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Sample records for mdea methyldiethanolamine piperazine

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

    SciTech Connect

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

    1999-10-01

    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%.

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

    SciTech Connect

    Xu, G.W.; Zhang, C.F.; Qin, S.J.; Gao, W.H.; Liu, H.B.

    1998-04-01

    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.

  3. Effect of chlorides on solution corrosivity of methyldiethanolamine (MDEA) solutions

    SciTech Connect

    Rooney, P.C.; Bacon, T.R.; DuPart, M.S.; Willbanks, K.D.

    1997-08-01

    Solution corrosivity of MDEA/water solutions containing added HCl or NaCl have been measured by weight loss coupons at 250 F and by linear polarization resistance (LPR) at 208 F using carbon steel, 304SS, 316SS and 410SS. General corrosion as well as pitting or crevice corrosion tendencies were recorded for each species. Based on these results, recommendations are made for chlorides in MDEA that minimizes corrosion in gas treating operations.

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

    SciTech Connect

    Xu, G.W.; Zhang, C.F.; Qin, S.J.; Zhu, B.C.

    1995-03-01

    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.

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

    PubMed

    Fürhacker, M; Pressl, A; Allabashi, R

    2003-09-01

    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 study, the aerobic biodegradability of MDEA was investigated in a standardised batch test and a continuous flow experiment (40 l/d). The results of the batch test indicated that the MDEA-solution was non-biodegradable during the test period of 28 days, whereas the continuous flow experiments showed biodegradation of more than 96% based on TOC-measurements. This was probably due to the adaptation of the microorganisms to this particular waste water contamination during continuous flow experiment. PMID:12871741

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

    SciTech Connect

    Ho, A.S.; Equren, P.R. )

    1988-01-01

    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.

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

    SciTech Connect

    Yu, W.C.

    1985-01-01

    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.

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

    SciTech Connect

    Khalil, N.M.

    1984-01-01

    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.

  9. Absorption of carbonyl sulfide in aqueous methyldiethanolamine

    SciTech Connect

    Al-Ghawas, H.A.; Ruiz-Ibanez, G.; Sandall, O.C. )

    1988-01-01

    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.

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

    SciTech Connect

    Weiland, R.H.; Dingman, J.C.; Cronin, D.B.

    1997-09-01

    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.

  11. Solubility of carbon dioxide in methyldiethanolamine + methanol + water

    SciTech Connect

    Henni, A.; Mather, A.E.

    1995-03-01

    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.

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

    SciTech Connect

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

    1995-05-01

    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.

  13. Solubility of CO{sub 2} in aqueous methyldiethanolamine solutions

    SciTech Connect

    Rho, S.W.; Yoo, K.P.; Lee, J.S.; Nam, S.C.; Son, J.E.; Min, B.M.

    1997-11-01

    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}.

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

    PubMed

    Puxty, Graeme; Rowland, Robert

    2011-03-15

    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

  15. Viscosity of aqueous solutions of n-methyldiethanolamine and of diethanolamine

    SciTech Connect

    Teng, T.T.; Maham, Y.; Hepler, L.G.; Mather, A.E. )

    1994-04-01

    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.

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

    SciTech Connect

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

    1997-04-01

    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.

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

    SciTech Connect

    Not Available

    1984-01-09

    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.

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

    SciTech Connect

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

    1995-07-01

    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.

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

    SciTech Connect

    Tamimi, A.; Rinker, E.B.; Sandall, O.C. . Dept. of Chemical and Nuclear Engineering)

    1994-04-01

    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.

  20. Densities and viscosities for binary mixtures of N-methyldiethanolamine + triethylene glycol monomethyl ether from 25 C to 70 C and N-methyldiethanolamine + ethanol mixtures at 40 C

    SciTech Connect

    Henni, A.; Maham, Y.; Tontiwachwuthikul, P.; Chakma, A.; Mather, A.E.

    2000-04-01

    Recent studies done on the absorption and desorption of acid gases (CO{sub 2}, H{sub 2}S) from natural gas, petroleum, and ammonia synthesis streams have shown that aqueous solutions of N-methyldiethanolamine (MDEA) can be used effectively for the selective removal of H{sub 2}S. This paper reports the measured values of the density and viscosity of binary mixtures of N-methyldiethanolamine (MDEA) and triethylene glycol monomethyl ether (TEGMME) at five temperatures in the range 25 C to 70 C over the whole concentration range. The authors also report the density and viscosity of the binary mixture MDEA + ethanol at 40 C. The results are compared with data for aqueous mixtures and other alkanolamines when these are available. The derived excess molar volumes and viscosity deviations were correlated as a function of composition. The Grunberg-Nissan interaction energy constants are also reported.

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

    SciTech Connect

    Jou, F.Y.; Mather, A.E.; Schmidt, K.A.G.; Ng, H.J.

    1999-07-01

    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.

  2. Gas plant converts amine unit to MDEA-based solvent

    SciTech Connect

    Mak, H.Y. )

    1992-10-01

    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].

  3. Series of isostructural planar lanthanide complexes [Ln(III)4(mu3-OH)2(mdeaH)2(piv)8] with single molecule magnet behavior for the Dy4 analogue.

    PubMed

    Abbas, Ghulam; Lan, Yanhua; Kostakis, George E; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

    2010-09-01

    A series of five isostructural tetranuclear lanthanide complexes of formula [Ln(4)(mu(3)-OH)(2)(mdeaH)(2)(piv)(8)], (mdeaH(2) = N-methyldiethanolamine; piv = pivalate; Ln = Tb (1), Dy (2), Ho (3), Er (4), and Tm (5)) have been synthesized and characterized. These clusters have a planar "butterfly" Ln(4) core. Magnetically, the Ln(III) ions are weakly coupled in all cases; the Dy(4) compound 2 shows Single Molecule Magnet (SMM) behavior. PMID:20704320

  4. Design and operation of a selective sweetening plant using MDEA

    SciTech Connect

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

    1986-01-01

    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.

  5. Simultaneous absorption of H2S and Co2 into aqueous methyldiethanolamine

    SciTech Connect

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

    1987-01-01

    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.

  6. 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

    Rinker, E.B.; Oelschlager, D.W.; Colussi, A.T.; Henry, K.R.; Sandall, O.C. . Dept. of Chemical and Nuclear Engineering)

    1994-04-01

    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.

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

    SciTech Connect

    Li, M.H.; Lie, Y.C. . Dept. of Chemical Engineering)

    1994-07-01

    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.

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

    SciTech Connect

    Pani, F.; Gaunand, A.; Richon, D.; Cadours, R.; Bouallou, C.

    1997-09-01

    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.

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

    SciTech Connect

    Posey, M.L.; Rochelle, G.T.

    1997-09-01

    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.

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

    SciTech Connect

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

    1982-10-01

    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.

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

    SciTech Connect

    Jou, F.Y.; Otto, F.D.; Mather, A.E. . Dept. of Chemical Engineering)

    1994-08-01

    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.

  12. 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

    Adams, M.E.; Marshall, T.L.; Rowley, R.L.

    1998-07-01

    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.

  13. N-methyldiethanolamine: a multifunctional structure-directing agent for the synthesis of SAPO and AlPO molecular sieves.

    PubMed

    Wang, Dehua; Tian, Peng; Fan, Dong; Yang, Miao; Gao, Beibei; Qiao, Yuyan; Wang, Chan; Liu, Zhongmin

    2015-05-01

    In the present study, N-methyldiethanolamine (MDEA) is demonstrated to be a multifunctional structure-directing agent for the synthesis of aluminophosphate-based molecular sieves. Four types of molecular sieves, including SAPO-34, -35, AlPO-9 and -22, are for the first time acquired with MDEA as a novel template. The phase selectivity of the present synthesis is found to be condition-dependent. SAPO-34 (CHA) crystallizes from a conventional hydrothermal system with a higher MDEA concentration. When using MDEA as both the template and solvent, pure SAPO-35 (LEV) is obtained from the synthetic gel with a high P2O5/Al2O3 ratio of (2-3), in which the concentration of MDEA could be varied in a wide range. AlPO-9 and AlPO-22 (AWW) are synthesized under the similar conditions to SAPO-35, except without the addition of Si source. The physicochemical properties of the obtained samples are investigated by XRD, XRF, SEM, N2 physisorption, TG-DSC, and various NMR spectra ((13)C, (29)Si, (27)Al and (31)P). Both SAPO-34 and SAPO-35 show good thermal stability, large surface area, and high pore volume. The catalytic performance of SAPO-34 is evaluated by the methanol-to-olefins (MTO) reaction and a good (C2H4+C3H6) selectivity of 82.7% has been achieved. PMID:25616250

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

    SciTech Connect

    Rowley, R.L.; Adams, M.E.; Marshall, T.L.; Oscarson, J.L.; Wilding, W.V.; Anderson, D.J.

    1997-03-01

    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.

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

    SciTech Connect

    Amann, J.M.G.; Bouallou, C.

    2009-04-15

    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.

  16. 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

    Kuranov, G.; Smirnova, N.A.; Rumpf, B.; Maurer, G.

    1996-06-01

    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.

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

    SciTech Connect

    Hagewiesche, D.P.; Ashour, S.S.; Sandall, O.C.

    1995-05-01

    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.

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

    SciTech Connect

    Li, Y.; Mather, A.E.

    1997-07-01

    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.

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

    SciTech Connect

    Bonenfant, D.; Minleault, M.; Hausler, R.

    2007-12-15

    A study of carbon dioxide (CO{sub 2}) and sulfur dioxide (SO{sub 2})/CO{sub 2} 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{sub 2}, MDEA, and TEA on the CO{sub 2} absorption capacity of the AEE. The CO{sub 2} absorption loading has been estimated in 15 wt % AEE alone and in the presence of either 5 and 10 wt % MDEA or 5 and 10 wt % TEA solutions with 100 vol % CO{sub 2} and 5.03 and 15.02 vol % SO{sub 2}/CO{sub 2} mixtures at a starting temperature of 296 K and flow rates of 3.067, 3.229, and 3.605 L/min, respectively. The results revealed that the presence of SO{sub 2} in the gas decreases the CO{sub 2} absorption rate and loading in the AEE solution as a function of the concentration of SO{sub 2}. The additions of 5 and 10 wt % of MDEA and TEA do not seem to influence the CO{sub 2} absorption rate in the AEE solution. Moreover, the addition of MDEA increases slightly the CO{sub 2} absorption capacity of AEE, while TEA decreases the absorption capacity of AEE in the absence and presence Of SO{sub 2}. These effects were enhanced with increases of MDEA and TEA. Altogether, the results indicated that the blend of 15 wt % AEE + 10 wt % MDEA represents an interesting solvent which could be used as absorbent for the removal of CO{sub 2} from emission into the atmosphere by industries.

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

    SciTech Connect

    Lindner, J.R.

    1988-01-01

    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.

  1. Determination of diethanolamine or N-methyldiethanolamine in high ammonium concentration matrices by capillary electrophoresis with indirect UV detection: application to the analysis of refinery process waters.

    PubMed

    Bord, N; Crétier, G; Rocca, J-L; Bailly, C; Souchez, J-P

    2004-09-01

    Alkanolamines such as diethanolamine (DEA) and N-methyldiethanolamine (MDEA) are used in desulfurization processes in crude oil refineries. These compounds may be found in process waters following an accidental contamination. The analysis of alkanolamines in refinery process waters is very difficult due to the high ammonium concentration of the samples. This paper describes a method for the determination of DEA in high ammonium concentration refinery process waters by using capillary electrophoresis (CE) with indirect UV detection. The same method can be used for the determination of MDEA. Best results were achieved with a background electrolyte (BGE) comprising 10 mM histidine adjusted to pH 5.0 with acetic acid. The development of this electrolyte and the analytical performances are discussed. The quantification was performed by using internal standardization, by which triethanolamine (TEA) was used as internal standard. A matrix effect due to the high ammonium content has been highlighted and standard addition was therefore used. The developed method was characterized in terms of repeatability of migration times and corrected peak areas, linearity, and accuracy. Limits of detection (LODs) and quantification (LOQs) obtained were 0.2 and 0.7 ppm, respectively. The CE method was applied to the determination of DEA or MDEA in refinery process waters spiked with known amounts of analytes and it gave excellent results, since uncertainties obtained were 8 and 5%, respectively. PMID:15338092

  2. 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

    Cadours, R.; Bouallou, C.; Gaunand, A.; Richon, D.

    1997-12-01

    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.

  3. 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

    Silkenbaeumer, D.; Lichtenthaler, R.N.; Rumpf, B.

    1998-08-01

    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.

  4. Improvement of amine-modification with piperazine for the adsorption of CO2

    NASA Astrophysics Data System (ADS)

    Xue, Quanmin; Wu, Di; Zhou, Yaping; Zhou, Li

    2012-02-01

    Both selectivity and capacity of CO2 adsorption were considerably increased when PZ (piperazine) was added in MDEA (methyldiethylamine) that used to modify the surface of silica gels. The adsorbent saturated with CO2 was regenerated at ambient temperature through nitrogen purge. A set of PSA (pressure swing adsorption) operation with 200 cycles was carried out and applicability of the modified adsorbent was thus illustrated. The CO2 content in the column-top stream decreased from 13% to below 0.05% at steady state.

  5. Modeling CO{sub 2} and H{sub 2}S solubility in MDEA and DEA: Design implications

    SciTech Connect

    Rochelle, G.T.; Posey, M.

    1996-12-31

    The solubility of H{sub 2}S and CO{sub 2} in aqueous alkanolamines affects solution capacity and the required circulation rate for acid gas absorption. These thermodynamics also determine the relationship of steam rate and the lean loading of the solution which in turn sets the leak of acid gas from the top of the absorber. Finally, the mechanisms of mass transfer and the role of kinetics, especially in stripping, depend on the vapor/liquid equilibria. Published measurements of CO{sub 2} and H{sub 2}S solubility in methyldiethanolamine (MDEA) and diethanolamine (DEA) are not in general agreement, especially at low loading of acid gas. The available sets of solubility data have been regressed with the AspenPlus electrolyte/NRTL model. All of the parameters and constants that make up this model have been carefully evaluated. Independent thermodynamic data such as freezing point and heat of mixing have been included in the regression to strengthen the estimates of model parameters. The parameters for each set of solubility data have been evaluated in an attempt to determine which set is correct. Each evaluated model has been used to calculate the acid gas capacity and minimum stripping steam rate for several industrial cases of acid gas absorption/stripping.

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

    SciTech Connect

    Schubert, C.N.

    1988-01-01

    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.

  7. Simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine.

    PubMed

    Mandald, Bishnupada; Bandyopadhyay, Shyamalendu S

    2006-10-01

    Removal of CO2 from gaseous streams by absorption with chemical reaction in the liquid phase is usually employed in industry as a method to retain atmospheric CO2 to combat the greenhouse effect. A broad spectrum of alkanolamines and, more recently, their mixtures are being employed for the removal of acid gases such as CO2, H2S, and COS from natural and industrial gas streams. In this research, simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine is studied theoretically and experimentally. The effect of contact time, temperature, and amine concentration on the rate of absorption and the selectivity were studied by absorption experiments in a wetted wall column at atmospheric pressure and constant feed gas ratio. The diffusion-reaction processes for CO2 and H2S mass transfer in blended amines are modeled according to Higbie's penetration theory with the assumption that all reactions are reversible. A rigorous parametric sensitivity test is done to quantify the effects of possible errors in the pertinent model parameters on the prediction accuracy of the absorption rates and enhancement factors. Model results based on the kinetics-equilibrium-mass transfer coupled model developed in this work are found to be in good agreement with the experimental results of rates of absorption of CO2 and H2S into (MDEA + DEA + H2O). PMID:17051803

  8. 21 CFR 556.513 - Piperazine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine. 556.513 Section 556.513 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Residues of New Animal Drugs § 556.513 Piperazine. A tolerance of 0.1 part per million piperazine base...

  9. 21 CFR 556.513 - Piperazine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine. 556.513 Section 556.513 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Residues of New Animal Drugs § 556.513 Piperazine. A tolerance of 0.1 part per million piperazine base...

  10. 21 CFR 556.513 - Piperazine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine. 556.513 Section 556.513 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Residues of New Animal Drugs § 556.513 Piperazine. A tolerance of 0.1 part per million piperazine base...

  11. 21 CFR 556.513 - Piperazine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine. 556.513 Section 556.513 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Residues of New Animal Drugs § 556.513 Piperazine. A tolerance of 0.1 part per million piperazine base...

