rings making a dihedral angle of 57.66?(7)° and the piperazine ring adopts a chair conformation with the methyl group in an equatorial position.

Bhardwaj, Rajni M.; Florence, Alastair J.

2013-01-01

253

Structure–activity relationships, and drug metabolism and pharmacokinetic properties for indazole piperazine and indazole piperidine inhibitors of ROCK-II  

Microsoft Academic Search

ROCK has been implicated in many diseases ranging from glaucoma to spinal cord injury and is therefore an important target for therapeutic intervention. In this study, we have designed a series of 1-(4-(1H-indazol-5-yl)piperazin-1-yl)-2-hydroxy(or 2-amino) analogs and a series of 1-(4-(1H-indazol-5-yl amino)piperidin-1-yl)-2-hydroxy(or 2-amino) inhibitors of ROCK-II. SR-1459 has IC50=13nM versus ROCK-II while the IC50s for SR-715 and SR-899 are 80nM and

Yangbo Feng; Michael D. Cameron; Bozena Frackowiak; Evelyn Griffin; Li Lin; Claudia Ruiz; Thomas Schröter; Philip LoGrasso

2007-01-01

254

Synthesis and characterization of Ni(II), Cu(II) and Zn(II) complexes with new macrocyclic Schiff base ligands containing piperazine moiety  

Microsoft Academic Search

Two new macrocyclic Schiff base ligands L1 and L2 from [1+1] and [2+2] condensation reaction, respectively, have been obtained in a one-pot synthesis starting from 1,4-bis(2-formylphenyl)piperazine and 2,2-dimethyl-propylendiamine. Unfortunately, because of the low solubility of two products, we were unable to separate them effectively. Macrocyclic Schiff base complexes [NiL1](ClO4)2, [CuL1](ClO4)2 and [ZnL1](ClO4)2 were prepared from the reaction of a mixture

Hassan Keypour; Parisa Arzhangi; Nasibeh Rahpeyma; Majid Rezaeivala; Yalcin Elerman; Orhan Büyükgüngör; Laura Valencia; Hamid Reza Khavasi

2010-01-01

255

Investigation of the mode of binding of a novel series of N-benzyl-4-heteroaryl-1-(phenylsulfonyl)piperazine-2-carboxamides to the hepatitis C virus polymerase  

SciTech Connect

Structure based rationales for the activities of potent N-benzyl-4-heteroaryl-1-(phenylsulfonyl)piperazine-2-carboxamide inhibitors of the hepatitis C viral polymerase are described herein. These compounds bind to the hepatitis C virus non-structural protein 5B (NS5B), and co-crystal structures of select examples from this series with NS5B are reported. Comparison of co-crystal structures of a potent analog with both NS5B genotype 1a and genotype 1b provides a possible explanation for the genotype-selectivity observed with this compound class and suggests opportunities for the further optimization of the series.

Gentles, Robert G.; Sheriff, Steven; Beno, Brett R.; Wan, Changhong; Kish, Kevin; Ding, Min; Zheng, Xiaofan; Chupak, Louis; Poss, Michael A.; Witmer, Mark R.; Morin, Paul; Wang, Ying-Kai; Rigat, Karen; Lemm, Julie; Voss, Stacey; Liu, Mengping; Pelosi, Lenore; Roberts, Susan B.; Gao, Min; Kadow, John F. (BMS) [BMS

2013-11-20

256

Synthesis, 5HT 1A and 5HT 2A receptor affinity and QSAR study of 1-benzhydryl-piperazine derivatives with xanthine moiety at N4  

Microsoft Academic Search

\\u000a Abstract  Three novel 1-benzhydryl-piperazines with xanthine moiety at N4 were synthesized and tested for 5-HT1A and 5-HT2A receptor affinity. One of the compounds showed the highest affinity (58.6 nM) and selectivity (34 times) to 5-HT2A receptor known for this class of compounds. A set of the three new and 31 previously synthesized 1-arylpiperazines with xanthine\\u000a moiety at N4 was compiled and a

Iva Valkova; Alexander Zlatkov; Krystyna N?dza; Irini Doytchinova

257

The 5-HT(1A) agonism potential of substituted piperazine-ethyl-amide derivatives is conserved in the hexyl homologues: molecular modeling and pharmacological evaluation.  

PubMed

In a series of carboxamide and sulphonamide alkyl (ethyl to hexyl) piperazine analogues, although the size of the linker is very different, ethyl and hexyl derivatives possess a high affinity for 5-HT(1A) receptors. Docking studies clearly show that hexyl and ethyl compounds favorably interact with the binding site of the active conformation of 5-HT(1A) receptors, thus confirming a possible agonist profile. This activity is effectively detected in electrophysiological experiments in which all four compounds inhibit the activity of rat dorsal raphe serotonergic neurons. PMID:21957888

Dilly, Sébastien; Scuvée-Moreau, Jacqueline; Wouters, Johan; Liégeois, Jean-François

2011-11-28

258

Synthesis and anticancer activities of 4-(4-substituted piperazin)-5,6,7-trialkoxy quinazoline derivatives.  

PubMed

A series of 4-(4-substituted piperazin)-5,6,7-trialkoxy quinazoline was prepared by conventional heating methods. Among these compounds, the crystal structure of compound 10o (CCDC: 916922) was determined by X-ray crystallography. Bioassay results showed that most target compounds had certain inhibition activities against proliferation of tumor cells, and some compounds even had good broad-spectrum inhibition activities. The ethoxyl series of compounds possessed higher inhibition activities against tumor cells than the methoxyl series of compounds. Bioactivity tests showed that the IC50 values of compound 10s against PC3, MGC803, A375, and A549 cells were 1.8, 2.8, 1.3, and 2.9 ??, respectively, which were much higher than those of commercial gefitinib (7.2, 7.6, 7.2, and 9.8 ?M, respectively). Conversely, the IC50 values of compound 10s were very low against NH3T3, indicating only weak effect on normal cells as also proven by lactate dehydrogenase and acridine orange/ethidium bromide staining. Analyses of cell configuration and cell cycle revealed that compound 10s possibly caused cells to remain at G0/G1 phase by inhibiting cell proliferation for 24 h. Compound 10s also inhibited the phosphorylation of ERK1/2 and P38 with obvious concentration dependence. Thus, these compounds can inhibit the proliferation of A549 cells through the interruption of ERK1/2 and P38signaling pathways. PMID:24675177

Zhang, Ying; Huang, Yin-Jiu; Xiang, Hong-Mei; Wang, Pei-Yi; Hu, De-Yu; Xue, Wei; Song, Bao-An; Yang, Song

2014-05-01

259

alpha-Keto amides as precursors to heterocycles--generation and cycloaddition reactions of piperazin-5-one nitrones.  

PubMed

alpha-Keto amides 10a,b, formed from reaction of pyruvic or benzoylformic acid with allyl amine are found to present as single rotameric forms whilst their tertiary amido analogues 10c, d present as two rotamers in solution at rt. The hydroxyimino derivatives 8 share the conformational characteristics of their parents. The geometrical make-up of the new alpha-amidooximes is seen to depend on the structure of the starting acid and on the degree of substitution of the amido group. The oxime 8a derived from pyruvic acid and allyl amine is formed solely as the (E)-isomer whilst its tertiary amido analogue 8c is formed as both (E)- and (Z)-isomers. Oximes derived from benzoylformic acid have the opposite selectivity with both geometrical isomers forming from the secondary amide 8b and only the (Z)-isomer from the tertiary amide 8d. With the exception of 8b all oximes were configurationally stable with (Z)-isomers reacting to form isoxazolopyrrolidinones 11--compounds with a relatively rare bicyclic nucleus and (E)-isomers cyclising to piperazin-5-one nitrones 1--ketopiperazine N-oxides have to date only appeared once in the literature. New nitrones were trapped with phenyl vinyl sulfone, dimethyl acetylenedicarboxylate and methyl propiolate yielding isoxazolidine and isoxazoline fused piperazinones 13, 15, 21 and 22. Cycloadducts from dimethyl acetylenedicarboxylate and 8a, b are thermally labile and their rearrangement provides a novel route to pyrrolopiperazinones 16. The structure of a representative isoxazolopyrrolidinone, 11c, and a 2,3-dihydroisoxazoline fused piperazinone, 21b, are unambiguously solved following x-ray structural analysis. PMID:12926386

Heaney, Frances; Fenlon, Julie; McArdle, Patrick; Cunningham, Desmond

2003-04-01

260

3-(Adamantan-1-yl)-4-ethyl-1-{[4-(2-meth-oxy-phen-yl)piperazin-1-yl]meth-yl}-1H-1,2,4-triazole-5(4H)-thione.  

PubMed

In the title compound, C26H37N5OS, the piperazine ring adopts a chair conformation. The triazole ring forms dihedral angles of 67.85?(9) and 59.41?(9)° with the piperazine and benzene rings, respectively, resulting in an approximate V-shaped conformation for the mol-ecule. An intra-molecular C-H?O hydrogen bond generates an S(6) ring motif. The crystal structure features C-H?? inter-actions, producing a two-dimensional supramolecular architecture. PMID:24526973

El-Emam, Ali A; Al-Tuwaijri, Hanaa M; Al-Abdullah, Ebtehal S; Chidan Kumar, C S; Fun, Hoong-Kun

2014-01-01

261

3-(Adamantan-1-yl)-4-ethyl-1-{[4-(2-meth-oxy-phen-yl)piperazin-1-yl]meth-yl}-1H-1,2,4-triazole-5(4H)-thione  

PubMed Central

In the title compound, C26H37N5OS, the piperazine ring adopts a chair conformation. The triazole ring forms dihedral angles of 67.85?(9) and 59.41?(9)° with the piperazine and benzene rings, respectively, resulting in an approximate V-shaped conformation for the mol­ecule. An intra­molecular C—H?O hydrogen bond generates an S(6) ring motif. The crystal structure features C—H?? inter­actions, producing a two-dimensional supramolecular architecture.

El-Emam, Ali A.; Al-Tuwaijri, Hanaa M.; Al-Abdullah, Ebtehal S.; Chidan Kumar, C. S.; Fun, Hoong-Kun

2014-01-01

262

(C 6H 17N 3)[Zn 4(PO 4) 2(HPO 3) 2]: a new layered zinc phosphate-phosphite templated by 1-(2-Aminoethyl) piperazine  

NASA Astrophysics Data System (ADS)

Employing 1-(2-Aminoethyl) piperazine as a template, a new organically templated layered zinc phosphate-phosphite (C 6H 17N 3)[Zn 4(PO 4) 2(HPO 3) 2] has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group Cc with a=5.3272(11) Å, b=17.146(3) Å, c=22.071(4) Å, ?=94.58(3)°, V=2009.5(7) Å 3, Z=4, R1=0.0201 ( I>2 ?( I)) and w R2=0.0812 (all data). The inorganic network is based on strictly alternating ZnO 4 tetrahedral units and P-centered units including PO 4 tetrahedra and HPO 3 pseudo-pyramids forming a double layered structure that contains columns of double six-membered rings. The diprotonated 1-(2-Aminoethyl) piperazine molecules reside in the interlayer region and interact with the inorganic network through H-bonds.

Chen, Xiaoxin; Wang, Yu; Yu, Jihong; Zou, Yongchun; Xu, Ruren

2004-07-01

263

1-{2-[4-(4-Nitro-phen-yl)piperazin-1-yl]eth-yl}-4-aza-1-azoniabicyclo-[2.2.2]octane iodide.  

PubMed

The title compound, C(18)H(28)N(5)O(2) (+)·I(-), was observed as a main product in an intended 1:1 reaction between 4-iodo-nitro-benzene and 1,4-diaza-bicyclo-[2.2.2]octane (DABCO). In the reaction, DABCO undergoes a ring opening to yield a quaternary salt of DABCO and 1-ethyl-4-(4-nitro-phen-yl)piperazine with an iodide anion. The crystal structure determination was carried out as no crystal structure had been previously reported in the investigations describing the corresponding reaction with 4-chloro-nitro-benze. Indeed, the crystal structure of the title compound confirms the mol-ecular composition proposed earlier for the analogous chloride salt. The cation conformation is similar to the previously reported dinitro analogue 1-{2-[4-(2,4-dinitro-phen-yl)piperazin-1-yl]eth-yl}-4-aza-1-azoniabicyclo-[2.2.2]octane chloride [Clegg et al. (2004 ?). Acta Cryst. E60, o291-o293]. The crystal packing is dominated by cation?I(-) inter-actions in addition to weak inter-molecular C-H?O(2)N and C-H?N inter-actions between the cations. PMID:22807819

Peuronen, Anssi; Lahtinen, Manu

2012-07-01

264

Selective gas treating produces better claus feeds  

SciTech Connect

Methyldiethanolamine (MDEA) systems with 20-25% by wt MDEA solutions in water are cheaper and more convenient than monoethanolamine (MEA) or diethanolamine (DEA) systems for selective H/sub 2/S removal from gas streams containing H/sub 2/S and CO/sub 2/, because the amine circulation rate will be much less for the MDEA system; apparently, the reaction between MDEA and H/sub 2/S is gas-film-diffusion-rate limited, and the reaction between MDEA and CO/sub 2/ is kinetically controlled. MDEA systems facilitate selective H/sub 2/S absorption by controlling residence time, which is done by limiting the number of contact trays and the amine circulation rate. At high pressures, MDEA systems can remove H/sub 2/S down to 0.25-0.50 g/100 std cu ft, with only 20-30% of the CO/sub 2/ being co-absorbed. The MDEA system at the Husky (Oil Co.) Clark Avenue Gas Plant in Santa Maria, Calif., uses selective amine regeneration technology licensed from Shell Development Co. to enrich Claus unit feed from approx. 23 mole Vertical Bar3< H/sub 2/S up to approx. 50 mole % H/sub 2/S, thus allowing 94% sulfur recovery in a once-through system. Two other MDEA systems for high-pressure gas treating are discussed.

Goar, B.G.

1980-01-01

265

Investigation of various N-heterocyclic substituted piperazine versions of 5/ 7-{[2-(4-Aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol: Effect on affinity and selectivity for dopamine D3 receptor  

PubMed Central

Here we report on the design and synthesis of several heterocyclic analogues belonging to the 5/ 7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol series of molecules. Compounds were subjected to [3H]spiperone binding assays, carried out with HEK-293 cells expressing either D2 or D3 dopamine receptors, in order to evaluate their inhibition constant (Ki) at these receptors. Results indicate that N-substitution on the piperazine ring can accommodate various substituted indole rings. The results also show that in order to maintain high affinity and selectivity for the D3 receptor the heterocyclic ring does not need to be connected directly to the piperazine ring as the majority of compounds included here are linked either via an amide or a methylene linker to the heterocyclic moiety. The enantiomers of the most potent racemic compound 10e exhibited differential activity with (-)-10e (Ki; D2 = 47.5 nM, D3 = 0.57 nM) displaying higher affinity at both D2 and D3 receptors compared to its enantiomer (+)-10e (Ki; D2 = 113 nM, D3 = 3.73 nM). Additionally, compound (-)-10e was more potent and selective for the D3 receptor compared to either 7-OH-DPAT or 5-OH-DPAT. Among the bioisosteric derivatives, the indazole derivative 10g and benzo[b]thiophene derivative 10i exhibited the highest affinity for D2 and D3 receptors. In the functional GTP?S binding study, one of the lead molecules, (-)-15, exhibited potent agonist activity at both D2 and D3 receptors with preferential activity at D3.

Brown, Dennis A.; Mishra, Manoj; Zhang, Suhong; Biswas, Swati; Parrington, Ingrid; Antonio, Tamara; Reith, Maarten E. A.; Dutta, Aloke K.

2009-01-01

266

Lanthanide N,N'-piperazine-bis(methylenephosphonates) (Ln=La, Ce, Nd) that display flexible frameworks, reversible hydration and cation exchange  

SciTech Connect

Hydrothermal syntheses of lanthanide bisphosphonate metal organic frameworks comprising the light lanthanides lanthanum, cerium and neodymium and N,N'-piperazine bis(methylenephosphonic acid) (H{sub 2}L(1) and its 2-methyl and 2,5-dimethyl derivatives (H{sub 2}L(2) and H{sub 2}L(3)) gives three new structure types. At elevated starting pH (ca. 5 and above) syntheses give 'type I' materials with all metals and acids of the study (MLnLxH{sub 2}O, M=Na, K, Cs; Ln=La, Ce, Nd; x{approx}4: KCeL(1).4H{sub 2}O, C2/c, a=23.5864(2) A, b=12.1186(2) A, c=5.6613(2) A, beta=93.040(2){sup o}). The framework of structure type I shows considerable flexibility as the ligand is changed, due mainly to rotation around the -N-CH{sub 2}- bond of the linker in response to steric considerations. Type I materials demonstrate cation exchange and dehydration and rehydration behaviour. Upon dehydration of KCeL.4H{sub 2}O, the space group changes to P2{sub 1}/n, a=21.8361(12) A, b=9.3519(4) A, c=5.5629(3) A, beta=96.560(4){sup o}, as a result of a change of the piperazine ring from chair to boat configuration. When syntheses are performed at lower pH, two other structure types crystallise. With the 'non-methyl' ligand 1, type II materials result (LnL(1)H{sub 2}L(1).4.5H{sub 2}O: Ln=La, P-1, a=5.7630(13) A, b=10.213(2) A, c=11.649(2) A, alpha=84.242(2){sup o}, beta=89.051(2){sup o}, gamma=82.876(2){sup o}) in which one half of the ligands coordinate via the piperazine nitrogen atoms. With the 2-methyl ligand, structure type III crystallises (LnHL(2).4H{sub 2}O: Ln=Nd, Ce, P2{sub 1}/c, a=5.7540(9) A, b=14.1259(18) A, c=21.156(5) A, beta=90.14(2){sup o}) due to unfavourable steric interactions of the methyl group in structure type II. - Graphical abstract: The lanthanides La, Ce and Nd give a family of metal organic frameworks based on N,N'-piperazinebismethylenephosphonate ligands: these display reversible dehydration, structural flexibility and cation exchange.

Mowat, John P.S.; Groves, John A.; Wharmby, Michael T.; Miller, Stuart R.; Li Yang; Lightfoot, Philip [School of Chemistry, University of St. Andrews, Purdie Building, North Haugh, St. Andrews, Fife KY16 9ST (United Kingdom); Wright, Paul A., E-mail: paw2@st-and.ac.u [School of Chemistry, University of St. Andrews, Purdie Building, North Haugh, St. Andrews, Fife KY16 9ST (United Kingdom)

2009-10-15

267

FT-IR, FT-Raman and DFT quantum chemical study on the molecular conformation, vibrational and electronic transitions of 1-(m-(trifluoromethyl)phenyl)piperazine.  

PubMed

The FTIR and FT-Raman spectra of 1-(m-(trifluoromethyl)phenyl)piperazine [TFMPP] have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of the compound was obtained by the density functional theory using 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. A detailed interpretation of the infrared and Raman spectra were also reported based on potential energy distribution (PED). UV-Vis spectrum of the compound was recorded and the electronic properties HOMO and LUMO energies were measured by TD-DFT approach. Furthermore, molecular electrostatic potential is performed and also the calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. PMID:24291424

Prabavathi, N; Nilufer, A; Krishnakumar, V

2014-03-01

268

catena-Poly[[[tetra-aqua-magnesium]-trans-?-[(piperazine-1,4-diium-1,4-di-yl)bis-(methyl-ene)]di-phospho-nato] hemihydrate  

PubMed Central

The structure of the title polymer, }[Mg(C6H14N2O6P2)(H2O)4]·0.5H2O}n, is based on centrosymmetric MgO6 octahedra, which are linked by [(piperazine-1,4-diium-1,4-di­yl)bis­(methyl­ene)]di­phospho­nate ligands, forming chains parallel to [1-1-1]. These chains are connected via hydrogen bonds primarily formed between the phospho­nate groups and water mol­ecules. The latter constitute four of the corners of the MgO6 polyhedra and bind to the O atoms of the phospho­nate groups of neighbouring chains. The lattice water molecule is disordered around an inversion centre, exhibiting an occupancy of 0.25.

Schilling, Lars-Hendrik; Stock, Norbert

2013-01-01

269

Design, synthesis, pharmacological evaluation and descriptor based similarities study of N,N-diphenyl-2-[4-(substituted phenyl)piperazin-1-yl]acetamides as potential antipsychotics.  

PubMed

A series of novel N,N-diphenyl-2-[4-(substituted phenyl)piperazin-1-yl]acetamides was designed, synthesized and evaluated for anti-dopaminergic activity, anti-serotonergic activity and catalepsy induction studies in mice as an approach to novel potential antipsychotic agent. Antipsychotic activity of these compounds in terms of blocking of dopaminergic transmission was evaluated by their ability to inhibit apomorphine induced climbing behavior in mice and antiserotonergic activity of synthesized compounds was assessed by studying inhibition of 5-HTP induced head twitches. All the synthesized compounds were found to exhibit anti-dopaminergic and anti-serotonergic activity in behavioral models. The compound 3f showed better antipsychotic potential among the different synthesized compounds. The descriptor based similarities study for blood brain permeation established a good similarity between the synthesized compounds with standard atypical antipsychotics. PMID:22779792

Dash, Radha Charan; Bhosale, Sharad H; Shelke, Suhas M; Suryawanshi, Mugdha R; Mahadik, Kakasaheb R

2012-11-01

270

Synthesis of novel 1-[5-(4-methoxy-phenyl)-[1,3,4]oxadiazol-2-yl]-piperazine derivatives and evaluation of their in vivo anticonvulsant activity.  

PubMed

A series of novel 1-[5-(4-methoxy-phenyl)-[1,3,4]oxadiazol-2-yl]-piperazine derivatives 8(a-o) were synthesized and characterized by elemental analyses, (1)H NMR, (13)C NMR and mass spectral studies. The newly synthesized compounds were screened for their anticonvulsant activity against maximal electroshock seizure (MES) model in male wistar rats and compared with the standard drug phenytoin. The neurotoxic effects were determined by rotorod test by using mice. Compounds 8d, 8e, 8f and 8h were found to be most potent of this series. The same compounds showed no neurotoxicity at the maximum dose administered (100 mg/kg). The efforts were also made to establish the structure activity relationships among synthesized compounds. The pharmacophore model was used to validate the anticonvulsant activity of the synthesized molecules. PMID:23727537

Harish, Kikkeri P; Mohana, Kikkeri N; Mallesha, Lingappa; Prasanna Kumar, Basavapatna N

2013-07-01

271

Synthesis and in vivo evaluation of [18F]N-(2-benzofuranylmethyl)-N'-[4-(2-fluoroethoxy)benzyl]piperazine, a novel ?1 receptor PET imaging agent.  

PubMed

N-(2-Benzofuranylmethyl)-N'-[4-(2-fluoroethoxy)benzyl]piperazine (6, ?(1)K(i)=2.6 nM) was radiolabeled with fluorine-18 to provide a potential ?(1) receptor radioligand for use in positron emission tomography (PET). Radiofluorination of the appropriate tosylate precursor furnished [(18)F]6 with a specific activity of 45 GBq/?mol, in an average radiochemical yield of 18% and greater than 98% radiochemical purity. MicroPET imaging in Papio hamadryas baboon brain revealed [(18)F]6 uptake consistent with ? receptor distribution, and specificity for ? receptors was demonstrated in a haloperidol pre-treated animal. [(18)F]6 possesses suitable properties for PET imaging of ?(1) receptors, and further investigation of this ?(1) receptor tracer is warranted. PMID:21962578

Moussa, Iman A; Banister, Samuel D; Giboureau, Nicolas; Meikle, Steven R; Kassiou, Michael

2011-11-15

272

Design, synthesis and biological evaluation of a novel series of bisintercalating DNA-binding piperazine-linked bisanthrapyrazole compounds as anticancer agents  

PubMed Central

A series of bisintercalating DNA binding bisanthrapyrazole compounds containing piperazine linkers were designed by molecular modeling and docking techniques. Because the anthrapyrazoles are not quinones they are unable to be reductively activated like doxorubicin and other anthracyclines and thus they should not be cardiotoxic. The concentration dependent increase in DNA melting temperature was used to determine the strength of DNA binding and the bisintercalation potential of the compounds. Compounds with more than a three-carbon linker that could span 4 DNA base pairs achieved bisintercalation. All of the bisanthrapyrazoles inhibited human erythroleukemic K562 cell growth in the low to submicromolar concentration range. They also strongly inhibited the decatenation activity of topoisomerase II and the relaxation activity of topoisomerase I. However, as measured by their ability to induce double strand breaks in plasmid DNA, the bisanthrapyrazole compounds did not act as topoisomerase II poisons. In conclusion, a novel group of bisanthrapyrazole compounds were designed, synthesized, and biologically evaluated as potential anticancer agents.

Zhang, Rui; Wu, Xing; Yalowich, Jack C.; Hasinoff, Brian B.

2011-01-01

273

Novel 3-nitro-1H-1,2,4-triazole-based piperazines and 2-amino-1,3-benzothiazoles as antichagasic agents.  

PubMed

We have previously shown that 3-nitro-1H-1,2,4-triazole-based amines demonstrate significant trypanocidal activity, in particular against Trypanosoma cruzi, the causative parasite of Chagas disease. In the present work we further expanded our research by evaluating in vitro the trypanocidal activity of nitrotriazole-based piperazines and nitrotriazole-based 2-amino-1,3-benzothiazoles to establish additional SARs. All nitrotriazole-based derivatives were active or moderately active against T. cruzi; however two of them did not fulfill the selectivity criteria. Five derivatives were active or moderately active against Trypanosoma brucei rhodesiense while one derivative was moderately active against Leishmania donovani. Active compounds against T. cruzi demonstrated selectivity indexes (toxicity to host cells/toxicity to T. cruzi amastigotes) from 117 to 1725 and 12 of 13 compounds were up to 39-fold more potent than the reference compound benznidazole. Detailed SARs are discussed. PMID:24012457

Papadopoulou, Maria V; Bloomer, William D; Rosenzweig, Howard S; Kaiser, Marcel; Chatelain, Eric; Ioset, Jean-Robert

2013-11-01

274

4-(2-Meth-oxy-phen-yl)piperazin-1-ium 6-chloro-5-isopropyl-2,4-dioxopyrimidin-1-ide  

PubMed Central

In the cation of the title salt, C11H17N2O+·C7H8ClN2O2 ?, the piperazine ring adopts a distorted chair conformation and contains a positively charged N atom with quaternary character. Its mean plane makes a dihedral angle of 42.36?(8)° with the phenyl ring of its 2-meth­oxy­phenyl substituent. The 2,4-dioxopyrimidin-1-ide anion is generated by deprotonation of the N atom at the 1-position of the pyrimidine­dione ring. Intra­molecular C—H?O hydrogen bonds generate S(6) ring motifs in both the cation and the anion. In the crystal, N—H?O, N—H?N and C—H?O hydrogen bonds are also observed, resulting in a two-dimensional network parallel to the ab plane. The crystal stability is further consolidated by weak C—H?? inter­actions.

Al-Omary, Fatmah A. M.; Ghabbour, Hazem A.; El-Emam, Ali A.; Chidan Kumar, C. S.; Fun, Hoong-Kun

2014-01-01

275

4-(2-Meth-oxy-phen-yl)piperazin-1-ium 6-chloro-5-isopropyl-2,4-dioxopyrimidin-1-ide.  