  12. The Neuropsychopharmacology and Toxicology of 3,4-methylenedioxy-N-ethyl-amphetamine (MDEA).

    PubMed

    Freudenmann, Roland W; Spitzer, Manfred

    2004-01-01

    This paper reviews the pharmacology and toxicology of 3,4-methylenedioxy-N-ethylamphetamine (MDEA, "eve"). MDEA is a ring-substituted amphetamine (RSA) like MDMA, its well known N-methyl analog. Both have become very popular substances of abuse in the techno- and house-music scene. They can evoke psychomotor stimulation, mild alterations of perception, sensations of closeness and a positive emotional state as well as sympathomimetic physical effects. At present, the name "ecstasy" is no longer used only for MDMA, but for the whole group of RSAs (MDA, MDMA, MDEA and MBDB) as they are chemically and pharmacologically nearly identical; moreover, many ecstasy pills contain mixtures of the RSAs. Hence, for a selective review on MDEA, it is crucial to strictly differentiate between: 1) street and chemical names, and 2) studies with or without chemically defined substances. In order to present MDEA-specific information, the pharmacodynamics and kinetics are described on the basis of MDEA challenge studies in animals and humans. In the toxicology section, we present a collection of case reports on fatalities where MDEA was toxicologically confirmed. On the question of serotonergic neurotoxicity and possible long-term consequences, however, MDEA-specific information is available from animal studies only. The neurotoxic potential of MDEA in humans is difficult to estimate, as ecstasy users do not consume pure substances. For future research, challenge studies in animals using dosing regimens adapted to human consumption patterns are needed. Such challenge studies should directly compare individual RSAs. They will represent the most viable and fruitful approach to the resolution of the highly controversial issues of serotonergic neurotoxicity and its functional consequences. PMID:15179441

  13. Piperazine-induced occupational asthma

    SciTech Connect

    Hagmar, L.; Bellander, T.; Bergoeoe, B.; Simonsson, B.G.

    1982-03-01

    Asthmatic reactions were studied among some 130 factory workers who handled amines and other chemicals. Among present employees, we found 15 cases of asthma associated with occupational exposure to chemicals; among former employees there were at least 18. The inducing agent was judged to be piperazine in 29 persons and ethylenediamine (EDA) in three. The asthma was of the late or dual type; immediate reactions alone were to seen. No one had attacks of asthma before employment, and atopic subjects were not preferentially affected. Routine spirometry revealed airway obstruction in fewer than half of the recent cases. Tests of nonspecific bronchial reactivity with methacholine in six subjects with recent asthma showed hyperactivity in five, while tow subjects with earlier asthma did not have hyperactivity. Bronchial provocation tests with piperazine in one subject were positive both in the factory and in the laboratory. The level of piperazine was 1.2 mg/m3 time-weighted average (TWA) in a work place associated with induction of the asthmatic state, and 0.3 mg/m3 in a place connected with attacks in ''sensitized'' subjects.

  14. 21 CFR 520.2380f - Thiabendazole, piperazine phosphate powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Thiabendazole, piperazine phosphate powder. 520....2380f Thiabendazole, piperazine phosphate powder. (a) Specifications. Each ounce of water dispersible powder contains 6.67 grams of thiabendazole and 8.33 grams of piperazine (as piperazine phosphate)....

  15. 21 CFR 520.2380f - Thiabendazole, piperazine phosphate powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Thiabendazole, piperazine phosphate powder. 520....2380f Thiabendazole, piperazine phosphate powder. (a) Specifications. Each ounce of water dispersible powder contains 6.67 grams of thiabendazole and 8.33 grams of piperazine (as piperazine phosphate)....

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

    PubMed

    da Costa, José Luiz; da Matta Chasin, Alice Aparecida

    2004-11-01

    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 and efficiency. The method showed good linearity and precision. Recovery was between 85 and 102% and detection limits were 10, 15 and 20 ng/ml for MDA, MDMA and MDEA, respectively. No interfering substances were detected with fluorescence detection. PMID:15458720

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

    SciTech Connect

    Huttenhuis, P.J.G.; Agrawal, N.J.; Versteeg, G.F.

    2009-04-15

    In this work, 72 new experimental solubility data points for H{sub 2}S and CO{sub 2} mixtures in aqueous N-methyldiethanol amine (MDEA) solutions at different methane partial pressures (up to 69 bara) are presented. They are correlated using an electrolyte equation of state (E-EOS) thermodynamic model. This model has already been used to estimate the CO{sub 2} solubility in aqueous MDEA (Huttenhuis et al. Fluid Phase Equilib. 2008, 264, 99-112) and the H{sub 2}S solubility in aqueous MDEA (Huttenhuis et al. Int. J. Oil, Gas Coal Technol. 2008, 1, 399-424). Here, the model is further extended to predict the behavior of CO{sub 2} and H{sub 2}S when they are present simultaneously in aqueous MDEA. The application of an equation of state is a new development for this type of system, i.e., of acid-gas-amine systems. The molecular interactions are described by Schwarzentruber et al.'s modification of the Redlich-Kwong-Soave equation of state, with terms added to account for ionic interactions in the liquid phase. The model is used to describe acid-gas solubility data for the CO{sub 2}-H{sub 2}S-MDEA-H{sub 2}O system reported in the open literature and experimental data reported here for the CO{sub 2}-H{sub 2}S-MDEA-H{sub 2}O-CH{sub 4} system.

  18. Piperazine pivoted transition metal dithiocarbamates

    NASA Astrophysics Data System (ADS)

    Khan, Sadaf; Nami, Shahab A. A.; Siddiqi, K. S.

    2008-03-01

    A quadridentate ligand disodium bis(2,2'-dithiopiperazinato-2,2'-diamino diethylamine) Na 2L 2 and its self assembled transition metal complexes of the type, M 2(L 2) 2 {M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)} have been reported. The piperazine pivoted homodinuclear complexes have been characterized by a range of spectral, thermal, microanalytical and conductometric techniques. On the basis of IR and 1HNMR data a symmetrical bidentate coordination of the dithiocarbamato moiety has been observed in all the cases. The TGA profile of the ligand exhibits two stage thermolytic pattern although the complexes decompose in three steps, respectively. Metal sulfide is found to be the end product. The formation of homodinuclear complexes has been ascertained on the basis of FAB mass spectral data and a probable fragmentation pattern has been proposed. On the basis of UV-visible spectroscopic results and room temperature magnetic moment data a tetrahedral geometry has been proposed for all the complexes except for the Ni(II) and Cu(II) which are found to be square-planar.

  19. 21 CFR 520.2380f - Thiabendazole, piperazine phosphate powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... powder contains 6.67 grams of thiabendazole and 8.33 grams of piperazine (as piperazine phosphate). (b) Sponsor. See No. 050604 in § 510.600(c) of this chapter. (c) Conditions of use—(1) Amount. 2 grams of thiabendazole and 2.5 grams of piperazine (0.3 ounce of powder) per 100 pounds of body weight. (2)...

  20. Enantioselective Synthesis of α-Secondary and α-Tertiary Piperazin-2-ones and Piperazines by Catalytic Asymmetric Allylic Alkylation

    PubMed Central

    Korch, Katerina M.; Eidamshaus, Christian; Behenna, Douglas C.; Nam, Sangkil; Horne, David

    2014-01-01

    The asymmetric Pd-catalyzed decarboxylative allylic alkylation of differentially N-protected piperazin-2-ones allows for the synthesis of a variety of highly enantioenriched tertiary piperazine-2-ones. Deprotection and reduction affords the corresponding tertiary piperazines, which can be employed for the synthesis of medicinally important analogs. The introduction of these chiral tertiary piperazines resulted in imatinib analogs that exhibited comparable antiproliferative activity to that of their corresponding imatinib counterparts. PMID:25382664

  1. Conformational analysis of 2-substituted piperazines.

    PubMed

    Kallel, E Adam; Vangel, Colin; Elbaum, Daniel

    2016-07-01

    The unusual activity differences of carbon linked versus oxygen linked 2-substituted piperazines as α7 nicotinic acetylcholine receptor agonists led to a conformational study of several examples. The conformational preferences of which are absent from the literature. We report the first study and explanation of the conformational preference of 2-substiturted piperazines and show an example of how this preference controls binding in a pharmaceutically relevant case. In all cases the axial conformation for these 1-acyl and 1 aryl 2-substituted piperazines was found to be preferred. For the ether linked compounds, the axial conformation was found to be further stabilized by an intramolecular hydrogen bond. The axial orientation also places the basic and pyridyl nitrogens into a special orientation that closely mimics nicotine. Molecular modeling studies confirm that the R enantiomers of the compounds can bind to the α7 nicotinic acetylcholine receptor with the basic and pyridyl nitrogens colocalized with their counterparts in Epibatidine. PMID:27212066

  2. Corrosion in MDEA sour gas treating plants: Correlation between laboratory testing and field experience

    SciTech Connect

    Bich, N.N.; Vacha, F.; Schubert, R.

    1996-08-01

    Corrosion in MDEA sour gas treating systems operating in severely loaded conditions is investigated using both laboratory data and actual gas plant experience. Effects of acid gas loading, flow turbulence, solution quality, temperature, etc. on corrosion are being studied. Preliminary results indicated severe corrosion of several mm/y would occur if acid gas loading, circulation rate and level of suspended solids are all high. A mitigation strategy based on operating envelopes is formulated.

  3. 21 CFR 556.513 - Piperazine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine. 556.513 Section 556.513 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD Specific Tolerances for Residues of New Animal Drugs § 556.513...

  4. Piperazine-based nucleic acid analogs

    DOEpatents

    Schmidt, Jurgen; Silks, Louis A.; Michalczyk, Ryszard

    2005-01-11

    A novel nucleoside analog is disclosed which comprises a piperazine ring in the place of the ring ribose or deoxyribose sugar. Monomers utilizing a broad variety of nucleobases are disclosed, as well as oligomers comprising the monomers disclosed herein linked by a variety of linkages, including amide, phosphonamide, and sulfonamide linkages. A method of synthesizing the nucleoside analogs is also disclosed.

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

    SciTech Connect

    Meng Hui Li; Keh Perng Shen . Dept. of Chemical Engineering)

    1993-01-01

    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.

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

    SciTech Connect

    Al-Ghawas, H.A.

    1988-01-01

    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.

  7. An experimental investigation into the atmospheric degradation of piperazine

    NASA Astrophysics Data System (ADS)

    White, Stephen; Angove, Dennys; Azzi, Merched; Tibbett, Anne; Campbell, Ian; Patterson, Michael

    2015-05-01

    The atmospheric degradation of piperazine was investigated using an indoor smog chamber. Experiments were carried out in the presence of nitrogen oxides (NOx), ozone or nitric acid. Piperazine reacted rapidly under all evaluated conditions: irradiated in the presence of NOx and with ozone and nitric acid in the dark. Gas phase products from the oxidation of piperazine were identified by infrared spectroscopy, DNPH cartridges followed by HPLC analysis, and by sampling chamber gas through Tenax sorbent material followed by analysis using thermal desorption GC-ITMS (gas chromatography ion trap mass spectrometry). Eight compounds were positively identified, with a further nine compounds tentatively identified using GC-MS based on molecular weight and mass spectra. Ammonia formation was observed from piperazine oxidation, and its formation was from the subsequent reactions of photooxidation products of piperazine rather than directly from the reaction of piperazine. The nitrosamine and nitramine expected from piperazine, N-nitrosopiperazine, and N-nitropiperazine, were both identified and confirmed using 15NO, with a tentative maximum yield of nitrosamine of less than 5% observed. Aerosol yields, relative to total piperazine reacted not including that which absorbed to the walls, were considerably high but were not able to be quantified absolutely due to unusual behaviour of the scanning mobility particle sizer instrument to aerosol containing amines. The reaction of piperazine with gas phase nitric acid gave rise to immediate formation of aerosol.

  8. 21 CFR 520.1804 - Piperazine phosphate capsules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine phosphate capsules. 520.1804 Section... phosphate capsules. (a) Specifications. Each capsule contains 120, 300, or 600 milligrams of piperazine phosphate monohydrate. (b) Sponsor. See No. 051311 in § 510.600(c) of this chapter. (c) Conditions of...

  9. 21 CFR 520.1804 - Piperazine phosphate capsules.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine phosphate capsules. 520.1804 Section... phosphate capsules. (a) Specifications. Each capsule contains 120, 300, or 600 milligrams of piperazine phosphate monohydrate. (b) Sponsor. See No. 051311 in § 510.600(c) of this chapter. (c) Conditions of...

  10. 21 CFR 520.1803 - Piperazine citrate capsules.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine citrate capsules. 520.1803 Section 520.1803 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1803 Piperazine...

  11. 21 CFR 520.1803 - Piperazine citrate capsules.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine citrate capsules. 520.1803 Section 520.1803 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1803 Piperazine...

  12. 21 CFR 520.1803 - Piperazine citrate capsules.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine citrate capsules. 520.1803 Section 520.1803 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1803 Piperazine...

  13. 21 CFR 520.1803 - Piperazine citrate capsules.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine citrate capsules. 520.1803 Section 520.1803 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1803 Piperazine...

  14. 21 CFR 520.1803 - Piperazine citrate capsules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine citrate capsules. 520.1803 Section 520.1803 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1803 Piperazine...

  15. 21 CFR 520.1804 - Piperazine phosphate capsules.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine phosphate capsules. 520.1804 Section... phosphate capsules. (a) Specifications. Each capsule contains 120, 300, or 600 milligrams of piperazine phosphate monohydrate. (b) Sponsor. See No. 051311 in § 510.600(c) of this chapter. (c) Conditions of...

  16. 21 CFR 520.1804 - Piperazine phosphate capsules.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine phosphate capsules. 520.1804 Section... phosphate capsules. (a) Specifications. Each capsule contains 120, 300, or 600 milligrams of piperazine phosphate monohydrate. (b) Sponsor. See No. 051311 in § 510.600(c) of this chapter. (c) Conditions of...

  17. 21 CFR 520.1804 - Piperazine phosphate capsules.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine phosphate capsules. 520.1804 Section... phosphate capsules. (a) Specifications. Each capsule contains 120, 300, or 600 milligrams of piperazine phosphate monohydrate. (b) Sponsor. See No. 051311 in § 510.600(c) of this chapter. (c) Conditions of...

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

    SciTech Connect

    Critchfield, J.E.; Rochelle, G.T. )

    1988-01-01

    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.

  19. 21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine phosphate with thenium closylate... § 520.1805 Piperazine phosphate with thenium closylate tablets. (a) Specifications. Each scored tablet contains the equivalent of 250 milligrams piperazine hexahydrate (as piperazine phosphate) and...

  20. 21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine phosphate with thenium closylate... § 520.1805 Piperazine phosphate with thenium closylate tablets. (a) Specifications. Each scored tablet contains the equivalent of 250 milligrams piperazine hexahydrate (as piperazine phosphate) and...

  1. 21 CFR 520.1802a - Piperazine-carbon disulfide complex suspension.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine-carbon disulfide complex suspension... § 520.1802a Piperazine-carbon disulfide complex suspension. (a) Specifications. Each fluid ounce of suspension contains 7.5 grams of piperazine-carbon disulfide complex. The piperazine-carbon disulfide...

  2. 21 CFR 520.1802a - Piperazine-carbon disulfide complex suspension.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine-carbon disulfide complex suspension... § 520.1802a Piperazine-carbon disulfide complex suspension. (a) Specifications. Each fluid ounce of suspension contains 7.5 grams of piperazine-carbon disulfide complex. The piperazine-carbon disulfide...

  3. 21 CFR 520.1802a - Piperazine-carbon disulfide complex suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine-carbon disulfide complex suspension... § 520.1802a Piperazine-carbon disulfide complex suspension. (a) Specifications. Each fluid ounce of suspension contains 7.5 grams of piperazine-carbon disulfide complex. The piperazine-carbon disulfide...

  4. 21 CFR 520.1802a - Piperazine-carbon disulfide complex suspension.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine-carbon disulfide complex suspension... § 520.1802a Piperazine-carbon disulfide complex suspension. (a) Specifications. Each fluid ounce of suspension contains 7.5 grams of piperazine-carbon disulfide complex. The piperazine-carbon disulfide...

  5. 21 CFR 520.1802a - Piperazine-carbon disulfide complex suspension.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine-carbon disulfide complex suspension... § 520.1802a Piperazine-carbon disulfide complex suspension. (a) Specifications. Each fluid ounce of suspension contains 7.5 grams of piperazine-carbon disulfide complex. The piperazine-carbon disulfide...

  6. 21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine phosphate with thenium closylate... § 520.1805 Piperazine phosphate with thenium closylate tablets. (a) Specifications. Each scored tablet contains the equivalent of 250 milligrams piperazine hexahydrate (as piperazine phosphate) and...

  7. 21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine phosphate with thenium closylate... § 520.1805 Piperazine phosphate with thenium closylate tablets. (a) Specifications. Each scored tablet contains the equivalent of 250 milligrams piperazine hexahydrate (as piperazine phosphate) and...

  8. 21 CFR 520.1805 - Piperazine phosphate with thenium closylate tablets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine phosphate with thenium closylate... § 520.1805 Piperazine phosphate with thenium closylate tablets. (a) Specifications. Each scored tablet contains the equivalent of 250 milligrams piperazine hexahydrate (as piperazine phosphate) and...

  9. Contribution of artifacts to N-methylated piperazine cyanide adduct formation in vitro from N-alkyl piperazine analogs.