PubMed

In the cation of the title salt, C11H17N2O(+)·C7H8ClN2O2 (-), the piperazine ring adopts a distorted chair conformation and contains a positively charged N atom with quaternary character. Its mean plane makes a dihedral angle of 42.36?(8)° with the phenyl ring of its 2-meth-oxy-phenyl substituent. The 2,4-dioxopyrimidin-1-ide anion is generated by deprotonation of the N atom at the 1-position of the pyrimidine-dione ring. Intra-molecular C-H?O hydrogen bonds generate S(6) ring motifs in both the cation and the anion. In the crystal, N-H?O, N-H?N and C-H?O hydrogen bonds are also observed, resulting in a two-dimensional network parallel to the ab plane. The crystal stability is further consolidated by weak C-H?? inter-actions. PMID:24764966

Al-Omary, Fatmah A M; Ghabbour, Hazem A; El-Emam, Ali A; Chidan Kumar, C S; Fun, Hoong-Kun

2014-03-01

276

2-{[2-(Piperazin-4-ium-1-yl)ethyl-iminio]meth-yl}phenolate 0.06-chloride 0.94-perchlorate  

PubMed Central

The structure of the title salt, C13H20N3O+·0.94ClO4 ?·0.06Cl?, contains a zwitterionic Schiff base with a net positive charge and a perchlorate anion having substitutional disorder with Cl. In the cation, the azomethine N atom is protonated and donates hydrogen bonds to the phenolate O atom and to the tertiary N atom of the piperazine ring. In the crystal, two Schiff base mol­ecules are linked about a center of inversion by a pair of N—H?O hydrogen bonds. The resulting dimers are N—H?O and C—H?O hydrogen bonded to the perchlorate anions, forming a three-dimensional structure. The network is further consolidated by C—H?? inter­actions.

Reisi, Mohammad Reza; Khaledi, Hamid; Mohd Ali, Hapipah

2011-01-01

277

Discovery of Novel 2-((Pyridin-3-yloxy)methyl)piperazines as ?7 Nicotinic Acetylcholine Receptor Modulators for the Treatment of Inflammatory Disorders.  

PubMed

Herein we report the design, synthesis, and structure-activity relationships for a new class of ?7 nicotinic acetylcholine receptor (nAChR) modulators based on the 2-((pyridin-3-yloxy)methyl)piperazine scaffold. The oxazolo[4,5-b]pyridine, (R)-18, and 4-methoxyphenylurea, (R)-47, were identified as potent and selective modulators of the ?7 nAChR with favorable in vitro safety profiles and good oral bioavailability in mouse. Both compounds were shown to significantly inhibit cellular infiltration in a murine model of allergic lung inflammation. Despite the structural and in vivo functional similarities in the compounds, only (R)-18 was shown to be an agonist. Compound (R)-47 demonstrated silent agonist activity. These data support the hypothesis that the anti-inflammatory activity of the ?7 nAChR is mediated by a signal transduction pathway that is independent of ion current. PMID:24814197

Clark, Roger B; Lamppu, Diana; Libertine, Lyn; McDonough, Amy; Kumar, Anjali; LaRosa, Greg; Rush, Roger; Elbaum, Daniel

2014-05-22

278

4-[Bis(4-fluoro-phen-yl)meth-yl]-1-[(2E)-3-phenyl-prop-2-en-1-yl]piperazin-1-ium 3-carb-oxy-propano-ate  

PubMed Central

In the title salt, C26H27F2N2 +·C4H5O4 ?, the piperazine N atom bearing the vinylic substituent is protonated. The piperazine ring adopts a chair conformation. In ther crystal, the succinate monoanions are connected via short O—H?O hydrogen bonds between the carb­oxy­lic acid and carboxyl­ate groups into undulating chains extending along [001] and the flunarizinium monocations are attached to these chains via N+—H?O? hydrogen bonds. C—H?O inter­actions connect these chains into a three-dimensional network. The shortest centroid–centroid distance of 3.7256?(10)?Å was found between one of the fluorinated benzene rings and the non-fluorinated phenyl ring in the neighbouring mol­ecule related by a glide plane.

Kavitha, Channappa N.; Yathirajan, Hemmige S.; Narayana, Badiadka; Gerber, Thomas; van Brecht, Benjamin; Betz, Richard

2013-01-01

279

Measurement of nitrosamine and nitramine formation from NOx reactions with amines during amine-based carbon dioxide capture for postcombustion carbon sequestration.  

PubMed

With years of full-scale experience for precombustion CO(2) capture, amine-based technologies are emerging as the prime contender for postcombustion CO(2) capture. However, concerns for postcombustion applications have focused on the possible contamination of air or drinking water supplies downwind by potentially carcinogenic N-nitrosamines and N-nitramines released following their formation by NO(x) reactions with amines within the capture unit. Analytical methods for N-nitrosamines in drinking waters were adapted to measure specific N-nitrosamines and N-nitramines and total N-nitrosamines in solvent and washwater samples. The high levels of amines, aldehydes, and nitrite in these samples presented a risk for the artifactual formation of N-nitrosamines during sample storage or analysis. Application of a 30-fold molar excess of sulfamic acid to nitrite at pH 2 destroyed nitrite with no significant risk of artifactual nitrosation of amines. Analysis of aqueous morpholine solutions purged with different gas-phase NO and NO(2) concentrations indicated that N-nitrosamine formation generally exceeds N-nitramine formation. The total N-nitrosamine formation rate was at least an order of magnitude higher for the secondary amine piperazine (PZ) than for the primary amines 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA) and the tertiary amine methyldiethanolamine (MDEA). Analysis of pilot washwater samples indicated a 59 ?M total N-nitrosamine concentration for a system operated with a 25% AMP/15% PZ solvent, but only 0.73 ?M for a 35% MEA solvent. Unfortunately, a greater fraction of the total N-nitrosamine signal was uncharacterized for the MEA-associated washwater. At a 0.73 ?M total N-nitrosamine concentration, a ~25000-fold reduction in concentration is needed between washwater units and downwind drinking water supplies to meet proposed permit limits. PMID:22831707

Dai, Ning; Shah, Amisha D; Hu, Lanhua; Plewa, Michael J; McKague, Bruce; Mitch, William A

2012-09-01

280

Toward understanding amines and their degradation products from postcombustion CO2 capture processes with aerosol mass spectrometry.  

PubMed

Amine-based postcombustion CO2 capture (PCCC) is a promising technique for reducing CO2 emissions from fossil fuel burning plants. A concern of the technique, however, is the emission of amines and their degradation byproducts. To assess the environmental risk of this technique, standardized stack sampling and analytical methods are needed. Here we report on the development of an integrated approach that centers on the application of a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) for characterizing amines and PCCC-relevant species. Molecular characterization is achieved via ion chromatography (IC) and electrospray ionization high-resolution mass spectrometry (ESI-MS). The method has been optimized, particularly, by decreasing the AMS vaporizer temperature, to gain quantitative information on the elemental composition and major nitrogen-containing species in laboratory-degraded amine solvents commonly tested for PCCC applications, including ethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PIP). The AMS-derived nitrogen-to-carbon (N/C) ratios for the degraded solvent and product mixtures agree well with the results from a total organic carbon and total nitrogen (TOC/TN) analyzer. In addition, marker ions identified in the AMS spectra are used to estimate the mass contributions of individual species. Overall, our results indicate that this new approach is suitable for characterizing PCCC-related mixtures as well as organic nitrogen species in other sample types. As an online instrument, AMS can be used for both real-time characterization of emissions from operating PCCC plants and ambient particles in the vicinity of the facilities. PMID:24617831

Ge, Xinlei; Shaw, Stephanie L; Zhang, Qi

2014-05-01

281

N-Nitrosopiperazines form at high pH in post-combustion capture solutions containing piperazine: a low-energy collisional behaviour study.  

PubMed

During the process of exploring aqueous piperazine chemistry under simulated flue-gas scrubbing conditions, positive-ion electrospray ionisation mass spectrometric (ESI-MS) analyses of the resulting reaction mixtures in a triple quadrupole system revealed the presence of peaks at m/z 116 and 145, the putative N-nitroso derivatives of piperazine. Confirmation of the presence of these species in the reaction mixtures was achieved using collision-induced dissociation experiments. A purchased standard, together with in-house synthesised N-nitrosopiperazine standards (including N-nitroso derivatives derived from deuterium-labelled precursor materials), were used for this purpose. Across a small range of collision energies, large fluctuations in the abundance of the two major product ions of protonated N-nitrosopiperazine, m/z 86 and 85, were observed. Using B3LYP/6-311?+?+G(d,p) computations, the potential energy surface was determined for loss of NO and [H,N,O]. At an activation energy slightly in excess of 1?eV, intramolecular isomerisation precedes loss of NO (m/z 86) via a 4,1 H-shift, and at activation energies between 2.1-2.3?eV, consecutive loss of NO and atomic hydrogen competes with the direct loss of nitrosyl hydride (m/z 85). It is recommended that any multiple reaction monitoring method for quantifying N-nitrosopiperazines at low collision energies use the sum of both transitions (m/z 116???85, m/z 116???86) to avoid errors that could be introduced by subtle changes in ES source conditions or collision voltages. This approach is adopted in an HPLC/MS/MS method used to monitor the degradation of N-nitrosopiperazine exposed to (i) broad-band UV light and (ii) heat typical of an amine regeneration (stripper) tower. The results reveal that aqueous N-nitrosopiperazine is thermally stable at 150°C but will degrade slowly upon exposure to UV light. PMID:21108305

Jackson, Phil; Attalla, Moetaz I

2010-12-30

282

N-Methyl-d-aspartate (NMDA) Receptor NR2 Subunit Selectivity of a Series of Novel Piperazine-2,3-dicarboxylate Derivatives: Preferential Blockade of Extrasynaptic NMDA Receptors in the Rat Hippocampal CA3-CA1 Synapse  

PubMed Central

N-Methyl-d-aspartate (NMDA) receptor antagonists that are highly selective for specific NMDA receptor 2 (NR2) subunits have several potential therapeutic applications; however, to date, only NR2B-selective antagonists have been described. Whereas most glutamate binding site antagonists display a common pattern of NR2 selectivity, NR2A > NR2B > NR2C > NR2D (high to low affinity), (2S*,3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA) has a low selectivity for NR2C- and NR2D-containing NMDA receptors. A series of PPDA derivatives were synthesized and then tested at recombinant NMDA receptors expressed in Xenopus laevis oocytes. In addition, the optical isomers of PPDA were resolved; the (?) isomer displayed a 50- to 80-fold greater potency than the (+) isomer. Replacement of the phenanthrene moiety of PPDA with naphthalene or anthracene did not improve selectivity. However, phenylazobenzoyl (UBP125) or phenylethynylbenzoyl (UBP128) substitution significantly improved selectivity for NR2B-, NR2C-, and NR2D-containing receptors over NR2A-containing NMDA receptors. Phenanthrene attachment at the 3 position [(2R*,3S*)-1-(phenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP141); (2R*,3S*)-1-(9-bromophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP145); (2R*,3S*)-1-(9-chlorophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP160); and (2R*,3S*)-1-(9-iodophenanthrene-3-carbonyl)piperazine-2,3-dicarboxylic acid (UBP161)] displayed improved NR2D selectivity. UBP141 and its 9-brominated homolog (UBP145) both display a 7- to 10- fold selectivity for NR2D-containing receptors over NR2B- or NR2A-containing receptors. Schild analysis indicates that these two compounds are competitive glutamate binding site antagonists. Consistent with a physiological role for NR2D-containing receptors in the hippocampus, UBP141 (5 ?M) displayed greater selectivity than PPDA for inhibiting the slow-decaying component of the NMDA receptor-mediated CA3-CA1 synaptic response in rat hippocampal slices. UBP125, UBP128, UBP141, and UBP145 may be useful tools for determining the function of NMDA receptor subtypes.

Feng, Bihua; Tsintsadze, Timur S.; Morley, Richard M.; Irvine, Mark W.; Tsintsadze, Vera; Lozovaya, Natasha A.; Jane, David E.; Monaghan, Daniel T.

2009-01-01

283

Amine-degradation products play no part in corrosion at gas-sweetening plants  

SciTech Connect

Gas-sweetening units using diethanolamine (DEA) and methyldiethanolamine (MDEA) are occasionally subject to corrosion. Discounting the basic degradation products of DEA as the cause, researchers (1) confirmed the presence of formic, oxalic, and acetic acids in used amine solutions, (2) defined oxygen's role in forming these carboxylic acids, and (3) demonstrated that the acid contents of different units are about the same order of magnitude for both DEA and MDEA. In most cases, oxygen can be easily excluded from gas-treating units, especially in storage tanks, thereby limiting the formation of acid products.

Blanc, C.; Grall, M.; Demarais, G.

1982-11-15

284

Synthesis, growth, structural and optical studies of organic nonlinear optical material - Piperazine-1,4-diium bis 2,4,6-trinitrophenolate  

NASA Astrophysics Data System (ADS)

Piperazine-1,4-diium bis 2,4,6-trinitrophenolate is one of the useful organic materials with nonlinear optical (NLO) and pharmaceutical applications. The material was grown by slow evaporation solution growth method at room temperature. The crystal system and lattice parameters were identified by single crystal XRD analysis. The grown material crystallizes in monoclinic system with P21/n space group. The main functional groups NH2, NO2, Csbnd N, Cdbnd C, and phenolic ‘O’ atom were identified using FTIR analysis. The protons and carbons of grown crystal with various chemical environments were studied by 1H and 13C NMR spectroscopy to confirm the molecular structure. The optical properties of the crystal were studied by UV-vis-NIR spectroscopy and the transmission 100% range starts from 532 nm onwards. The optical band gap was measured as 2.63 eV from the plot of (?h?)2 versus h?. The thermal stability was detected at 304.1 °C using TG-DTA analysis. The dielectric studies of the sample were carried out at different temperatures in the frequency range from 50 Hz to 5 MHz to establish the dielectric nature of the crystal. Photoconductivity measurements were carried out on the grown crystal. The Second Harmonic Generation (SHG) of the crystal was tested to confirm the nonlinear optical property.

Suguna, S.; Anbuselvi, D.; Jayaraman, D.; Nagaraja, K. S.; Jeyaraj, B.

2014-11-01

285

Comparative behavioural profiles of buspirone and its metabolite 1-(2-pyrimidinyl)-piperazine (1-PP) in the murine elevated plus-maze.  

PubMed

It has been suggested that in vivo formation of the metabolite 1-(2-pyrimidinyl)-piperazine (1-PP) may be a major drawback in the use of buspirone as an anti-anxiety agent. To test this hypothesis, the effects of buspirone, alone or with proadifen (an inhibitor of liver microsomal enzymes) pretreatment, were contrasted with those of 1-PP in the murine elevated plus-maze test of anxiety. At 3.0 mg/kg (but not lower doses), buspirone per se had modest anxiolytic-like effects (increased percentage of open arm entries; reduced stretched-attend postures and flatback approach) that were associated with increased grooming and immobility. However, in proadifen-pretreated mice, buspirone produced behavioural depression only, with marked effects evident both at 1.0 and 3.0 mg/kg. As proadifen blocks the biotransformation of buspirone to 1-PP, these data suggest that any anxiolytic activity of buspirone in the murine plus-maze may be attributable to its principal active metabolite. Consistent with this hypothesis, 1-PP (0.5-13.5 mg/kg) produced dose-dependent anti-anxiety effects on both conventional and ethological measures that were not confounded by motoric impairment. Results are discussed in relation to biochemical and electrophysiological studies suggesting that 1-PP has a direct action at 5-HT1A receptors. PMID:9294974

Cao, B J; Rodgers, R J

1997-08-01

286

Synthesis, growth, structural and optical studies of organic nonlinear optical material - Piperazine-1,4-diium bis 2,4,6-trinitrophenolate.  

PubMed

Piperazine-1,4-diium bis 2,4,6-trinitrophenolate is one of the useful organic materials with nonlinear optical (NLO) and pharmaceutical applications. The material was grown by slow evaporation solution growth method at room temperature. The crystal system and lattice parameters were identified by single crystal XRD analysis. The grown material crystallizes in monoclinic system with P21/n space group. The main functional groups NH2, NO2, CN, CC, and phenolic 'O' atom were identified using FTIR analysis. The protons and carbons of grown crystal with various chemical environments were studied by (1)H and (13)C NMR spectroscopy to confirm the molecular structure. The optical properties of the crystal were studied by UV-vis-NIR spectroscopy and the transmission 100% range starts from 532nm onwards. The optical band gap was measured as 2.63eV from the plot of (?h?)(2) versus h?. The thermal stability was detected at 304.1°C using TG-DTA analysis. The dielectric studies of the sample were carried out at different temperatures in the frequency range from 50Hz to 5MHz to establish the dielectric nature of the crystal. Photoconductivity measurements were carried out on the grown crystal. The Second Harmonic Generation (SHG) of the crystal was tested to confirm the nonlinear optical property. PMID:24878440

Suguna, S; Anbuselvi, D; Jayaraman, D; Nagaraja, K S; Jeyaraj, B

2014-11-11

287

Study on action mechanism of 1-(4-methoxy-2-methylphenyl)piperazine (MMPP) in acquisition, formation, and consolidation of memory in mice.  

PubMed

In the present study, the mechanism of action of MMPP (1-(4-methoxy-2-methylphenyl) piperazine) in the acquisition (pretraining administration), formation (posttraining administration), and consolidation (pretest administration) of memory was assessed in the passive avoidance test using a short- and long-term memory protocol in mice. MMPP modified avoidance in the acquisition and formation of memory protocols but not in the consolidation protocol. Scopolamine (0.1?mg/kg i.p.), dizocilpine (0.003?mg/kg i.p.), and buspirone (0.1?mg/kg i.p.) completely inhibited MMPP-induced effects on memory acquisition and partially inhibited memory formation in the short-term but not long-term paradigm. This suggested that cholinergic, N-methyl-D-aspartate (NMDA) and 5-hydroxytryptamine-1A (5-HT1A ) receptors were implicated in the MMPP-induced improvements in memory. The sedative, anxiolytic, motor impairment, myorelaxant, and anticonvulsive (pentylenetetrazole-induced seizures) properties of MMPP were also assessed with the compound only showing a nondose-dependent myorelaxation. These results suggest that MMPP can enhance acquisition and formation, but not consolidation, of memory in short-term and long-term protocol via cholinergic, NMDA-glutamatergic, and 5-HT1A receptors. PMID:24648132

Navarrete, Andrés; Flores-Machorro, Francisco X; Téllez-Ballesteros, Ruth I; Alfaro-Romero, Alejandro; Balderas, José Luis; Reyes, Adelfo

2014-03-01

288

Radiosynthesis binding affinity and biodistribution of 3-[F-18]fluoro-N-({alpha},{alpha},{alpha}-trifluoro-m-tolyl)piperazine (FTFMPP), a radioligand for the Serotonin system  

SciTech Connect

The serotonin agonist N({alpha},{alpha},{alpha}-trifluoro-m-tolyl)piperazine (TFMPP) is a potent ligand for the serotonin system. Angelini and co-workers previously synthesized the c.a [F-18]TFMPP but the low specific activity (less than 0.2GBq/mmol) limited the application of this ligand. We have recently reported the formation of phenylpiperazines by a novel alumina supported bis-alkylation. We report the application of this method and biological evaluation of 3-[F-18]FTFMPP, a fluoro derivative of TFMPP. Reaction of [F-18]fluoride with 3,5-dinitrobenzotrifluoride gave the 3-[F-18]fluoro-5-nitrobenzotrifluoride in 70% yield. Reduction of the nitro group with Raney nickel and hydrazine hydrate gave the [F-18]aniline derivative in 70% yield. Finally, the phenylpiperazine was constructed by reaction of the [F-18]aniline derivative with bis-2-bromoethyl-N-(ethoxy carbonyl)amine on basic alumina (pH=9) as a solid support. After extraction of the activity with basic MeOH and HPLC purification on normal phase the final product- [F-18]FTFMPP was obtained in 50% yield (98% radiochemical purity). The specific activity of the final product was 100GBq/mmol. The binding affinity of FTFMPP to 5-HT receptor was determined (Ki = 80-100 nM) and found to be similar to the binding affinity of the TFMPP (160-180 nM). The biodistribution of [F-18]FTFMPP was performed in rats.

Mishani, E.; Cristel, M.E.; McCarthy, T.J.; Welch, M.J. [Washington Univ., Saint Louis, MO (United States)

1996-05-01

289

Antioxidant, DNA binding and nuclease activities of heteroleptic copper(II) complexes derived from 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols and diimines.  

PubMed

A series of heteroleptic copper(II) complexes of the type [CuL(1-4)(diimine)](ClO4)2 (1-8) [L(1-4)=2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols, and diimine=2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen)], have been synthesized and characterized by spectroscopic methods. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions and the electronic spectra revealed the square pyramidal geometry with N4O coordination environment around copper(II) nuclei. Electrochemical studies of the mononuclear complexes evidenced one-electron irreversible reduction wave in the cathodic region. The EPR spectra of complexes with g|| (2.206-2.214) and A|| (154-172×10(-)(4)cm(-)(1)) values support the square-based CuN3O coordination chromophore and the presence of unpaired electron localized in [Formula: see text] ground state. Antioxidant studies against DPPH revealed effective radical scavenging properties of the synthesized complexes. Binding studies suggest that the heteroleptic copper(II) complexes interact with calf thymus DNA (CT-DNA) through minor-groove and electrostatic interaction, and all the complexes display pronounced nuclease activity against supercoiled pBR322 DNA. PMID:24998685

Ravichandran, J; Gurumoorthy, P; Imran Musthafa, M A; Kalilur Rahiman, A

2014-12-10

290

Synthesis and in vivo anticonvulsant activity of 2-methyl-2-[3-(5-piperazin-1-yl-[1,3,4]oxadiazol-2-yl)-phenyl]-propionitrile derivatives.  

PubMed

A series of new 2-methyl-2-[3-(5-piperazin-1-yl-[1,3,4]oxadiazol-2-yl)-phenyl]-propionitrile derivatives 8a-o, 9a-c, 10a-d, and 11a-d were synthesized to meet the structural requirements essential for anticonvulsant property. The structures of all the synthesized compounds were confirmed by means of (1)H NMR, (13)C NMR, and mass spectral studies. The purity of the novel compounds was confirmed by elemental analyses. All the compounds were screened for their anticonvulsant activity against maximal electroshock (MES) seizure method and their neurotoxic effects were determined by rotorod test. Compounds 8d, 8e, and 8f were found to be the most potent of this series. The same compounds showed no neurotoxicity at the maximum dose administered (100?mg/kg). The efforts were also made to establish the structure-activity relationships among the synthesized compounds. The pharmacophore model was used to validate the anticonvulsant activity of the synthesized molecules. PMID:24395602

Harish, Kikkeri P; Mohana, Kikkeri N; Mallesha, Lingappa; Veeresh, Bantal

2014-04-01

291

Solubility of acid gases in a mixed solvent  

SciTech Connect

The solubility of hydrogen sulphide and carbon dioxide and their mixtures has been measured at 40/sup 0/ and 100/sup 0/C in a mixed solvent consisting of 20.9 wt% (2.0 M) MDEA (methyldiethanolamine), 30.5 wt% sulfolane, and 48.6 wt% water. The results have been compared with those for aqueous 2.0 M MDEA and an analogous mixed solvent, containing AMP (2-amino-2-methyl-1-propanol), which are available in the literature. At solution loadings less than 1 mol acid gas/mol MDEA, the solubility of the acid gas was lower in the mixed solvent that in the corresponding aqueous MDEA solvent; at solution loadings greater than 1 mol acid gas/mol MDEA, the reverse was true. At all loadings and at both temperatures studied, the mixed MDEA solvent absorbed equal or lesser quantities of acid gas than the comparable mixed AMP solvent. However, the shapes of the solubility curves show that the mixed MDEA solvent would be a better choice for certain industrial applications. These data were used to modify the solubility model of Deshmukh and Mather to account for the mixed solvent effects on the system thermodynamics. Results show that the model is useful as a first approximation in predicting acid gas solubilities; agreement with experiment was generally found to be within +-15%.

MacGregor, R.J.; Mather, A.E.

1987-01-01

292

Optically active antifungal azoles: synthesis and antifungal activity of (2 R,3 S)-2-(2,4-difluorophenyl)-3-(5-{2-[4-aryl-piperazin-1-yl]-ethyl}-tetrazol-2-yl\\/1-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol  

Microsoft Academic Search

A series of (2R,3S)-2-(2,4-difluorophenyl)-3-(5-{2-[4-aryl-piperazin-1-yl]-ethyl}-tetrazol-2-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol (11a–n) and (2R,3S)-2-(2,4-difluorophenyl)-3-(5-{2-[4-aryl-piperazin-1-yl]-ethyl}-tetrazole-1-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol (12a–n) has been synthesized. The antifungal activity of compounds was evaluated by in vitro agar diffusion and broth dilution assay. Compounds 11d and its positional isomer 12d having 3-trifluoromethyl substitution on the phenyl ring of piperazine demonstrated significant antifungal activity against variety of fungal cultures (Candida spp. C. neoformans and Aspergillus spp.). The

Ram Shankar Upadhayaya; Neelima Sinha; Sanjay Jain; Nawal Kishore; Ramesh Chandra; Sudershan K. Arora

2004-01-01

293

Solubility of nitrous oxide in amine solutions  

Microsoft Academic Search

The solubility of nitrous oxide (NâO) in 13 amine solvents and solutions was correlated to amine mole fractions and temperature using feedforward neural networks. This general correlation, using a massive database, predicted NâO solubility at temperatures between 283 and 398 K in pure solvents [HâO, monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanolamine (AMP)], in binary aqueous amine solutions [HâO\\/MEA,

Z. Bensetiti; I. Iliuta; F. Larachi; B. P. A. Grandjean

1999-01-01

294

2-{2-[4-(4-Fluoro-phen-yl)piperazin-1-yl]-2-oxoeth-yl}-6-(morpholin-4-yl)-4-phenyl-pyridazin-3(2H)-one  

PubMed Central

In the title compound, C26H28FN5O3, the morpholine ring adopts a chair conformation. The piperazine ring is puckered [Q T = 0.5437?(15)?Å, ? = 8.89?(15) and ? = 357.2?(11)°]. The 1,6-dihydro­pyridazine ring makes dihedral angles of 28.03?(7) and 77.46?(7)° with the phenyl and benzene rings, respectively. In the crystal, mol­ecules are linked along the c axis by C—H?O inter­actions and are flattened parallel to the ac plane. C–H?? inter­actions also contribute to the stability of the structure.

Ayd?n, Abdullah; Sukuroglu, Murat; Akkurt, Mehmet; Buyukgungor, Orhan

2011-01-01

295

Synthesis, radiolabeling, and preliminary biological evaluation of [3H]-1-[(S)-N,O-bis-(isoquinolinesulfonyl)-N-methyl-tyrosyl]-4-(o-tolyl)-piperazine, a potent antagonist radioligand for the P2X7 receptor.  

PubMed

The design, synthesis, and preliminary biological evaluation of the first potent radioligand antagonist for the P2X(7) receptor, named [(3)H]-1-[(S)-N,O-bis-(isoquinolinesulfonyl)-N-methyl-tyrosyl]-4-(o-tolyl)-piperazine (compound 13), are reported. This compound bound to human P2X(7) receptors expressed in HEK transfected cells with K(D) and B(max) value of 3.46+/-0.1 nM and 727+/-73 fmol/mg of protein, respectively. The high affinity and facile labeling makes it a promising radioligand for a further characterization of P2X(7) receptor subtype. PMID:15482953

Romagnoli, Romeo; Baraldi, Pier Giovanni; Pavani, Maria Giovanna; Tabrizi, Mojgan Aghazadeh; Moorman, Allan R; Di Virgilio, Francesco; Cattabriga, Elena; Pancaldi, Cecilia; Gessi, Stefania; Borea, Pier Andrea

2004-11-15

296

Thermodynamic constants of N-(2-hydroxyethyl)piperazine- N?-3-propanesulfonic acid (HEPPS) and (3-[ N-morpholinol])-2-hydroxypropanesulfonic acid (MOPSO) from the temperatures 278.15 K to 328.15 K  

Microsoft Academic Search

Electromotive-force measurements were taken for cells without a liquid junction of the type: Pt|H2(g,p0=101.325 kPa)|buffer (m1), Na salt of buffer (m2), NaCl (m3)|AgCl|Ag, wheremdenotes molality. Values of the second thermodynamic dissociation constant pK2forN-(2-hydroxyethyl)piperazine-N?-3-propanesulfonic acid (HEPPS) and (3-[N-morpholinol])-2-hydroxypropanesulfonic acid (MOPSO) have been determined fromT= 278.15 K toT= 328.15 K. These zwitterionic compounds are useful as secondary standard buffers in the pH

Rabindra N. Roy; Catherine P. Moore; Pamala Lord; Dawn Mrad; Lakshmi N. Roy; William S. Good; Jodi Niederschmidt; Kathleen M. Kuhler

1997-01-01

297

Effect of 1-(1-naphthylmethyl)-piperazine on antimicrobial agent susceptibility in multidrug-resistant isogenic and veterinary Escherichia coli field strains.  

PubMed

The objective of this study was to evaluate the interaction of the efflux pump inhibitor 1-(1-naphthylmethyl)-piperazine (NMP) when combined with different families of antimicrobial agents against isogenic strains and multidrug-resistant (MDR) Escherichia coli field strains isolated from animals. Laboratory isogenic strains of E. coli with different levels of expression of efflux pumps were used as quality controls. Ten MDR E. coli strains were collected from healthy animals in a cross-sectional study in four commercial dairy farms. The MICs of florfenicol, ciprofloxacin, tetracycline and ampicillin were determined by a serial microdilution method in Luria-Bertani broth in the presence or absence of NMP. NMP used with ampicillin exerted no effect on the isogenic or field strains. In most of the field MDRE. coli strains and in an acrAB-overexpressing (AG112) isogenic strain, the MICs of florfenicol, ciprofloxacin and tetracycline decreased at least fourfold when the antimicrobial was combined with the highest NMP concentrations. In the wild-type strain (AG100), there were no decreases of more than twice the MIC, whilst in strain AG100A, an efflux pump-deficient strain, the MIC did not change, regardless of the concentration of NMP used with these three antimicrobials. Thus, ampicillin was not affected by the efflux pump mechanism, whereas ciprofloxacin, tetracycline and florfenicol were shown to be substrates of efflux pumps, with a consequent significant reduction in MICs. Resistance could not be completely reversed in the E. coli field strains by NMP, probably because other resistance mechanisms were also present. However, in strain AG112, the MIC results demonstrated that NMP expressed an important synergistic activity with florfenicol. The reduction in florfenicol MIC value was sufficient to reverse antimicrobial resistance completely for AG112. PMID:22345599

Marchetti, M L; Errecalde, J; Mestorino, N

2012-06-01

298

1-[Bis(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium dichloride hemihydrate  

PubMed Central

The asymmetric unit of the title monohydrated salt, 2C26H28F2N2 2+·4Cl?.H2O, consists of a 1-[bis­(4-fluoro­phen­yl)meth­yl]-4-[(2Z)-3-phenyl­prop-2-en-1-yl]piperazine-1,4-diium cation with a diprotonated piperizine ring in close proximity to two chloride anions and a single water mol­ecule that lies on a twofold rotation axis. In the cation, the piperazine ring adopts a slightly distorted chair conformation. The dihedral angles between the phenyl ring and the 4-fluoro­phenyl rings are 89.3?(9) and 35.0?(5)°. The two fluoro­phenyl rings are inclined at 65.0?(5)° to one another. In the crystal, N—H?Cl hydrogen bonds and weak C—H?Cl inter­molecular inter­actions link the mol­ecules into chains along [010]. In addition, weak C—H?O inter­actions between the piperizine and prop-2-en-1-yl groups with the water mol­ecule, along with weak C—H?Cl inter­actions between the prop-2en-1-yl and methyl groups with the chloride ions, weak C—H?F inter­actions between the two fluoro­phenyl groups and weak O—H?Cl inter­actions between the water mol­ecule and chloride ions form a three-dimensional supra­molecular network.

Shivaprakash, S.; Chandrasekara Reddy, G.; Jasinski, Jerry P.

2014-01-01

299

CO2 Capture by Absorption with Potassium Carbonate Fourth Quarterly Report 2006. Quarterly Progress Report. Reporting Period: October 1, 2006 through December 31, 2006.  

National Technical Information Service (NTIS)

The objective of this work is to improve the process for CO2 capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K2CO3 promoted by piperazine. The best solvent and process configuration, matrix with MDEA/PZ, offers 2...

A. Sexton B. Oyenekan E. Chen G. T. Rochelle J. Davis M. Hilliard

2007-01-01

300

Diffusion coefficients and heats of mixing in aqueous alkanolamines. Annual report, January-December 1992  

SciTech Connect

The objective of the work is to provide accurate data on diffusion coefficients and heats of absorption of acid gases in aqueous amine solutions to assist in the design of economical new amine treating systems and to improve the efficiency of existing plants. Specifically covered in the report are measurements of the mutual diffusion coefficient of methyldiethanolamine(MDEA) and diethanolamine in water. Measurements have been made at 25, 50 and 75C and at 0, 20, 35 and 50 wt% amine. Heats of absorption of CO2 into aqueous mixtures of MDEA have also been measured calorimetrically. Results are reported at temperatures of 120 and 260F and pressures of 500 and 1000 psia at total MDEA concentrations of 20, 35 and 50%.

Rowley, R.L.; Oscarson, J.L.

1993-01-01

301

Density and viscosity of some partially carbonated aqueous alkanolamine solutions and their blends  

SciTech Connect

Very little information is available concerning the effect of acid gas loading on the physical properties of amine-treating solutions flowing through the absorption and regeneration columns used in gas processing. The densities and viscosities of partially carbonated monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA) solutions were measured at 298 K. With increasing carbon dioxide loadings, significant increases in both density and viscosity were observed. These results were combined with literature data to produce correlations for alkanolamine solution density and viscosity as a function of amine concentration, carbon dioxide loading, and temperature. The resulting single-amine correlations were used to predict the densities and viscosities of DEA + MDEA and MEA + MDEA blends. Predictions are compared with data measured for these blends.

Weiland, R.H.; Dingman, J.C.; Cronin, D.B.; Browning, G.J. [Optimized Gas Treating, Inc., Houston, TX (United States)] [Optimized Gas Treating, Inc., Houston, TX (United States)

1998-05-01

302

4-(3-Chloro-5-(trifluoromethyl)pyridin-2-yl)-N-(4-methoxypyridin-2-yl)piperazine-1-carbothioamide (ML267), a potent inhibitor of bacterial phosphopantetheinyl transferase that attenuates secondary metabolism and thwarts bacterial growth.  

PubMed

4'-Phosphopantetheinyl transferases (PPTases) catalyze a post-translational modification essential to bacterial cell viability and virulence. We present the discovery and medicinal chemistry optimization of 2-pyridinyl-N-(4-aryl)piperazine-1-carbothioamides, which exhibit submicromolar inhibition of bacterial Sfp-PPTase with no activity toward the human orthologue. Moreover, compounds within this class possess antibacterial activity in the absence of a rapid cytotoxic response in human cells. An advanced analogue of this series, ML267 (55), was found to attenuate production of an Sfp-PPTase-dependent metabolite when applied to Bacillus subtilis at sublethal doses. Additional testing revealed antibacterial activity against methicillin-resistant Staphylococcus aureus , and chemical genetic studies implicated efflux as a mechanism for resistance in Escherichia coli . Additionally, we highlight the in vitro absorption, distribution, metabolism, and excretion and in vivo pharmacokinetic profiles of compound 55 to further demonstrate the potential utility of this small-molecule inhibitor. PMID:24450337

Foley, Timothy L; Rai, Ganesha; Yasgar, Adam; Daniel, Thomas; Baker, Heather L; Attene-Ramos, Matias; Kosa, Nicolas M; Leister, William; Burkart, Michael D; Jadhav, Ajit; Simeonov, Anton; Maloney, David J

2014-02-13

303

Powder X-ray study of racemic (2RS,3RS)-5-amino-3-[4-(3-methoxyphenyl)piperazin-1-yl]-1,2,3,4-tetrahydronaphthalen-2-ol.  

PubMed

The structure of the title benzovesamicol analogue, C(21)H(27)N(3)O(2), an important compound for the diagnosis of Alzheimer's disease, has been determined by X-ray powder diffraction. The title compound was firstly synthesized and characterized by spectroscopic methods (FT-IR, and (13)C and (1)H NMR). The compound is a racemic mixture of enantiomers which crystallizes in the monoclinic system in a centrosymmetric space group (P2(1)/c). Crystallography, in particular powder X-ray diffraction, was pivotal in revealing that the enantio-resolution did not succeed. The piperazine ring is in a chair conformation, while the cyclohexene ring assumes a half-chair conformation. The crystal packing is dominated by intermolecular O-H···N hydrogen bonding which links molecules along the c direction. PMID:22051965

Assaad, Thaer; Rukiah, Mwaffak

2011-11-01

304

Poly[[[[1-ethyl-6,8-difluoro-7-(3-methyl-piperazin-1-yl)-4-oxo-1,4-dihydro-quinoline-3-carboxyl-ato]cadmium]-?-benzene-1,4-dicarboxyl-ato] trihydrate  

PubMed Central

In the title layered coordination polymer, {[Cd(C17H18F2N3O3)(C8H4O4)]·3H2O}n, the CdII atom exhibits a very distorted CdO6 octa­hedral geometry defined by one O 3,O 4-bidentate 1-ethyl-6,8-difluoro-7-(3-methyl­piperazin-1-yl)-4-oxo-1,4-dihydro­quinoline-3-carboxyl­ate (lome) ligand, one O,O?-bidentate benzene-1,4-dicarboxyl­ate (bdc) dianion and two O-monodentate bdc dianions. Both the bdc species in the asymmetric unit are completed by crystallographic inversion symmetry. The bridging bdc dianions link the cadmium nodes into a recta­ngular grid lying parallel to (01). A network of N—H?O and O—H?O hydrogen bonds helps to establish the packing.

Kang, Xin-Ping; An, Zhe; Kasimu, Rena

2010-01-01

305

catena-Poly[[diaqua-cadmium(II)]bis-(?-2,2-dimethyl-butane-dioato-?4 O,O?:O??,O???)[diaqua-cadmium(II)]-?-1,4-bis-(3-pyridylmeth-yl)piperazine-?2 N 3:N 3?  

PubMed Central

In the title compound, [Cd2(C6H8O4)2(C16H20N4)(H2O)4]n, penta­gonal-bipyramidally coordinated CdII ions are connected into {Cd2(2,2-dimethyl­succinate)2(H2O)4} centrosymmetric dimeric clusters. In turn, these clusters are linked by tethering 1,4-bis­(3-pyridylmeth­yl)piperazine (3-bpmp) ligands into [Cd2(2,2-dimethyl­succinate)2(3-bpmp)(H2O)4]n coordination polymer chains. The chain motifs are oriented parallel to [10]. Individual chains are connected into supra­molecular layers via O—H?N and O—H?O hydrogen-bonding mechanisms.

Pochodylo, Amy L.; LaDuca, Robert L.

2010-01-01

306

?-1,4-Bis(pyridin-4-ylmeth-yl)piperazine-?2 N:N?-bis-[aqua-bis-(3-bromo-5-carb-oxy-benzoato-?O 1)copper(II)  

PubMed Central

In the title compound, [Cu2(C8H4BrO4)4(C16H20N4)(H2O)2], slightly distorted square-planar-coordinated CuII ions are bound by one aqua ligand and two monodentate 3-bromo-5-carb­oxy­benzoate anions, and linked into a centrosymmetric dinuclear mol­ecule by a bridging 1,4-bis­(pyridin-4-ylmeth­yl)piperazine (4-bpmp) ligand. In the crystal, mol­ecules are connected into a supra­molecular two-dimensional network parallel to (131) via O—H?O hydrogen bonds involving the aqua ligands and 3-bromo-5-carb­oxy­benzoate carboxyl­ate groups.

Meyer, Jodi L.; LaDuca, Robert L.

2012-01-01

307

4-{[5-(4-Chloro-phen-yl)-1-(4-fluoro-phen-yl)-1H-pyrazol-3-yl]carbon-yl}-N-(4-cyano-phen-yl)piperazine-1-carboxamide  

PubMed Central

In the title compound, C28H22ClFN6O2, the piperazine ring adopts a chair conformation and the least-squares plane through the four coplanar atoms forms dihedral angles of 69.37?(13) and 56.56?(12)°, respectively, with the pyrazole and cyano­phenyl rings. The dihedral angles formed between the pyrazole and the attached fluoro- and chloro­phenyl rings are 34.16?(10) and 73.27?(12)°, respectively. In the crystal, inter­molecular N—H?O, C—H?N and C—H?O hydrogen bonds link the mol­ecules into sheets parallel to the ac plane.

Loh, Wan-Sin; Fun, Hoong-Kun; Ragavan, R. Venkat; Vijayakumar, V.; Venkatesh, M.

2010-01-01

308

tert-Butyl 4-{[5-(4-chloro-phen-yl)-1-(4-fluoro-phen-yl)-1H-pyrazol-3-yl]carbon-yl}piperazine-1-carboxyl-ate  

PubMed Central

In the title pyrazole derivative, C25H26ClFN4O3, both benzene rings are twisted out of the plane through the pyrazole ring, with dihedral angles of 67.62?(10) and 27.63?(10)° for the fluoro- and chloro-substituted rings, respectively. The dihedral angle between the two benzene rings is 64.54?(9)°. The piperazine ring (with a chair conformation) is linked to the pyrazole ring via a carbonyl spacer and is orientated to lie to one side of the pyrazole plane. In addition to an intra­molecular C—H?N contact, there are inter­molecular C—H?O inter­actions, which generate a supra­molecular chain with an undulating topology along the c axis that is sustained by alternating centrosymmetric ten-membered {?HCNCO}2 and {?HC3O}2 synthons.

Ragavan, R. Venkat; Vijayakumar, V.; Sarveswari, S.; Ng, Seik Weng; Tiekink, Edward R. T.

2010-01-01

309

Synthesis, radiolabeling and in vivo evaluation of [(11)C](R)-1-[4-[2-(4-methoxyphenyl)phenyl]piperazin-1-yl]-3-(2-pyrazinyloxy)-2-propanol, a potential PET radioligand for the 5-HT(7) receptor.  

PubMed

In the search for a novel serotonin 7 (5-HT7) receptor PET radioligand we synthesized and evaluated a new series of biphenylpiperazine derivatives in vitro. Among the studied compounds, (R)-1-[4-[2-(4-methoxyphenyl)phenyl]piperazin-1-yl]-3-(2-pyrazinyloxy)-2-propanol ((R)-16), showed the best combination of affinity, selectivity, and lipophilicity, and was thus chosen for carbon-11 labelling and evaluation in pigs. After intravenous injection, [(11)C](R)-16 entered the pig brain and displayed reversible tracer kinetics. Pretreatment with the 5-HT7 receptor selective antagonist SB-269970 (1) resulted in limited decrease in the binding of [(11)C](R)-16, suggesting that this radioligand is not optimal for imaging the brain 5-HT7 receptor in vivo but it may serve as a lead compound for the design of novel 5-HT7 receptor PET radioligands. PMID:24732791

Hansen, Hanne D; Lacivita, Enza; Di Pilato, Pantaleo; Herth, Matthias M; Lehel, Szabolcs; Ettrup, Anders; Andersen, Valdemar L; Dyssegaard, Agnete; De Giorgio, Paola; Perrone, Roberto; Berardi, Francesco; Colabufo, Nicola Antonio; Niso, Mauro; Knudsen, Gitte M; Leopoldo, Marcello

2014-05-22

310

N-{[2-(4-Phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides with dopamine D? and 5-Hydroxytryptamine 5HT(1A) activity: synthesis, testing, and molecular modeling.  

PubMed

The ratio of affinities toward the dopamine D? and the 5-hydroxytryptamine 5-HT(1A) receptors is one of the important parameters that determine the efficiency of antipsychotic drugs. Here, we present the synthesis of ortho-, meta-, and para-N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides and their structure-activity relationship studies on dopamine D? and 5-hydroxytryptamine 5-HT(1A) receptors. It was shown that the biological activity of the described ligands strongly depends on their topology as well as on the nature of the heteroaryl group in the head of the molecules. Docking simulations together with conformational analysis revealed a rational explanation for the ligands' behavior. The molecular model of receptor-ligand interactions described herein provided us with a tool for the rational design of new compounds with a favorable D?/5-HT(1A) profile. PMID:24105736

Sukalovic, Vladimir; Bogdan, Anca Elena; Tovilovic, Gordana; Ignjatovic, Djurdjica; Andric, Deana; Kostic-Rajacic, Sladjana; Soskic, Vukic

2013-10-01

311

1-[Bis(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium dichloride hemihydrate.  

PubMed

The asymmetric unit of the title monohydrated salt, 2C26H28F2N2 (2+)·4Cl(-.)H2O, consists of a 1-[bis-(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium cation with a diprotonated piperizine ring in close proximity to two chloride anions and a single water mol-ecule that lies on a twofold rotation axis. In the cation, the piperazine ring adopts a slightly distorted chair conformation. The dihedral angles between the phenyl ring and the 4-fluoro-phenyl rings are 89.3?(9) and 35.0?(5)°. The two fluoro-phenyl rings are inclined at 65.0?(5)° to one another. In the crystal, N-H?Cl hydrogen bonds and weak C-H?Cl inter-molecular inter-actions link the mol-ecules into chains along [010]. In addition, weak C-H?O inter-actions between the piperizine and prop-2-en-1-yl groups with the water mol-ecule, along with weak C-H?Cl inter-actions between the prop-2en-1-yl and methyl groups with the chloride ions, weak C-H?F inter-actions between the two fluoro-phenyl groups and weak O-H?Cl inter-actions between the water mol-ecule and chloride ions form a three-dimensional supra-molecular network. PMID:24940270

Shivaprakash, S; Chandrasekara Reddy, G; Jasinski, Jerry P

2014-06-01

312

Collection of VLE data for acid gas - alkanolamine systems using Fourier transform infrared spectroscopy. Final report, September 29, 1990--September 30, 1996  

SciTech Connect

This report describes research from September 29, 1990 through September 30, 1996, involving the development a novel Fourier transform infrared (FTIR) spectroscopic apparatus and method for measuring vapor - liquid equilibrium (VLE) systems of carbon dioxide and hydrogen sulfide with aqueous alkanolamine solutions. The original apparatus was developed and modified as it was used to collect VLE data on acid gas systems. Vapor and liquid calibrations were performed for spectral measurements of hydrogen sulfide and carbon dioxide in the vapor and in solution with aqueous diethanolamine (DEA) and methyldiethanolamine (MDEA). VLE measurements were made of systems of hydrogen sulfide and carbon dioxide in 20 wt % DEA at 50{degrees}C and 40{degrees}C. VLE measurements were made of systems of hydrogen sulfide and carbon dioxide in 50 wt% and 23 wt% MDEA at 40{degrees}C and in 23 wt% MDEA at 50{degrees}C. VLE measurements were made of systems of hydrogen sulfide and carbon dioxide in 35 wt% MDEA + 5 wt% DEA and in 35 wt% MDEA + 10 wt% DEA at 40{degrees}C and 50{degrees}C. Measurements were made of residual amounts of carbon dioxide in each VLE system. The new FTIR spectrometer is now a consistently working and performing apparatus.

Bullin, J.A.; Rogers, W.J.

1996-11-01

313

Solubility of nitrous oxide in amine solutions  

SciTech Connect

The solubility of nitrous oxide (N{sub 2}O) in 13 amine solvents and solutions was correlated to amine mole fractions and temperature using feedforward neural networks. This general correlation, using a massive database, predicted N{sub 2}O solubility at temperatures between 283 and 398 K in pure solvents [H{sub 2}O, monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanolamine (AMP)], in binary aqueous amine solutions [H{sub 2}O/MEA, H{sub 2}O/DEA, H{sub 2}O/MDEA, and H{sub 2}O/AMP], and in ternary aqueous amine blends [AMP/MDEA/H{sub 2}O, AMP/DEA/H{sub 2}O, DEA/MDEA/H{sub 2}O, MDEA/MEA/H{sub 2}O, and AMP/MEA/H{sub 2}O]. Combined with the N{sub 2}O analogy, this present improved correlation can be advantageously implemented in amine plant design software and procedures for the prediction of CO{sub 2} solubility in amine blend solutions over wide temperature and concentration ranges.

Bensetiti, Z.; Iliuta, I.; Larachi, F.; Grandjean, B.P.A. [Laval Univ., Quebec (Canada)] [Laval Univ., Quebec (Canada)

1999-01-01

314

N-(3-Fluoro-4-(4-(2-methoxy or 2,3-dichlorophenyl) piperazine-1-yl)-butyl)-aryl carboxamides as Selective Dopamine D3 Receptor Ligands: Critical Role of the Carboxamide Linker for D3 Receptor Selectivity  

PubMed Central

N-(3-fluoro-4-(4-(2,3-dichloro- or 2-methoxyphenyl)piperazine-1-yl)-butyl)-aryl carboxamides were prepared and evaluated for binding and function at dopamine D3 (D3R) and D2 receptors (D2R). In this series, we discovered some of the most D3R selective compounds reported to date, (e.g. 8d and 8j >1000-fold D3R-selective over D2R.) In addition, chimeric receptor studies further identified the second extracellular (E2) loop as an important contributor to D3R binding selectivity. Further, compounds lacking the carbonyl group in the amide linker were synthesized and while these amine-linked analogues bound with similar affinities to the amides at D2R, this modification dramatically reduced binding affinities at D3R by >100-fold (e.g. D3RKi for 15b = 393 v. for 8j = 2.6 nM) resulting in compounds with significantly reduced D3R selectivity. This study supports a pivotal role for the D3R E2 loop and the carbonyl group in the 4-phenylpiperazine class of compounds and further reveals a point of separation between structure-activity relationships at D3R and D2R.

Banala, Ashwini K.; Levy, Benjamin A.; Khatri, Sameer S.; Furman, Cheryse A.; Roof, Rebecca A.; Mishra, Yogesh; Griffin, Suzy A.; Sibley, David R.; Luedtke, Robert R.; Newman, Amy Hauck

2011-01-01

315

Fluorescent Derivatives of ? Receptor Ligand 1-Cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine (PB28) as a Tool for Uptake and Cellular Localization Studies in Pancreatic Tumor Cells  

PubMed Central

Fluorescent derivatives of ?2 high affinity ligand 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine 1 (PB28) were synthesized. NBD or Dansyl fluorescent tags were connected through a 5- or 6-atoms linker in two diverse positions of 1 structure. Good ?2 affinities were obtained when the fluorescent tag was linked to 5-methoxytetralin nucleus replacing the methyl function. NBD-bearing compound 16 displayed high ?2 affinity (Ki = 10.8 nM) and optimal fluorescent properties. Its uptake in pancreatic tumor cells was evaluated by flow cytometry showing that it partially occurs through endocytosis. In proliferating cells the uptake was higher supporting that ?2 receptors are markers of cell proliferation and that the higher is the proliferation, the stronger is the antiproliferative effect of ?2 agonists. Colocalization of 16 with subcellular organelles was studied by confocal microscopy: the greatest was in endoplasmic reticulum and lysosomes. Fluorescent ?2 ligands show their potential in clarifying the mechanisms of action of ?2 receptors.

Abate, Carmen; Hornick, John R.; Spitzer, Dirk; Hawkins, William G; Niso, Mauro; Perrone, Roberto; Berardi, Francesco

2011-01-01

316

Bis[1-cyclo-propyl-6-fluoro-4-oxo-7-(1-piperazin-4-ium-1-yl)-1,4-dihydro-quinoline-3-carboxyl-ate-?2 O 3,O 4]bis-(nitrato-?O)copper(II)  

PubMed Central

In the title complex, [Cu(NO3)2(C17H18FN3O3)2], the CuII ion is located on an inversion center. It exhibits a distorted octa­hedral geometry, being coordinated by six O atoms, four from two ciprofloxacin ligand mol­ecules (L), which act as bidentate ligands, and two from two nitrate anions. In the ligand, the piperazine ring has a chair conformation and the quinoline system is essentially planar [maximum deviation = 0.097?(2)?Å]. One of the nitrate O atoms is disordered over two positions [occupancy ratio = 0.51?(6):0.49?(6)]. There is a C—H?F inter­action in the complex. In the crystal, mol­ecules are linked via N—H?O hydrogen bonds generating a two-dimensional network lying parallel to (111). The presence of C—H?O inter­actions leads to the formation of a three-dimensional structure. The title complex was prepared by hydro­thermal synthesis, and the hexa­hydrate form of this complex, synthesized by conventional methods, has been reported previously [Hernandez-Gil et al. (2009 ?). Polyhedron, 28, 138–144].

Yang, Juan; Yan, Shi-Wei; Ye, Zhong-Li; Xin, Guang-Hua; Chang, Suo-Cheng

2012-01-01

317

Poly[[di-aqua-[?-1,4-bis(pyridin-4-ylmeth-yl)piperazine-?2 N:N?]{?-2,2?-[(1,4-phenyl-ene)bis(-oxy)]di-acetato-?2 O:O?}cobalt(II)] penta-hydrate  

PubMed Central

In the title compound, {[Co(C10H8O6)(C16H20N4)(H2O)2]·5H2O}n, octa­hedrally coordinated CoII ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydro­quinone-O,O?-di­acetate (hqda) anions {systematic name: 2,2?-[(1,4-phenyl­ene)bis­(­oxy)]di­acetate}, two trans-pyridine N-donor atoms from two bis­(pyridin-4-ylmeth­yl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H2O)2]n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O—H?O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water mol­ecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ?). Acta Cryst. D65, 148–155]; the crystal data take the presence of these mol­ecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement.

Sample, Alexander D.; LaDuca, Robert L.

2014-01-01

318

Novel derivatives of 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine (PB28) with improved fluorescent and ? receptors binding properties.  