    PubMed

    Zhang, Minli; Resuello, Christina M; Guo, Jian; Powell, Mark E; Elmore, Charles S; Hu, Jun; Vishwanathan, Karthick

    2013-05-01

    In the liver microsome cyanide (CN)-trapping assays, piperazine-containing compounds formed significant N-methyl piperazine CN adducts. Two pathways for the N-methyl piperazine CN adduct formation were proposed: 1) The α-carbon in the N-methyl piperazine is oxidized to form a reactive iminium ion that can react with cyanide ion; 2) N-dealkylation occurs followed by condensation with formaldehyde and dehydration to produce N-methylenepiperazine iminium ion, which then reacts with cyanide ion to form the N-methyl CN adduct. The CN adduct from the second pathway was believed to be an artifact or metabonate. In the present study, a group of 4'-N-alkyl piperazines and 4'-N-[¹³C]methyl-labeled piperazines were used to determine which pathway was predominant. Following microsomal incubations in the presence of cyanide ions, a significant percentage of 4'-N-[¹³C]methyl group in the CN adduct was replaced by an unlabeled natural methyl group, suggesting that the second pathway was predominant. For 4'-N-alkyl piperazine, the level of 4'-N-methyl piperazine CN adduct formation was limited by the extent of prior 4'-N-dealkylation. In a separate study, when 4'-NH-piperaziens were incubated with potassium cyanide and [¹³C]-labeled formaldehyde, 4'-N-[¹³C]methyl piperazine CN-adduct was formed without NADPH or liver microsome suggesting a direct Mannich reaction is involved. However, when [¹³C]-labeled methanol or potassium carbonate was used as the one-carbon donor, 4'-N-[¹³C]methyl piperazine CN adduct was not detected without liver microsome or NADPH present. The biologic and toxicological implications of bioactivation via the second pathway necessitate further investigation because these one-carbon donors for the formation of reactive iminium ions could be endogenous and readily available in vivo. PMID:23431111

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

    SciTech Connect

    Jou, Fang Yuan; Carroll, J.J.; Mather, A.E.; Otto, F.D. . Dept. of Chemical Engineering)

    1993-01-01

    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.

  11. Surface tension of binary mixtures of water + N-methyldiethanolamine and ternary mixtures of this amine and water with monoethanolamine, diethanolamine, and 2-amino-2-methyl-1-propanol from 25 to 50 C

    SciTech Connect

    Alvarez, E.; Rendo, R.; Sanjurjo, B.; Sanchez-Vilas, M.; Navaza, J.M.

    1998-11-01

    The surface tension of aqueous solutions of N-methyldiethanolamine and diethanolamine + N-methyldiethanolamine, monoethanolamine + N-methyldiethanolamine and 2-amino-2-methyl-1-propanol + N-methyldiethanolamine was measured at temperatures from 25 C to 50 C. For binary mixtures the concentration range was 0--50 mass % N-methyldiethanolamine, and for the tertiary mixtures the concentration range for each amine was 0--50 mass %. The experimental values were correlated with temperature and mole fraction. The maximum deviation in both cases was always less than 0.5%.

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

    SciTech Connect

    Pani, F.; Gaunand, A.; Cadours, R.; Bouallou, C.; Richon, D.

    1997-03-01

    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.

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

    SciTech Connect

    Qian, W.M.; Li, Y.G.; Mather, A.E.

    1995-07-01

    The Clegg-Pitzer equations with some simplifications are used to correlate the vapor-liquid equilibrium data for the CO{sub 2}-methyldiethanolamine-sulfolane-H{sub 2}O and H{sub 2}S-methyldiethanolamine-sulfolane-H{sub 2}O systems. The interaction parameters determined from data for the binary, ternary, and quaternary systems can be used to predict the quinary mixed solvent systems without any additional parameters. The model is applied to the CO{sub 2}-H{sub 2}S-methyldiethanolamine-sulfolane-H{sub 2}O system containing three neutral solvents (methyldiethanolamine, sulfolane, and H{sub 2}O), two neutral solutes (CO{sub 2} and H{sub 2}S), and three ionic species (MDEAH{sup +}, HCO{sub 3}{sup {minus}}, and HS{sup {minus}}) with three main chemical equilibria simultaneously involved.

  14. Effect of hydrogen sulfide loading on the density and viscosity of aqueous solutions of methyldiethanolamine

    SciTech Connect

    Rinker, E.B.; Colussi, A.T.; McKnight, N.L.; Sandall, O.C.

    2000-04-01

    Aqueous alkanolamine solutions are commonly used to remove acid gases such as carbon dioxide and hydrogen sulfide from natural gas. The change in the density and viscosity of aqueous methyldiethanolamine on the addition of hydrogen sulfide was investigated in this study. At 25 C densities and viscosities were measured for loadings up to 0.5 mol of H{sub 2}S per 1 mol of amine for amine concentrations up to 50 mass % and for H{sub 2}S loadings up to 0.5. It was found that the solution density increases with H{sub 2}S loading whereas the viscosity decreases as the H{sub 2}S loading increases.

  15. 21 CFR 520.1802b - Piperazine-carbon disulfide complex boluses.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine-carbon disulfide complex boluses. 520....1802b Piperazine-carbon disulfide complex boluses. (a) Specifications. Each bolus contains 20 grams of piperazine-carbon disulfide complex. (b) Sponsor. See 000009 in § 510.600(c) of this chapter. (c)...

  16. 21 CFR 520.1802c - Piperazine-carbon disulfide complex with phenothiazine suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine-carbon disulfide complex with... ANIMAL DRUGS § 520.1802c Piperazine-carbon disulfide complex with phenothiazine suspension. (a) Specifications. Each fluid ounce contains 5 grams of piperazine-carbon disulfide complex and 0.83 gram...

  17. 21 CFR 520.1802b - Piperazine-carbon disulfide complex boluses.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine-carbon disulfide complex boluses. 520....1802b Piperazine-carbon disulfide complex boluses. (a) Specifications. Each bolus contains 20 grams of piperazine-carbon disulfide complex. (b) Sponsor. See 000009 in § 510.600(c) of this chapter. (c)...

  18. 21 CFR 520.1802c - Piperazine-carbon disulfide complex with phenothiazine suspension.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine-carbon disulfide complex with... ANIMAL DRUGS § 520.1802c Piperazine-carbon disulfide complex with phenothiazine suspension. (a) Specifications. Each fluid ounce contains 5 grams of piperazine-carbon disulfide complex and 0.83 gram...

  19. 21 CFR 520.1802b - Piperazine-carbon disulfide complex boluses.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine-carbon disulfide complex boluses. 520....1802b Piperazine-carbon disulfide complex boluses. (a) Specifications. Each bolus contains 20 grams of piperazine-carbon disulfide complex. (b) Sponsor. See 000009 in § 510.600(c) of this chapter. (c)...

  20. 21 CFR 520.1802c - Piperazine-carbon disulfide complex with phenothiazine suspension.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine-carbon disulfide complex with... ANIMAL DRUGS § 520.1802c Piperazine-carbon disulfide complex with phenothiazine suspension. (a) Specifications. Each fluid ounce contains 5 grams of piperazine-carbon disulfide complex and 0.83 gram...

  1. 21 CFR 520.1802b - Piperazine-carbon disulfide complex boluses.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine-carbon disulfide complex boluses. 520....1802b Piperazine-carbon disulfide complex boluses. (a) Specifications. Each bolus contains 20 grams of piperazine-carbon disulfide complex. (b) Sponsor. See 000009 in § 510.600(c) of this chapter. (c)...

  2. 21 CFR 520.1802c - Piperazine-carbon disulfide complex with phenothiazine suspension.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine-carbon disulfide complex with... ANIMAL DRUGS § 520.1802c Piperazine-carbon disulfide complex with phenothiazine suspension. (a) Specifications. Each fluid ounce contains 5 grams of piperazine-carbon disulfide complex and 0.83 gram...

  3. 21 CFR 520.1802c - Piperazine-carbon disulfide complex with phenothiazine suspension.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine-carbon disulfide complex with... ANIMAL DRUGS § 520.1802c Piperazine-carbon disulfide complex with phenothiazine suspension. (a) Specifications. Each fluid ounce contains 5 grams of piperazine-carbon disulfide complex and 0.83 gram...

  4. 21 CFR 520.1802b - Piperazine-carbon disulfide complex boluses.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine-carbon disulfide complex boluses. 520....1802b Piperazine-carbon disulfide complex boluses. (a) Specifications. Each bolus contains 20 grams of piperazine-carbon disulfide complex. (b) Sponsor. See 000009 in § 510.600(c) of this chapter. (c)...

  5. Solubility of nitrous oxide in aqueous blends of N-methyldiethanolamine and 2-amino-2-methyl-1-propanol

    SciTech Connect

    Davis, R.A.; Pogainis, B.J.

    1995-11-01

    Aqueous solutions of alkanolamines have applications in acid gas treatment for the removal of acid gases such as carbon dioxide and hydrogen sulfide. The solubility of nitrous oxide in aqueous blends of N-methyldiethanolamine and 2-amino-2-methyl-1 propanol was measured over the temperature range 10--60 C. The total composition of the alkanolamines in water ranged from 30 to 50 mass %. The experimental results were interpreted in terms of Henry`s constants.

  6. 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

    SciTech Connect

    Nexant, Inc., San Francisco, California

    2011-05-01

    The first section (Task 1) of this report by Nexant includes a survey and screening of various acid gas removal processes in order to evaluate their capability to meet the specific design requirements for thermochemical ethanol synthesis in NREL's thermochemical ethanol design report (Phillips et al. 2007, NREL/TP-510-41168). MDEA and selexol were short-listed as the most promising acid-gas removal agents based on work described in Task 1. The second report section (Task 2) describes a detailed design of an MDEA (methyl diethanol amine) based acid gas removal system for removing CO2 and H2S from biomass-derived syngas. Only MDEA was chosen for detailed study because of the available resources.

  7. Application of ORAL.screen saliva drug test for the screening of methamphetamine, MDMA, and MDEA incorporated in hair.

    PubMed

    Miki, Akihiro; Katagi, Munehiro; Shima, Noriaki; Tsuchihashi, Hitoshi

    2004-03-01

    By the use of a one-step immunoassay drug test for oral fluid, a convenient and fairly sensitive screening method has been devised for methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) incorporated in hair. These drugs, in a 10-mg portion of hair, were extracted into 5M HCl/methanol (1:20, v/v), and the extract reconstituted in 100 micro L water was assayed with the saliva drug test ORAL.screen trade mark. The limits of detection were 0.5 ng/mg hair for d-MA, 0.8 ng/mg for dl-MDMA, and 1.0 ng/mg for dl-MDEA. The results are in good agreement with those of gas chromatography-mass spectrometry (GC-MS) determination. Although all positive results must be confirmed by either GC-MS or a specific alternative methodology, this method provided a simple screening, suitable for drug enforcement purposes, while requiring only a 10-mg hair specimen. PMID:15068568

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

    SciTech Connect

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

    1987-01-01

    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.

  9. 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

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

    1999-06-01

    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

  10. Probing of different conformations of piperazine using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  11. High-nuclearity homometallic iron and nickel clusters: Fe22 and Ni24 complexes from the use of N-methyldiethanolamine.

    PubMed

    Foguet-Albiol, Dolos; Abboud, Khalil A; Christou, George

    2005-09-14

    The use of N-methyldiethanolamine (mdaH2) in reactions with Fe(III) and Ni(II) sources has led to Fe22 and Ni24 products; the clusters are the highest and second-highest, respectively, homometallic clusters for these metals to date, and possess S = 0 and S = 6 ground states, respectively. PMID:16113722

  12. 21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520.1802 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... § 520.1802 Piperazine-carbon disulfide complex oral dosage forms....

  13. 21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520.1802 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... § 520.1802 Piperazine-carbon disulfide complex oral dosage forms....

  14. 21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520.1802 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... § 520.1802 Piperazine-carbon disulfide complex oral dosage forms....

  15. 21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520.1802 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... § 520.1802 Piperazine-carbon disulfide complex oral dosage forms....

  16. 21 CFR 520.1802 - Piperazine-carbon disulfide complex oral dosage forms.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Piperazine-carbon disulfide complex oral dosage forms. 520.1802 Section 520.1802 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... § 520.1802 Piperazine-carbon disulfide complex oral dosage forms....

  17. 21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... an aqueous solution which contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine dihydrochloride equivalent to 3.98 grams of piperazine base. (2) The drug is a soluble powder which when reconstituted with water contains in each fluid ounce 0.45 gram of levamisole...

  18. 21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... an aqueous solution which contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine dihydrochloride equivalent to 3.98 grams of piperazine base. (2) The drug is a soluble powder which when reconstituted with water contains in each fluid ounce 0.45 gram of levamisole...

  19. Synthesis and characterization of the novel phosphonates- and phosphonothioate-piperazine as flame retardants for cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tetraethyl piperazine-1,4-diyldiphosphonate (PDP) and O,O,O',O'-tetramethyl piperazine-1,4-diyldiphosphonothioate (PDSP) were synthesized in one simple step and their structures were confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and elemental analysis (EA). Print cloth, twil...

  20. Hepatotoxicity of piperazine designer drugs: Comparison of different in vitro models.

    PubMed

    Dias-da-Silva, D; Arbo, M D; Valente, M J; Bastos, M L; Carmo, H

    2015-08-01

    Piperazine derived drugs emerged on the drug market in the last decade. The aim of this study was to investigate in vitro the potential hepatotoxicity of the designer drugs N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), 1-(4-methoxyphenyl)piperazine (MeOPP) and 1-(3,4-methylenedioxybenzyl)piperazine (MDBP) in two human hepatic cell lines (HepaRG and HepG2) and in primary rat hepatocytes. Cell death was evaluated by the MTT assay, after 24 h-incubations. Among the tested drugs, TFMPP was the most cytotoxic. HepaRG cells and primary hepatocytes revealed to be the most and the least resistant cellular models, respectively. To ascertain whether the CYP450 metabolism could explain their higher susceptibility, primary hepatocytes were co-incubated with the piperazines and the CYP450 inhibitors metyrapone and quinidine, showing that CYP450-mediated metabolism contributes to the detoxification of these drugs. Additionally, the intracellular contents of reactive species, ATP, reduced (GSH) and oxidized (GSSG) glutathione, changes in mitochondrial membrane potential (Δψm) and caspase-3 activation were further evaluated in primary cells. Overall, an increase in reactive species formation, followed by intracellular GSH and ATP depletion, loss of Δψm and caspase-3 activation was observed for all piperazines, in a concentration-dependent manner. In conclusion, piperazine designer drugs produce hepatic detrimental effects that can vary in magnitude among the different analogues. PMID:25863214

  1. Opportunities and challenges for direct C–H functionalization of piperazines

    PubMed Central

    Ye, Zhishi; Gettys, Kristen E

    2016-01-01

    Summary Piperazine ranks within the top three most utilized N-heterocyclic moieties in FDA-approved small-molecule pharmaceuticals. Herein we summarize the current synthetic methods available to perform C–H functionalization on piperazines in order to lend structural diversity to this privileged drug scaffold. Multiple approaches such as those involving α-lithiation trapping, transition-metal-catalyzed α-C–H functionalizations, and photoredox catalysis are discussed. We also highlight the difficulties experienced when successful methods for α-C–H functionalization of acyclic amines and saturated mono-nitrogen heterocyclic compounds (such as piperidines and pyrrolidines) were applied to piperazine substrates. PMID:27340462

  2. 21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Specifications. Each 54.10 grams (1.91 ounces) of water dispersible powder contains 9.10 grams of trichlorfon, 6.25 grams of phenothiazine, and the equivalent of 20.0 grams of piperazine base (as...

  3. Pharmacological profiles of aminoindanes, piperazines, and pipradrol derivatives.

    PubMed

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

    2014-03-15

    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

  4. Chrysin-piperazine conjugates as antioxidant and anticancer agents.

    PubMed

    Patel, Rahul V; Mistry, Bhupendra; Syed, Riyaz; Rathi, Anuj K; Lee, Yoo-Jung; Sung, Jung-Suk; Shinf, Han-Seung; Keum, Young-Soo

    2016-06-10

    Synthesis of 7-(4-bromobutoxy)-5-hydroxy-2-phenyl-4H-chromen-4-one intermediate treating chrysin with 1,4-dibromobutane facilitated combination of chrysin with a wide range of piperazine moieties which were equipped via reacting the corresponding amines with bis(2-chloroethyl)amine hydrochloride in diethylene glycol monomethyl ether solvent. Free radical scavenging potential of prepared products was analyzed in vitro adopting DPPH and ABTS bioassay in addition to the evaluation of in vitro anticancer efficacies against cervical cancer cell lines (HeLa and CaSki) and an ovarian cancer cell line SK-OV-3 using SRB assay. Bearable toxicity of 7a-w was examined employing Madin-Darby canine kidney (MDCK) cell line. In addition, cytotoxic nature of the presented compounds was inspected utilizing Human bone marrow derived mesenchymal stem cells (hBM-MSCs). Overall, 7a-w indicated remarkable antioxidant power in scavenging DPPH(·) and ABTS(·+), particularly analogs 7f, 7j, 7k, 7l, 7n, 7q, 7v, 7w have shown promising free radical scavenging activity. Analogs 7j and 7o are identified to be highly active candidates against HeLa and CaSki cell lines, whereas 7h and 7l along with 7j proved to be very sensitive towards ovarian cancer cell line SKOV-3. None of the newly prepared scaffolds showed cytotoxic nature toward hBM-MSCs cells. From the structure-activity point of view, nature and position of the electron withdrawing and electron donating functional groups on the piperazine core may contribute to the anticipated antioxidant and anticancer action. Different spectroscopic techniques (FT-IR, (1)H NMR, (13)C NMR, Mass) and elemental analysis (CHN) were utilized to confirm the desired structure of final compounds. PMID:26924226

  5. Synthesis and antifungal activity of novel triazole compounds containing piperazine moiety.

    PubMed

    Wang, Yanwei; Xu, Kehan; Bai, Guojing; Huang, Lei; Wu, Qiuye; Pan, Weihua; Yu, Shichong

    2014-01-01

    Design and synthesis of triazole library antifungal agents having piperazine side chains, analogues to fluconazole were documented. The synthesis highlighted utilization of the click chemistry on the basis of the active site of the cytochrome P450 14α-demethylase (CYP51). Their structures were characterized by (1)H-NMR, (13)C-NMR, MS and IR. The influences of piperazine moiety on in vitro antifungal activities of all the target compounds were evaluated against eight human pathogenic fungi. PMID:25090121

  6. Separation and detection of ammonia, amines, and alkanolamines with single-column ion chromatography. [Alkylamines, ethanolamine and methyldiethanolamine

    SciTech Connect

    Poulson, R.E.; Borg, H.M.