PubMed

Despite the promising potentials of ?2 receptors in cancer therapy and diagnosis, there are still ambiguities related to the nature and physiological role of the ?2 protein. With the aim of providing potent and reliable tools to be used in ?2 receptor research, we developed a novel series of fluorescent ?2 ligands on the basis of our previous work, where high-affinity ?2 ligand 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)-n-propyl]piperazine (1, PB28) was used as the pharmacophore. Compared to the previous compounds, these novel ligands displayed improved fluorescence and ?2 binding properties, were ?2-specifically taken up by breast tumor cells, and were successfully employed in confocal microscopy. Compound 14, which was the best compromise between pharmacological and fluorescent properties, was successfully employed in flow cytometry, demonstrating its potential to be used as a tool in nonradioactive binding assays for studying the affinity of putative ?2 receptor ligands. PMID:24697311

Abate, Carmen; Niso, Mauro; Marottoli, Roberta; Riganti, Chiara; Ghigo, Dario; Ferorelli, Savina; Ossato, Giulia; Perrone, Roberto; Lacivita, Enza; Lamb, Don C; Berardi, Francesco

2014-04-24

319

Poly[[di-aqua-[?-1,4-bis(pyridin-4-ylmeth-yl)piperazine-?(2) N:N']{?-2,2'-[(1,4-phenyl-ene)bis(-oxy)]di-acetato-?(2) O:O'}cobalt(II)] penta-hydrate].  

PubMed

In the title compound, {[Co(C10H8O6)(C16H20N4)(H2O)2]·5H2O} n , octa-hedrally coordinated Co(II) ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydro-quinone-O,O'-di-acetate (hqda) anions {systematic name: 2,2'-[(1,4-phenyl-ene)bis-(-oxy)]di-acetate}, two trans-pyridine N-donor atoms from two bis-(pyridin-4-ylmeth-yl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H2O)2] n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O-H?O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water mol-ecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ?). Acta Cryst. D65, 148-155]; the crystal data take the presence of these mol-ecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement. PMID:24940193

Sample, Alexander D; LaDuca, Robert L

2014-06-01

320

Coordination chemistry of two new tetraaza Ni(II) and Cu(II) macrocyclic and two new Co(II) and Zn(II) macroacyclic Schiff base complexes containing piperazine moiety: X-ray crystal structures of Ni(II) and Zn(II) complexes  

Microsoft Academic Search

A new potentially tetradentate (N4) Schiff base ligand (L), 1,9,12,20-tetraazatetracyclo[18.2.2.02,7.014,19]tetracosa-2(7),3,5,8,12,14(19),15,17-octaene containing a piperazine moiety is described. Macrocyclic Schiff base complexes, [NiL](ClO4)2 (1) and [CuL](ClO4)2 (2) have been obtained from equimolar amounts of ligand (L) with nickel(II) and copper(II) metal ions. While the equilibrium reaction in the presence of cobalt(II) and zinc(II) metal ions with ligand L in a 1:1 molar

Hassan Keypour; Parisa Arzhangi; Nasibeh Rahpeyma; Majid Rezaeivala; Yalcin Elerman; Hamid Reza Khavasi

2011-01-01

321

Surface tension of aqueous solutions of diethanolamine and triethanolamine from 25 C to 50 C  

SciTech Connect

Aqueous solutions of alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP) are good solvents for the removal of acid gases such CO{sub 2} and H{sub 2}S from the gas streams of many processes in the natural gas, ammonia synthesis, and some chemical industries. The surface tension of aqueous solutions of diethanolamine and triethanolamine was measured over the entire concentration range at temperatures of 25 C to 50 C. The experimental values were correlated with temperature and with mole fraction. The maximum deviation was in both cases always less than 0.5%.

Vazquez, G.; Alvarez, E.; Rendo, R.; Romero, E.; Navaza, J.M. [Univ. of Santiago de Compostela (Spain). Dept. of Chemical Engineering] [Univ. of Santiago de Compostela (Spain). Dept. of Chemical Engineering

1996-07-01

322

Advanced process selectively removes H/sub 2/S  

SciTech Connect

A selective H/sub 2/S-removal scheme called the HS process is being tested at a New Mexico pilot plant having an 18-in-diam contactor, a 24-in-diam stripping still, and a 30-gpm solution flow capacity. The test program goals are to (1) demonstrate the technical and economic superiority of the process over other options, and (2) redefine mass-transfer and ray hydraulic data for scale-up to commercial size. The technology combines a selective chemical solvent based on methyldiethanolamine (MDEA), a unique contactor design, and an innovative selective contactor tray.

Not Available

1981-06-08

323

Shell coal gasification plant (SCGP-1) environmental performance results  

SciTech Connect

Environmental studies in slip-stream process development units at SCGP-1, Shell's advanced coal gasification demonstration plant, located near Houston, Texas, have demonstrated that the gas and water effluents from the Shell Coal Gasification Process (SCGP) are environmentally benign on a broad slate of coals. This report presents the results of those environmental studies. It contains two major subjects, which describe, respectively, the experiments on gas treating and the experiments on water treating. Gas treatment focused on the performance of aqueous methyldiethanolamine (MDEA) and sulfinol-M. 8 refs., 24 figs., 13 tabs.

Bush, W.V.; Baker, D.C.; Tijm, P.J.A. (Shell Development Co., Houston, TX (United States))

1991-07-01

324

Physical solubility of carbon dioxide in aqueous alkanolamines via nitrous oxide analogy  

SciTech Connect

In the petrochemical and natural gas industry, the removal of carbon dioxide and hydrogen sulfide from process gas streams is commonly achieved by reacting these impurities with aqueous alkanolamines. Van Krevelen coefficients for protonated monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA), the carbamates of MEA and DEA, and the bicarbonate ion have been determined experimentally from measurements of the solubility of N[sub 2]O at 25 C and atmospheric pressure in aqueous solutions of these ions. Measured values different significantly from values recommended by others in the absence of experimental data. By analogy with N[sub 2]O, the solubility of carbon dioxide in the same solutions can be estimated.

Browning, G.J.; Weiland, R.H. (Univ. of Newcastle, Callaghan, New South Wales (Australia). Dept. of Chemical Engineering)

1994-10-01

325

Prevalence of efflux-mediated ciprofloxacin and levofloxacin resistance in recent clinical isolates of Pseudomonas aeruginosa and its reversal by the efflux pump inhibitors 1-(1-naphthylmethyl)-piperazine and phenylalanine-arginine-?-naphthylamide.  

PubMed

To assess the prevalence of efflux-driven fluoroquinolone (FQ) resistance in recent clinical isolates of Pseudomonas aeruginosa, a worrisome and often hospital-acquired pathogen, 115 unique strains were collected over a 5-month period, of which 27 and 33 had decreased susceptibility to ciprofloxacin (CIP) and levofloxacin (LVX), respectively. The MIC(50) (minimum inhibitory concentration for 50% of the organisms) was 16 ?g/mL for both FQs. The efflux pump inhibitors (EPIs) phenylalanine-arginine-?-naphthylamide (PA?N) and 1-(1-naphthylmethyl)-piperazine (NMP) were then used to evaluate their efficacy in reducing CIP and LVX MICs. NMP did not significantly modify CIP MICs, whilst PA?N resulted in MIC(50) values of 2 ?g/mL and 0.125 ?g/mL for CIP and LVX, respectively. With the addition of PA?N, susceptibility to CIP and LVX was recovered in 6 (22.2%) and 31 (93.9%) strains, respectively. The best combination to reverse FQ resistance in this set of strains was LVX with PA?N. The results of this study show that the effect of an EPI is not only dependent on the species on which it is used but also on the molecule associated with it. Therefore, the design of an EPI equally efficient on all resistance-nodulation-cell division (RND) efflux pumps appears to be difficult and, from a practical point of view, if an EPI is developed for clinical use, the efficiency of its combination with a definite molecule should be assessed carefully against a wide range of clinical isolates to evaluate the real benefit of this combination. PMID:21974858

Sonnet, Pascal; Izard, Daniel; Mullié, Catherine

2012-01-01

326

Amine plant troubleshooting and optimization  

SciTech Connect

A systematic method for troubleshooting and optimization of amine plants, if properly used, will result in fewer plant upsets, quick and correct responses to changing conditions and long-term profitable operations of any amine unit. It is important for amine plants to maintain safe, continuous and optimized operations for short- and long-term success. Effective and fast resolution of maine unit upsets plays a large part in this success. These considerations are as important in plants using generic amines such as monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA) and specialty amines based on MDEA. The key to troubleshooting and optimization is a systematic approach. Developing and using control charts can also be used to monitor amine plant operations. By using these techniques collectively, a formal method for troubleshooting and optimization can be established. This will ultimately result in a more trouble-free, continuous operation.

Abry, R.G.F. [Dow Chemical Co., Ft. Saskatchewan, Alberta (Canada); DuPart, M.S. [Dow Chemical Co., Freeport, TX (United States)

1995-04-01

327

9?-Hy-droxy-12-{[4-(4-hy-droxy-phen-yl)piperazin-1-yl]meth-yl}-4,8-dimethyl-3,14-dioxatri-cyclo-[9.3.0.02,4]tetra-dec-7-en-13-one  

PubMed Central

The title compound, C25H34N2O5, was synthesized from 9?-hy­droxy­parthenolide (9?-hy­droxy-4,8-dimethyl-12-methylen-3, 14-dioxa-tri­cyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which in turn was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule comprises a ten-membered ring fused to a five-membered ring with an additional ep­oxy ring system fused to the ten-membered ring. The five-membered ring also carries a 4-hy­droxy­phenyl-piperazin-1-ylmethyl substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy­droxy group forming the flap. Two C atoms in the phenyl ring and the O atom of the hydroxyl group are disordered over two sites, with an occupancy ratio of 0.53?(5):0.47?(5). An intra­molecular O—H?N hydrogen-bond stabilizes the mol­ecular conformation. In the crystal, C—H?O hydrogen bonds link the mol­ecules into zigzag chains running along the a-axis direction.

Loubidi, Mohamed; Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

2014-01-01

328

12-{[4-(4-Bromo-phen-yl)piperazin-1-yl]meth-yl}-9?-hy-droxy-4,8-dimethyl-3,14-dioxatri-cyclo-[9.3.0.02,4]tetra-dec-7-en-13-one  

PubMed Central

The title compound, C25H33BrN2O4, was synthesized from 9?-hy­droxy­parthenolide (9?-hy­droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tri­cyclo­[9.3.0.02,4]tetra­dec-7-en-13-one), which was isolated from the chloro­form extract of the aerial parts of Anvillea radiata. The mol­ecule is built up from two fused five- and ten-membered rings with an additional ep­oxy ring system and a bromo­phenyl­piperazine group as a substituent. The ten-membered ring adopts an approximate chair–chair–chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy­droxy group forming the flap. An intra­molecular O—H?N hydrogen bond stabilizes the mol­ecular conformation. The crystal packing features C—H?O hydrogen bonds, which link the mol­ecules into zigzag chains running along the b-axis direction.

Loubidi, Mohamed; Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

2014-01-01

329

12-{[4-(4-Bromo-phen-yl)piperazin-1-yl]meth-yl}-9?-hy-droxy-4,8-dimethyl-3,14-dioxatri-cyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one.  

PubMed

The title compound, C25H33BrN2O4, was synthesized from 9?-hy-droxy-parthenolide (9?-hy-droxy-4,8-dimethyl-12-methylen-3,14-dioxa-tri-cyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one), which was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The mol-ecule is built up from two fused five- and ten-membered rings with an additional ep-oxy ring system and a bromo-phenyl-piperazine group as a substituent. The ten-membered ring adopts an approximate chair-chair-chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy-droxy group forming the flap. An intra-molecular O-H?N hydrogen bond stabilizes the mol-ecular conformation. The crystal packing features C-H?O hydrogen bonds, which link the mol-ecules into zigzag chains running along the b-axis direction. PMID:24826186

Loubidi, Mohamed; Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

2014-04-01

330

9?-Hy-droxy-12-{[4-(4-hy-droxy-phen-yl)piperazin-1-yl]meth-yl}-4,8-dimethyl-3,14-dioxatri-cyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one.  

PubMed

The title compound, C25H34N2O5, was synthesized from 9?-hy-droxy-parthenolide (9?-hy-droxy-4,8-dimethyl-12-methylen-3, 14-dioxa-tri-cyclo-[9.3.0.0(2,4)]tetra-dec-7-en-13-one), which in turn was isolated from the chloro-form extract of the aerial parts of Anvillea radiata. The mol-ecule comprises a ten-membered ring fused to a five-membered ring with an additional ep-oxy ring system fused to the ten-membered ring. The five-membered ring also carries a 4-hy-droxy-phenyl-piperazin-1-ylmethyl substituent. The ten-membered ring adopts an approximate chair-chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hy-droxy group forming the flap. Two C atoms in the phenyl ring and the O atom of the hydroxyl group are disordered over two sites, with an occupancy ratio of 0.53?(5):0.47?(5). An intra-molecular O-H?N hydrogen-bond stabilizes the mol-ecular conformation. In the crystal, C-H?O hydrogen bonds link the mol-ecules into zigzag chains running along the a-axis direction. PMID:24860343

Loubidi, Mohamed; Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

2014-05-01

331

Acute toxicity and primary irritancy of alkylalkanolamines.  

PubMed

The acute handling hazards of several alkylalkanolamines were determined by investigating their potential acute toxicity and primary irritancy. Materials studied were N-methylethanolamine (MEA), N, N, -dimethylethanolamine (DMEA), N, N, -dimethylisopropanolamine (DMIPA), N-methyldiethanolamine (MDEA), and tertbutyldiethanolamine (BDEA). All these alkylalkanolamines were of comparable acute peroral toxicity in the rat (LD50 range 1.48-2.83 ml/kg). By 24 h occluded epicutaneous contact in the rabbit, MEA, DMEA and DMIPA were of moderate acute percutaneous toxicity (LD50 range 1.13-2.0 ml/kg), MDEA was of slight acute percutaneous toxicity (LD50 male 9.85 ml/kg, female 10.90 ml/kg), and BDEA of intermediate toxicity (LD50 6.4 ml/kg). Due to differences in vapor pressure the acute vapor exposure toxicity of the alkylalkanolamines to rats varied; MEA, MDEA and BDEA were of a low order of acute toxicity, and DMIPA was moderately toxic with an LT50 of 3.2 h for a saturated vapor atmosphere exposure. A 4 h-LC50 (rat combined sex) of 1461 ppm was determined for DMEA. All alkylalkanolamines studied, except MDEA, were moderately to markedly irritating and caused variable degrees of skin corrosivity; MDEA caused only transient minor skin irritation. In accord with the skin irritancy results, the eye irritancy from 0.005 ml MEA, DMEA, DMIPA and BDEA was severe, and that from MDEA was slight. Exposure to these compounds has implications for occupational health procedures. PMID:8948072

Ballantyne, B; Leung, H W

1996-12-01

332

Converting to DEA\\/MDEA mix ups sweetening capacity  

Microsoft Academic Search

Mixing amines can be the best method for increasing capacity or improving efficiency in an amine sweetening unit. In many cases, it may be possible simply to add a second amine to the existing solution on the fly, or as the unit is running. Union Pacific Resources` Bryan, Tex., gas plant provides one example. The plant was converted from diethanolamine

MICHAEL L. SPEARS; KATHY M. HAGAN; JERRY A. BULLIN; CARL J. MICHALIK

1996-01-01

333

Design and operation of a selective sweetening plant using MDEA  

Microsoft Academic Search

The Signalta Resources Forestburg Gas Plant was constructed during the winter of 1983 and placed on stream in April of 1984. A design outlet gas specification of 1\\/4 grain HâS\\/100 scf was requested to ensure meeting the contract commitment of 1 grain\\/100 scf. The design gas flowrate was 30 MMSCFD containing 0.5% HâS and 3% COâ at 415 psia and

DOUGLAS H. MACKENZIE; F. Chiraka-Parambil; C. A. Daniels; J. A. Bullin

1986-01-01

334

Buffer Standards for pH Measurement of N-(2-Hydroxyethyl)piperazine-N'-2-ethanesulfonic Acid (HEPES) for I = 0.16 mol?kg?1 from 5 to 55?C  

PubMed Central

The values of the second dissociation constant, pK2 of N-(2-hydroxyethyl) piperazine-N’-2-ethanesulfonic acid (HEPES) have been reported at 12 temperatures over the temperature range 5 to 55°C, including 37°C. This paper reports the results for the paH of eight isotonic saline buffer solutions with an I = 0.16 mol•kg?1 including compositions: (a) HEPES (0.01 mol•kg?1) + NaHEPES (0.01 mol•kg?1) + NaCl (0.15 mol•kg?1); (b) HEPES (0.02 mol•kg?1) + NaHEPES (0.02 mol•kg?1) + NaCl (0.14 mol•kg?1); (c) HEPES (0.03 mol•kg?1) + NaHEPES (0.03 mol•kg?1) + NaCl (0.13 mol•kg?1); (d) HEPES (0.04 mol•kg?1) + NaHEPES (0.04 mol•kg?1) + NaCl (0.12 mol•kg?1); (e) HEPES (0.05 mol•kg?1) + NaHEPES (0.05 mol•kg?1) + NaCl (0.11 mol•kg?1); (f) HEPES (0.06 mol•kg?1) + NaHEPES (0.06 mol•kg?1) + NaCl (0.10 mol•kg?1); (g) HEPES (0.07 mol•kg?1) + NaHEPES (0.07 mol•kg?1) + NaCl (0.09 mol•kg?1); and (h) HEPES (0.08 mol•kg?1) + NaHEPES (0.08 mol•kg?1) + NaCl (0.08 mol•kg?1). Conventional paH values, for all eight buffer solutions from 5 to 55°C have been calculated. The operational pH values with liquid junction corrections, at 25 and 37°C have been determined based on the NBS/NIST standard between the physiological phosphate standard and four buffer solutions. These are recommended as pH standards for physiological fluids in the range of pH 7.3 to 7.5 at I = 0.16 mol•kg?1.

Roy, Rabindra N.; Roy, Lakshmi N.; Ashkenazi, Shahaf; Wollen, Joshua T.; Dunseth, Craig D.; Fuge, Michael S.; Durden, Jared L.; Roy, Chandra N.; Hughes, Hannah M.; Morris, Brett T.; Cline, Kevin L.

2009-01-01

335

Bis[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carb-oxy-lic acid] 2,5-dicarb-oxy-benzene-1,4-di-carboxyl-ate octa-hydrate.  

PubMed

The asymmetric unit of the title compound, 2C(14)H(18)N(5)O(3) (+)·C(10)H(5)O(8) (2-)·8H(2)O, contains one [H(2)ppa](+)cation, one half of an [H(2)btec](2-) anion (H(4)btec = 1,2,4,5-benzene-tetra-carb-oxy-lic acid and Hppa = 8-ethyl-5-oxo-2-piperazin-1-yl-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carb-oxy-lic acid) that is completed by inversion symmetry and four water mol-ecules. In the crystal, the mol-ecules are connected by inter-molecular hydrogen-bonding inter-actions and ?-? stacking between the benzene rings of the [H(2)btec](2-) anion and the pyrimidine rings of the [H(2)ppa](+) cation [centroid-centroid distance = 3.597?(3)?Å], generating a three-dimensional supra-molecular structure. PMID:21754029

Zhang, Guang-Ju; He, Jiang-Hong; Yan, Shi-Wei; Ye, Zhong-Li; Xin, Guang-Hua

2011-04-01

336

In vitro and in vivo characterization of JNJ-31020028 ( N -(4-{4-[2-(diethylamino)-2-oxo-1-phenylethyl]piperazin-1-yl}-3-fluorophenyl)-2-pyridin-3-ylbenzamide), a selective brain penetrant small molecule antagonist of the neuropeptide Y Y 2 receptor  

Microsoft Academic Search

Rationale  The lack of potent, selective, brain penetrant Y2 receptor antagonists has hampered in vivo functional studies of this receptor.\\u000a \\u000a \\u000a \\u000a Objective  Here, we report the in vitro and in vivo characterization of JNJ-31020028 (N-(4-{4-[2-(diethylamino)-2-oxo-1-phenylethyl]piperazin-1-yl}-3-fluorophenyl)-2-pyridin-3-ylbenzamide), a novel Y2 receptor antagonist.\\u000a \\u000a \\u000a \\u000a Methods  The affinity of JNJ-31020028 was determined by inhibition of the PYY binding to human Y2 receptors in KAN-Ts cells and rat Y2 receptors

James R. Shoblock; Natalie Welty; Diane Nepomuceno; Brian Lord; Leah Aluisio; Ian Fraser; S. Timothy Motley; Steve W. Sutton; Kirsten Morton; Ruggero Galici; John R. Atack; Lisa Dvorak; Devin M. Swanson; Nicholas I. Carruthers; Curt Dvorak; Timothy W. Lovenberg; Pascal Bonaventure

2010-01-01

337

21 CFR 520.1807 - Piperazine.  

Code of Federal Regulations, 2013 CFR

...Amount. 50 milligrams per pound of body weight. (ii) Indications for use. For removal of large roundworm (Ascaris suum ) and nodular worms (Oesophagostomum spp.). (iii) Limitations. For use in drinking water or...

2013-04-01

338

Polymerization Behavior and Polymer Properties of Eosin-Mediated Surface Modification Reactions.  

PubMed

Surface modification by surface-mediated polymerization necessitates control of the grafted polymer film thicknesses to achieve the desired property changes. Here, a microarray format is used to assess a range of reaction conditions and formulations rapidly in regards to the film thicknesses achieved and the polymerization behavior. Monomer formulations initiated by eosin conjugates with varying concentrations of poly(ethylene glycol) diacrylate (PEGDA), N-methyldiethanolamine (MDEA), and 1-vinyl-2-pyrrolidone (VP) were evaluated. Acrylamide with MDEA or ascorbic acid as a coinitiator was also investigated. The best formulation was found to be 40 wt% acrylamide with MDEA which yielded four to eight fold thicker films (maximum polymer thickness increased from 180 nm to 1420 nm) and generated visible films from 5-fold lower eosin surface densities (2.8 vs. 14 eosins/µm(2)) compared to a corresponding PEGDA formulation. Using a microarray format to assess multiple initiator surface densities enabled facile identification of a monomer formulation that yields the desired polymer properties and polymerization behavior across the requisite range of initiator surface densities. PMID:19838291

Avens, Heather J; Randle, Thomas James; Bowman, Christopher N

2008-10-17

339

Viscosities of aqueous blended amines  

SciTech Connect

Solutions of alkanolamines are an industrially important class of compounds used in the natural gas, oil refineries, petroleum chemical plants, and synthetic ammonia industries for the removal of acidic components like CO{sub 2} and H{sub 2}S from gas streams. The viscosities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA), DEA + 2-amino-2-methyl-1-propanol (AMP), and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) were measured from 30 C to 80 C. A Redlich-Kister equation for the viscosity deviation was applied to represent the viscosity. On the basis of the available viscosity data for five ternary systems, MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. For the viscosity calculation of the systems tested, the overall average absolute percent deviation is about 1.0% for a total of 499 data points.

Hsu, C.H.; Li, M.H. [Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering] [Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering

1997-07-01

340

Collection of VLE data for acid gas---alkanolamine systems using fourier transform infrared spectroscopy. Phase 2, October 1, 1991--September 30, 1992  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor--liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as ``hindered`` amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor--liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 {times} 10{sup 14} BTU/yr.

Bullin, J.A.; Frazier, R.E.

1992-12-01

341

Collection of VLE data for acid gas---alkanolamine systems using fourier transform infrared spectroscopy. [Vapor-liquid equilibrium  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor--liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as hindered'' amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor--liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 [times] 10[sup 14] BTU/yr.

Bullin, J.A.; Frazier, R.E.

1992-01-01

342

Alternative stripper configurations for CO{sub 2} capture by aqueous amines  

SciTech Connect

Aqueous absorption/stripping is a promising technology for the capture of CO{sub 2} from existing or new coal-fired power plants. Four new stripper configurations (matrix, internal exchange, flashing feed, and multipressure with split feed) have been evaluated with seven model solvents that approximate the thermodynamic and rate properties of 7m (30 wt %) monoethanolamine (MEA), potassium carbonate promoted bypiperazine (PZ), promoted MEA, methyldiethanolamine (MDEA) promoted by PZ, and hindered amines. The results show that solvents with high heats of absorption (MEA, MEA/PZ) favor operation at normal pressure. The relative performance of the alternative configurations is matrix > internal exchange > multipressure with split feed > flashing feed. MEA/PZ and MDEA/PZ are attractive alternatives to 7m MEA. The best solvent and process configuration, matrix with MDEA/PZ, offers 22 and 15% energy savings over the baseline and improved baseline, respectively,with stripping and compression to 10 MPa. The energy requirement for stripping and compression to 10 MPa is about 20% of the power output from a 500 MW power plant with 90% CO{sub 2} removal.

Oyenekan, B.A.; Rochelle, G.T. [University of Texas Austin, Austin, TX (USA). Dept. of Chemical Engineering

2007-12-15

343

Densities of aqueous blended amines  

SciTech Connect

Solutions of alkanolamines are an industrially important class of compounds used in the natural gas and synthetic ammonia industries and petroleum chemical plants for the removal of CO{sub 2} and H{sub 2}S from gas streams. The densities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water, DEA + 2-amino-2-methyl-1-propanol (AMP) + water, and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) + water were measured from 30 C to 80 C. A Redlich-Kister equation of the excess volume was applied to represent the density. Based on the available density data for five ternary systems: MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. The density calculations show quite satisfactory results. The overall average absolute percent deviation is about 0.04% for a total of 686 data points.

Hsu, C.H.; Li, M.H. [Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering] [Chung Yuan Christian Univ., Chung Li (Taiwan, Province of China). Dept. of Chemical Engineering

1997-05-01

344

Collection of VLE data for acid gas-alkanolamine systems using Fourier transform infrared spectroscopy  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor -- liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as hindered'' amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor -- liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 {times} 10{sup 14} BTU/yr.

Bullin, J.A.; Frazier, R.E.

1991-09-01

345

Collection of VLE data for acid gas-alkanolamine systems using Fourier transform infrared spectroscopy. Phase 1, September 29, 1990--September 30, 1991  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor -- liquid equilibrium (VLE) hinder the industry from converting operations to more energy efficient amine mixtures and conserving energy. Some energy reductions have been realized in the past decade by applying such amine systems as ``hindered`` amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate fundamental VLE data impedes the commercial application of these more efficient alkanolamine systems. The first project objective is to improve the accuracy of vapor -- liquid equilibrium measurements at low hydrogen sulfide concentrations. The second project objective is to measure the VLE for amine mixtures. By improving the accuracy of the VLE measurements on MDEA and mixtures with other amines, energy saving can be quickly and confidently implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy savings are estimated to be about 3 {times} 10{sup 14} BTU/yr.

Bullin, J.A.; Frazier, R.E.