    1986-03-01

    A single-column ion chromatographic method was developed for separation and detection of aqueous ammonia, C/sub 1/-, C/sub 2/-, and C/sub 3/- alkylamines, ethanolamine, and methyldiethanolamine. A precolumn concentrator was used to take detection of ammonium ion by electrical conductivity to fractional ppB levels and detection of the organic cations to ppB levels. Analysis of ppM ammonia levels in 3 wt % alkanolamine scrubber-type solutions was possible, but resolution of alkylamines was lost. A post-column reaction system for fluorescence detection of primary amine o-phthalaldehyde derivatives with reversed-phase separation allowed amine separation in the presence of large amounts of ammonia. The same system might be used in place of concentration and conductivity for determination of the alkylamine levels. A large variety of oil shale retort by-product waters and one underground coal gasification condensate were screened for alkylamines, but none were detected. 7 refs., 8 figs., 1 tab.

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

    PubMed Central

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

    2010-01-01

    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. PMID:20099888

  8. 2-Butyl-4-chloroimidazole based substituted piperazine-thiosemicarbazone hybrids as potent inhibitors of Mycobacterium tuberculosis.

    PubMed

    Jallapally, Anvesh; Addla, Dinesh; Yogeeswari, Perumal; Sriram, Dharmarajan; Kantevari, Srinivas

    2014-12-01

    Here a series of 2-butyl-4-chloroimidazole based substituted piperazine-thiosemicarbazone hybrids were designed by combining three different pharmacophoric fragments in single molecular architecture. 2-Butyl-4-chloro-1-(3-(4-substituted)piperazin-1-yl)propyl)-1H-imidazole-5-carbaldehydes (4a-p) prepared by reacting carboxaldehyde 2 with N-alkyl piperazines 3a-p which were condensed with thiosemicarbazine to give desired compounds 5a-p in very good yields. Among all sixteen compounds screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB), two compounds (E)-2-((2-butyl-4-chloro-1-(3-(4-(o-tolyl) piperazin-1-yl)propyl)-1H-imidazol-5-yl)methylene)hydrazinecarbothioamide 5e and (E)-2-((2-butyl-4-chloro-1-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl)-1H-imidazol-5-yl)methylene) hydrazine carbothioamide 5f were found to be the most potent antitubercular agents (MIC: 3.13 μg/mL) with low toxicity profile. PMID:25451998

  9. Piperazine-induced airway symptoms: exposure-response relationships and selection in an occupational setting

    SciTech Connect

    Hagmar, L.; Bellander, T.; Ranstam, J.; Skerfving, S.

    1984-01-01

    The heterocyclic secondary amine piperazine is known to cause asthma. In a cohort of 602 workers, employed during the period 1942-1979, at a chemical industry where piperazine is handled, a study conducted by means of a mailed questionnaire showed a strong exposure-response relationship as to frequency of work-related airway symptoms indicating asthma. In the most exposed group about a third of the workers had experienced such symptoms. Age, length of employment, smoking habits, and previous work-related asthmatic symptoms, but not atopy, modified the response. Further, there was an association between piperazine exposure and chronic bronchitis. In the most exposed group every fourth subject had chronic bronchitis. The frequency was modified by smoking habits; atopy was a confounder. Although many subjects, especially high-exposed ones, left work because of airway symptoms, there was no difference in occurrence of airway symptoms between former and present employees.

  10. Stability constants and molar absorptivities for complexes of copper(II) with N-methyldiethanolamine, 1,4-bis(2-hydroxypropyl)-2-methylpiperazine, and 2-amino-2-methyl-1-propanol.

    PubMed

    Siefker, J R; Aroc, R V

    1986-09-01

    The stability constants and molar absorptivities of complexes of Cu(2+) with N-methyldiethanolamine, 1,4-bis(2-hydroxypropyl)-2-methylpiperazine, and 2-amino-2-methyl-1-propanol have been determined from spectrophotometric data for very dilute aqueous solutions. PMID:18964197

  11. Synthesis and antitubercular activity of 1,2,4-trisubstitued piperazines.

    PubMed

    Rohde, Kyle H; Michaels, Heather A; Nefzi, Adel

    2016-05-01

    Parallel solid phase synthesis offers a unique opportunity for the synthesis and screening of large numbers of compounds and significantly enhances the prospect of finding new leads. We report the synthesis and antitubercular activity of chiral 1,2,4-trisubstituted piperazines derived from resin bound acylated dipeptides against Mycobacterium tuberculosis strain H37Rv. PMID:27020522

  12. Thermal decomposition reactions of cotton fabric treated with piperazine-phosphonates derivatives as a flame retardant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There has been a great scientific interest in exploring the great potential of the piperazine-phosphonates in flame retardant (FR) application on cotton fabric by investigating the thermal decomposition of cotton fabric treated with them. This research tries to understand the mode of action of the t...

  13. The mechanism of action of piperazine-phosphonates derivatives in cotton fabric

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Piperazine-phosphonates additives are known to be very effective flame retardants on different polymeric systems, especially cotton cellulose. In order to understand their mechanism of action, we carried out the investigation of their thermal behavior on cotton fabric by, first, employing the attenu...

  14. 21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... suspension. 520.763c Section 520.763c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS... piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status....

  15. 21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... suspension. 520.763c Section 520.763c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS... piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status....

  16. 21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... suspension. 520.763c Section 520.763c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS... piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status....

  17. 21 CFR 520.763c - Dithiazanine iodide and piperazine citrate suspension.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... suspension. 520.763c Section 520.763c Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS... piperazine citrate). (b) Sponsor. See 000010 in § 510.600(c) of this chapter. (c) NAS/NRC status....

  18. The influences of piperazine-phosphonates derivatives on flame retardancy and thermal behaviors of cotton cellulose

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In an effort to create the environmentally-friendly flame retardants (FRs) for cotton cellulose, two phosphoramidates derivatives, tetraethyl piperazine-1,4-diyldiphosphonate (PDP) and diethyl 4-methylpiperazin-1-ylphosphoramidate (PAP), have been developed. Both were synthesized in high yield and ...

  19. 40 CFR 721.9800 - Poly(substituted triazinyl) piperazine (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... triazinyl) piperazine (PMN P-88-436) is subject to reporting under this section for the significant new uses...) through (c), (g), and (h). (2) Limitations or revocation of certain notification requirements. The... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses...

  20. 21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... dihydrochloride powder. 520.2520g Section 520.2520g Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... ANIMAL DRUGS § 520.2520g Trichlorfon, phenothiazine, and piperazine dihydrochloride powder. (a) Specifications. Each 54.10 grams (1.91 ounces) of water dispersible powder contains 9.10 grams of trichlorfon,...

  1. 21 CFR 520.2520g - Trichlorfon, phenothiazine, and piperazine dihydrochloride powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... dihydrochloride powder. 520.2520g Section 520.2520g Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... ANIMAL DRUGS § 520.2520g Trichlorfon, phenothiazine, and piperazine dihydrochloride powder. (a) Specifications. Each 54.10 grams (1.91 ounces) of water dispersible powder contains 9.10 grams of trichlorfon,...

  2. Piperazine-phosphonate derivatives: their flame retardant and thermal degradation properties on cotton fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been known that phosphorus-nitrogen system shows greater flame resistance in cotton textiles at a lower level than phosphorus used alone. This research aims to compare the effectiveness of Tetraethyl piperazine-1,4-diyldiphosphonate (TEPP) as a flame retardant (FR) for cotton fabric to a prev...

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

    PubMed

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

    2007-11-01

    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

  4. Influence of superheated water on the hydrogen bonding and crystallography of piperazine-based (Co)polyamides.

    PubMed

    Vinken, Esther; Terry, Ann E; Spoelstra, Anne B; Koning, Cor E; Rastogi, Sanjay

    2009-05-01

    Here we demonstrate that superheated water is a solvent for polyamide 2,14 and piperazine-based copolyamides up to a piperazine content of 62 mol %. The incorporation of piperazine allows for a variation of the hydrogen bond density without altering the crystal structure (i.e., the piperazine units cocrystallize with the PA2,14 units (Hoffmann, S.; Vanhaecht, B.; Devroede, J.; Bras, W.; Koning, C. E.; Rastogi, S. Macromolecules 2005, 38, 1797-1803). It is shown that the crystallization of PA2,14 from superheated water greatly influences the crystal structure. Water molecules incorporated in the PA2,14 crystal lattice cause a slip on the hydrogen bonded planes, resulting in a coexistence of a triclinic and a monoclinic crystal structure. On heating above the Brill transition, the water molecules exit from the lattice, restoring the triclinic crystal structure. With increasing piperazine content, and hence decreasing hydrogen bond density, the dissolution temperature decreases. It is only possible to grow single crystals from superheated water up to a piperazine content of 62 mol %. For these single crystals, the incorporation of water molecules in the vicinity of the amide group is seen by the presence of COO- stretch vibrations with FTIR spectroscopy. These vibrations disappear on heating above the Brill transition temperature, and the water molecules leave the amide groups. For copolyamides with more than 62 mol % piperazine, no Brill transition is observed, no single crystals can be grown from water, and no water molecules are observed in the vicinity of the amide groups (Vinken, E.; Terry, A. E.; Hoffmann, S.; Vanhaecht, B.; Koning, C. E.; Rastogi, S. Macromolecules 2006, 39, 2546-2552). The high piperazine content (co)polyamides have fewer hydrogen bond donors and are therefore less likely to have interactions with the water molecules. This work demonstrates the relation among the Brill transition, the dissolution of polyamide in superheated water, and its

  5. Syntheses, biological activities and SAR studies of novel carboxamide compounds containing piperazine and arylsulfonyl moieties.

    PubMed

    Wang, Bao-Lei; Shi, Yan-Xia; Zhang, Shu-Jun; Ma, Yi; Wang, Hong-Xue; Zhang, Li-Yuan; Wei, Wei; Liu, Xing-Hai; Li, Yong-Hong; Li, Zheng-Ming; Li, Bao-Ju

    2016-07-19

    A series of novel carboxamide compounds 19a-19j, 20a-20j and 22a-22d containing piperazine and arylsulfonyl moieties have been synthesized. The bioassay results showed that some compounds exhibited favorable herbicidal activities against dicotyledonous plants and many of them possessed excellent antifungal activities. Among 24 novel compounds, some showed superiority over the commercial fungicides Chlorothalonil, Dimethomorph, Thiophanate-methyl, Iprodione, and Zhongshengmycin at 500 mg/L concentration. Some compounds also exhibited high KARI inhibitory activity at 100 μg/mL concentration and could be used as new KARI lead inhibitors for further studies. Moreover, SAR of these new compounds were comprehensively investigated using different computational methods in which 3D-QSAR model obtained provided useful information for further structural optimization for the discovery of new fungicides. The results of this research will contribute to explore comprehensive biological activities of piperazine-containing compounds in different areas of chemistry. PMID:27092414

  6. Novel 1-(2-aryl-2-adamantyl)piperazine derivatives with antiproliferative activity.

    PubMed

    Fytas, Christos; Zoidis, Grigoris; Tsotinis, Andrew; Fytas, George; Khan, Mohsin A; Akhtar, Samar; Rahman, Khondaker M; Thurston, David E

    2015-03-26

    Novel 1-(2-aryl-2-adamantyl)piperazine derivatives have been synthesized and evaluated in vitro for their antitumor properties against HeLa cervical carcinoma, MDA MB 231 breast cancer, MIA PaCa2 pancreatic cancer, and NCI H1975 non-small cell lung cancer. The parent piperazine 6 was found to exhibit a reasonable activity toward the HeLa and MDA MB 231 tumor cell lines (IC50= 9.2 and 8.4 μΜ, respectively). Concurrent benzene ring C4-fluorination and piperidine acetylation of the piperazino NH of compound 6 resulted in the most active compound 13 of the series in both of the above cell lines (IC50=8.4 and 6.8 μΜ, respectively). Noticeably, compounds 6 and 13 exhibited a significantly low cytotoxicity level over the normal human cells HUVEC (Human Umbilical Vein Endothelial Cells) and NHDF (Normal Human Dermal Fibroblasts). PMID:25703296

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

    PubMed Central

    Ingham, Richard J; Battilocchio, Claudio; Hawkins, Joel M

    2014-01-01

    Summary 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

  8. Scalable Synthesis of Piperazines Enabled by Visible-Light Irradiation and Aluminum Organometallics

    PubMed Central

    Suárez-Pantiga, Samuel; Colas, Kilian; Johansson, Magnus J; Mendoza, Abraham

    2015-01-01

    The development of more active C–H oxidation catalysts has inspired a rapid, scalable, and stereoselective assembly of multifunctional piperazines through a [3+3] coupling of azomethine ylides. A combination of visible-light irradiation and aluminum organometallics is essential to promote this transformation, which introduces visible-light photochemistry of main-group organometallics and sets the basis for new and promising catalysts. PMID:26337253

  9. N-(4-Chloro­phen­yl)-4-methyl­piperazine-1-carboxamide

    PubMed Central

    Li, Yu-Feng; Wang, Wen-Mei

    2011-01-01

    In the title compound, C12H16ClN3O, the piperazine ring has a chair conformation. Within this ring, the N-methyl nitro­gen atom has a pyramidal geometry and the N-carboxamide nitro­gen atom is almost planar (bond-angle sum = 359.8°). In the crystal, the mol­ecules are linked by N—H⋯O hydrogen bonds into C(4) chains propagating in [010]. PMID:22059021

  10. Screening of Transient Receptor Potential Canonical Channel Activators Identifies Novel Neurotrophic Piperazine Compounds.

    PubMed

    Sawamura, Seishiro; Hatano, Masahiko; Takada, Yoshinori; Hino, Kyosuke; Kawamura, Tetsuya; Tanikawa, Jun; Nakagawa, Hiroshi; Hase, Hideharu; Nakao, Akito; Hirano, Mitsuru; Rotrattanadumrong, Rachapun; Kiyonaka, Shigeki; Mori, Masayuki X; Nishida, Motohiro; Hu, Yaopeng; Inoue, Ryuji; Nagata, Ryu; Mori, Yasuo

    2016-03-01

    Transient receptor potential canonical (TRPC) proteins form Ca(2+)-permeable cation channels activated upon stimulation of metabotropic receptors coupled to phospholipase C. Among the TRPC subfamily, TRPC3 and TRPC6 channels activated directly by diacylglycerol (DAG) play important roles in brain-derived neurotrophic factor (BDNF) signaling, promoting neuronal development and survival. In various disease models, BDNF restores neurologic deficits, but its therapeutic potential is limited by its poor pharmacokinetic profile. Elucidation of a framework for designing small molecules, which elicit BDNF-like activity via TRPC3 and TRPC6, establishes a solid basis to overcome this limitation. We discovered, through library screening, a group of piperazine-derived compounds that activate DAG-activated TRPC3/TRPC6/TRPC7 channels. The compounds [4-(5-chloro-2-methylphenyl)piperazin-1-yl](3-fluorophenyl)methanone (PPZ1) and 2-[4-(2,3-dimethylphenyl)piperazin-1-yl]-N-(2-ethoxyphenyl)acetamide (PPZ2) activated, in a dose-dependent manner, recombinant TRPC3/TRPC6/TRPC7 channels, but not other TRPCs, in human embryonic kidney cells. PPZ2 activated native TRPC6-like channels in smooth muscle cells isolated from rabbit portal vein. Also, PPZ2 evoked cation currents and Ca(2+) influx in rat cultured central neurons. Strikingly, both compounds induced BDNF-like neurite growth and neuroprotection, which were abolished by a knockdown or inhibition of TRPC3/TRPC6/TRPC7 in cultured neurons. Inhibitors of Ca(2+) signaling pathways, except calcineurin, impaired neurite outgrowth promotion induced by PPZ compounds. PPZ2 increased activation of the Ca(2+)-dependent transcription factor, cAMP response element-binding protein. These findings suggest that Ca(2+) signaling mediated by activation of DAG-activated TRPC channels underlies neurotrophic effects of PPZ compounds. Thus, piperazine-derived activators of DAG-activated TRPC channels provide important insights for future development of a

  11. A case of levocetirizine-induced fixed drug eruption and cross-reaction with piperazine derivatives.

    PubMed

    Kim, Mi-Yeong; Jo, Eun-Jung; Chang, Yoon-Seok; Cho, Sang-Heon; Min, Kyung-Up; Kim, Sae-Hoon