1991-09-01

346

Evaluation of the electrode method for measuring H/sub 2/S vapor pressure over alkanolamine solutions  

SciTech Connect

A new electrode method for measuring the equilibrium vapor pressure of H/sub 2/S over any sulfide solution was tested. The method relates the electropotential difference produced between pH and silver/sulfide ion specific electrodes to the H/sub 2/S equilibrium vapor pressure of solution. The experimental technique is simple and time efficient. In this work, H/sub 2/S equilibrium vapor pressures were measured from 10/sup -4/ kPa to 10 kPa at 25/sup 0/C in aqueous solutions of monoethanolamine-MEA (2.5 N), diethanolamine-DEA (2.0N), and methyldiethanolamine-MDEA (1.0 N and 4.28 N). The H/sub 2/S vapor-liquid equilibria (VLE) of 4.28 N MDEA was also examined at 40/sup 0/C. The results indicate that the addition of MEA to a MDEA solution reduces the H/sub 2/S vapor pressure only at low H/sub 2/S loadings.

Austgen, D.M.; Rochelle, G.T.

1987-01-01

347

Collection of VLE data for acid gas-alkanolamine systems using Fourier transform infrared spectroscopy. Technical report, October 1, 1994--July 31, 1995  

SciTech Connect

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. The natural gas industry requires vapor-liquid equilibrium (VLE) data to develop more energy efficient amine mixtures. Some energy reductions have been realized in the past decade by applying such amine systems as hindered amines, methyldiethanolamine (MDEA), and MDEA based amine mixtures. However, the lack of reliable and accurate VLE data impedes the commercial application of these more efficient alkanolamine systems. The first objective of this project is to improve the accuracy of vapor-liquid equilibrium measurements at low hydrogen sulfide concentrations. The second objective is to make VLE measurements for amine mixtures. By improving the accuracy of the VLE data on MDEA and other amines, energy savings can be implemented in the many existing absorption units already in use. If about 25% of the existing 95.3 billion SCFD gas purification capacity is converted to these new amine systems, the energy saved is estimated to be 3 {times} 10{sup 14} BTU/yr. 14 refs., 31 figs., 12 tabs.

Bullin, J.A.; Rogers, W.J.

1995-08-01

348

Identification of Metabolites of N-(5-Benzoyl-2-(4-(2-Methoxyphenyl)piperazin-1-yl)thiazol-4-yl)pivalamide Including CYP3A4-Mediated C-Demethylation in Human Liver Microsomes with High-Resolution/High-Accuracy Tandem Mass.  

PubMed

KRO-105714 [N-(5-benzoyl-2-(4-(2-methoxyphenyl)piperazin-1-yl)thiazol-4-yl)pivalamide] is a 2,4,5-trisubstituted 1,3-thiazole derivative that exerts anti-atopic dermatitis activity via robust suppression of the sphingosylphosphorylcholine receptor. This study used high-resolution/high-accuracy tandem mass spectroscopy (HRMS) and recombinant cDNA-expressed cytochrome P450 (P450) isoforms to identify the metabolic pathway and metabolites of KRO-105714 in human liver microsomes (HLMs) as therapeutic agents for inflammation. The incubation of KRO-105714 with pooled HLMs in the presence of NADPH generated four metabolites (M1-M4). The metabolites were identified using HRMS and confirmed using synthetic standards for M2 and M4. M1 and M2 were identified as monohydroxylated metabolites, and M3 and M4 were identified as O-demethyl KRO-105714 and C-demethyl KRO-105714, respectively. In the inhibition study with selective CYP3A4 inhibitors and incubation in recombinant cDNA-expressed P450 enzymes, all the metabolites of KRO-105714 were formed by CYP3A4 in HLMs. The CYP3A4-mediated formation of M4 from M2 was confirmed via incubation of M2 in HLMs. These results showed that the unusual C-demethylated metabolite M4 was generated from monohydroxyl metabolite M2 via a CYP3A4-mediated enzymatic reaction in HLMs. PMID:24829290

Song, Min; Lee, Doohyun; Kim, Sun; Bae, Jong-Sup; Lee, Jaeick; Gong, Young-Dae; Lee, Taeho; Lee, Sangkyu

2014-08-01

349

Discovery and preclinical profile of teneligliptin (3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine): a highly potent, selective, long-lasting and orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes.  

PubMed

Dipeptidyl peptidase IV (DPP-4) inhibition is suitable mechanism for once daily oral dosing regimen because of its low risk of hypoglycemia. We explored linked bicyclic heteroarylpiperazines substituted at the ?-position of the proline structure in the course of the investigation of l-prolylthiazolidines. The efforts led to the discovery of a highly potent, selective, long-lasting and orally active DPP-4 inhibitor, 3-[(2S,4S)-4-[4-(3-methyl-1-phenyl-1H-pyrazol-5-yl)piperazin-1-yl]pyrrolidin-2-ylcarbonyl]thiazolidine (8 g), which has a unique structure characterized by five consecutive rings. An X-ray co-crystal structure of 8 g in DPP-4 demonstrated that the key interaction between the phenyl ring on the pyrazole and the S(2) extensive subsite of DPP-4 not only boosted potency, but also increased selectivity. Compound 8 g, at 0.03 mg/kg or higher doses, significantly inhibited the increase of plasma glucose levels after an oral glucose load in Zucker fatty rats. Compound 8 g (teneligliptin) has been approved for the treatment of type 2 diabetes in Japan. PMID:22959556

Yoshida, Tomohiro; Akahoshi, Fumihiko; Sakashita, Hiroshi; Kitajima, Hiroshi; Nakamura, Mitsuharu; Sonda, Shuji; Takeuchi, Masahiro; Tanaka, Yoshihito; Ueda, Naoko; Sekiguchi, Sumie; Ishige, Takayuki; Shima, Kyoko; Nabeno, Mika; Abe, Yuji; Anabuki, Jun; Soejima, Aki; Yoshida, Kumiko; Takashina, Yoko; Ishii, Shinichi; Kiuchi, Satoko; Fukuda, Sayaka; Tsutsumiuchi, Reiko; Kosaka, Keigo; Murozono, Takahiro; Nakamaru, Yoshinobu; Utsumi, Hiroyuki; Masutomi, Naoya; Kishida, Hiroyuki; Miyaguchi, Ikuko; Hayashi, Yoshiharu

2012-10-01

350

Diaqua-(5-carb-oxy-benzene-1,3-dicarboxyl-ato-?O 1)[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carboxyl-ato-?2 O 5,O 6]zinc monohydrate  

PubMed Central

In the title compound, [Zn(C14H17N5O3)(C9H4O6)(H2O)2]·H2O, the complex mol­ecule exists in a zwitterionic form. The ZnII ion exhibits a distorted tetra­gonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ate (L) ligand, one O atom from the 5-carb­oxy­benzene-1,3-dicarboxyl­ate dianion, [Hbtc]2?, and two O atoms from two aqua ligands. In the crystal, N—H?O and O—H?O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits ?–? inter­actions between the aromatic rings, with centroid–centroid distances in the range 3.466?(3)–3.667?(3)?Å.

Ye, Zhong-Li; Xin, Guang-Hua; Zhang, Fu-Tian; Xiao, Dong-Rong

2013-01-01

351

Spectroscopic (FT-IR, FT-Raman) investigations and quantum chemical calculations of 1,7,8,9-tetrachloro-10,10-dimethoxy-4-{3-[4-(3-methoxyphenyl)piperazin-1-yl]propyl}-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5-dione.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1,7,8,9-tetrachloro-10,10-dimethoxy-4-{3-[4-(3-methoxyphenyl) piperazin-1-yl]propyl}-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5-dione have been investigated experimentally and theoretically using Gaussian09 software package. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular Electrostatic Potential was performed by the DFT method and the infrared and Raman intensities have also been reported. First hyperpolarizability is calculated in order to find its role in non-liner optics. The calculated geometrical parameters (SDD) are in agreement with that of similar derivatives. Mulliken's net charges have been calculated and compared with the atomic natural charges. PMID:24747931

Renjith, R; Sheena Mary, Y; Yohannan Panicker, C; Varghese, Hema Tresa; Pakosi?ska-Parys, Magdalena; Van Alsenoy, C; Al-Saadi, Abdulaziz A

2014-08-14

352

Spectroscopic (FT-IR, FT-Raman) investigations and quantum chemical calculations of 1,7,8,9-tetrachloro-10,10-dimethoxy-4-{3-[4-(3-methoxyphenyl)piperazin-1-yl]propyl}-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1,7,8,9-tetrachloro-10,10-dimethoxy-4-{3-[4-(3-methoxyphenyl) piperazin-1-yl]propyl}-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione have been investigated experimentally and theoretically using Gaussian09 software package. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Gauge-including atomic orbital 1H NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular Electrostatic Potential was performed by the DFT method and the infrared and Raman intensities have also been reported. First hyperpolarizability is calculated in order to find its role in non-liner optics. The calculated geometrical parameters (SDD) are in agreement with that of similar derivatives. Mulliken’s net charges have been calculated and compared with the atomic natural charges.

Renjith, R.; Mary, Y. Sheena; Panicker, C. Yohannan; Varghese, Hema Tresa; Pakosi?ska-Parys, Magdalena; Van Alsenoy, C.; Al-Saadi, Abdulaziz A.

2014-08-01

353

Offshore desulfurization unit permits gas lift operations  

SciTech Connect

This paper reports on the installation of a desulfurization unit for the Tchibouela oil field, offshore Congo, which allowed produced low-pressure associated gas containing CO{sub 2} to be kept for gas lift operations while, for safety reasons, the large volume of H{sub 2}S at low pressure was removed prior to compression. Since October 1989, the world's first offshore amine sweetening unit has worked satisfactorily and continues to prove that it is an attractive production alternative. For desulfurization, a selective methyldiethanolamine (MDEA) process, developed by Elf Aquitaine, was chosen because it was the only process that met the required specifications at a low pressure of 3.5 bar (51 psi).

Cabes, A.; Elgue, J.; Tournier-Lasserve, J. (Societe Nationale Elf Aquitaine Paris (FR))

1992-01-13

354

Kinetics of the reaction between carbon dioxide and tertiary amines  

SciTech Connect

The reaction between carbon dioxide and amines is of great technical importance and has been the subject of many investigations. The authors have shown that the reaction for secondary amines in anhydrous ethanol and in aqueous solution is exclusively second-order in amine and that the zwitterion intermediate postulated by Danckwerts is probably of negligible significance in the mechanism. The reaction with tertiary amines has also been studied, but the data are less controversial. In order to complete their studies of the reactions of carbon dioxide with amines, using their conductimetric stopped-flow apparatus, they have studied this reaction for MDEA (methyldiethanolamine, IUPAC name N-methyl-2,2{prime}-iminodiethanol) and TEA (triethanolamine, IUPAC name 2,2{prime},2{double prime}-nitrilotris(ethanol)).

Crooks, J.E.; Donnellan, J.P. (King's Coll., London (England))

1990-02-16

355

A more energy efficient product for carbon dioxide separation  

SciTech Connect

Aqueous solutions of alkanolamines such as monoethanolamine (MEA) have been used for years to separate carbon dioxide and hydrogen sulfide from other gases in continuous absorption/desorption processes to meet very low treated gas specifications. However, MEA can undergo side reactions with CO{sub 2} which produce various types of degradation compounds. These by-products reduce performance of the solvent leading to increased energy consumption and corrosion. This can be a serious problem in applications such as the removal of CO{sub 2} in synthesis gas and natural gas treating with down stream cryogenic equipment. Formulated alkanolamine products based on methyldiethanolamine (MDEA) have made significant advances in energy efficiency, but are still susceptible to degradation and decreased performance. A next generation product, GAS/SPEC CS-PLUS, has now been developed and shown to be even more energy efficient. In addition, it improves separation and overall capacity while maintaining long term performance.

Niswander, R.H.; Edwards, D.J.; DuPart, M.S.; Tse, J.P. [Dow Chemical Co., Freeport, TX (United States)

1993-01-01

356

Michigan plant opens up nearby sour-gas field  

SciTech Connect

The article discusses several shut-in sour-gas wells in the Manistee, Mich., area which prompted the construction and subsequent start-up in May 1986 of the Manistee gas-processing plant. The plant is currently serving several wells (operated by independent oil and gas producers) which were in need of processing prior to gas sales. The new plant consists of an MDEA (methyldiethanolamine) gas-processing unit, a conventional glycol dehydrator, and a Lo-Cat (registered trademark) hydrogen sulfide oxidation process for conversion of the hydrogen sulfide to elemental sulfur. Rated at 20 MMscfd, it is capable of removing 13.3 light tons/day of sulfur. The combination of an amine plant followed by a Lo-Cat unit has been used in several smaller plants but never before on this large a scale. The Manistee plant's Lo-Cat is the largest autocirculation unit yet build, the next largest being approximately one tenth its capacity.

Marsh, R.J.

1987-08-31

357

Kinetic study of carbon dioxide reaction with tertiary amines in aqueous solutions  

SciTech Connect

Reaction kinetics of CO/sub 2/ with triethanolamine (TEA) and methyldiethanolamine (MDEA) in aqueous solution have been studied by using a stopped-flow technique with pH detection. Rate constants are obtained from the comparison of experimental and theoretical curves giving the optical density as a function of time. At concentrations of CO/sub 2/ well below the saturation limit, the results are consistent with the hydration reactions of the CO/sub 2/ molecules either with neutral water molecules or with hydroxide ions, depending upon the pH, itself governed by the ionization equilibrium of the dissolved amine. Moreover, a specific (catalytic) reaction, first order with respect to both carbon dioxide and amine (rate constant, 2.85 M/sup -1/ s/sup -1/ at 25/sup 0/C), has been shown to contribute significantly to the reaction rate in the case of the first amine (TEA) only.

Barth, D.; Tondre, C.; Lappai, G.; Delpuech, J.J.

1981-11-26

358

Predict amine solution properties accurately  

SciTech Connect

Improved process design begins with using accurate physical property data. Especially in the preliminary design stage, physical property data such as density viscosity, thermal conductivity and specific heat can affect the overall performance of absorbers, heat exchangers, reboilers and pump. These properties can also influence temperature profiles in heat transfer equipment and thus control or affect the rate of amine breakdown. Aqueous-amine solution physical property data are available in graphical form. However, it is not convenient to use with computer-based calculations. Developed equations allow improved correlations of derived physical property estimates with published data. Expressions are given which can be used to estimate physical properties of methyldiethanolamine (MDEA), monoethanolamine (MEA) and diglycolamine (DGA) solutions.

Cheng, S.; Meisen, A. [Univ. of British Columbia, Vancouver, British Columbia (Canada); Chakma, A. [Univ. of Calgary, Alberta (Canada)

1996-02-01

359

Highly stretchable nanoalginate based polyurethane elastomers.  

PubMed

Highly stretchable elastomeric samples based on cationic polyurethane dispersions-sodium alginate nanoparticles (CPUD/SA) were prepared by the solution blending of sodium alginate and aqueous polyurethane dispersions. CPUDs were synthesized by step growth polymerization technique using N-methyldiethanolamine (MDEA) as a source of cationic emulsifier. The chemical structure and thermal-mechanical properties of these systems were characterized using FTIR and DMTA, respectively. The presence of nanoalginate particles including nanobead and nanorod particles were proved by SEM and EDX. It was observed that thermal properties of composites increased with increasing SA content. All prepared samples were known as thermoplastic-elastomers with high percentages of elongation. Excellent compatibility of prepared nanocomposites was proved by the DMTA data. PMID:23648022

Daemi, Hamed; Barikani, Mehdi; Barmar, Mohammad

2013-06-20

360

Modeling the simultaneous transport of two acid gases in tertiary amines with reversible reactions  

SciTech Connect

The objective of this work is to develop a model for the simultaneous mass transfer of two acid gases in tertiary amines accompanied by reversible chemical reactions. The model has been applied to the industrially important system of simultaneous absorption or desorption of CO/sub 2/ and H/sub 2/S in aqueous methyldiethanolamine (MDEA). In most applications the treated gas must be virtually free of H/sub 2/S; however, it is often not necessary or economical to remove substantial amounts of CO/sub 2/. Hence, selective removal of H/sub 2/S from gas streams such as natural or synthetic gases which contain CO/sub 2/ is desirable. In this research a film theory model describing the simultaneous diffusion and reversible reaction of two gases into reactive liquid has been used to predict the mass transfer enhancement factors of CO/sub 2/ and H/sub 2/S in aqueous MDEA solutions. The resulting unstable two point boundary value problem has been solved numerically for a range of the dimensionless parameters that characterize an important application for this system. In studying the simultaneous transport of CO/sub 2/ and H/sub 2/S, it is found that the reversibility of the reactions, under certain conditions, causes desorption to take place although absorption would be expected on the basis of overall driving forces. This showed that not only enhancement factors larger but also smaller than unity and even negative values are possible.

Al-Ghawas, H.A.; Sandall, O.C.

1988-10-01

361

Accelerated field facility development for hot sour gas  

SciTech Connect

This paper presents the chronological plan by which a grass roots sweetening facility was constructed in a minimum amount of time. The facility design was based on production with 9% carbon dioxide and 40 ppm hydrogen sulfide. Flowing wellhead temperatures were predicted to be approximately 300/sup 0/F with flowing wellhead pressures to 11,500 psi. The production facility, with a current total nominal capacity of 100 MMcf/D, was installed as five separate parallel sweetening units. The units were put on-stream in phases in order to maintain a sweetening capacity schedule compatible with wells being put on production. The first units were available for service in three months. All five units were complete in nine months, and a permanent facility installation was commissioned three months later. The process design, equipment procurement, and installation phases of the project were pursued concurrently. Three different sweetening systems were operated during the facility development. A conventional DEA (diethanolamine) system was used because of its simple operation. Conversions were made to a proprietary MDEA (methyldiethanolamine) system in order to increase capacity. A proprietary activated MDEA was tested and operated in order to determine sweetening system selection for future facility capacity and for other applications. Included is a discussion of the project development procedure and key considerations that led to minimal development time. General comparisons are made concerning the performance of several sweetening systems.

Kuntz, L.K.

1983-10-01

362

High-throughput sample preparation and simultaneous column regeneration liquid chromatography-tandem mass spectrometry method for determination of nitrogen mustard metabolites in human urine.  

PubMed

Nitrogen mustards (NMs) are known to have DNA alkylation and strong vesicant properties. Their availability to terrorist organizations makes them a potential choice for chemical attacks on civilian populations. After an exposure, it is difficult to measure NMs directly because of their rapid metabolism in the human body. Therefore to determine an individual's level of exposure to NMs, it is necessary to analyze for NM metabolites being excreted by the body. The metabolites of NMs are generated by a hydrolysis reaction, and are easily detectable by liquid chromatography tandem mass spectrometry (LC-MS/MS). This work is focused on the development of a high-throughput assay for the quantitation of N-ethyldiethanolamine (EDEA) and N-methyldiethanolamine (MDEA) metabolites of bis (2-chloroethyl) ethylethanamine (HN1) and bis (2-chloroethyl) methylethanamine (HN2), respectively. The method uses automated 96-well plate sample preparation of human urine samples and a 2-position 10-port switching valve to allow for simultaneous regeneration of the liquid chromatography (LC) columns. Using this method, over 18 h was saved through the reduction of sample preparation and analysis time when compared to a conventional method for 96 samples. The validated method provided excellent accuracy for both EDEA (100.9%) and MDEA (100.6%) with precision better than 5.27% for each analyte. PMID:21764395

Reddy, Muntha K; Mills, Grier; Nixon, Christopher; Wyatt, Shane A; Croley, Timothy R

2011-08-15

363

Micelles of enzymatically synthesized PEG-poly(amine-co-ester) block copolymers as pH-responsive nanocarriers for docetaxel delivery.  

PubMed

A series of PEGylated poly(amine-co-ester) terpolymers were successfully synthesized in one step via lipase-catalyzed copolymerization of ?-pentadecalactone (PDL), diethyl sebacate (DES), and N-methyldiethanolamine (MDEA) comonomers in the presence of poly(ethylene glycol) methyl ether as a chain-terminating agent. The resultant amphiphilic poly(ethylene glycol)-poly(PDL-co-MDEA-co-sebacate) (PEG-PPMS) block copolymers consisted of hydrophilic PEG chain segments and hydrophobic random PPMS chain segments, which self-assembled in aqueous medium to form stable, nanosized micelles at physiological pH of 7.4. Upon decreasing the medium pH from 7.4 to 5.0, the copolymer micelles swell significantly due to protonation of the amino groups in the micelle PPMS cores. Correspondingly, docetaxel (DTX)-encapsulated PEG2K-PPMS copolymer micelles showed gradual sustained drug release at pH of 7.4, but remarkably accelerated DTX release at acidic pH of 5.0. The drug-loaded micelle particles were readily internalized by SK-BR-3 cancer cells and, compared to free DTX drug, DTX-loaded micelles of the copolymers with optimal compositions exhibited enhanced potency against the cells. Biodegradable PEG-PPMS copolymer micelles represent a new type of promising, pH-responsive nanocarriers for anticancer drug delivery, and the drug release rate from the micelles can be systematically controlled by both pH and the copolymer composition. PMID:24398083

Zhang, Xiaofang; Liu, Bo; Yang, Zhe; Zhang, Chao; Li, Hao; Luo, Xingen; Luo, Huiyan; Gao, Di; Jiang, Qing; Liu, Jie; Jiang, Zhaozhong

2014-03-01

364

Solubility calculations for acid gases in amine blends  

SciTech Connect

Treating with alkanolamines is often used to sweeten gases containing only a few parts per million of CO/sub 2/ and H/sub 2/S. Primary amines such as monoethanolamine (MEA) have great affinity for acid gases and are able to produce high purity sweet gas; on the other hand, tertiary amines like methyldiethanolamine (MDEA) have large capacity and are easy to regenerate but, because they do not bind chemically with CO/sub 2/, they are unable to produce a sweetened gas low in this component. Recently, the use of amine blends has become a subject of potentially great commercial importance. Since, the range of possible amines and blend formulations is large, a method for predicting equilibrium solubility is needed. A rigorous thermodynamic model has been developed which uses the extended Debye-Huckel expression, is very similar to one developed for single-amine solutions, and involves the fitting of binary interaction parameters to experimental data. In this work the interaction parameters found to be important in the activity coefficient expression were fitted to each single-acid-gas single-amine subsystem using all published solubility data. The resulting model was then validated by comparing mixed-acid-gas single-amine solubility predictions with published VLE data. MEA-MDEA and DEA-MDEA blends have been studied in detail in this work. It is found that each amine contributes to the overall acid gas solubility in a nonlinear way and that the solubility curves can exhibit maxima and minima as a function of the relative concentrations of the amines.

Chakravarty, T.

1985-01-01

365

New MDEA design in gas plant improves sweetening, reduces CO[sub 2  

SciTech Connect

Initial tests on a newly installed gas-sweetening unit at a Hungarian gas plant indicate that H[sub 2]S can be removed from inlet feed gas in a high-pressure system to less than 6 mg/cu m (4 ppmv) while rejecting most of the CO[sub 2]. This result was accomplished by use of significantly fewer amine contractor trays than in conventional practice and confirmed earlier computer simulations employed in the design phase. The paper describes the plant, the selective absorption process, the high-pressure stream being processed, the performance tests, and contributions by companies to the process development.

Law, D. (Titan Industrial Constructors Ltd., Calgary, Alberta (Canada))

1994-08-29

366

Determination of the liquid-phase speciation in the MDEA - H 2O - CO 2 system  

Microsoft Academic Search

Aqueous solutions of alkanolamines are commonly used in CO2 capture processes. To describe these complex processes rigorous mass transfer models are needed, in which all mass transfer, kinetics and thermodynamics are incorporated correctly. To improve the quality of the thermodynamic models, not only commonly used P-? (CO2 partial pressure versus CO2 liquid loading) experimental data, but also liquid phase speciation

Peter W. J. Derks; Patrick J. G. Huttenhuis; Coen van Aken; Jan-Henk Marsman; Geert F. Versteeg

2011-01-01

367

Piperine as an inhibitor of the MdeA efflux pump of Staphylococcus aureus.  

PubMed

Piperine, a trans-trans-isomer of 1-piperoyl-piperidine, was tested in combination with mupirocin for antimicrobial activity against Staphylococcus aureus strains including meticillin-resistant S. aureus. The combination markedly reduced the MIC of mupirocin and also lowered the mutation frequency. Enhanced accumulation and efflux of ethidium bromide from wild-type and mutant (Mup(r)-1) strains in the presence of piperine indicated that inhibition of efflux could be a possible mechanism of potentiation of mupirocin activity by piperine. The combination of piperine with mupirocin in a dermal infection model of mice showed better in vivo efficacy when compared with the commercially available formulation of 2?% mupirocin. PMID:21680766

Mirza, Zahid Mehmood; Kumar, Ashwani; Kalia, Nitin Pal; Zargar, Afzal; Khan, Inshad Ali

2011-10-01

368

21 CFR 520.1803 - Piperazine citrate capsules.  

Code of Federal Regulations, 2013 CFR

... (c) Conditions of use. (1) It is used in dogs and cats for the removal of large roundworms (Toxocara canis and Toxascaris...dosed food, the remainder of the food may be given. Dogs and cats may be wormed at 6 to 8 weeks of age. The first treatment...

2013-04-01

369

A model of vapor-liquid equilibria for acid gas-alkanolamine-water systems  

SciTech Connect

A physico-chemical model was developed for representing liquid phase chemical equilibria and vapor-liquid (phase) equilibria of H{sub 2}SCO{sub 2}-alkanolamine-water systems. The equilibrium composition of the liquid phase is determined by minimization of the Gibbs free energy. Activity coefficients are represented with the Electrolyte-NRTL equation treating both long-range electrostatic interactions and short-range binary interactions between liquid phase species. Vapor phase fugacity coefficients are calculated using the Redlich-Kwong-Soave Equation of State. Adjustable parameters of the model, binary interaction parameters and carbamate stability constants, were fitted on published binary system alkanolamine-water and ternary system (H{sub 2}S-alkanolamine-water, CO{sub 2}-alkanolamine-water) VLE data. The Data Regression System of ASPEN PLUS, based upon the Maximum Likelihood Principle, was used to estimate adjustable parameters. Ternary system measurements used in parameter estimation ranged in temperature from 25 to 120{degree}C in alkanolamine concentration from 1 to 5 M, in acid gas loading from 0 to 1.5 moles per mole alkanolamine, and in acid gas partial pressure from 0.1 to 1,000 kPa. Maximum likelihood estimates of ternary system H{sub 2} or CO{sub 2} equilibrium partial pressures and liquid phase concentrations were found to be in good agreement with measurements for aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), diglycolamine (DGA), and methyldiethanolamine (MDEA) indicating that the model successfully represents ternary system data. The model was extended to represent CO{sub 2} solubility in aqueous mixtures of MDEA with MEA or DEA. The solubility was measured at 40 and 80{degree}C over a wide range of CO{sub 2} partial pressures. These measurements were used to estimate additional binary parameters of the mixed solvent systems.

Austgen, D.M. Jr.

1989-01-01

370

A liquid chromatography-electrospray ionization-tandem mass spectrometry study of ethanolamines in high salinity industrial wastewaters.  

PubMed

The detection and quantitation of four ethanolamines, tris(2-hydroxyethyl)amine (triethanolamine, TEA), N,N-bis(2-hydroxyethyl)methylamine (methyldiethanolamine, MDEA), N-(2-aminoethyl)ethanolamine (AEA), and N,N-diethylethanolamine (DEA), were achieved in wastewaters from two aerobic activated sludge bioreactors located in an industrial wastewater treatment plant. The streams had salt concentrations of approximately 3% and 7% by weight in Reactor 1 and Reactor 2, respectively. The use of liquid chromatography-electrospray ionization-tandem mass spectrometry avoided the need for some sample preparation steps such as extraction, concentration, and derivatization. Ion suppression in the electrospray, attributable to the presence of sodium clusters, was attenuated by a 10-fold dilution of the wastewaters with acetonitrile. A matrix-matched calibration model averted other potential interferences. For the compounds analyzed in selected reaction monitoring mode (TEA, MDEA, and DEA), the calibration curves presented linearity in a range of 10-1000microg/L with corresponding detection limits ranging from 2 to 11microg/L, depending upon the specific analyte and aqueous matrix. AEA was calibrated in selected ion monitoring mode (100-1000microg/L), with corresponding detection limits in the two wastewaters of 74.6 and 85.3microg/L, respectively. Overall good precision (<10%) and accuracy (97-110%) were achieved for both matrices, which fell within-laboratory reproducibility. Finally, the amines were introduced into six mixed liquor samples from both reactors and quantified following the reported protocol. Again, recoveries were close to 100% with a relative standard deviation of less than 10% in all cases. PMID:20006060

Campo, Pablo; Suidan, Makram T; Chai, Yunzhou; Davis, John

2010-01-15

371

Comparison of absorption rates and absorption capacity of ammonia solvents with MEA and MDEA aqueous blends for CO 2 capture  

Microsoft Academic Search

In this work we present the experimental results of absorption rates and absorption capacity for the CO2 absorption by ammonia (NH3) aqueous solutions. Experiments are carried out in a thermoregulated Lewis-type cell reactor and are achieved in temperature and concentration ranges of 278–303K and 2–5wt.% NH3 respectively. The obtained values for absorption kinetic rates and absorption capacity are compared with

Rodrigo Rivera-Tinoco; Chakib Bouallou

2010-01-01

372

Ion-exchange membranes for bulk separation of acid gases  

SciTech Connect

The field test has continued with PFSA composite membranes. The substrates have been a microporous polypropylene supplied by 3M Co. The membranes have been imbibed with either aqueous solutions of methyldiethanolamine (MDEA) or n-methylpyrrolidone (NMP). Data from five composite membranes have thusfar been obtained and are presented in the following Figure 6. The composite 1 membrane gave erratic performance before it mechanically failed, but most of the observed separation factors were high enough (>35) to be consistent with the initial results from the gel-NE 111 membrane. The separation factor for the other four composites have been consistently low (between 13 and 3). The main difference is that between composite l and the rest we installed an inertial separator to remove excess moisture from the feed stream. This separator may be too efficient and the membranes may be drying out. Another possibility is that the membranes may just not be made well enough and sufficient uncoated pores may exist to subvert the separation efficiency. We tested a membrane which had been removed from the field test rig in our laboratory permeation equipment. Those results are presented in Figures 7 and 8. Again good agreement between the field test and our lab experiments.

Giarratano, P.; Pellegrino, J.J.

1992-01-01

373

Ion-exchange membranes for bulk separation of acid gases  

SciTech Connect

The field test has continued with PFSA composite membranes. The substrates have been a microporous polypropylene supplied by 3M Co. The membranes have been imbibed with either aqueous solutions of methyldiethanolamine (MDEA) or n-methylpyrrolidone (NMP). Data from five composite membranes have thusfar been obtained and are presented in the following Figure 6. The composite 1 membrane gave erratic performance before it mechanically failed, but most of the observed separation factors were high enough (>35) to be consistent with the initial results from the gel-NE 111 membrane. The separation factor for the other four composites have been consistently low (between 13 and 3). The main difference is that between composite l and the rest we installed an inertial separator to remove excess moisture from the feed stream. This separator may be too efficient and the membranes may be drying out. Another possibility is that the membranes may just not be made well enough and sufficient uncoated pores may exist to subvert the separation efficiency. We tested a membrane which had been removed from the field test rig in our laboratory permeation equipment. Those results are presented in Figures 7 and 8. Again good agreement between the field test and our lab experiments.

Giarratano, P.; Pellegrino, J.J.

1992-12-01

374

Diffusion coefficients of several aqueous alkanolamine solutions  

SciTech Connect

In absorption processes of acid gases (H[sub 2]S, CO[sub 2], COS) in alkanolamine solutions, diffusion coefficients are used for the calculation of the mass transfer rate. The Taylor dispersion technique was applied for the determination of diffusion coefficients of various systems. Experiments with the system KCl in water showed that the experimental setup provides accurate data. For the alkanolamines monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and di-2-propanolamine (DIPA), correlations for the diffusion coefficient as a function of temperature at different concentrations are given. A single relation for every amine has been derived which correlates the diffusion coefficients as a function of temperature and concentration. The temperature was varied between 298 and 348 K, and the concentration between 0 and 4000-5000 mol/m[sup 3]. Furthermore, a modified Stokes-Einstein relation is presented for the prediction of the diffusion coefficients in the alkanolamines in relation to the viscosity of the solvent and the diffusion coefficient at infinite dilution. The diffusion coefficients at low concentrations are compared with some available relations for the estimation of diffusion coefficients at infinite dilution, and it appears that the agreement is fairly good.

Snijder, E.D.; Riele, M.J.M. te; Versteeg, G.F.; Swaaij, W.P.M. van (Twente Univ. of Technology, Enschede (Netherlands). Dept. of Chemical Engineering)

1993-07-01

375

Clean amine solvents economically and online  

SciTech Connect

Using electrodialysis technology to clean amine solvents is economically competitive with traditional change-out or ``bleed and feed`` methods, even for small systems, because a unit shutdown is not necessary to perform the process. Electrodialysis also has advantages over other online cleanup processes like ion exchange and vacuum reclamation. Off gases and olefinic and saturate liquefied petroleum gas (LPG) streams generated during operation of fluid catalytic crackers (FCC), cokers and other refinery processing equipment must be treated to remove undesirable components like hydrogen sulfide and carbon dioxide before they can be sold or used in downstream processes. At an Arkansas City, Kansas, refinery, a classic amine-based chemical absorbent system is used for this purpose. It comprises two absorbing contacts for gas and two for liquids. The system is charged with an N-methyldiethanolamine (MDEA)-based product that selectively absorbs contaminants. Amine is regenerated by removing contaminants with steam stripping. Lean amine is then recirculated to the absorbers. This case history demonstrates the effectiveness of electrodialysis technology for contaminant removal.

Price, J. [Total Petroleum, Arkansas City, KS (United States); Burns, D. [Union Carbide Corp., Houston, TX (United States)

1995-08-01

376

Tertiary ethanolamines more economical for removal of H/sub 2/S and carbon dioxide  

SciTech Connect

At present, it appears that tertiary ethanolamines, if properly used, are substantially more economical for a variety of selective and nonselective gas-purification operations than primary and secondary ethanolamines. Examples of such operations are: selective H/sub 2/S removal from natural and synthesis gases, absorption of high concentrations of CO/sub 2/ from gas streams available at high pressure, and selective H/sub 2/S removal from waste gases, e.g., Claus tail gas. The principal advantages of tertiary over primary and secondary ethanolamines are, besides their selectivity for H/sub 2/S, their lower heat of reaction with the acid gases (and consequent lower heat requirements for solution stripping); their lower vapor pressure, permitting use of high concentration and high capacity in the treating solution; their nonreactivity with COS and CS/sub 2/, avoiding formation of nonregenerable compounds; and their lower corrosiveness, allowing carbon-steel construction throughout the plant. If these features are combined, it becomes clear that tertiary ethanolamines are the proper choice for many gas-purification systems. Among the tertiary ethanolamines, methyldiethanolamine (MDEA) is the preferred amine, although triethanolamine (TEA) is also useful for CO/sub 2/ absorption.

Riesenfeld, F.C.; Brocoff, J.C.

1986-09-01

377

Electropolymerized carbonic anhydrase immobilization for carbon dioxide capture.  

PubMed

Biomimetic carbonation carried out with carbonic anhydrase (CA) in CO2-absorbing solutions, such as methyldiethanolamine (MDEA), is one approach that has been developed to accelerate the capture of CO2. However, there are several practical issues, such as high cost and limited enzyme stability, that need to be overcome. In this study, the capacity of CA immobilization on a porous solid support was studied to improve the instability in the tertiary amine solvent. We have shown that a 63% porosity macroporous carbon foam support makes separation and reuse facile and allows for an efficient supply and presentation of CO2 to an aqueous solvent and the enzyme catalytic center. These enzymatic supports conserved 40% of their initial activity after 42 days at 70 °C in an amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical barrier associated with the recovery of the biocatalyst after operation, and most of all, these electropolymerized enzymatic supports have shown a remarkable increase of thermal stability in an amine-based CO2 sequestration solvent. PMID:24856780

Merle, Geraldine; Fradette, Sylvie; Madore, Eric; Barralet, Jake E

2014-06-17

378

New 7-[4-(4-(un)substituted)piperazine-1-carbonyl]- piperazin-1-yl] derivatives of fluoroquinolone: synthesis and antimicrobial evaluation.  

PubMed

Fluoroquinolones have been a class of important synthetic antimicrobial agents broadly and effectively used in clinic for infectious diseases. In this study, the synthesis of a range of fluoroquinolone derivatives with 4-(carbopiperazin-1-yl)piperazinyl moieties at the C7 position and their inhibition of bacterial pathogens commonly disseminated in hospital environment were described. The results indicated that a 7-[4-(4-(benzoyl)carbopiperazin-1-yl)]piperazinyl derivative 5h and two 7-[4-(4- (benzenesulfonyl)carbopiperazin-1-yl)]piperazinyl derivatives 5k and 5l showed more promising growth inhibition of ciprofloxacin-resistant P. aeruginosa (CRPA) with MIC values as low as 16 ?g/mL which is 16-fold more potent than ciprofloxacin, while most of other derivatives maintained potency against methicillin-resistant Staphylococcus aureus (MRSA). PMID:23807580

Chen, Po-Ting; Lin, Wen-Po; Lee, An-Rong; Hu, Ming-Kuan

2013-01-01

379

21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.  

Code of Federal Regulations, 2013 CFR

... â(1) Amount. Administer orally to dogs as follows: Number of Tablets at Each...Toxocara canis ) from weaned pups and adult dogs. (3) Limitations. Do not use this product to treat dogs weighing less than 2 pounds,...

2013-04-01

380

Acidity constant determination of novel drug precursor benzothiazolon derivatives including acyl and piperazine moieties  

NASA Astrophysics Data System (ADS)

In this study, protonation and deprotonation behaviors of eight new drug precursor benzothiazolon derivatives in all of acidic and basic scale (super acidic, pH, super basic regions) are analyzed by using UV-visible spectrophotometric technique. Acidity constants (pKa), elucidation of the structure and protonation mechanisms of the studied molecules are obtained. Substituent effect on acidity constant values is discussed. These molecules are protonated from oxygen atom of acetamide group in the keto form. The protonation is found to be considerably contributed by the keto form.

S?d?r, ?sa; Gülseven S?d?r, Yadigar; Berber, Halil

2013-07-01

381

Synthesis, molecular docking and biological evaluation of metronidazole derivatives containing piperazine skeleton as potential antibacterial agents.  

PubMed

Metronidazole has a broad-spectrum antibacterial activity. Hereby a series of novel metronidazole derivatives were designed and synthesized based on nitroimidazole scaffold in order to find some more potent antibacterial drugs. For these compounds which were reported for the first time, their antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus were tested. These compounds showed good antibacterial activities against Gram-positive strains. Compound 4m represented the most potent antibacterial activity against S. aureus ATCC 25923 with MIC of 0.003 ?g/mL and it showed the most potent activity against S. aureus TyrRS with IC50 of 0.0024 ?M. Molecular docking of 4m into S. aureus tyrosyl-tRNA synthetase active site were also performed to determine the probable binding mode. PMID:24680059

Wang, She-Feng; Yin, Yong; Qiao, Fang; Wu, Xun; Sha, Shao; Zhang, Li; Zhu, Hai-Liang

2014-04-15

382

A Novel Substituted Piperazine, CM156, Attenuates the Stimulant and Toxic Effects of Cocaine in Mice  

PubMed Central

Cocaine is a highly abused drug without effective pharmacotherapies to treat it. It interacts with sigma (?) receptors, providing logical targets for the development of medications to counteract its actions. Cocaine causes toxic and stimulant effects that can be categorized as acute effects such as convulsions and locomotor hyperactivity and subchronic effects including sensitization and place conditioning. In the present study, 3-(4-(4-cyclohexylpiperazin-1-yl)butyl)benzo[d]thiazole-2(3H)-thione (CM156), a novel compound, was developed and tested for interactions with ? receptors using radioligand binding studies. It was also evaluated against cocaine-induced effects in behavioral studies. The results showed that CM156 has nanomolar affinities for each of the ? receptor subtypes in the brain and much weaker affinities for non-? binding sites. Pretreatment of male Swiss-Webster mice with CM156, before administering either a convulsive or locomotor stimulant dose of cocaine, led to a significant attenuation of these acute effects. CM156 also significantly reduced the expression of behavioral sensitization and place conditioning evoked by subchronic exposure to cocaine. The protective effects of CM156 are consistent with ? receptor-mediated actions. Together with previously reported findings, the data from CM156 and related ? compounds indicate that ? receptors can be targeted to alleviate deleterious actions of cocaine.

Xu, Yan-Tong; Kaushal, Nidhi; Shaikh, Jamaluddin; Wilson, Lisa L.; Mesangeau, Christophe; McCurdy, Christopher R.

2010-01-01

383

21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.  

Code of Federal Regulations, 2013 CFR

...520.2520g Section 520.2520g Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...Administer by stomach tube. Do not fast horses before or after treatment...used in horses intended for use as food. Federal law restricts this...

2013-04-01

384

N-(4-Methyl-piperazin-4-ium-1-yl)dithio-carbamate sesquihydrate  

PubMed Central

In the crystal structure of the title compound, C6H13N3S2·1.5H2O, weak N—H?S inter­actions between the zwitterionic mol­ecules are observed, leading to an extensively folded layered arrangement parallel to (100). There are three crystallographically independent water mol­ecules in the asymmetric unit, which are disordered and only half occupied.

Mietlarek-Kropidlowska, Anna; Chojnacki, Jaroslaw; Wityk, Pawel; Wieczor, Milosz; Becker, Barbara

2012-01-01

385

2-[3,5-Dioxo-4-(pyridin-3-yl)piperazin-1-yl]acetic acid  

PubMed Central

In the title compound, C11H11N3O4, the 3,5-dioxopiperazine ring adopts an envelope conformation, with the N atom connecting to the –CH2COOH group on the flap. In the crystal, mol­ecules are linked by O—H?N hydrogen bonds to produce a linear chain running along the c axis. ?–? stacking is observed between parallel pyridine rings of adjacent mol­ecules, the centroid–centroid distance being 3.834?(2)?Å.

Mosslemin, Mohammad Hossein

2012-01-01

386

4-(Pyrimidin-2-yl)piperazin-1-ium (E)-3-carb-oxy-prop-2-enoate  

PubMed Central

In the cation of the title salt, C8H13N4 +·C4H3O4 ?, the piperazinium ring adopts a slightly distorteded chair conformation. In the crystal, a single strong O—H?O inter­molecular hydrogen bond links the anions, forming chains along the c-axis direction. The chains of anions are linked by the cations, via N—H?O hydrogen bonds, forming sheets parallel to (100). These layers are linked by weak C—H?O hydrogen bonds, forming a three-dimensional structure. In addition, there are weak ?–? inter­actions [centroid–centroid distance = 3.820?(9)?Å] present involving inversion-related pyrimidine rings.

Yamuna, Thammarse S.; Kaur, Manpreet; Jasinski, Jerry P.; Yathirajan, H. S.

2014-01-01

387

Design, synthesis and preliminary pharmacological evaluation of new piperidine and piperazine derivatives as cognition-enhancers  

Microsoft Academic Search

A series of 2-oxopiperazine, 4-aminomethyl-, 3-amino- and 3-aminomethylpiperidine analogues of DM235 (sunifiram) and MN19 (sapunifiram), two previously reported potent cognition-enhancers, have been synthesized and tested in the mouse passive-avoidance test. The compounds display minimal effective doses in the range 0.3–10mg\\/kg. Although the new substances do not show improved activity when compared to the parent compounds, some useful information has been

Elisabetta Martini; Carla Ghelardini; Silvia Dei; Luca Guandalini; Dina Manetti; Michele Melchiorre; Monica Norcini; Serena Scapecchi; Elisabetta Teodori; Maria Novella Romanelli

2008-01-01

388

Design, synthesis and preliminary pharmacological evaluation of new piperidine and piperazine derivatives as cognition-enhancers.  

PubMed

A series of 2-oxopiperazine, 4-aminomethyl-, 3-amino- and 3-aminomethylpiperidine analogues of DM235 (sunifiram) and MN19 (sapunifiram), two previously reported potent cognition-enhancers, have been synthesized and tested in the mouse passive-avoidance test. The compounds display minimal effective doses in the range 0.3-10mg/kg. Although the new substances do not show improved activity when compared to the parent compounds, some useful information has been obtained to understand structure-activity relationships. In addition, the 3-aminopiperidine moiety appears to be a promising scaffold to synthesize new drugs endowed with cognition-enhancing activity. PMID:17981042

Martini, Elisabetta; Ghelardini, Carla; Dei, Silvia; Guandalini, Luca; Manetti, Dina; Melchiorre, Michele; Norcini, Monica; Scapecchi, Serena; Teodori, Elisabetta; Romanelli, Maria Novella

2008-02-01

389

21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.  

Code of Federal Regulations, 2012 CFR

...520.2520g Section 520.2520g Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...Administer by stomach tube. Do not fast horses before or after treatment...used in horses intended for use as food. Federal law restricts this...

2012-04-01

390

21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.  

Code of Federal Regulations, 2011 CFR

...520.2520g Section 520.2520g Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...Administer by stomach tube. Do not fast horses before or after treatment...used in horses intended for use as food. Federal law restricts this...

2011-04-01

391

4-(Pyrimidin-2-yl)piperazin-1-ium (E)-3-carb-oxy-prop-2-enoate.  

PubMed

In the cation of the title salt, C8H13N4 (+)·C4H3O4 (-), the piperazinium ring adopts a slightly distorteded chair conformation. In the crystal, a single strong O-H?O inter-molecular hydrogen bond links the anions, forming chains along the c-axis direction. The chains of anions are linked by the cations, via N-H?O hydrogen bonds, forming sheets parallel to (100). These layers are linked by weak C-H?O hydrogen bonds, forming a three-dimensional structure. In addition, there are weak ?-? inter-actions [centroid-centroid distance = 3.820?(9)?Å] present involving inversion-related pyrimidine rings. PMID:24940275

Yamuna, Thammarse S; Kaur, Manpreet; Jasinski, Jerry P; Yathirajan, H S

2014-06-01

392

Quantitative and qualitative analysis of MDMA, MDEA, MA and amphetamine in urine by head-space\\/solid phase micro-extraction (SPME) and GC\\/MS  

Microsoft Academic Search

The results of qualitative and quantitative analysis of some amphetamines and their analogs isolated from urine samples by solid phase micro-extraction with polydimethylsiloxane fibers are reported. The analytical method employed was gas-chromatography\\/mass spectrometry of head space samples.

F. Centini; A. Masti; I. Barni Comparini

1996-01-01

393

Self-assembled 3D heterometallic Cu(II)/Fe(II) coordination polymers with octahedral net skeletons: structural features, molecular magnetism, thermal and oxidation catalytic properties.  

PubMed

The new three-dimensional (3D) heterometallic Cu(II)/Fe(II) coordination polymers [Cu(6)(H(2)tea)(6)Fe(CN)(6)](n)(NO(3))(2n)·6nH(2)O (1) and [Cu(6)(Hmdea)(6)Fe(CN)(6)](n)(NO(3))(2n)·7nH(2)O (2) have been easily generated by aqueous-medium self-assembly reactions of copper(II) nitrate with triethanolamine or N-methyldiethanolamine (H(3)tea or H(2)mdea, respectively), in the presence of potassium ferricyanide and sodium hydroxide. They have been isolated as air-stable crystalline solids and fully characterized including by single-crystal X-ray diffraction analyses. The latter reveal the formation of 3D metal-organic frameworks that are constructed from the [Cu(2)(?-H(2)tea)(2)](2+) or [Cu(2)(?-Hmdea)(2)](2+) nodes and the octahedral [Fe(CN)(6)](4-) linkers, featuring regular (1) or distorted (2) octahedral net skeletons. Upon dehydration, both compounds show reversible escape and binding processes toward water or methanol molecules. Magnetic susceptibility measurements of 1 and 2 reveal strong antiferromagnetic [J = -199(1) cm(-1)] or strong ferromagnetic [J = +153(1) cm(-1)] couplings between the copper(II) ions through the ?-O-alkoxo atoms in 1 or 2, respectively. The differences in magnetic behavior are explained in terms of the dependence of the magnetic coupling constant on the Cu-O-Cu bridging angle. Compounds 1 and 2 also act as efficient catalyst precursors for the mild oxidation of cyclohexane by aqueous hydrogen peroxide to cyclohexanol and cyclohexanone (homogeneous catalytic system), leading to maximum total yields (based on cyclohexane) and turnover numbers (TONs) up to about 22% and 470, respectively. PMID:21028781

Karabach, Yauhen Y; Guedes da Silva, M Fátima C; Kopylovich, Maximilian N; Gil-Hernández, Beatriz; Sanchiz, Joaquin; Kirillov, Alexander M; Pombeiro, Armando J L

2010-12-01

394

Laser direct-write microfabrication and patterning  

NASA Astrophysics Data System (ADS)

The ability to generate small structures is central to modern science and technology. In this work, four laser direct-write microfabrication and micropatterning techniques were studied: (a) Laser micromachining of channels in PMMA using a CO2 laser was investigated experimentally and theoretically. Heat transfer models for the channel depth, channel profile, laser power and scanning speed were developed and applied in this work. These models, are in excellent agreement with experimental results, with a maximum deviation of approximately 5% for the range of experimental parameters (laser power, scanning speed) tested. (b) A sub-micrometer resolution laser direct-write polymerization system for 1 creating two-dimensional and three-dimensional structures was developed using a frequency-doubled Nd:YAG laser. Experimental studies and Monte Carlo simulations were conducted to understand the detailed microscale optical scattering, chemical reaction, polymerization, and their influence on critical fabrication parameters. The experimental data are in good agreement with the theoretical model. (c) Direct laser interference was developed for rapid and large area fabrication of two-dimensional and three dimensional periodic structures on photopolymerizable materials with 10ns pulses from a frequency-tripled Nd:YAG laser emitting at 355 nm. Three different photopolymerizable materials were investigated: pentaerythritol triacrylate (PETIA) with photoinitiator N-methyldiethanolamine (N-MDEA); SU-8 with absorber TINUVIN 384-2; and Shipley 1813. (d) A new approach to fabricating nanometer sized cavity arrays on Poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) thin films using laser-assisted near-field patterning was investigated. Periodic nano-cavity arrays were patterned by combining direct laser interference technology and laser induced near-field technology. An analytical model based on Mie theory was developed, the predicted intensity distributions on the substrate indicate a strong near-field enhancement confined to a very small area (nanometer scale).

Yuan, Dajun

395

Wipe selection for the analysis of surface materials containing chemical warfare agent nitrogen mustard degradation products by ultra-high pressure liquid chromatography-tandem mass spectrometry.  

PubMed

Degradation products arising from nitrogen mustard chemical warfare agent were deposited on common urban surfaces and determined via surface wiping, wipe extraction, and liquid chromatography–tandem mass spectrometry detection. Wipes investigated included cotton gauze, glass fiber filter, non-woven polyester fiber and filter paper, and surfaces included several porous (vinyl tile, painted drywall, wood) and mostly non-porous (laminate, galvanized steel, glass) surfaces. Wipe extracts were analyzed by ultra-high pressure liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) and compared with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) results. An evaluation of both techniques suggests UPLC–MS/MS provides a quick and sensitive analysis of targeted degradation products in addition to being nearly four times faster than a single HPLC run, allowing for greater throughput during a wide-spread release concerning large-scale contamination and subsequent remediation events. Based on the overall performance of all tested wipes, filter paper wipes were selected over other wipes because they did not contain interferences or native species (TEA and DEA) associated with the target analytes, resulting in high percent recoveries and low background levels during sample analysis. Other wipes, including cotton gauze, would require a pre-cleaning step due to the presence of large quantities of native species or interferences of the targeted analytes. Percent recoveries obtained from a laminate surface were 47–99% for all nitrogen mustard degradation products. The resulting detection limits achieved from wipes were 0.2 ng/cm(2) for triethanolamine (TEA), 0.03 ng/cm(2) for N-ethyldiethanolamine (EDEA), 0.1 ng/cm(2) for N-methyldiethanolamine (MDEA), and 0.1 ng/cm(2) for diethanolamine (DEA). PMID:23218189

Willison, Stuart A

2012-12-28

396

Survey and Down-Selection of Acid Gas Removal Systems for the Thermochemical Conversion of Biomass to Ethanol with a Detailed Analysis of an MDEA System. Task 1: Acid Gas Removal Technology Survey and Screening for Thermochemical Ethanol Synthesis. Task 2: Detailed MDEA Process Analysis.  

National Technical Information Service (NTIS)

NRELs recent published report, Thermochemical Ethanol via Indirect Gasification and Mixed Alcohol Synthesis of Lignocellulosic Biomass (NREL/TP-510-41168), evaluated the techno-economics of a biomass gasification process to produce synthesis gas (syngas) ...

2011-01-01

397

O2-Dependent Efficacy of Novel Piperidine- and Piperazine-Based Chalcones against the Human Parasite Giardia intestinalis  

PubMed Central

Giardia intestinalis is the most frequent protozoan agent of intestinal diseases worldwide. Though commonly regarded as an anaerobic pathogen, it preferentially colonizes the fairly oxygen-rich mucosa of the proximal small intestine. Therefore, when testing new potential antigiardial drugs, O2 should be taken into account, since it also reduces the efficacy of metronidazole, the gold standard drug against giardiasis. In this study, 46 novel chalcones were synthesized by microwave-assisted Claisen-Schmidt condensation, purified, characterized by high-resolution mass spectrometry, 1H and 13C nuclear magnetic resonance, and infrared spectroscopy, and tested for their toxicity against G. intestinalis under standard anaerobic conditions. As a novel approach, compounds showing antigiardial activity under anaerobiosis were also assayed under microaerobic conditions, and their selectivity against parasitic cells was assessed in a counterscreen on human epithelial colorectal adenocarcinoma cells. Among the tested compounds, three [30(a), 31(e), and 33] were more effective in the presence of O2 than under anaerobic conditions and killed the parasite 2 to 4 times more efficiently than metronidazole under anaerobiosis. Two of them [30(a) and 31(e)] proved to be selective against parasitic cells, thus representing potential candidates for the design of novel antigiardial drugs. This study highlights the importance of testing new potential antigiardial agents not only under anaerobic conditions but also at low, more physiological O2 concentrations.