    2013-10-01

    Fixed drug eruption is an uncommon adverse drug reaction caused by delayed cell-mediated hypersensitivity. Levocetirizine is an active (R)-enatiomer of cetirizine and there have been a few reports of fixed drug eruption related to these antihistamines. We experienced a case of levocetirizine-induced fixed drug eruption and cross-reaction with other piperazine derivatives confirmed by patch test. A 73-year-old female patient presented with recurrent generalized itching, cutaneous bullae formation, rash and multiple pigmentation at fixed sites after taking drugs for common cold. She took bepotastine besilate (Talion®) and levocetirizine (Xyzal®) as antihistamine. She took acetaminophen, pseudoephedrine 60 mg / triprolidine 2.5 mg (Actifed®), dihydrocodeinebitartrate 5 mg / di-methylephedrine hydrochloride 17.5 mg / chlorpheniramine maleate 1.5 mg / guaifenesin 50 mg (Codening®) and aluminium hydroxide 200 mg / magnesium carbonate 120 mg (Antad®) at the same time. Patch test was done with suspected drugs and the result was positive with levocetirizine. We additionally performed patch test for other antihistamines such as cetirizine, hydroxyzine, fexofenadine and loratadine. Piperazine derivatives (cetirizine and hydroxyzine) were positive, but piperidine derivatives (fexofenadine and loratadine) were negative to patch test. There was no adverse drug reaction when she was challenged with fexofenadine. We report a case of levocetirizine-induced fixed drug eruption confirmed by patch test. Cross-reactions were only observed in the piperazine derivatives and piperidine antihistamine was tolerant to the patient. PMID:24260733

  12. Multicomponent Synthesis and Biological Evaluation of a Piperazine-Based Dopamine Receptor Ligand Library.

    PubMed

    Stucchi, Mattia; Gmeiner, Peter; Huebner, Harald; Rainoldi, Giulia; Sacchetti, Alessandro; Silvani, Alessandra; Lesma, Giordano

    2015-08-13

    A series of 1,4-disubstituted piperazine-based compounds were designed, synthesized, and evaluated as dopamine D2/D3 receptor ligands. The synthesis relies on the key multicomponent split-Ugi reaction, assessing its great potential in generating chemical diversity around the piperazine core. With the aim of evaluating the effect of such diversity on the dopamine receptor affinity, a small library of compounds was prepared, applying post-Ugi transformations. Ligand stimulated binding assays indicated that some compounds show a significant affinity, with K i values up to 53 nM for the D2 receptor. Molecular docking studies with the D2 and D3 receptor homology models were also performed on selected compounds. They highlighted key interactions at the indole head and at the piperazine moiety, which resulted in good agreement with the known pharmacophore models, thus helping to explain the observed structure-activity relationship data. Molecular insights from this study could enable a rational improvement of the split-Ugi primary scaffold, toward more selective ligands. PMID:26288260

  13. A case of levocetirizine-induced fixed drug eruption and cross-reaction with piperazine derivatives

    PubMed Central

    Kim, Mi-Yeong; Jo, Eun-Jung; Chang, Yoon-Seok; Cho, Sang-Heon; Min, Kyung-Up

    2013-01-01

    Fixed drug eruption is an uncommon adverse drug reaction caused by delayed cell-mediated hypersensitivity. Levocetirizine is an active (R)-enatiomer of cetirizine and there have been a few reports of fixed drug eruption related to these antihistamines. We experienced a case of levocetirizine-induced fixed drug eruption and cross-reaction with other piperazine derivatives confirmed by patch test. A 73-year-old female patient presented with recurrent generalized itching, cutaneous bullae formation, rash and multiple pigmentation at fixed sites after taking drugs for common cold. She took bepotastine besilate (Talion®) and levocetirizine (Xyzal®) as antihistamine. She took acetaminophen, pseudoephedrine 60 mg / triprolidine 2.5 mg (Actifed®), dihydrocodeinebitartrate 5 mg / di-methylephedrine hydrochloride 17.5 mg / chlorpheniramine maleate 1.5 mg / guaifenesin 50 mg (Codening®) and aluminium hydroxide 200 mg / magnesium carbonate 120 mg (Antad®) at the same time. Patch test was done with suspected drugs and the result was positive with levocetirizine. We additionally performed patch test for other antihistamines such as cetirizine, hydroxyzine, fexofenadine and loratadine. Piperazine derivatives (cetirizine and hydroxyzine) were positive, but piperidine derivatives (fexofenadine and loratadine) were negative to patch test. There was no adverse drug reaction when she was challenged with fexofenadine. We report a case of levocetirizine-induced fixed drug eruption confirmed by patch test. Cross-reactions were only observed in the piperazine derivatives and piperidine antihistamine was tolerant to the patient. PMID:24260733

  14. Multicomponent Synthesis and Biological Evaluation of a Piperazine-Based Dopamine Receptor Ligand Library

    PubMed Central

    2015-01-01

    A series of 1,4-disubstituted piperazine-based compounds were designed, synthesized, and evaluated as dopamine D2/D3 receptor ligands. The synthesis relies on the key multicomponent split-Ugi reaction, assessing its great potential in generating chemical diversity around the piperazine core. With the aim of evaluating the effect of such diversity on the dopamine receptor affinity, a small library of compounds was prepared, applying post-Ugi transformations. Ligand stimulated binding assays indicated that some compounds show a significant affinity, with Ki values up to 53 nM for the D2 receptor. Molecular docking studies with the D2 and D3 receptor homology models were also performed on selected compounds. They highlighted key interactions at the indole head and at the piperazine moiety, which resulted in good agreement with the known pharmacophore models, thus helping to explain the observed structure–activity relationship data. Molecular insights from this study could enable a rational improvement of the split-Ugi primary scaffold, toward more selective ligands. PMID:26288260

  15. Solubility and diffusivity of N{sub 2}O and CO{sub 2} in (diethanolamine + N-methyldiethanolamine + water) and in (diethanolamine + 2-amino-2-methyl-1-propanol + water)

    SciTech Connect

    Li, M.H.; Lee, W.C.

    1996-05-01

    Acid gases such as CO{sub 2} and H{sub 2}S are frequently removed from natural gas, synthetic natural gas, and other process gas streams by means of absorption into aqueous alkanol-amine solutions. The solubility and diffusivity of N{sub 2}O in (diethanolamine + N-methyldiethanolamine + water) and in (diethanolamine + 2-amino-2-methyl-1-propanol + water) were measured at (30, 35, and 40)C and at atmospheric pressure. Five (diethanolamine + N-methyldiethanolamine + water) and four (diethanolamine + 2-amino-2-methyl-1-propanol + water) systems were studied. The total amine mass percent in all cases was 30. A solubility apparatus was used to measure the solubility of N{sub 2}O in amine solutions. The diffusivity was measured by a wetted wall column absorber. The N{sub 2}O analogy was used to estimate the solubility and diffusivity of CO{sub 2} in (diethanolamine + N-methyldiethanolamine + water) and in (diethanolamine + 2-amino-2-methyl-1-propanol + water).

  16. Solubility and diffusivity of N{sub 2}O and CO{sub 2} in (monoethanolamine + N-methyldiethanolamine + water) and in (monoethanolamine + 2-amino-2-methyl-1-propanol + water)

    SciTech Connect

    Li, M.H.; Lai, M.D.

    1995-03-01

    Solutions of amines are frequently used in gas-treating processes to remove acid 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 solubility and diffusivity of N{sub 2}O in (monoethanolamine + N-methyldiethanolamine + water) and in (monoethanolamine + 2-amino-2-methyl-l-propanol + water) were measured at 30, 35, and 40 C and at atmospheric pressure. Six (monoethanolamine + N-methyldiethanolamine + water) and five (monoethanolamine + 2-amino-2-methyl-l-propanol + water) systems were studied. The total amine mass percent in all cases was 30. The solubilities were measured by a solubility apparatus similar to that of Haimour and Sandall (1984). A wetted wall column absorber was used to obtain the diffusivity of N{sub 2}O in amines. The N{sub 2}O solubilities in amine solutions have been correlated on the basis of the excess Henry constant correlation of Wang et al. (1992). The N{sub 2}O analogy was used to estimate the solubility and diffusivity of CO{sub 2} in (monoethanolamine + N-methyldiethanolamine + water) and in (monoethanolamine + 2-amino-2-methyl-l-propanol + water).

  17. Biochip array technology immunoassay performance and quantitative confirmation of designer piperazines for urine workplace drug testing.

    PubMed

    Castaneto, Marisol S; Barnes, Allan J; Concheiro, Marta; Klette, Kevin L; Martin, Thomas A; Huestis, Marilyn A

    2015-06-01

    Designer piperazines are emerging novel psychoactive substances (NPS) with few high-throughput screening methods for their identification. We evaluated a biochip array technology (BAT) immunoassay for phenylpiperazines (PNP) and benzylpiperazines (BZP) and analyzed 20,017 randomly collected urine workplace specimens. Immunoassay performance at recommended cutoffs was evaluated for PNPI (5 μg/L), PNPII (7.5 μg/L), and BZP (5 μg/L) antibodies. Eight hundred forty positive and 206 randomly selected presumptive negative specimens were confirmed by liquid chromatography high-resolution mass spectrometry (LC-HRMS). Assay limits of detection for PNPI, PNPII, and BZP were 2.9, 6.3, and 2.1 μg/L, respectively. Calibration curves were linear (R (2) > 0.99) with upper limits of 42 μg/L for PNPI/PNII and 100 μg/L for BZP. Quality control samples demonstrated imprecision <19.3 %CV and accuracies 86.0-94.5 % of target. There were no interferences from 106 non-piperazine substances. Seventy-eight of 840 presumptive positive specimens (9.3 %) were LC-HRMS positive, with 72 positive for 1-(3-chlorophenyl)piperazine (mCPP), a designer piperazine and antidepressant trazodone metabolite. Of 206 presumptive negative specimens, one confirmed positive for mCPP (3.3 μg/L) and one for BZP (3.6 μg/L). BAT specificity (21.1 to 91.4 %) and efficiency (27.0 to 91.6 %) increased, and sensitivity slightly decreased (97.5 to 93.8 %) with optimized cutoffs of 25 μg/L PNPI, 42 μg/L PNPI, and 100 μg/L BZP. A high-throughput screening method is needed to identify piperazine NPS. We evaluated performance of the Randox BAT immunoassay to identify urinary piperazines and documented improved performance when antibody cutoffs were raised. In addition, in randomized workplace urine specimens, all but two positive specimens contained mCPP and/or trazodone, most likely from legitimate medical prescriptions. Graphical Abstract Biochip array technology (BAT) immunoassay for designer piperazines

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

    SciTech Connect

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

    2007-06-28

    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.

  19. Rate-based modeling of reactive absorption of CO{sub 2} and H{sub 2}S into aqueous methyldiethanolamine

    SciTech Connect

    Pacheco, M.A.; Rochelle, G.T.

    1998-10-01

    A general framework was developed to model the transport processes that take place during reactive absorption when both rate- and equilibrium-controlled reactions occur in the liquid phase. This framework was applied to the selective absorption of H{sub 2}S from fuel gas containing CO{sub 2} using aqueous methyldiethanolamine. A rate-based distillation column module was used for the column integration. The Maxwell-Stefan and enhancement factor theories were utilized. In packed columns, CO{sub 2} absorption is controlled by diffusion with fast chemical reactions; in trayed columns it is controlled primarily by physical absorption. Gas-film resistance is never significant for CO{sub 2} absorption. For H{sub 2}S absorption, gas- and liquid-film resistances are important, and diffusion of bisulfide controls the liquid-film resistance. Heat effects produce temperatures bulges that can cause equilibrium pinches at the maximum temperature. This phenomenon gives an optimum packing height for the H{sub 2}S removal. Trayed columns are more selective than packed columns for H{sub 2}S removal, primarily because of the larger number of liquid-film mass transfer units.

  20. Ozonation of piperidine, piperazine and morpholine: Kinetics, stoichiometry, product formation and mechanistic considerations.

    PubMed

    Tekle-Röttering, Agnes; Jewell, Kevin S; Reisz, Erika; Lutze, Holger V; Ternes, Thomas A; Schmidt, Winfried; Schmidt, Torsten C

    2016-01-01

    Piperidine, piperazine and morpholine as archetypes for secondary heterocyclic amines, a structural unit that is often present in pharmaceuticals (e.g., ritalin, cetirizine, timolol, ciprofloxacin) were investigated in their reaction with ozone. In principle the investigated compounds can be degraded with ozone in a reasonable time, based on their high reaction rate constants with respect to ozone (1.9 × 10(4)-2.4 × 10(5) M(-1) s(-1)). However, transformation is insufficient (13-16%), most likely due to a chain reaction, which decomposes ozone. This conclusion is based on OH scavenging experiments, leading to increased compound transformation (18-27%). The investigated target compounds are similar in their kinetic and stoichiometric characteristics. However, the mechanistic considerations based on product formation indicate various reaction pathways. Piperidine reacts with ozone via a nonradical addition reaction to N-hydroxypiperidine (yield: 92% with and 94% without scavenging, with respect to compound transformation). However, piperazine degradation with ozone does not lead to N-hydroxypiperazine. In the morpholine/ozone reaction, N-hydroxymorpholine was identified. Additional oxidation pathways in all cases involved the formation of OH with high yields. One important pathway of piperazine and morpholine by ozonation could be the formation of C-centered radicals after ozone or OH radical attack. Subsequently, O2 addition forms unstable peroxyl radicals, which in one pathway loose superoxide radicals by generating a carbon-centered cation. Subsequent hydrolysis of the carbon-centered cation leads to formaldehyde, whereby ozonation of the N-hydroxy products can proceed in the same way and in addition give rise to hydroxylamine. A second pathway of the short-lived peroxyl radicals could be a dimerization to form short-lived tetraoxides, which cleave by forming hydrogen peroxide. All three products have been found. PMID:26624229

  1. Design, synthesis and anticancer activity of novel hybrid compounds between benzofuran and N-aryl piperazine.

    PubMed

    Mao, Ze-Wei; Zheng, Xi; Lin, Yu-Ping; Hu, Chun-Yan; Wang, Xiu-Li; Wan, Chun-Ping; Rao, Gao-Xiong

    2016-08-01

    A series of novel hybrid compounds between benzofuran and N-aryl piperazine have been designed and prepared. These derivatives were evaluated for their in vitro anti-tumor activity against a panel of human tumor cell lines by MTT assay. The results demonstrated that amide derivatives were more bioactive than sulfonamide compounds in general, and that chloro or trifluoromethyl substituent was vital for modulating cytotoxic activity. In particular, compound 13 was found to be the most potent compound against 4 strains human tumor cell lines, and exhibited cytotoxic activity selectively against Hela (0.03μM). PMID:27371110

  2. 1-Methyl­piperazine-1,4-dium bis­(hydrogen oxalate)

    PubMed Central

    Essid, Manel; Marouani, Houda; Rzaigui, Mohamed

    2014-01-01

    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. PMID:24765024

  3. (4-(Bis(4-Fluorophenyl)Methyl)Piperazin-1-yl)(Cyclohexyl)Methanone Hydrochloride (LDK1229): A New Cannabinoid CB1 Receptor Inverse Agonist from the Class of Benzhydryl Piperazine Analogs

    PubMed Central

    Mahmoud, Mariam M.; Olszewska, Teresa; Liu, Hui; Shore, Derek M.; Hurst, Dow P.; Reggio, Patricia H.; Lu, Dai

    2015-01-01

    Some inverse agonists of cannabinoid receptor type 1 (CB1) have been demonstrated to be anorectic antiobesity drug candidates. However, the first generation of CB1 inverse agonists, represented by rimonabant (SR141716A), otenabant, and taranabant, are centrally active, with a high level of psychiatric side effects. Hence, the discovery of CB1 inverse agonists with a chemical scaffold distinct from these holds promise for developing peripherally active CB1 inverse agonists with fewer side effects. We generated a new CB1 inverse agonist, (4-(bis(4-fluorophenyl)methyl)piperazin-1-yl)(cyclohexyl)methanone hydrochloride (LDK1229), from the class of benzhydryl piperazine analogs. This compound binds to CB1 more selectively than cannabinoid receptor type 2, with a Ki value of 220 nM. Comparable CB1 binding was also observed by analogs 1-[bis(4-fluorophenyl)methyl]-4-cinnamylpiperazine dihydrochloride (LDK1203) and 1-[bis(4-fluorophenyl)methyl]-4-tosylpiperazine hydrochloride (LDK1222), which differed by the substitution on the piperazine ring where the piperazine of LDK1203 and LDK1222 are substituted by an alkyl group and a tosyl group, respectively. LDK1229 exhibits efficacy comparable with SR141716A in antagonizing the basal G protein coupling activity of CB1, as indicated by a reduction in guanosine 5′-O-(3-thio)triphosphate binding. Consistent with inverse agonist behavior, increased cell surface localization of CB1 upon treatment with LDK1229 was also observed. Although docking and mutational analysis showed that LDK1229 forms similar interactions with the receptor as SR141716A does, the benzhydryl piperazine scaffold is structurally distinct from the first-generation CB1 inverse agonists. It offers new opportunities for developing novel CB1 inverse agonists through the optimization of molecular properties, such as the polar surface area and hydrophilicity, to reduce the central activity observed with SR141716A. PMID:25411367

  4. Synthesis and characterization of a disubstituted piperazine derivative with T-type channel blocking action and analgesic properties

    PubMed Central

    Pudukulatham, Zubaidha; Zhang, Fang-Xiong; Gadotti, Vinicius M; M’Dahoma, Said; Swami, Prabhuling; Tamboli, Yasinalli

    2016-01-01

    Background T-type calcium channels are important contributors to signaling in the primary afferent pain pathway and are thus important targets for the development of analgesics. It has been previously reported that certain piperazine-based compounds such as flunarizine are able to inhibit T-type calcium channels. Thus, we hypothesized that novel piperazine compounds could potentially act as analgesics. Results Here, we have created a series of 14 compound derivatives around a diphenyl methyl-piperazine core pharmacophore. Testing their effects on transiently expressed Cav3.2 calcium channels revealed one derivative (3-((4-(bis(4-fluorophenyl)methyl)piperazin-1-yl)methyl)-4-(2-methoxyphenyl)-1,2,5-oxadiazole 2-oxide, compound 10e) as a potent blocker. 10e mediate tonic block of these channels with an IC50 of around 4 micromolar. 10e also blocked Cav3.1 and Cav3.3 channels, but only weakly affected high-voltage-activated Cav1.2 and Cav2.2 channels. Intrathecal delivery of 10e mediated relief from formalin and complete Freund’s adjuvant induced inflammatory pain that was ablated by genetic knockout of Cav3.2 channels. Conclusions Altogether, our data identify a novel T-type calcium channel blocker with tight structure activity relationship (SAR) and relevant in vivo efficacy in inflammatory pain conditions. PMID:27053601

  5. Excretion of N-mononitrosopiperazine after low level exposure to piperazine in air: effects of dietary nitrate and ascorbate

    SciTech Connect

    Bellander, T.; Osterdahl, B.G.; Hagmar, L.