Bahadur, Vijay; Mastronicola, Daniela; Tiwari, Hemandra Kumar; Kumar, Yogesh; Falabella, Micol; Pucillo, Leopoldo Paolo; Sarti, Paolo

2014-01-01

398

O(2)-dependent efficacy of novel piperidine- and piperazine-based chalcones against the human parasite Giardia intestinalis.  

PubMed

Giardia intestinalis is the most frequent protozoan agent of intestinal diseases worldwide. Though commonly regarded as an anaerobic pathogen, it preferentially colonizes the fairly oxygen-rich mucosa of the proximal small intestine. Therefore, when testing new potential antigiardial drugs, O2 should be taken into account, since it also reduces the efficacy of metronidazole, the gold standard drug against giardiasis. In this study, 46 novel chalcones were synthesized by microwave-assisted Claisen-Schmidt condensation, purified, characterized by high-resolution mass spectrometry, (1)H and (13)C nuclear magnetic resonance, and infrared spectroscopy, and tested for their toxicity against G. intestinalis under standard anaerobic conditions. As a novel approach, compounds showing antigiardial activity under anaerobiosis were also assayed under microaerobic conditions, and their selectivity against parasitic cells was assessed in a counterscreen on human epithelial colorectal adenocarcinoma cells. Among the tested compounds, three [30(a), 31(e), and 33] were more effective in the presence of O2 than under anaerobic conditions and killed the parasite 2 to 4 times more efficiently than metronidazole under anaerobiosis. Two of them [30(a) and 31(e)] proved to be selective against parasitic cells, thus representing potential candidates for the design of novel antigiardial drugs. This study highlights the importance of testing new potential antigiardial agents not only under anaerobic conditions but also at low, more physiological O2 concentrations. PMID:24217695

Bahadur, Vijay; Mastronicola, Daniela; Tiwari, Hemandra Kumar; Kumar, Yogesh; Falabella, Micol; Pucillo, Leopoldo Paolo; Sarti, Paolo; Giuffrè, Alessandro; Singh, Brajendra Kumar

2014-01-01

399

Combination of cyclohexane and piperazine based ?-opioid receptor agonists: Synthesis and pharmacological evaluation of trans,trans-configured perhydroquinoxalines.  

PubMed

Desymmetrization of the pseudochiral (2r)-configured cyclohexane-1,2,3-triamines 8 with dimethyl oxalate led to racemic aminoquinoxaline-2,3-diones 9. Selective introduction of the ? pharmacophoric structural elements pyrrolidine and 3,4-dichlorophenylacetamide with a two-carbon distance afforded conformationally restricted ? agonists 13-15 based on the quinoxaline ring system. In competitive radioligand receptor binding studies the benzylamine 13b, the secondary amine 14b, and the carbamate 15 displayed high ? receptor affinity. The Ki value of the lead compound derived methoxycarbonyl derivative 15 is 9.7nM. However, the ? affinity of 15 is exceeded by 13b and 14b with a basic functional group instead of the methoxycarbonyl group in 1-position of the quinoxaline system. The chlorine atoms of the dichlorophenylacetyl residue are essential, since the corresponding phenylacetyl analogs show considerably reduced ? affinity. The potent ? ligands 13b, 14b and 15 are selective over the related ?- and ?-opioid receptors, ?1, ?2 and NMDA receptors. In the [(35)S]GTP?S-binding assay 13b behaved as partial agonist with lower activity than U-69,593. PMID:24856182

Bourgeois, Christian; Werfel, Elena; Schepmann, Dirk; Wünsch, Bernhard

2014-07-01

400

1-(4-Hy-droxy-phen-yl)piperazine-1,4-diium tetra-chlorido-cobalt(II) monohydrate  

PubMed Central

The asymmetric unit of the title inorganic–organic hybrid compound, (C10H16N2O)[CoCl4]·H2O, consists of a tetrahedral [CoCl4]2? anion, together with a [C10H18N2O]2+ cation and a water mol­ecule. Crystal cohesion is achieved through N—H?Cl, O—H?Cl and N—H?O hydrogen bonds between organic cations, inorganic anions and the water mol­ecules, building up a three-dimensional network.

Mghandef, Marwa; Boughzala, Habib

2014-01-01

401

The Biological Properties of 3,6-Epidithiadiketo Piperazines Inhibition of Growth of Bacillus Subtilis by Gliotoxins, Sporidesmins, and Chetomin.  

National Technical Information Service (NTIS)

The ability of chetomin and the sporidesmin and gliotoxin groups of fungal metabolites to inhibit the growth of Bacillus subtilis (HLX 373) was examined. With the exception of gliotoxin dibenzoate, compounds having the 3,6-epidithiadiketopiperazine struct...

D. Brewer D. E. Hannah A. Taylor

1965-01-01

402

Bis[4-(2-aza-niumyleth-yl)piperazin-1-ium] di-?-sulfido-bis-[disulfido-germanate(II)  

PubMed Central

In the title compound, (C6H17N3)2[Ge2S6], the dimeric [Ge2S6]4? anion is formed by two edge-sharing GeS4 tetra­hedral units. The average terminal and bridging Ge—S bond lengths are 2.164?(2) and 2.272?(8)?Å, respectively. The dimeric inorganic anions and the organic piperazinium cations are organized into a three-dimensional network by N—H?S hydrogen bonds.

Zhang, Bei-Bei; Xu, Chao; Duan, Taike; Chen, Qun; Zhang, Qian-Feng

2012-01-01

403

New Analytical Techniques for CO2 Capture Solvents  

Microsoft Academic Search

The densities and refractive indices of two binary systems (water + MEA and water + MDEA) and three ternary systems (water + MEA + CO2, water + MDEA + CO2 and water + MEA + MDEA) used for carbon dioxide (CO2) capture were measured over the range of compositions of the aqueous alkanolamine(s) used for CO2 absorption at temperatures from

F. Pouryousefi; R. O. Idem

2006-01-01

404

New analytical technique for carbon dioxide absorption solvents  

Microsoft Academic Search

The densities and refractive indices of two binary systems (water + MEA and water + MDEA) and three ternary systems (water + MEA + CO, water + MDEA + CO, and water + MEA + MDEA) used for carbon dioxide (CO) capture were measured over the range of compositions of the aqueous alkanolamine(s) used for CO absorption at temperatures from

Fatemeh Pouryousefi; Raphael O. Idem

2008-01-01

405

Thermodynamic performance assessment and comparison of IGCC with solid cycling process for CO{sub 2} capture at high and medium temperatures  

SciTech Connect

Solid sorbents can be used to capture CO{sub 2} from pre-combustion sources at various temperatures. MgO and CaO are typical medium- and high-temperature CO{sub 2} sorbents. However, pure MgO is not active toward CO{sub 2}. The addition of Na{sub 2}CO{sub 3} increases the operating temperature and significantly increases the reactivity of sorbents to capture CO{sub 2}. Na{sub 2}CO{sub 3}-promoted MgO is a promising medium-temperature CO{sub 2} sorbent. In this study, the thermodynamic performance of integrated gasification combined cycle (IGCC) systems with Na{sub 2}CO{sub 3}-MgO-based warm gas decarbonation (WGDC) and CaO-based hot gas decarbonation (HGDC) is evaluated and compared with that of an IGCC system with methyldiethanolamine (MDEA)-based cold gas decarbonation (CGDC). Assuming that the average CO{sub 2} capture capacities of solid sorbents are onethird of their theoretical maxima, we reveal that the IGCC system undergoes approximately 2.8% and 3.6% improvement on net efficiency when switching from CGDC to WGDC and to HGDC, respectively. The net efficiency of the system is increased by improving the CO{sub 2} capture capacity of the sorbent. The IGCC with Na{sub 2}CO{sub 3} -MgO experiences more significant increase in efficiency than that with CaO along with the improvement of sorbent average CO{sub 2} capture capacity. The efficiency of the IGCC systems reaches the same value when the average CO{sub 2} capture capacities of both sorbents are 53% of their theoretical levels. The effects of gas turbine combustor fuel gas inlet temperature on IGCC system performance are analyzed. Results show that the efficiency of the IGCC systems with HGDC and WGDC increases by 0.74% and 0.53% respectively as the fuel gas inlet temperature increases from 250{degrees}C to 650{degrees}#1;C.

Chi, Jinling; Zhao, Lifeng; Wang, Bo; Li, Zhen; Xiao, Yunhan; Duan, Yuhua

2014-01-01

406

Single-Molecule Magnetism in a Family of {Co(III)2Dy(III)2} Butterfly Complexes: Effects of Ligand Replacement on the Dynamics of Magnetic Relaxation.  

PubMed

The synthesis and structural characterization of four related heterometallic complexes of formulas [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2·MeOH·H2O (1a) and [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·H2O (1b), [Dy(III)2Co(III)2(OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (2), [Dy(III)2Co(III)2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2·0.5MeOH·H2O (4a) and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·1.5H2O (4b) are reported (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). Compounds 1 (? 1a and 1b) and 4 (? 4a and 4b) both display two unique molecules within the same crystal and all compounds display a butterfly type core, with the Dy(III) ions occupying the central body positions and the diamagnetic Co(III) ions the outer wing-tip sites. Compounds 1-4 were investigated via direct current and alternating current magnetic susceptibility measurements, and it was found that each complex displayed single-molecule magnet (SMM) behavior. All four compounds display unique coordination and geometric environments around the Dy(III) ions and it was found that each displays a different anisotropy barrier. Ab initio calculations were performed on 1-4 and these determined the low lying electronic structure of each Dy(III) ion and the magnetic interactions for each cluster. It was found that there was a strong correlation between the calculated energy gap between the ground and first excited states of the single-ion ligand-field split Dy(III) levels and the experimentally observed anisotropy barrier. Furthermore, the transverse g factors found for the Dy(III) ions, defining the tunnelling rates within the ground Kramers doublets, are largest for 1, which agrees with the experimental observation of the shortest relaxation time in the high-temperature domain for this complex. The magnetic exchange between the Dy(III) ions revealed overall antiferromagnetic interactions for each compound, derived from the dominant dipolar exchange resulting in nonmagnetic ground states for 1-4. The diamagnetic ground states coupled with small tunneling gaps resulted in quantum tunneling time scales at zero field of between 0.1 and >1.5 s. PMID:24749511

Langley, Stuart K; Ungur, Liviu; Chilton, Nicholas F; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

2014-05-01

407

Rapid and simple LC-MS/MS screening of 64 novel psychoactive substances using dried blood spots.  

PubMed

The range of novel psychoactive substances (NPS) including phenethylamines, cathinones, piperazines, tryptamines, etc. is continuously growing. Therefore, fast and reliable screening methods for these compounds are essential and needed. The use of dried blood spots (DBS) for a fast straightforward approach helps to simplify and shorten sample preparation significantly. DBS were produced from 10 µl of whole blood and extracted offline with 500 µl methanol followed by evaporation and reconstitution in mobile phase. Reversed-phase chromatographic separation and mass spectrometric detection (RP-LC-MS/MS) was achieved within a run time of 10 min. The screening method was validated by evaluating the following parameters: limit of detection (LOD), matrix effect, selectivity and specificity, extraction efficiency, and short-term and long-term stability. Furthermore, the method was applied to authentic samples and results were compared with those obtained with a validated whole blood method used for routine analysis of NPS. LOD was between 1 and 10 ng/ml. No interference from matrix compounds was observed. The method was proven to be specific and selective for the analytes, although with limitations for 3-FMC/flephedrone and MDDMA/MDEA. Mean extraction efficiency was 84.6 %. All substances were stable in DBS for at least a week when cooled. Cooling was essential for the stability of cathinones. Prepared samples were stable for at least 3 days. Comparison to the validated whole blood method yielded similar results. DBS were shown to be useful in developing a rapid screening method for NPS with simplified sample preparation. PMID:23868723

Ambach, Lars; Hernández Redondo, Ana; König, Stefan; Weinmann, Wolfgang

2014-04-01

408

Acute Oral Toxicity Evaluations of Some Zinc(II) Complexes Derived from 1-(2-Salicylaldiminoethyl)piperazine Schiff Bases in Rats  

PubMed Central

The current study described the synthesis and the in vivo acute oral toxicity evaluations in Sprague Dawley rats. The compounds were characterized by elemental analyses, LC-MS, FTIR, 1H NMR, 13C NMR and UV-visible spectroscopy. In the acute toxicity study, a single administration of the compounds was performed orally to the rats at the single doses of 2000 mg/kg and they were then monitored for possible side effects, mortality or behavioral changes up to 14 days. The serum level of aspartate (AST), alanine aminotransferases (ALT), alkaline phosphate (ALP), triglyceride, high density lipoprotein (HDL), immunoglobulins (GAM) and the C-reactive proteins did not significantly change. The hematological indices white blood cells (WBC), haematocrit (HCT), red blood cells (RBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), and mean corpuscular hemoglobin (MCH) were within the normal range. The renal function indices examined were also within the reference range. Generally, the compounds exhibited low toxic effects as required for further in vivo therapeutic studies.

Salga, Muhammad Saleh; Ali, Hapipah Mohd; Abdulla, Mahmood Ameen; Abdelwahab, Siddig Ibrahim

2012-01-01

409

Synthesis and biological activity of some novel trifluoromethyl-substituted 1,2,4-triazole and bis(1,2,4-triazole) Mannich bases containing piperazine rings.  

PubMed

A series of trifluoromethyl-substituted 1,2,4-triazole Mannich base 6 and bis(1,2,4-triazole) Mannich base 7 containing pyrimidinylpiperazine rings via the Mannich reaction were synthesized and characterized by infrared (IR), (1)H nuclear magnetic resonance (NMR), and elemental analysis. The fungicidal tests indicated that most of compounds 6 and 7 possessed excellent fungicidal activity. Among 19 novel compounds, some showed superiority over commercial fungicides Dimethomorph, Thiophanate-methyl, Iprodione, and Zhongshengmycin. Some compounds also exhibited favorable herbicidal activity in the preliminary studies. On the basis of the comparative molecular field analysis (CoMFA), five novel compounds were subsequently synthesized, their activities were estimated fairly accurately, and compounds 6-A1 and 7-A2 displayed good fungicidal activity against Pseudoperonospora cubensis (96.9 and 84.9%) as 6h and 7c, respectively. PMID:20384340

Wang, Bao-Lei; Shi, Yan-Xia; Ma, Yi; Liu, Xing-Hai; Li, Yong-Hong; Song, Hai-Bin; Li, Bao-Ju; Li, Zheng-Ming

2010-05-12

410

4-(2-Fluoro-benzo-yl)-1-[2-(4-hy-droxy-phen-yl)-2-oxoeth-yl]piperazin-1-ium trifluoro-acetate  

PubMed Central

In the crystal structure of the title compound, C19H20FN2O3 +·C2F3O2 ?, N—H?O and O—H?O hydrogen bonds link two cations and two anions into a 22-atom ring. These rings are further linked into a three dimensional network by weak C—H?O contacts.

Bian, Fuyong; Jin, Yi; Chi, Shaoming; Shi, Guojun; Xu, Sichuan

2012-01-01

411

Piperazine-1,4-diium bis-(hexa-hydroxido-hepta-oxidohexa-borato-?(3) O,O',O'')cobaltate(II) hexa-hydrate.  

PubMed

In the title hydrate, (C4H12N2)[Co{B6O7(OH)6}2]·6H2O, both the dication and dianion are generated by crystallographic inversion symmetry. The Co(2+) ion in the dianion adopts a fairly regular CoO6 octa-hedral coordination geometry arising from the two O,O',O''-tridentate ligands. In the crystal, the dianions and water mol-ecules are linked by O-H?O hydrogen bonds, generating a framework with large [100] channels, which are occupied by the organic dications. N-H?O and C-H?O hydrogen bonds consolidate the structure. PMID:24860303

Jamai, Nabil; Rzaigui, Mohamed; Toumi, Samah Akriche

2014-05-01

412

Piperazine-1,4-diium bis-(hexa-hydroxido-hepta-oxidohexa-borato-?3 O,O?,O??)cobaltate(II) hexa-hydrate  

PubMed Central

In the title hydrate, (C4H12N2)[Co{B6O7(OH)6}2]·6H2O, both the dication and dianion are generated by crystallographic inversion symmetry. The Co2+ ion in the dianion adopts a fairly regular CoO6 octa­hedral coordination geometry arising from the two O,O?,O??-tridentate ligands. In the crystal, the dianions and water mol­ecules are linked by O—H?O hydrogen bonds, generating a framework with large [100] channels, which are occupied by the organic dications. N—H?O and C—H?O hydrogen bonds consolidate the structure.

Jamai, Nabil; Rzaigui, Mohamed; Toumi, Samah Akriche

2014-01-01

413

21 CFR 573.940 - Silicon dioxide.  

Code of Federal Regulations, 2013 CFR

...components as an anticaking agent, and/or grinding aid, as follows: Feed component Limitations (percent) BHT (butylated hydroxytoluene) 2 Methionine hydroxy analog and its calcium salts 1 Piperazine, piperazine salts 0.8...

2013-04-01

414

The effect of the pyridyl nitrogen position in pyridylpiperazine sigma ligands  

PubMed Central

A series of pyridylpiperazines was synthesized and analyzed for sigma receptor binding affinity to determine the optimal pyridyl nitrogen position and chain length for the ?1 and ?2 receptor recognition. The (3-pyridyl)piperazines and (4-pyridyl)piperazines favor ?1 receptors, while previously studied (2-pyridyl)piperazines favor ?2 receptors.

Stavitskaya, Lidiya; Seminerio, Michael J.; Matthews-Tsourounis, Marilyn M.; Matsumoto, Rae R.

2012-01-01

415

Aminoalkoxo-supported heteroleptic hexanuclear gallium(III) wheel as a synthon for group 13 heterometallics: a rare sol-gel precursor for mixed Al-Ga oxide as support for gold catalysts.  

PubMed

A new heteroleptic gallium(III) complex, Ga(6)Cl(6)(mdea)(6) (1 x 2 CHCl(3)) (mdeaH(2) = N-methyl diethanolamine) was prepared in good yield by a chloro-aminoalkoxo exchange reaction and used as a synthon for the synthesis of a novel group 13 heterometallic derivative, Ga(2)Al(4)(O)(2)(mdea)(2)(OPr(i))(10) (2 x 2 CHCl(3)), the latter acting as a facile single source precursor for the sol-gel preparation of the mixed Al-Ga oxide as a high surface area support for gold catalysts. PMID:20625595

Mishra, Shashank; Jeanneau, Erwann; Daniele, Stéphane; Mendez, Violaine

2010-08-28

416

Buffer Standards for the Biological pH of the Amino Acid N-[2 hydroxyethyl]piperazine-N'-[3-propanesulfonic acid], HEPPS, From (278.15 to 328.15) K  

PubMed Central

For the HEPPS buffer under investigation, there are seven buffer solutions without NaCl and eight buffer solutions that contain Cl? and have an ionic strength (I = 0.16 mol·kg?1), which is similar to that of blood plasma. These buffer solutions have been evaluated in the temperature range of (278.15 to 328.15) K using the extended Debye- Hückel equation and the Bates-Guggenheim convention. The previously determined Ej values have been used to determine the operational pH values of HEPPS buffer solutions at (298.15 and 310.15) K. These are recommended as secondary standard reference solutions for pH measurements in saline media with an isotonic ionic strength of I = 0.16 mol·kg?1.

Roy, Lakshmi N.; Roy, Rabindra N.; Wollen, Joshua T.; Harmon, Meagan A.; Stegner, Jessica M.; Shah, Ankita A.; Henson, Isaac B.

2011-01-01

417

[TCL and HPLC separation of positional isomers of alkylester acids of 2-, 3-, 4-[2-hydroxy-3-[(4-diphenylmethyl) piperazine-1-yl]propoxy]phenylcarbamic acid and their lipohydrophilic properties].  

PubMed

The paper deals with chromatographic separations of newly prepared substances, aryloxyaminopropanol derivatives. The derivatives represent three homological series of four carbons and four groups of positional isomers (methyl- to butyl- in positions 2-, 3, and 4-). Thin-layer adsorption chromatography employed the foil Silufol UV 254 as the stationary phase and partition chromatography, commercially produced glass plates DC Fertigplatten MERCK RP-8 F254 S. High-performance liquid chromatography was used to separate positional isomers on the column Supelkosil ABZ + PLUS. The mobile phase was methanol and acetonitrile in graded rations with water and various flow rates of the mobile phase were tested. Partition chromatography, determination of partition coefficient in the system octanol-water, and the values of capacity factors k' of the substances was employed to evaluate their lipophilicity. PMID:12789774

Opatrilová, R; Blesová, M; Csöllei, J

2003-05-01

418

7-{4-[(1,3-Benzodioxol-5-yl)meth-yl]piperazin-1-yl}-1-cyclo-propyl-6-fluoro-4-oxo-1,4-dihydro-quinoline-3-carb-oxy-lic acid  

PubMed Central

In the title structure, C25H24FN3O5, a strong intra­molecular O—H?O hydrogen bond is present between the carb­oxy group at the 3-position and the carbonyl group at the 4-position. In the crystal, mol­ecules are held together by weak C—H?O, C—H?F and ?–? [centroid–centroid distance 3.6080?(8)?Å] inter­actions. The 1,4-dihydro­quinoline ring and cyclo­propyl group are not in the same plane, making an inter­planar angle of 57.52?(8)°.

Wang, Shuo; Shan, Guangzhi; Guo, Huiyuan; Liu, Mingliang

2012-01-01

419

Synthesis of new piperazine derived Cu(II)/Zn(II) metal complexes, their DNA binding studies, electrochemistry and anti-microbial activity: Validation for specific recognition of Zn(II) complex to DNA helix by interaction with thymine base  

NASA Astrophysics Data System (ADS)

New 3,4:9,10-dibenzo-2,11-dihydroxy-1,12-bispiperazine-5,8-dioxododecane complexes [C 24H 36N 4O 6Cu] ( 1), [C 24H 32N 4O 4Zn] ( 2) have been synthesized and characterized by elemental analysis, IR, NMR, Mass, EPR, UV-vis spectroscopy and molar conductance measurements. The complexes are non-ionic in nature and possess octahedral geometry around Cu 2+, Zn 2+ central metal ions. The binding studies of 1 and 2 with calf thymus DNA (CT-DNA) were investigated by UV-vis, fluorescence, cyclic voltammetery and viscosity measurements. The calculated binding constant Kb for 1 and 2 obtained from UV-vis absorption studies was 7.6 × 10 3 M -1, 80.8 × 10 4 M -1, respectively. The intrinsic binding constants were also estimated to be 7.0 × 10 4 M -1 and 7.53 × 10 5 M -1 for 1 and 2, respectively by using emission titrations. These experimental results suggest that complexes are groove binders and interact to CT-DNA with different affinities. Both the complexes in presence and absence of CT-DNA show quasireversible wave corresponding to Cu II/Cu I and Zn II/Zn I redox couple. The changes in E1/2, ? E, Ipa/ Ipc ascertain the interaction of 1 and 2 with CT-DNA. Further, decrease in viscosity of CT-DNA with increasing concentration of complexes was observed. In vitro, antimicrobial activity against fungi A. brassicicola, A. niger and bacteria E. coli, P. aeruginosa of complexes were carried out, which indicate that complex 2 is more active against both fungal and bacterial strains as shown by % inhibition data.

Bhat, Irshad-ul-Haq; Tabassum, Sartaj

2009-06-01

420

Synthesis and Characterization of (C 4H 12N 2) 2[Fe 6(HPO 4) 2(PO 4) 6(H 2O) 2]·H 2O, a New Iron Phosphate Templated by Piperazine  

NASA Astrophysics Data System (ADS)

An organically templated iron phosphate, (C 4H 12N 2) 2[Fe 6(HPO 4) 2(PO 4) 6(H 2O) 2]·H 2O, has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and Mössbauer spectroscopy. The compound crystallizes in the triclinic space group Poverline1(No. 2) with a=9.1768(1), b=12.7229(1), c=16.4830(2) Å, ?=68.530(1), ?=83.285(1), ?=73.259(1)°, V=1714.90(3) Å 3, and Z=2. The structure consists of layers of FeO 6octahedra and phosphate tetrahedra, which are pillared through FeO 5trigonal bipyramids and phosphate tetrahedra to form a three-dimensional framework structure. The framework contains infinite channels in which the charge compensating diprotonated piperazinium cations reside.

Zima, Vít?zslav; Lii, Kwang-Hwa

1998-09-01

421

4-(1-Cyclo-propyl-6-fluoro-4-oxo-1,4-dihydro-quinolin-7-yl)piperazin-1-ium 2,4,5-tricarb-oxy-benzene-1-carboxyl-ate monohydrate  

PubMed Central

In the crystal of title compound, C16H19FN3O+·C10H5O8 ?·H2O, the water mol­ecule and the ions are connected by inter­molecular N—H?O and O—H?O hydrogen bonds and ?–? stacking [centroid–centroid separation = 3.602?(1)?Å] between the benzene ring and the pyridine ring, generating a three-dimensional supra­molecular structure.

Yan, Shi-Wei; Liang, Yan-Chen; Liao, Qin; Xin, Guang-Hua; Ye, Zhong-Li

2012-01-01

422

Variable dimensionality in the uranium fluoride/2-methyl-piperazine system: Synthesis and structures of UFO-5, -6, and -7; Zero-, one-, and two-dimensional materials with unprecedented topologies  

SciTech Connect

Recently, low temperature (T < 300 C) hydrothermal reactions of inorganic precursors in the presence of organic cations have proven highly productive for the synthesis of novel solid-state materials. Interest in these materials is driven by the astonishingly diverse range of structures produced, as well as by their many potential materials chemistry applications. This report describes the high yield, phase pure hydrothermal syntheses of three new uranium fluoride phases with unprecedented structure types. Through the systematic control of the synthesis conditions the authors have successfully controlled the architecture and dimensionality of the phase formed and selectively synthesized novel zero-, one-, and two-dimensional materials.

Francis, R.J.; Halasyamani, P.S.; Bee, J.S.; O'Hare, D.

1999-02-24

423

Gas Cleanup for Indirect Liquefaction.  

National Technical Information Service (NTIS)

Visual aids are presented describing various classes of primary gas cleanup. These are: (1) amine systems (MDEA Process); (2) alkali salt systems; (3) physical absorption systems (Selexol Process, Stretford Process); (4) mixed solvent systems; and (5) Cla...

R. M. Wham

1984-01-01

424

Carbonic anhydrase promotes the absorption rate of CO2 in post-combustion processes.  