    1988-04-01

    The secondary amine piperazine may be nitrosated in vivo, following oral intake or occupational exposure by inhalation. The suspected carcinogen N-mononitrosopiperazine could be formed in the human stomach, and in part excreted in the urine. In this study, 0.4 microgram N-mononitrosopiperazine, determined by gas chromatography-Thermal Energy Analysis, was observed in the urine in one of four volunteers, at an experimental exposure by inhalation of 0.3 mg piperazine/m3. The intake of spinach and beetroot caused an increased nitrosation of piperazine, and up to 1.7 microgram N-mononitrosopiperazine was excreted in the urine in the four individuals. This excretion indicates that about 5% of the absorbed piperazine dose was converted to N-mononitrosopiperazine. With the same nitrate-rich diet, but with the addition of citrus fruits and fresh vegetables, the highest excretion was 0.6 microgram N-mononitrosopiperazine. The excretion was significantly correlated with the ratio between the maximum level of nitrite in saliva and the ascorbate level in plasma. There was also a significant interindividual variation. N,N'-Dinitrosopiperazine was not found in any sample of urine.

  6. Nitrosamine formation in amine scrubbing at desorber temperatures.

    PubMed

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

    2014-01-01

    Amine scrubbing is a thermodynamically efficient and industrially proven method for carbon capture, but amine solvents can nitrosate in the desorber, forming potentially carcinogenic nitrosamines. The kinetics of reactions involving nitrite and monoethanolamine (MEA), diethanolamine (DEA), methylethanolamine (MMEA), and methyldiethanolamine (MDEA) were determined under desorber conditions. The nitrosations of MEA, DEA, and MMEA are first order in nitrite, carbamate species, and hydronium ion. Nitrosation of MDEA, a tertiary amine, is not catalyzed by the addition of CO2 since it cannot form a stable carbamate. Concentrated and CO2 loaded MEA was blended with low concentrations of N-(2-hydroxyethyl) glycine (HeGly), hydroxyethyl-ethylenediamine (HEEDA), and DEA, secondary amines common in MEA degradation. Nitrosamine yield was proportional to the concentration of secondary amine and was a function of CO2 loading and temperature. Blends of tertiary amines with piperazine (PZ) showed n-nitrosopiperazine (MNPZ) yields close to unity, validating the slow nitrosation rates hypothesized for tertiary amines. These results provide a useful tool for estimating nitrosamine accumulation over a range of amine solvents. PMID:24956458

  7. Copper(I) cyanide networks: synthesis, structure, and luminescence behavior. Part 2. Piperazine ligands and hexamethylenetetramine.

    PubMed

    Lim, Mi Jung; Murray, Courtney A; Tronic, Tristan A; deKrafft, Kathryn E; Ley, Amanda N; deButts, Jordan C; Pike, Robert D; Lu, Haiyan; Patterson, Howard H

    2008-08-01

    A variety of photoluminescent, and in some cases thermochromic, metal-organic networks of CuCN were self-assembled in aqueous reactions with amine ligands: (CuCN) 2(Pip) ( 1a), (CuCN) 20(Pip) 7 ( 1b), (CuCN) 7(MePip) 2 ( 2), (CuCN) 2(Me 2Pip) ( 3a), (CuCN) 4(Me 2Pip) ( 3b), (CuCN) 7(EtPip) 2 ( 4), (CuCN) 4(Et 2Pip) ( 5), (CuCN) 3(BzPip) 2 ( 6a), (CuCN) 5(BzPip) 2 ( 6b), (CuCN) 7(BzPip) 2 ( 6c), (CuCN) 4(BzPip) ( 6d), (CuCN) 2(Bz 2Pip) ( 7), (CuCN)(Ph 2CHPip) ( 8a), (CuCN) 2(Ph 2CHPip) ( 8b), (CuCN) 3(HMTA) 2 ( 9a), (CuCN) 5(HMTA) 2 ( 9b), and (CuCN) 5(HMTA) ( 9c) (Pip = piperazine, MePip = N-methylpiperazine, Me 2Pip = N, N'-dimethylpiperazine, EtPip = N-ethylpiperazine, Et 2Pip = N, N'-diethylpiperazine, BzPip = N-benzylpiperazine, Bz 2Pip = N, N'-dibenzylpiperazine, Ph 2CHPip = N-(diphenylmethyl)piperazine, and HMTA = hexamethylenetetramine). New X-ray structures are reported for 1b, 2, 3b, 4, 5, 6a, 6d, 7, 8b, 9b, and 9c. An important structural theme is the formation of (6,3) (CuCN) 2(piperazine) sheets with or without threading of independent CuCN chains. Strong luminescence at ambient temperature is observed for all but complexes 6 and 7. All luminescent compounds show a broad emission band in the blue region at about 450 nm attributable to metal-to-ligand charge transfer behavior based on the large Stokes shift between excitation and emission maxima. 3, 8, and 9 are thermochromic due to an additional lower energy emission band, which is absent at 77 K. PMID:18597424

  8. Enantiomeric separation and quantitation of (+/-)-amphetamine, (+/-)-methamphetamine, (+/-)-MDA, (+/-)-MDMA, and (+/-)-MDEA in urine specimens by GC-EI-MS after derivatization with (R)-(-)- or (S)-(+)-alpha-methoxy-alpha-(trifluoromethy)phenylacetyl chloride (MTPA).

    PubMed

    Paul, Buddha D; Jemionek, John; Lesser, David; Jacobs, Aaron; Searles, Douglas A

    2004-09-01

    In drug testing, the presence of methamphetamine in urine is generally confirmed by a gas chromatography-mass spectrometry (GC-MS) method. Derivatization of the compound to a perfluoroalkylamide, prior to confirmation, typically yields better chromatographic separation. Once methamphetamine is detected, a second GC-MS test is necessary to distinguish positive results from the use of over-the-counter medication, Vicks inhaler, or from use of a prescription drug, selegiline (Deprenyl). R-(-)-Methamphetamine is the urinary product from legitimate use of these medications. The second GC-MS test is to confirm illicit use of (S)-(+)-methamphetamine. In the procedure, the two methamphetamine isomers are changed to the chromatographically separable diastereomers by a chiral derivatizing agent, (S)-(-)-trifluoroacetylprolyl chloride (TPC). But the method has inherent limitations. Racemization of the reagent produces mixed diastereomers even from pure (S)-(+)-methamphetamine. Instead of using TPC, we utilized (R)-(-)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetyl chloride (MTPA) to prepare the amides of diastereomers of methamphetamine. No racemization was observed with this reagent. The method was extended to resolve GC peaks of (R)-(-)- and (S)-(+)-isomers of amphetamine, 3,4-methylenedioxyamphetamine (MDA), N-methyl-MDA (MDMA), and N-ethyl-MDA (MDEA). Three ions from the drug and two ions from the deuterated internal standard were monitored to characterize and quantitate the drugs. For MDEA, only one ion was used. The quantitation was linear over 25 to 5000 ng/mL for MDEA and 25 to 10,000 ng/mL for all other drugs. Correlation coefficients were > 0.996. Precision calculated as the coefficient of variation at the calibrator concentration of 500 ng/mL was within +/- 11% for all drugs. The method was applied to test 43 urine specimens. In 91% of the methamphetamine-positive specimens, only the (S)-(+)-isomer was detected. In all MDMA-positive specimens, the concentrations

  9. Hypophagic and hypolocomotive effects of metachloro phenyl piperazine in rats treated with theophylline and caffeine.

    PubMed

    Alam, Nausheen; Haleem, Darakshan Jabeen; Najam, Rahila; Haider, Syeda; Ahmed, Shahida Perveen

    2011-07-01

    Long term intake of coffee is known to produce anxiety and suppression of appetite. 5- hydroxytryptamine (5-HT) acting via 5-HT-2C receptors elicits anorexia and anxiety. The present study is design to monitor metachloro phenyl piperazine (m-CPP) at a dose of 3mg/ml/kg, induces hypophagia and hypolocomotion in rats taking a solution of caffeine (a component of coffee and tea) or theophylline (a component of tea) as a sole source of water. We found that hypophagic and hypolocomotive effects of m-CPP were attenuated in theophylline but not in caffeine treated animals suggesting that long term intake of theophylline may attenuate anorexiogenic and anxiogenic effects of 5-HT. A possible role of 5-HT-2C receptors in the modulation of anxiety and appetite in people drinking coffee or tea discussed. PMID:21715256

  10. Structure characterization of 1:1 adducts of metal(II) halides and piperazine

    SciTech Connect

    Yu Jiehui Hou Qin; Wang Tiegang; Zhang Xiao; Xu Jiqing

    2007-02-15

    From the simple hydro/solvothermal reactions, two 1:1 adducts of MX{sub 2} and piperazine (pip) [CdI{sub 2}(pip)] 1 and [CoCl{sub 2}(pip)] 2 were prepared. Both were characterized by elemental analyses, IR spectra, ultra-violet visible spectra, thermogravimetric analyses and X-ray single-crystal diffraction. With pip as the bridges, the 1-D linear CdI{sub 2} chains are extended into a 2-D layered compound 1, while the mononuclear CoCl{sub 2} units are linked into a 1-D zigzag-type chain compound 2. The fluorescence emission spectrum indicates that compound 1 possesses fluorescence property with the peaks at 373nm ({lambda}{sub ex}=212nm) and 410nm ({lambda}{sub ex}=293nm)

  11. Atrazine removal by covalent bonding to piperazine functionalized PolyHIPEs.

    PubMed

    Pulko, Irena; Kolar, Mitja; Krajnc, Peter

    2007-11-01

    The removal of atrazine from water by a solid phase extraction technique using insoluble polymers is described. Porous crosslinked polymers bearing piperazine moieties were prepared in a one step reaction from the precursor 4-nitrophenylacrylate incorporating polymers (PolyHIPE type prepared by the polymerization of the continuous phase of a high internal phase emulsion and polymer beads prepared by suspension polymerization). Polymers were applied to sequester atrazine from aqueous solutions with a concentration of 33 ppb and irreversible covalent bonding to the polymers was achieved. GC/MS/MS was used to monitor the dynamics of atrazine uptake and it was found that almost complete removal of atrazine was accomplished with an excess of polymer after 48 hours at room temperature. For comparison, polymer beads of identical chemistry but lower porosity were also used and showed significantly slower action (near complete removal after 72 hours). PMID:17662371

  12. [Synthesis and bioactivities of novel dihydroartemisinin-piperazine derivatives containing sulfonamide].

    PubMed

    Ma, Chao; Li, Xue-qiang; Xu, Jian; Chen, Cou-xi

    2013-09-01

    Dihydroartemisinin is an important derivative of artemisinin. We used dihydroartemisinin as the starting material, through esterification, amination and acylation, a series of novel piperazine-sulfonamide contained dihydroartemisinin derivatives were firstly synthesized and their chemical structures were confirmed by IR, 1H NMR, 13C NMR and HR-MS. X-diffraction was used to determine the final configuration of the compound 3c. And the in vitro anti-HeLa activities of compounds 3 were analyzed with CCK-8 method. The preliminary bioassay test shows that compound 3 showed the best inhibition activities against HeLa with IC50 values of 0.14 micromol x L(-1). PMID:24358777

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

    PubMed Central

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

    2013-01-01

    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. PMID:23308267

  14. Synthesis and pharmacological evaluation of piperidine (piperazine)-substituted benzoxazole derivatives as multi-target antipsychotics.

    PubMed

    Huang, Ling; Zhang, Wenjun; Zhang, Xiaohua; Yin, Lei; Chen, Bangyin; Song, Jinchun

    2015-11-15

    The present study describes the optimization of a series of novel benzoxazole-piperidine (piperazine) derivatives combining high dopamine D2 and serotonin 5-HT1A, 5-HT2A receptor affinities. Of these derivatives, the pharmacological features of compound 29 exhibited high affinities for the DA D2, 5-HT1A and 5-HT2A receptors, but low affinities for the 5-HT2C and histamine H1 receptors and human ether-a-go-go-related gene (hERG) channels. Furthermore, compound 29 reduced apomorphine-induced climbing and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced head twitching without observable catalepsy, even at the highest dose tested. Thus, compound 29 is a promising candidate as a multi-target antipsychotic treatment. PMID:26483200

  15. LC-MS/MS screening method for designer amphetamines, tryptamines, and piperazines in serum.

    PubMed

    Wohlfarth, Ariane; Weinmann, Wolfgang; Dresen, Sebastian

    2010-04-01

    Since the late 1990s and early 2000s, derivatives of well-known designer drugs as well as new psychoactive compounds have been sold on the illicit drug market and have led to intoxications and fatalities. The LC-MS/MS screening method presented covers 31 new designer drugs as well as cathinone, methcathinone, phencyclidine, and ketamine which were included to complete the screening spectrum. All but the last two are modified molecular structures of amphetamine, tryptamine, or piperazine. Among the amphetamine derivatives are cathinone, methcathinone, 3,4-DMA, 2,5-DMA, DOB, DOET, DOM, ethylamphetamine, MDDMA, 4-MTA, PMA, PMMA, 3,4,5-TMA, TMA-6 and members of the 2C group: 2C-B, 2C-D, 2C-H, 2C-I, 2C-P, 2C-T-2, 2C-T-4, and 2C-T-7. AMT, DPT, DiPT, MiPT, DMT, and 5MeO-DMT are contained in the tryptamine group, BZP, MDBP, TFMPP, mCPP, and MeOPP in the piperazine group. Using an Applied Biosystems LC-MS/MS API 365 TurboIonSpray it is possible to identify all 35 substances. After addition of internal standards and mixed-mode solid-phase extraction the analytes are separated using a Synergi Polar RP column and gradient elution with 1 mM ammonium formate and methanol/0.1% formic acid as mobile phases A and B. Data acquisition is performed in MRM mode with positive electro spray ionization. The assay is selective for all tested substances. Limits of detection were determined by analyzing S/N-ratios and are between 1.0 and 5.0 ng/mL. Matrix effects lie between 65% and 118%, extraction efficiencies range from 72% to 90%. PMID:20069283

  16. Piperazine as counter ion for insulin-enhancing anions [VO2(dipic-OH)]-: Synthesis, characterization and X-ray crystal structure

    NASA Astrophysics Data System (ADS)

    Ghasemi, Fatemeh; Ghasemi, Khaled; Rezvani, Ali Reza; Graiff, Claudia

    2016-01-01

    The new complex [H2Pipz][VO2(dipic-OH)]2·2H2O (1), where H2dipic-OH = 4-hydroxypyridine-2,6-dicarboxylic acid and Pipz = piperazine, was synthesized and characterized by elemental analysis, FTIR, 1H NMR, 13C NMR and UV-Vis spectroscopy and single crystal X-ray diffraction. The crystal system is triclinic with space group Pī. In this compound, piperazine is diprotonated and acts as counter ion.

  17. Synthesis, alpha-adrenoceptors affinity and alpha 1-adrenoceptor antagonistic properties of some 1,4-substituted piperazine derivatives.

    PubMed

    Marona, H; Kubacka, M; Filipek, B; Siwek, A; Dybała, M; Szneler, E; Pociecha, T; Gunia, A; Waszkielewicz, A M

    2011-10-01

    A series of different 1,4-substituted piperazine derivatives (1-11) was synthesized. It comprised 1-(substituted-phenoxyalkyl)-4-(2-methoxyphenyl)piperazine derivatives (1-5); 1,4-bis(substituted-phenoxyethyl)piperazine derivatives (6-8) and 1-(substituted-phenoxy)-3-(substituted-phenoxyalkylpiperazin-1-yl)propan-2-ol derivatives (9-11). All compounds were evaluated for affinity toward alpha 1- and alpha 2-receptors by radioligand binding assays on rat cerebral cortex using [3H]prazosin and [3H]clonidine as specific radioligand, respectively. Furthermore alpha 1-antagonistic properties were checked for most promising compounds (1-5 and 10) by means of inhibition of phenylephrine induced contraction in isolated rat aorta. Antagonistic potency stayed in agreement with radioligand binding results. The most active compounds (1-5) displaced [3H]prazosin from cortical binding sites in low nanomolar range (Ki = 2.1-13.1 nM). Compound 10 showed slightly lower affinity for alpha 1-adrenoceptor (Ki = 781 nM). Compounds 2-5 displayed the strongest antagonistic activity with pA2 values ranging from 8.441 to 8.807. Compound 1 gave a pA2 value of 7.868, while compound 10 showed the weakest antagonistic potency, giving a pA2 value of 6.374. 1-[3-(2-Chloro-6-methylphenoxy)propyl]-4-(2-methoxyphenyl)piperazine hydrochloride (5) showed the best alpha 1- affinity properties with a Ki(alpha 1) value of 2.1 nM and it was 61.05 fold more selective toward alpha 1 than alpha 2-receptors. The best properties showed 1-[3-(2,6-dimethylphenoxy)propyl]-4-(2-methoxyphenyl)piperazine hydrochloride (4) with a Ki(alpha 1) value of 2.4 nM, a 142.13 fold better selectivity to alpha 1 - over alpha 2-adrenoceptors and the best antagonistic potency (pA2 = 8.807). It is worth to emphasized that all most promising compounds possessed an 1-(o-methoxyphenyl)piperazine moiety which probably plays an important role in the affinity to alpha-adrenoceptors. PMID:22026152

  18. DFT Study of Solvent Effects on Conformational Equilibria and Vibrational Spectra of 4-(1-PYRROLIDINYL)PIPERAZINE

    NASA Astrophysics Data System (ADS)

    Baglayan, O.; Kesan, G.; Parlak, C.; Senyel, M.

    2012-06-01

    The optimized structural parameters (bond lengths, bond and dihedral angles), conformational equilibria and normal mode frequencies and corresponding vibrational assignments of 4-(1-Pyrrolidinyl)piperazine (4-pypp) have been examined by means of B3LYP hybrid density functional theory (DFT) method with 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have made on the basis of potential energy distribution (PED) calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 4-pypp (C_8H17N_3) have been predicted. Calculations are employed for different conformations of 4-pypp both in gas phase and in solution. Solvent effects are investigated using chloroform and dimethylsulfoxide. Results from the theoretical values are showed that the structural parameters, mole fractions of stable conformers, vibrational frequencies, IR intensities and Raman activities of 4-pypp are solvent dependent. {Keywords}: 4-(1-Pyrrolidinyl)piperazine, vibrational spectra, solvent effect, DFT.

  19. Synthesis and antioxidant activity of some 1-aryl/aralkyl piperazine derivatives with xanthine moiety at N4

    PubMed Central

    Andonova, Lily; Zheleva-Dimitrova, Dimitrina; Georgieva, Maya; Zlatkov, Alexander

    2014-01-01

    Piperazine nucleus is one of the most important heterocyclic systems exhibiting remarkable pharmacological activities. Thus, in the current study six new aryl/aralkyl substituted piperazine derivatives, containing methylxanthine moiety were synthesized and their structures were confirmed by IR and 1H NMR analysis. All compounds were in vitro screened for their activity as antioxidants using DPPH (2,2′-Diphenyl-1-picrylhydrazyl), ABTS (2,2′-azinobis-(3-ethylbenzo thiazine-6-sulfonic acid)) and FRAP (ferric reducing/antioxidant power) methods. The antioxidant activity of the studied compounds against lipid peroxidation was also measured. The highest antioxidant activity was demonstrated by compound 3c. It is obvious that the presence of a hydroxyl group in the structure is essential for the antioxidant properties and should be taken into consideration in further design of structures with potential antioxidant properties. PMID:26019603

  20. Solubility of carbon dioxide in aqueous mixtures of alkanolamines

    SciTech Connect

    Dawodu, O.F.; Meisen, A. . Dept. of Chemical Engineering)

    1994-07-01

    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.

  1. Effects of gepirone, an aryl-piperazine anxiolytic drug, on aggressive behavior and brain monoaminergic neurotransmission.

    PubMed

    McMillen, B A; Scott, S M; Williams, H L; Sanghera, M K

    1987-04-01

    Gepirone (BMY 13805), a buspirone analog, was used to determine the antianxiety mechanism of the arylpiperazine class of drugs. Because of the weak effects of these drugs on conflict behavior, isolation-induced aggressive mice were used as the antianxiety model. Gepirone, like buspirone, potently inhibited attacks against group housed intruder mice (ED50 = 4.5 mg/kg i.p.) without causing sedation or ataxia. Inhibition of aggression was potentiated by co-administration of 0.25 mg/kg methiothepin or 2.5 mg/kg methysergide. Gepirone had variable effects on dopamine metabolism and reduced 5-hydroxytryptamine (5HT) metabolism about one third after a dose of 2.5 mg/kg. In contrast to buspirone, which markedly increased dopaminergic impulse flow, gepirone inhibited the firing of most cells recorded from the substantia nigra zona compacta in doses of 2.3-10 mg/kg i.v. and the effects were reversible by administration of haloperidol. The common metabolite of buspirone and gepirone, 1-(2-pyrimidinyl)-piperazine, caused increased firing rates only. Gepirone potently inhibited serotonergic impulse flow recorded from the dorsal raphe nucleus (88.3% after 0.04 mg/kg) and this effect was partially reversed by serotonergic antagonists. Both buspirone and gepirone displaced [3H]-5HT from the 5HT1a binding site in the hippocampus with IC50 values of 10 and 58 nM, respectively. Non-alkyl substituted aryl-piperazines displaced [3H]-5HT from both 5HT1a and 5HT1b binding sites. Thus, although gepirone may be a weak postsynaptic 5HT agonist, its primary effect is to decrease 5HT neurotransmission. In support of this conclusion was the observed potentiation of antiaggressive effects by blocking 5HT receptors wit small doses of methiothepin or methysergide, which would exacerbate the decreased release of 5HT caused by gepirone. These results are in harmony with reports that decreased serotonergic activity has anxiolytic-like effects in animal models of anxiety. PMID:2439924

  2. Efficacy and safety of Linkus, Aminophylline diphenhydramine and acefyllin piperazine for the treatment of cough in children.

    PubMed

    Rehman, Hina; Naveed, Safila; Usmanghani, Khan

    2016-05-01

    To evaluate the safety and efficacy of Linkus, Aminophylline with Diphenhydramine group and Acefyllin Piperazine with Diphenhydramine cough syrup on children having cough and sleep difficulty associated with cough. To determine the effects of Linkus polyherbal syrup (group A) and compared with other parallel allopathic groups (Group B and C) for cough on children and associated sleep quality and improvement. 360 children having cough inducted in 3 different groups randomly selected. Three parallel groups were the part of the study. The first study group was the herbal syrup Linkus, second group of children were taking a syrup of multinational pharmaceutical industry having Aminophylline plus Diphenhydramine however the third group received another famous brand having Acefyllin Piperazine with Diphenhydramine. Informed assent and informed consent have taken from the study subjects and their parents. Subjects with acute cough were included in the study however the subjects with chronic cough considered to be excluded. Every group of individual in the study was informed about the investigational drugs provided. Ethnic groups, frequency of cough and diseases illness (<0.05) were determine on every group on the investigational syrup. Cough impact on child and its sleep of three different syrups (every group) were assessed on day1 and day 14(p<0.001) via a likert scale. For the evaluation of pain assessment Wong baker face scale were used and level of significance in each group (p<0.001). Significant results were observed in the Linkus Group as compared to the other parallel groups including Aminophylline plus Diphenhydramine and Acefyllin Piperazine with Diphenhydramine on day 14 (p<0.001). Side effects on group B and group C (Aminophylline with Diphenhydramine and Acefyllin Piperazine with Diphenhydramine) were almost similar in number however Linkus syrup has minimum side effects on study duration. Polyherbal syrup Linkus shows better results in treatment of cough

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

    SciTech Connect

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

    1993-12-01

    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.

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

    SciTech Connect

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

    1992-12-01

    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 %.

  5. Charge-transfer complexes of 1-(2-aminoethyl) piperazine with σ- and π-acceptors

    NASA Astrophysics Data System (ADS)

    Mostafa, Adel; Bazzi, Hassan S.

    2010-11-01

    The solid charge-transfer (CT) molecular complexes formed in the reaction of 1-(2-aminoethyl) piperazine (AEPIP) with the σ-acceptor iodine and π-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 ɛCT, free energy change Δ G0 and CT energy ECT have been calculated for the CT-complexes [(AEPIP)(DDQ) 2], [(AEPIP)(TCNQ) 2] and [(AEPIP)(CHL)] as well.

  6. Novel piperazine core compound induces death in human liver cancer cells: possible pharmacological properties.

    PubMed

    Samie, Nima; Muniandy, Sekaran; Kanthimathi, M S; Haerian, Batoul Sadat; Raja Azudin, Raja Elina

    2016-01-01

    The current study evaluates the cytotoxic mechanism of a novel piperazine derivate designated as PCC against human liver cancer cells. In this context, human liver cancer cell lines, SNU-475 and 243, human monocyte/macrophage cell line, CRL-9855, and human B lymphocyte cell line, CCL-156, were used to determine the IC50 of PCC using the standard MTT assay. PCC displayed a strong suppressive effect on SNU-475 and SNU-423 cells with an IC50 value of 6.98 ± 0.11 μg/ml and 7.76 ± 0.45 μg/ml respectively, after 24 h of treatment. Significant dipping in the mitochondrial membrane potential and elevation in the released of cytochrome c from the mitochondria indicated the induction of the intrinsic apoptosis pathway by PCC. Activation of this pathway was further evidenced by significant activation of caspase 3/7 and 9. PCC was also shown to activate the extrinsic pathways of apoptosis via activation of caspase-8 which is linked to the suppression of NF-ƙB translocation to the nucleus. Cell cycle arrest in the G1 phase was confirmed by flow cytometry and up-regulation of glutathione reductase expression was quantified by qPCR. This study suggests that PCC is a simultaneous inducer of intrinsic and extrinsic pathways of apoptosis in liver cancer cell lines. PMID:27072064

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

    SciTech Connect

    Nainar, M.; Veawab, A.

    2009-10-15

    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}.

  8. Novel piperazine core compound induces death in human liver cancer cells: possible pharmacological properties

    PubMed Central

    Samie, Nima; Muniandy, Sekaran; Kanthimathi, M. S.; Haerian, Batoul Sadat; Raja Azudin, Raja Elina

    2016-01-01

    The current study evaluates the cytotoxic mechanism of a novel piperazine derivate designated as PCC against human liver cancer cells. In this context, human liver cancer cell lines, SNU-475 and 243, human monocyte/macrophage cell line, CRL-9855, and human B lymphocyte cell line, CCL-156, were used to determine the IC50 of PCC using the standard MTT assay. PCC displayed a strong suppressive effect on SNU-475 and SNU-423 cells with an IC50 value of 6.98 ± 0.11 μg/ml and 7.76 ± 0.45 μg/ml respectively, after 24 h of treatment. Significant dipping in the mitochondrial membrane potential and elevation in the released of cytochrome c from the mitochondria indicated the induction of the intrinsic apoptosis pathway by PCC. Activation of this pathway was further evidenced by significant activation of caspase 3/7 and 9. PCC was also shown to activate the extrinsic pathways of apoptosis via activation of caspase-8 which is linked to the suppression of NF-ƙB translocation to the nucleus. Cell cycle arrest in the G1 phase was confirmed by flow cytometry and up-regulation of glutathione reductase expression was quantified by qPCR. This study suggests that PCC is a simultaneous inducer of intrinsic and extrinsic pathways of apoptosis in liver cancer cell lines. PMID:27072064

  9. Mechanism of action of novel piperazine containing a toxicant against human liver cancer cells

    PubMed Central

    Kanthimathi, MS; Haerian, Batoul Sadat

    2016-01-01

    The purpose of this study was to assess the cytotoxic potential of a novel piperazine derivative (PCC) against human liver cancer cells. SNU-475 and 423 human liver cancer cell lines were used to determine the IC50 of PCC using the standard MTT assay. PCC displayed a strong suppressive effect on liver cancer cells with an IC50 value of 6.98 ± 0.11 µM and 7.76 ± 0.45 µM against SNU-475 and SNU-423 respectively after 24 h of treatment. Significant dipping in the mitochondrial membrane potential and elevation in the released of cytochrome c from the mitochondria indicated the induction of the intrinsic apoptosis pathway by PCC. Activation of this pathway was further evidenced by significant activation of caspase 3/7 and 9. PCC was also shown to activate the extrinsic pathways of apoptosis via activation of caspase-8 which is linked to the suppression of NF-κB translocation to the nucleus. Cell cycle arrest in the G1 phase was confirmed by flow cytometry and up-regulation of glutathione reductase expression was quantified by qPCR. Results of this study suggest that PCC is a potent anti-cancer agent inducing both intrinsic and extrinsic pathways of apoptosis in liver cancer cell lines. PMID:27019772

  10. Decomposition of nitrosamines in CO2 capture by aqueous piperazine or monoethanolamine.

    PubMed

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

    2014-05-20

    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 β = 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

  11. Regio- and Stereoselective Synthesis of Spiropyrrolizidines and Piperazines through Azomethine Ylide Cycloaddition Reaction.

    PubMed

    Haddad, Saoussen; Boudriga, Sarra; Porzio, François; Soldera, Armand; Askri, Moheddine; Knorr, Michael; Rousselin, Yoann; Kubicki, Marek M; Golz, Christopher; Strohmann, Carsten

    2015-09-18

    A series of original spiropyrrolizidine derivatives has been prepared by a one-pot three-component [3 + 2] cycloaddition reaction of (E)-3-arylidene-1-phenyl-pyrrolidine-2,5-diones, l-proline, and the cyclic ketones 1H-indole-2,3-dione (isatin), indenoquinoxaline-11-one and acenaphthenequinone. We disclose an unprecedented isomerization of some spiroadducts leading to a new family of spirooxindolepyrrolizidines. Furthermore, these cycloadducts underwent retro-1,3-dipolar cycloaddition yielding unexpected regioisomers. Upon treatment of the dipolarophiles with in situ generated azomethine ylides from l-proline or acenaphthenequinone, formation of spiroadducts and unusual polycyclic fused piperazines through a stepwise [3 + 3] cycloaddition pathway is observed. The stereochemistry of these N-heterocycles has been confirmed by several X-ray diffraction studies. Some of these compounds exhibit extensive hydrogen bonding in the crystalline state. To enlighten the observed regio- and stereoselectivity of the [3 + 2] cycloaddition, calculations using the DFT approach at the B3LYP/6-31G(d,p) level were carried out. It was found that this reaction is under kinetic control. PMID:26291879

  12. Quantum chemical studies on solvents for post-combustion carbon dioxide capture: calculation of pKa and carbamate stability of disubstituted piperazines.

    PubMed

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

    2014-06-23

    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 -CH(3), -CH(2)F, -CH(2)OH, -CH(2)NH(2), -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 pK(a) values of piperazine, 2-methylpiperazine, and 2,5-dimethylpiperazine agree well with the calculated values. The present study indicates that substitution of -CH(3), -CH(2) NH(2), and -CH(2) OH groups on the 2- and 5-positions of piperazine has a positive impact on the CO(2) 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

  13. Anti-nociceptive and anti-inflammatory activities of 4-[(1-phenyl-1H-pyrazol-4-yl) methyl] 1-piperazine carboxylic acid ethyl ester: A new piperazine derivative.

    PubMed

    Silva, Daiany P B; Florentino, Iziara F; Oliveira, Lanussy P; Lino, Roberta C; Galdino, Pablinny M; Menegatti, Ricardo; Costa, Elson A

    2015-10-01

    Piperazine compounds possess anti-infective, anti-carcinogenic, anxiolytic, hypotensive, anti-hypertensive and vasorelaxant properties and are attractive candidates for the development of new analgesic and anti-inflammatory drugs. This study investigates the anti-nociceptive and anti-inflammatory effects of piperazine derivative 4-[(1-phenyl-1H-pyrazol-4-yl) methyl]1-piperazine carboxylic acid ethyl ester (LQFM-008) and the involvement of the serotonergic pathway. In the formalin test, treatments with LQFM-008 (15 and 30mg/kg p.o.) reduced the licking time in both neurogenic and inflammatory phases of this test. In the tail flick and hot plate tests, LQFM008 treatment (15 and 30mg/kg p.o.) increased latency to thermal stimulus, suggesting the involvement of central mechanisms in the anti-nociceptive effect of LQFM-008. In the carrageenan-induced paw edema test, LQFM-008 (p.o.) at the doses of 15 and 30mg/kg reduced the edema at all tested time points, while the dose of 7.5mg/kg reduced the edema only for the first hour. LQFM-008 (30mg/kg p.o.) reduced both cell migration and protein exudation in the carrageenan-induced pleurisy test. Furthermore, pre-treatment with NAN-190 (0.6mg/kgi.p.) and PCPA (100mg/kgi.p.) antagonized the anti-nociceptive effect of LQFM-008 in both phases of the formalin test. Our data suggest that LQFM-008 possesses anti-inflammatory and anti-nociceptive effects mediated through the serotonergic pathway. PMID:26276732

  14. Formation of p-cresol:piperazine complex in solution monitored by spin-lattice relaxation times and pulsed field gradient NMR diffusion measurements

    NASA Astrophysics Data System (ADS)

    de Carvalho, Erika Martins; Velloso, Marcia Helena Rodrigues; Tinoco, Luzineide Wanderley; Figueroa-Villar, José Daniel

    2003-10-01

    A study of the nature of the anthelmintic p-cresol:piperazine complex in chloroform solution has been conducted using different NMR techniques: self-diffusion coefficients using DOSY; NOE, NULL, and double-selective T1 measurements to determine inter-molecular distances; and selective and non-selective T1 measurements to determine correlation times. The experimental results in solution and CP-MAS were compared to literature X-ray diffraction data using molecular modeling. It was shown that the p-cresol:piperazine complex exists in solution in a very similar manner as it does in the solid state, with one p-cresol molecule hydrogen bonded through the hydroxyl hydrogen to each nitrogen atom of piperazine. The close correspondence between the X-ray diffraction data and the inter-proton distances obtained by NULL and double selective excitation techniques indicate that those methodologies can be used to determine inter-molecular distances in solution.