PubMed

The rate of carbon dioxide (CO2) absorption by monoethanol amine (MEA), diethanol amine (DEA), N-methyl-2,2'-iminodiethanol (MDEA), and 2-amino-2-methyl 1-propanol (AMP) solutions was found to be enhanced by the addition of bovine carbonic anhydrase (CA), has been investigated using a vapor-liquid equilibrium (VLE) device. The enthalpy (-?Habs) of CO2 absorption and the absorption capacities of aqueous amines were measured in the presence and/or absence of CA enzyme via differential reaction calorimeter (DRC). The reaction temperature (?T) under adiabatic conditions was determined based on the DRC analysis. Bicarbonate and carbamate species formation mechanisms were elucidated by (1)H and (13)C NMR spectral analysis. The overall CO2 absorption rate (flux) and rate constant (kapp) followed the order MEA > DEA > AMP > MDEA in the absence or presence of CA. Hydration of CO2 by MDEA in the presence of CA directly produced bicarbonate, whereas AMP produced unstable carbamate intermediate, then underwent hydrolytic reaction and converted to bicarbonate. The MDEA > AMP > DEA > MEA reverse ordering of the enhanced CO2 flux and kapp in the presence of CA was due to bicarbonate formation by the tertiary and sterically hindered amines. Thus, CA increased the rate of CO2 absorption by MDEA by a factor of 3 relative to the rate of absorption by MDEA alone. The thermal effects suggested that CA yielded a higher activity at 40 °C. PMID:23621860

Vinoba, Mari; Bhagiyalakshmi, Margandan; Grace, Andrews Nirmala; Kim, Dae Hoon; Yoon, Yeoil; Nam, Sung Chan; Baek, Il Hyun; Jeong, Soon Kwan

2013-05-01

425

Evaluation of the genotoxic potential of alkylalkanolamines.  

PubMed

Three alkylalkanolamines, N,N-dimethylethanolamine, N-methyldiethanolamine, and tert-butyldiethanolamine, were evaluated for potential genotoxic activity using the Salmonella/microsome reverse gene mutation test, the CHO/HGPRT forward gene mutation test, a sister chromatid exchange test in cultured CHO cells, and an in vivo peripheral blood micronucleus test in Swiss-Webster mice. None of the three alkylalkanolamines produced any significant or dose-related increases in the frequencies of mutations, sister chromatid exchanges or micronuclei. These results indicate that N,N-dimethylethanolamine, N-methyldiethanolamine, and tert-butyldiethanolamine are not genotoxic in the tests conducted. PMID:9357557

Leung, H W; Ballantyne, B

1997-09-18

426

Preparation of Potential Antimalarial Compounds.  

National Technical Information Service (NTIS)

Satisfactory procedures were developed and samples were prepared of the following compounds: chloroacetone oxime, 1,4-bis(2-oximinopropyl)piperazine, 1,4-bis(2(7-chloro-4-quinolyamino)propyl) piperazine, 3,5-bis(1-pyrrolidinomethyl)-4-hydroxyacetanilide, ...

D. A. Warner

1966-01-01

427

Solvent changeouts without plant shutdown  

SciTech Connect

For reasons of greater selectivity, lower regeneration energy requirements, reduced corrosivity and possible greater amine stability, MDEA continues to replace DEA in numerous selective H/sub 2/S removal applications. Solvent changeouts from DEA to MDEA often require no equipment modification, yet they are generally achieved by shutting down the plant, draining the old solvent, cleaning, and finally recharging with MDEA. However, in at least one plant, solvent changeout was done on the fly simply by periodically making up normal DEA losses with MDEA until the plant was finally operating on MDEA alone. Gradual solvent changeouts have the advantages of no lost production, no disposal problems with the environmentally-hazardous old solvent, no use and subsequent disposal of cleaning agents, and no additional manpower requirements. An advanced flowsheet simulation capability can suggest when such a procedure is feasible and, when it is, plant simulation can help to ensure that the solvent changeout is done reliably and with no production or cost penalties. GASPLANT-PLUS(TM) is currently the only commercial simulator having formulated solvent (mixed amine) capabilities within a fully flexible flowsheeting environment. After highlighting its technical foundations, they will compare GASPLANT-PLUS predictions with some commercial plant data and, through examples, they will show how solvent changeouts can be done gradually, without plant shutdown.

Vickery, D.J.; Campbell, S.W. (Taylor, Weiland and Associates, Inc., Potsdam, NY (US))

1988-01-01

428

Determination of nitrogen mustard hydrolysis products in rat urine samples using GC-MS.  

PubMed

A gas chromatographic-mass spectrometric method was developed, validated and demonstrated by measuring the levels of nitrogen mustard hydrolysis products in the urine collected from dosed rats. The recovery values for trimethylsilyl derivatives of EDEA and MDEA are between 82-95% and 88-112%, respectively. In vivo studies performed by using three different doses (0.5 mg/kg, 1.0 mg/kg, and 2.0 mg/kg) of HN2 base of nitrogen mustard. MDEA concentrations were between 43.1-232.2 ng/mL. The limit of detection (S/N = 3) values are 2.5 ng/mL and 1.6 ng/mL for EDEA and MDEA, respectively, and the precision of the method in terms of RSD is between 5-8%. PMID:21549026

Kenar, Levent; Alp, Orkun

2011-05-01

429

Absorption of CO/sub 2/ into aqueous tertiary amine/MEA solutions  

SciTech Connect

Absorption rates for CO/sub 2/ into aqueous solutions of TEA, MDEA and blends of MEA with MDEA and TEA were measured in a stirred cell by a method similar to that used. Second-order rate constants for CO/sub 2/- TEA and CO/sub 2/-MDEA were obtained for temperatures in the range 25-60{sup 0}C. A model based on the film theory is used to predict the rate of absorption of CO/sub 2/ into mixed amine solutions. This model accounts for the variation of amine concentration in the film. Bulk liquid concentrations of the various species present are obtained from a simplified thermodynamic model. Predicted rates are in reasonable agreement with measurements.

Rangwala, B.A.; Morrell, B.R.; Mather, A.E.; Otto, F.D. (Dept. of Chemical Engineering, Univ. of Alberta, Edmonton, Alberta (CA))

1988-01-01

430

Antihelminthic activity of some newly synthesized 5(6)-(un)substituted-1H-benzimidazol-2-ylthioacetylpiperazine derivatives.  

PubMed

Piperazine derivatives of 5(6)-substituted-(1H-benzimidazol-2-ylthio)acetic acids were synthesized by using two methods and studied for antihelminthic activity. The antiparasitic screening showed that compounds 18-24 exhibited higher activity against Trichinella spiralis in vitro in comparison to methyl 5-(propylthio)-1H-benzimidazol-2-yl-carbamate (albendazole). Most active were compounds 2-({2-[4-(4-chlorophenyl)piperazin-1-yl]-2-oxoethyl}thio)-1H-benzimidazole 21 and 2-{[2-oxo-2-(4-benzhydrylpiperazin-1-yl)ethyl]thio}-5(6)-methyl-1(H)-benzimidazole 19 as well as 2-({2-[4-(4-chlorophenyl)piperazin-1-yl]-2-oxoethyl}thio)-5(6)-methyl-1(H)-benzimidazole 23 with efficacy of 96.0%, 98.4% and 100%, respectively. The tested derivatives 15-19 and 20-23 were less active against Syphacia obvelata in vivo than albendazole and exhibited the same efficacy as piperazine, but in twice lower concentration.Compounds 2-({2-[4-(4-chlorophenyl)piperazin-1-yl]-2-oxoethyl}thio)-1H-benzimidazole 21, 1,4-bis[(5(6)-methyl-1(H)-benzimidazol-2-ylthio)acetyl]piperazine 17 and 2-({2-[4-(4-chlorophenyl)piperazin-1-yl]-2-oxoethyl}thio)-5(6)-methyl-1(H)-benzimidazole 23 had higher efficacies of 73%, 76%, and 77%, respectively. PMID:16996654

Mavrova, Anelia Ts; Anichina, Kamelya K; Vuchev, Dimitar I; Tsenov, Jordan A; Denkova, Pavletta S; Kondeva, Magdalena S; Micheva, Mitka K

2006-12-01

431

Cationic Mn4 single-molecule magnet with a sterically isolated core.  

PubMed

The synthesis, structure, and magnetic properties of a ligand-modified Mn(4) dicubane single-molecule magnet (SMM), [Mn(4)(Bet)(4)(mdea)(2)(mdeaH)(2)](BPh(4))(4), are presented, where the cationic SMM units are significantly separated from neighboring molecules in the crystal lattice. There are no cocrystallized solvate molecules, making it an ideal candidate for single-crystal magnetization hysteresis and high-frequency electron paramagnetic resonance studies. Increased control over intermolecular interactions in such materials is a crucial factor in the future application of SMMs. PMID:21751785

Heroux, Katie J; Quddusi, Hajrah M; Liu, Junjie; O'Brien, James R; Nakano, Motohiro; del Barco, Enrique; Hill, Stephen; Hendrickson, David N

2011-08-15

432

Synthesis, spectral, magnetic, electrochemical and kinetic studies of copper(II), nickel(II) and zinc(II) acetate complexes derived from phenol based ‘end-off’ ligands: Effect of p-substituents  

Microsoft Academic Search

A new class of symmetric, end-off, N-methyl piperazine armed binucleating ligands 2,6-bis(4-methyl piperazin-1-yl-methyl)-4-acetyl phenol (HL1) and 2,6-bis[(4-methyl piperazin-1-yl-methyl)]-(4-methylcarboxy) phenol (HL2) were synthesized by the Mannich reaction. Their mononuclear and binuclear Cu(II), Ni(II) and Zn(II) complexes have been synthesized. These complexes were characterized by elemental analysis, infra-red and electronic spectral analysis. In the electronic spectra, the lower electron withdrawing nature of

K. Shanmuga Bharathi; S. Sreedaran; A. Kalilur Rahiman; K. Rajesh; V. Narayanan

2007-01-01

433

Acidic gas capture by diamines  

DOEpatents

Compositions and methods related to the removal of acidic gas. In particular, the present disclosure relates to a composition and method for the removal of acidic gas from a gas mixture using a solvent comprising a diamine (e.g., piperazine) and carbon dioxide. One example of a method may involve a method for removing acidic gas comprising contacting a gas mixture having an acidic gas with a solvent, wherein the solvent comprises piperazine in an amount of from about 4 to about 20 moles/kg of water, and carbon dioxide in an amount of from about 0.3 to about 0.9 moles per mole of piperazine.

Rochelle, Gary (Austin, TX); Hilliard, Marcus (Missouri City, TX)

2011-05-10

434

New Chemotherapeutic Mustard Analogs.  

National Technical Information Service (NTIS)

The present invention is related to nitrogen mustard analogs with arms of unequal reactivity on different nitrogen atoms. More particularly, the present invention is related to 1-(2-chloroethyl)-4-(3-chloropropyl)-piperazine, dihydrochloride or similar ha...

M. Rabinovitz

1986-01-01

435

Dipodazine, a diketopiperazine from Penicillium dipodomyis  

Microsoft Academic Search

Dipodazine, (Z)-1?,3-didehydro-3-(3?-indolylmethylene)-piperazine-2,5-dione (1), has been isolated from Penicillium dipodomyis and is also present in P. nalgiovense. The structure was established by spectroscopical methods.

Dan Sørensen; Thomas Ostenfeld Larsen; Carsten Christophersen; Per Halfdan Nielsen; Uffe Anthoni

1999-01-01

436

Nature and Control of Side-Reactions Due to Diethylcarbamazine in the Treatment of Malayan Filariasis.  

National Technical Information Service (NTIS)

The chemotherapy against human filariasis has developed since Santiago-Stevenson (1947) had reported that 1-diethylcarbamyl-4-methyl-piperazine hydrochloride has an activity of the rapid disappearance of microfilaria from the peripheral blood. And many tr...

B. S. Seo

1974-01-01

437

Deuterated ammonium formate as deuterium source in a mild catalytic deuterium transfer reaction of pyridines, pyrazines and isoquinolines  

Microsoft Academic Search

The application of deuterated ammonium formate as deuterium source in transfer deuteration reactions of aromatic heterocycles (4–6) for the synthesis of highly deuterated, substituted piperidines (1), piperazines (2) and tetrahydroisoquinolines (3) has been developed.

Volker Derdau

2004-01-01

438

Development of Hollow Fiber Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

Work conducted under this contract is a continuation of the development of a hollow fiber reverse osmosis composite membrane. Five systems (sulfonated polysulfone, piperazine phthalamide, immobilized zirconium, chemically bound tannins, and direct membran...

D. K. Schiffer R. B. Davis M. J. Coplan C. E. Kramer

1980-01-01

439

Synthesis of Perfluoro Highly Branched Heterocyclic Fluorine Compounds by Direct Fluorination. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

The direct fluorination of hexamethyleneimine, heptamethyleneimine, 2,6-dimethylmorpholine, thiomorpholine, 1,4-dimethylpiperazine and piperazine produced the corresponding perfluorinated products. The 19F NMR spectrum of perfluoro N,N1 - difluoropiperazi...

W. H. Lin R. J. Lagow

1990-01-01

440

Structure-activity-relationship study of N6-(2(4-(1H-indol-5-yl)piperazin-1-yl)ethyl)-N6-propyl-4,5,6,7-tetrahydrobenzo[d]thiazole-2,6-diamine analogues: Development of highly selective D3 dopamine receptor agonists along with a highly potent D2/D3 agonist and their pharmacological characterization  

PubMed Central

In our effort to develop multifunctional drugs against Parkinson’s disease, a structure-activity-relationship study was carried out based on our hybrid molecular template targeting D2/D3 receptors. Competitive binding with [3H]spiroperidol was used to evaluate affinity (Ki) of test compounds. Functional activity of selected compounds in stimulating [35S]GTP?S binding was assessed in CHO-cells expressing either human D2 or D3 receptors. Our results demonstrated development of highly selective compounds for D3 receptor ((?)-40; Ki D3 = 1.84 nM, D2/D3 = 583.2, (?)-45; Ki D3 = 1.09 nM, D2/D3 = 827.5). Functional data identified (?)-40 (EC50 D2 = 114 nM and D3 = 0.26 nM, D2/D3 = 438) as one of the highest D3 selective agonists known to date. In addition, high affinity, non-selective, D3 agonist, (?)-19 (EC50 D2 = 2.96 nM and D3 = 1.26 nM), was also developed. Lead compounds with antioxidant activity were evaluated using an in vivo PD animal model.

Johnson, Mark; Antonio, Tamara; Reith, Maarten E. A.; Dutta, Aloke K.

2012-01-01

441

Copper(II) Complexation Properties and Surfactant Activity of 3-[ N,NBis(2-hydroxyethyl)amino]-2-hydroxypropanesulfonic Acid and N-(2-Hydroxyethyl)piperazine- N?-2-hydroxypropanesulfonic Acid pH Buffers Which May Affect Trace Metal Speciation in in VitroStudies  

Microsoft Academic Search

Disadvantages of the some zwitterionic pH buffers are (i) that they can interact with metal ions as well as protons, and (ii) that they may have a surfactant effect in chemical orin vitrobiological or biochemical studies. This has to be taken into account when a buffer is selected. Here, the copper-complexing capacity and the surfactant activity of three compounds, 3-[N,N-bis

M. T. S. D. Vasconcelos; M. A. G. O. Azenha; C. M. R. Almeida

1998-01-01

442

Synthesis and structural characterization of (H 4APPIP)[V 3(C 2O 4) 2(HPO 4) 3(PO 4)(H 2O)]·6H 2O (APPIP=1,4-bis(3-aminopropyl)piperazine), a layered vanadium oxalatophosphate containing double 6-ring units  

NASA Astrophysics Data System (ADS)

A new vanadium(III) oxalatophosphate has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. It crystallizes in the triclinic space group P 1¯ with a=11.604(2) Å, b=12.391(2) Å, c=15.220(3) Å, ?=71.090(3)°, ?=82.630(3)°, ?=62.979(3)°, V=1843.8(5) Å 3 and Z=2. The structure consists of V 6(HPO 4) 6 double 6-ring (D6R) units connected by coordinating C 2O 42- and PO 43- anions to form anionic sheets in the ab plane with charge-compensating quadruply protonated 1,4-bis(3-aminopropyl)piperazinium cations and water molecules between the sheets. It is one of the few compounds with 2D layer structures and the second example containing D6R units in the system of metal oxalatophosphates. The iron analogue was also synthesized.

Tang, Ming-Feng; Lii, Kwang-Hwa

2004-06-01

443

Selective inhibition of human cytochrome P450 3A4 by N-[2(R)-hydroxy-1(S)-indanyl]-5-[2(S)-(1, 1-dimethylethylaminocarbonyl)-4-[(furo[2, 3-b]pyridin-5-yl)methyl]piperazin-1-yl]-4(S)-hydroxy-2(R)-phenylmethy lpentanamide and P-glycoprotein by valspodar in gene transfectant systems.  

PubMed

Our previous report showed that L754.394 and valspodar (PSC833) are potent inhibitors of midazolam hydroxylation in human jejunum microsomes and vectorial transport of vinblastine in Caco-2 cells, respectively. In the present study, to directly examine the interactions of these compounds as well as other substrates with CYP3A4 and P-glycoprotein (P-gp), we performed in vitro inhibition studies using recombinant CYP3A4-expressed microsomes and an MDR1-transfected cell line, LLC-MDR1, respectively. In CYP3A4-expressed microsomes, both L754.394 and ketoconazole, at a concentration less than 0.5 microM, are the most potent inhibitors of the formation of 1'-hydroxymidazolam, a major metabolite of midazolam formed by CYP3A4. The greatest inhibitory effect on the transcellular transport of digoxin in LLC-MDR1 cells was observed in the presence of valspodar (<0.1 microM), followed by verapamil. From a comparison of the IC(50) values, it was shown that L754.394 and valspodar exhibited the highest selectivity for CYP3A4 and P-gp, respectively. To demonstrate such specificity, both midazolam hydroxylation and digoxin transport were observed in CYP3A4 transfected Caco-2 cells, which coexpress both P-gp and CYP3A4, in the presence or absence of L754.394 (0.5 microM) and valspodar (1.0 microM). L754.394 almost completely inhibited midazolam hydroxylation, but not digoxin transport, whereas almost complete inhibition of digoxin transport was observed in the presence of valspodar, but inhibition of the hydroxylation was minimal. Thus, the present study has demonstrated that L754.394 has a specific inhibitory effect on CYP3A4, whereas valspodar is specific for P-gp. PMID:10997946

Kawahara, I; Kato, Y; Suzuki, H; Achira, M; Ito, K; Crespi, C L; Sugiyama, Y

2000-10-01

444

Modification of agonist binding moiety in hybrid derivative 5/7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-1-ol/-2-amino versions: Impact on functional activity and selectivity for dopamine D2/D3 receptors  

PubMed Central

The goal of the present study was to explore, in our previously developed hybrid template, the effect of introduction of additional heterocyclic rings (mimicking catechol hydroxyl groups as bioisosteric replacement) on selectivity and affinity for the D3 versus D2 receptor. In addition, we wanted to explore the effect of derivatization of functional groups of the agonist binding moiety in compounds developed by us earlier from the hybrid template. Binding affinity (Ki) of the new compounds was measured with tritiated spiperone as the radioligand and HEK-293 cells expressing either D2 or D3 receptors. Functional activity of selected compounds was assessed in the GTP?S binding assay. In the imidazole series, compound 10a exhibited the highest D3 affinity whereas the indole derivative 13 exhibited similar high D3 affinity. Functionalization of the amino group in agonist (+)-9d with different sulfonamides derivatives improved the D3 affinity significantly with (+)-14f exhibiting the highest affinity. However, functionalization of the hydroxyl and amino groups of 15 and (+)-9d, known agonist and partial agonist, to sulfonate ester and amide in general modulated the affinity. In both cases loss of agonist potency resulted from such derivatization.

Gopishetty, Bhaskar; Zhang, Suhong; Kharkar, Prashant S.; Antonio, Tamara; Reith, Maarten; Dutta, Aloke K.

2013-01-01

445

Photoluminescent Mn4 single-molecule magnet.  

PubMed

The synthesis of [Mn(4)(anca)(4)(Hmdea)(2)(mdea)(2)].2CHCl(3) (1) is reported along with room temperature fluorescence, UV-vis, and NMR spectra. Direct current magnetization versus field data reveal a S = 8 ground state. Quantized steps in temperature- and field-dependent magnetization versus field hysteresis loops confirm single-molecule magnet behavior. PMID:18947226

Beedle, Christopher C; Stephenson, Casey J; Heroux, Katie J; Wernsdorfer, Wolfgang; Hendrickson, David N

2008-12-01

446

An “Accidental” Acute Psychosis with Ecstasy Use  

Microsoft Academic Search

Over the last 10 years, Europe has witnessed the development of the ecstasy phenomenon; this term is used to describe several products sharing more or less the same effects. The most widely used and hence the most well known is 3,4 MDMA, but MDA, MDEA, MBDB and even 2CB or nexus are available. The psychopathological consequences of MDMA use in

Guillaume Vaiva; Virginie Boss; Daniel Bailly; Pierre Thomas; Philippe Lestavel; Michel Goudemand

2001-01-01

447

Arsenic in Natural Gas: Analysis and Characterization of Pipeline Solids by H NMR and Other Methods  

Microsoft Academic Search

Natural gas from the Abo gas field in New Mexico is known to contain arsenic in the form of tertiary alkylarsines. Deposition of alkylarsine sulfides near the pressure regulation equipment in the transmission lines may cause serious operational problems. 'H NMR spectra of CDCl3 solutions of the pure compounds, trimethylarsine sulfide (TMAS), dimethylethylarsine sulfide (DMEAS) and methyldiethylarsine sulfide (MDEAS) were

W. Delgado-morales; R. A. Zingaro; M. S. Mohan

1994-01-01

448

75 FR 59105 - Procedures for Transportation Workplace Drug and Alcohol Testing Programs: Federal Drug Testing...  

Federal Register 2010, 2011, 2012, 2013

...on Copy 1 of the CCF, the new drug analytes MDMA, MDA, and MDEA are added, as are ``[Delta]9-THCA'' after ``Marijuana Metabolite'' and ``BZE'' after ``Cocaine Metabolite'' to specify the drug analytes; (3) In Step 6 on Copy 2...

2010-09-27

449

H Sub 2 S-Removal Processes for Low-Btu Coal Gas.  

National Technical Information Service (NTIS)

Process descriptions are provided for seven methods of removing H sub 2 S from a low-Btu coal-derived gas. The processes include MDEA, Benfield, Selexol, Sulfinol, Stretford, MERC Iron Oxide, and Molecular Sieve. Each of these processes was selected as re...

M. S. Edwards

1979-01-01

450

Efficiency of an Integrated Gasification Combined Cycle (IGCC) power plant including CO 2 removal  

Microsoft Academic Search

This study is devoted to technical evaluation of a carbon dioxide removal in an existing Integrated Gasification Combined Cycle (IGCC) plant. This IGCC case is based on an oxygen blown entrained flow gasifier operating at 27bar, the removal of acid gas (H2S) is performed with MDEA unit, the efficiency of this IGCC is 43% based on the low heating value

C. Descamps; C. Bouallou; M. Kanniche

2008-01-01

451

The skin sensitization potential of four alkylalkanolamines.  

PubMed

The skin sensitization potential of 4 alkylalkanolamines (N-methylethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine and N,N-diethylethanolamine), was evaluated in a guinea pig maximation procedure by the method of Magnusson and Kligman. While all 4 alkylalkanolamines tested were irritating to the guinea pig skin, only N-methylethanolamine showed potential to induce allergic contact dermatitis. None of the remaining 3 alkylalkanolamines exhibited clear skin responses suggestive of sensitization. PMID:9554055

Leung, H W; Blaszcak, D L

1998-04-01

452

Enhanced detectability of fluorinated derivatives of N, N-dialkylamino alcohols and precursors of nitrogen mustards by gas chromatography coupled to Fourier transform infrared spectroscopy analysis for verification of chemical weapons convention  

Microsoft Academic Search

N,N-Dialkylamino alcohols, N-methyldiethanolamine, N-ethyldiethanolamine and triethanolamine are the precursors of VX type nerve agents and three different nitrogen mustards respectively. Their detection and identification is of paramount importance for verification analysis of chemical weapons convention. GC–FTIR is used as complimentary technique to GC–MS analysis for identification of these analytes. One constraint of GC–FTIR, its low sensitivity, was overcome by converting

Prabhat Garg; Ajay Purohit; Vijay K. Tak; D. K. Dubey

2009-01-01

453

Enthalpy of absorption of CO 2 with alkanolamine solutions predicted from reaction equilibrium constants  

Microsoft Academic Search

Differential enthalpies of absorption of CO2 in aqueous solutions of 2-aminoethanol (MEA) and N-methyldiethanolamine were predicted from reaction equilibrium constants using the Gibbs–Helmholtz equation. Correlations for the reaction equilibrium constants and enthalpies of reaction found in the literature for each of the individual reactions taking place at CO2 absorption were compared to experimental data, and from this, a set of

Inna Kim; Karl A. Hoff; Erik T. Hessen; Tore Haug-Warberg; Hallvard F. Svendsen

2009-01-01

454

Solubility of carbon dioxide and hydrogen sulfide in aqueous alkanolamines  

Microsoft Academic Search

The Deshmukh-Mather thermodynamic model has been fitted to all available, public, phase-equilibrium data for CO[sub 2] and H[sub 2]S in aqueous solutions of monoethanolamine, diethanolamine, diglycolamine, and N-methyldiethanolamine. The fitting was done for both acid gases simultaneously, and the best numerical values of the most important interaction parameters for each amine were obtained. Although the method used for data regression

Ralph H. Weiland; Tanmoy Chakravarty; Alan E. Mather

1993-01-01

455

Biotransformation von ausgewählten Gyrasehemmern  

Microsoft Academic Search

Zusammenfassung Die Gyrasehemmer Norfloxacin, Ciprofloxacin, Pefloxacin und Ofloxacin haben als gemeinsame Grundstruktur das 3-Carboxy-4-oxo-6-fluor-7-(1-piperazinyl)-1,4-dihydrochinolin. Sie durchlaufen verschiedene Biotransformationen, die an Tieren und teilweise auch beim Menschen beschrieben worden sind: 1. Konjugation der Carboxylgruppe mit Glukuronsäure. (Die Bildung des O-Methylesters von Norfloxacin ist nur bei der Ratte gefunden worden). 2. Oxidation des Piperazin-Ringes zur 3-Oxo-Verbindung und Abbau (oder Zerfall) des Piperazin-Ringes

K. Borner; H. Lode

1986-01-01

456

Studies on the metabolism and toxicological detection of the new designer drug N-benzylpiperazine in urine using gas chromatography–mass spectrometry  

Microsoft Academic Search

Studies are described on the metabolism and on the toxicological analysis of the piperazine-like designer drug N-benzylpiperazine (BZP, scene name “A2”) in rat and human urine using gas chromatography–mass spectrometry (GC–MS). The identified metabolites indicated that BZP was hydroxylated at the aromatic ring and that the piperazine moiety is metabolically degraded. Our systematic toxicological analysis (STA) procedure using full-scan GC–MS

Roland F. Staack; Giselher Fritschi; Hans H. Maurer

2002-01-01

457

Effect of selected anthelmintics on three common helminths in the brown pelican (Pelecanus occidentalis).  

PubMed

The effect of selected anthelmintics (albendazole, fenbendazole, piperazine dihydrochloride and clorsulon) against three major helminths (Contracaecum multipapillatum, Mesostephanus appendiculatoides, and Phagicola longus) were studied in 29 brown pelicans (Pelecanus occidentalis). Albendazole and fenbendazole were highly effective against all three parasites. Clorsulon had moderate effect against M. appendiculatoides and poor effect against C. multipapillatum and P. longus. Piperazine dihydrochloride had no effect against these helminths. PMID:2915399

Grimes, J; Suto, B; Greve, J H; Albers, H F

1989-01-01

458