  15. 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

    2014-01-01

    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 [(η6-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. PMID:24927493

  16. 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

    Filak, Lukas K; Kalinowski, Danuta S; Bauer, Theresa J; Richardson, Des R; Arion, Vladimir B

    2014-07-01

    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 L(1-3) were prepared in situ and isolated as six ruthenium and osmium complexes [(η(6)-p-cymene)M(L(1-3))Cl]Cl, where L(1) = 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), L(2) = 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), L(3) = 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. PMID:24927493

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

    NASA Astrophysics Data System (ADS)

    Qiblawi, Sultan H.; LaDuca, Robert L.

    2014-01-01

    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.

  18. Design and synthesis of a series of piperazine-1-carboxamidine derivatives with antifungal activity resulting from accumulation of endogenous reactive oxygen species.

    PubMed

    François, Isabelle E; Thevissen, Karin; Pellens, Klaartje; Meert, Els M; Heeres, Jan; Freyne, Eddy; Coesemans, Erwin; Viellevoye, Marcel; Deroose, Frederik; Martinez Gonzalez, Sonia; Pastor, Joaquin; Corens, David; Meerpoel, Lieven; Borgers, Marcel; Ausma, Jannie; Dispersyn, Gerrit D; Cammue, Bruno P

    2009-10-01

    In this study, we screened a library of 500 compounds for fungicidal activity via induction of endogenous reactive oxygen species (ROS) accumulation. Structure-activity relationship studies showed that piperazine-1-carboxamidine analogues with large atoms or large side chains substituted on the phenyl group at the R(3) and R(5) positions are characterized by a high ROS accumulation capacity in Candida albicans and a high fungicidal activity. Moreover, we could link the fungicidal mode of action of the piperazine-1-carboxamidine derivatives to the accumulation of endogenous ROS. PMID:19705386

  19. Synthesis and an angiolytic role of novel piperazine-benzothiazole analogues on neovascularization, a chief tumoral parameter in neoplastic development.

    PubMed

    Al-Ghorbani, Mohammed; Pavankumar, G S; Naveen, P; Thirusangu, Prabhu; Prabhakar, B T; Khanum, Shaukath Ara

    2016-04-01

    A novel series of benzoic acid N'-[2-(4-benzothiazol-2-yl-piperazin-1-yl)-acetyl]-hydrazides 6a-j were synthesized and characterized by IR, (1)H, (13)C NMR, elemental and mass spectral analyses. The in-vitro cytotoxicity and cell viability assay of the synthesized compounds 6a-j were evaluated against Dalton's lymphoma ascites (DLA) cells. Our results showed that compound 6c with a bromo group on phenyl ring has showed promising antiproliferative efficacy. Further investigation of compound 6c on in-vivo treatment model depicts the increased tumor suppression through inhibition of angiogenesis. PMID:26918263

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

    SciTech Connect

    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

    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-2α signaling. In sum, our results show that DMPP could induce glioma regression grown on CAM by inhibiting vasculogenesis and angiogenesis. - Highlights: ●We demonstrated that DMPP inhibited the growth of glioma cells on chick CAM. ●DMPP did not significantly affect the proliferation and survival of U87 cells. ●We revealed that DMPP suppressed vasculogenesis and angiogenesis in chick embryo. ●Angiogenesis in chick CAM was inhibited by DMPP via most probably Ang-1 and HIF-2α. ●DMPP could be potentially developed as an anti-tumor drug in the future.

  1. Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes

    NASA Astrophysics Data System (ADS)

    Khan, Shamim Ahmad; Nishat, Nahid; Parveen, Shadma; Rasool, Raza

    2011-10-01

    A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, 1H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand.

  2. Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes.

    PubMed

    Khan, Shamim Ahmad; Nishat, Nahid; Parveen, Shadma; Rasool, Raza

    2011-10-15

    A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, (1)H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand. PMID:21757398

  3. Fire self-extinguishing cotton fabric: development of piperazine derivatives containing phosphorous-sulfur-nitrogen and their flame retardant and thermal behaviors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent studies have shown interest in flame retardants containing phosphorus, nitrogen and sulfur a combination small molecule with a promising new approach in preparing an important class of flame retardant materials. Tetraethyl piperazine-1,4-diyldiphosphonate (TEPP) and O,O,O',O'-tetramethyl pip...

  4. Anti-hypertensive property of a nickel-piperazine/NO donor in spontaneously hypertensive rats.

    PubMed

    Monti, Martina; Ciccone, Valerio; Pacini, Aurora; Roggeri, Riccardo; Monzani, Enrico; Casella, Luigi; Morbidelli, Lucia

    2016-05-01

    The nickel-piperazine/NO donor compound, Ni(PipNONO)Cl, belonging to the family of compounds labelled as "metal-nonoates", due to its promising vasodilating activity, has been considered as a potential drug candidate in anti-hypertensive therapy. Drug efficacy has been evaluated in spontaneously hypertensive rats (SHR) in comparison with normotensive animals (C57BL/6 mice and WKY rats). In normotensive animals the metal-nonoate maintained blood pressure at basal level both following acute administration and after 30 days of treatment. In SHR, Ni(PipNONO)Cl reduced blood pressure in the dose range of 3-10mg/kg. When compared with a commercial NONOate, DETA/NO, used at the same doses, Ni(PipNONO)Cl was more active in reducing blood pressure in SHR than DETA/NO in the first two weeks, while the effect of the two molecules was similar in the third and fourth week. The degradation and control compound Ni(Pip)Cl2 had no effect on blood pressure and heart rate in same animal models. Remarkably, the blood pressure reduction induced by the new NO-donor Ni(PipNONO)Cl does not evoke changes in the heart rate and tolerance. Considering the mechanisms of vascular protection, 30 days of administration of Ni(PipNONO)Cl improved endothelial function in SHR by upregulating endothelial NO synthase (eNOS) through increased eNOS protein levels and downregulated Caveolin-1 (Cav-1), and by increasing superoxide dismutase 1 (SOD1) protein level in aortae. In cultured endothelial cells Ni(PipNONO)Cl restored the cell functions (cytoskeletal protein expression, migration and proliferation) altered by the inflammatory mediator interleukin-1β (IL-1β), impairing the endothelial to mesenchimal transition. In conclusion, Ni(PipNONO)Cl maintained unaltered blood pressure in normotensive mice and rats, and it exerted anti-hypertensive effect in SHR through the restoration of vascular endothelial protective functions. PMID:27063892

  5. Coordination Chemistry and Structural Dynamics of a Long and Flexible Piperazine-Derived Ligand.

    PubMed

    Hawes, Chris S; Hamilton, Sophie E; Hicks, Jamie; Knowles, Gregory P; Chaffee, Alan L; Turner, David R; Batten, Stuart R

    2016-07-01

    A long and highly flexible internally functionalized dipyridyl ligand α,α'-p-xylylenebis(1-(4-pyridylmethylene)-piper-4-azine), L, has been employed in the synthesis of a series of coordination polymer materials with Co(II), Cd(II), and Ag(I) ions. In poly-[Cd(L)(TPA)] 1 and poly-[Co(L)(IPA)], 2, (TPA = terephthalate, IPA = isophthalate) the ligand adopts a similar linear conformation to that seen in the structure of the unbound molecule and provides a long (2.6 nm) metal-metal bridging distance. Due to the mismatch of edge lengths with that provided by the carboxylate coligands, geometric distortions from the regular dia and (4,4) network geometries for 1 and 2, respectively, are observed. In poly-[Ag2(CF3SO3)2(L)], 3, the ligand coordinates through both pyridine groups and two of the four piperazine nitrogen donors, forming a high-connectivity 2-dimensional network. The compound poly-[Ag2(L)](BF4)2·2MeCN, 4, a porous 3-dimensional cds network, undergoes a fascinating and rapid single-crystal-to-single-crystal rearrangement on exchange of the acetonitrile guests for water in ambient air, forming a nonporous hydrated network poly-[Ag2(L)](BF4)2·2H2O, 5, in which the well-ordered guest water molecules mediate the rearrangement of the tetrafluoroborate anions and the framework itself through hydrogen bonding. The dynamics of the system are examined in greater detail through the preparation of a kinetic product, the dioxane-solvated species poly-[Ag2(L)](BF4)2·2C4H8O2, 6, which undergoes a slow conversion to 5 over the course of approximately 16 h, a transition which can be monitored in real time. The reverse transformation can also be observed on immersing the hydrate 5 in dioxane. The structural features and physical properties of each of the materials can be rationalized based on the flexible and multifunctional nature of the ligand molecule, as well as the coordination behavior of the chosen metal ions. PMID:27328206

  6. Comparison of impact of the different hydrophilic carriers on the properties of piperazine-containing drug.

    PubMed

    Ahmed, M O

    2001-05-01

    The objective of this study was to determine the impact of a series of nonionic surfactants on the solubility of piperazine-containing drug (meclizine, MZ) in comparison to that of natural cyclodextrins (alpha-CD and beta-CD) and dimethyl-beta-cyclodextrin (DM-beta-CD). The solubility of the drug was studied in either CDs solutions or nonionic surfactant solutions. Three classes of nonionic surfactants were used namely; polyoxyethylene (POE) sorbitan fatty acid esters (polysorbates), POE fatty acid esters (Myrjs) and polyethylene oxide (PEO) fatty alcohol ethers (Brijs and Eumulgins). The solubility of MZ was increased linearly with the increasing surfactant concentration, indicating that micellar solubilization follows the partition model. It was found that the longer the hydrocarbon chain in a homologous series, the more efficient is the solubilizing power of surfactant. For example, polysorbate 80 (Tween-80) is a more efficient solubilizer than polysorbate 20 (Tween-20), indicating that the drug was incorporated in the core of micelle more than the capsular region of the micelle. On the other hand, in case of POE fatty acid esters, the solubilizing power increased with decreasing polyoxyethylene chain as Myrj 53 was more efficient than Myrj 59. In class of PEO fatty alcohol ethers, the shorter the hydrophilic chain and longer lipophilic chain, the more efficient was the solubilizing capacity. Thus, Brij 58 was more efficient solubilizer than Brij 35 and Eumulgin C1000 was more active than Eumulgin C1500. Comparatively, Eumulgin C1000 had the highest solubilizing power for MZ among the studied PEO fatty alcohol ethers and other groups of surfactants. The solubility action of surfactants toward MZ was increased by raising the temperature of the surfactant solutions from 30 to 45 degrees C. Hydrophilic macromolecules (PEG 1000 and PEG 6000) or cosolvents (glycerol and propylene glycol) have a very slight effect on the solubility of MZ and confirm the predominance

  7. Temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine in the synthesis of open-framework aluminophosphates

    PubMed Central

    Huang, Pai; Xu, Jun; Qi, Guodong; Deng, Feng; Xu, Ruren; Yan, Wenfu

    2016-01-01

    The temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine in the synthesis of open-framework aluminophosphates was investigated. By heating the initial mixture with the composition of Al2O3:1.5 P2O5:R:125 H2O at 160 °C, where R is the structure-directing agent of 2-methylpiperazine or piperazine, layered aluminophosphates APMeP150 (R = 2-methylpiperazine) and AP2pip (R = piperazine) were obtained. When the same initial reaction mixture was heated at 190 °C, layered aluminophosphates APMeP200 (R = 2-methylpiperazine) and AP2pip (R = piperazine) were crystallized. APMeP200 and AP2pip have the same inorganic sheet topology. We investigated the crystallization processes of the four open-framework aluminophosphates and found that increasing the heating temperature slowed the crystallization of the initial mixtures. The non-bonding interactions between the inorganic layers of the four open-framework aluminophosphates and the experimental or theoretically generated structure-directing agents were calculated. The possible starting points of the crystallization of the four open-framework aluminophosphates were analysed and compared. The temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine revealed that the structure-directing effect, the most important factor in the synthesis of zeolites and related open-framework materials, is determined by multiple factors. The structural parameters of the same compound can be affected by the synthesis conditions. PMID:26912387

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

    PubMed Central

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

    2014-01-01

    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

  9. Influence of silica nanospheres on the separation performance of thin film composite poly(piperazine-amide) nanofiltration membranes

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Wang, Yihua; Song, Jie; Guan, Yipeng; Yu, Hui; Pan, Xianhui; Wu, Feiyang; Zhang, Meng

    2015-01-01

    A novel thin film nanocomposite nanofiltration (TFNN) membrane was fabricated by introducing silica nanospheres (ca. 235 ± 11 nm) in the interfacial polymerization process of trimesoyl chloride (TMC) and piperazine (PIP) over polysulfone (PS) support for investigating the effect of silica nanofiller on the separation performance (i.e., permeability and salt rejection) of conventional thin film composite poly(piperazine-amide) nanofiltration (TFCN) membrane. The physicochemical characterization results show that all of the silica nanospheres are uniformly embedded on the surface of TFNN membrane. The introduction of silica nanospheres improves the hydrophilicity of the TFCN membrane and also causes its isoelectric point shift to a lower pH value. Moreover, the active poly(piperazine-amide) barrier layer of TFNN membrane (60.8 ± 2.3 nm) is thinner than that of the pristine TFCN membrane (72.1 ± 2.5 nm) as a control sample. The separation performance tests reveal that the addition of silica nanospheres can obviously elevate the salt rejection of the pristine TFCN membrane from 87.58 ± 0.15 to 94.81 ± 0.17% under 2000 ppm of MgSO4 solution and 0.5 MPa operating pressure, simultaneously accompanied by the increases of permeate flux from 19.36 ± 0.75 to 22.65 ± 0.68 L/m2 h. Additionally, compared with pristine TFCN membrane, the fabricated TFNN membrane has relatively low salt rejection (43.20 ± 0.27%) in 0.5 MPa operating pressure for 500 ppm of NaCl aqueous solution, which demonstrates that the introduction of silica nanospheres can dramatically promote the divalent-ionic separation selectivity. Furthermore, the experimental results suggest that the nanocomposite TFNN membrane possesses stable filtration performance in the softening process of MgSO4 aqueous solution. The separation performance improvement should be attributed to the optimizations of microstructures and surface features of active barrier layer of TFNN membrane, caused by the addition of silica

  10. Crystal structure of the 1:2:2 adduct of piperazine, o-phthalic acid and water.

    PubMed

    Jin, Zhi Min; Pan, Yuan Jiang; He, Ling; Li, Zu Guang; Yu, Kai Bei

    2003-02-01

    The adduct of piperazine, o-phthalic acid and water (1:2:2), C20H26N2O10, crystallizes in the monoclinic space group P21/c with a = 6.129(1), b = 12.810(2), c = 13.137(2)A, beta = 95.87(1) degrees, V = 1026.0(3)A3, Z = 2. The piperazinium adopts a chair comformer, and is tied with the hydrogen orthophthalate via a hydrogen bond of the N-H...O type. Because of bifurcated hydrogen bonding of C(sp3)H-O [3.0801(17) and 3.1408(18)A] and the shortest hydrogen bond of C(sp3)H-O [2.9758(17)A], C(sp3)H-O hydrogen bonds play important roles in stablizing the title adduct. PMID:12608772

  11. Synthesis and antitumor activity evaluation of quinazoline derivatives bearing piperazine-1-carbodithioate moiety at C4-position.

    PubMed

    Zhang, Ying; Yang, Chao-Rui; Tang, Xue; Cao, Sheng-Li; Ren, Ting-Ting; Gao, Man; Liao, Ji; Xu, Xingzhi

    2016-10-01

    A series of quinazoline derivatives bearing piperazine-1-carbodithioate moiety at the C4-position were synthesized using piperidine and 1-bromo-3-chloropropane as starting materials via eight steps. Final compounds 8a-q and 9a-i were evaluated for their antiproliferative activity against human lung cancer A549, breast adenocarcinoma MCF-7, and colorectal cancer HCT-116 cell lines. The results showed that fourteen of twenty-six final compounds inhibited the proliferation of three cancer cell lines with IC50 values less than 10μM. When treated with a representative compound 8n, HCT-116 cells were arrested at G0/G1 phase of the cell cycle. This provided a clue to further investigation of the mechanism of action. PMID:27575478

  12. Crystal structure of piperazine-1,4-diium bis­(4-amino­benzene­sulfonate)

    PubMed Central

    Kumar, K. Sathesh; Ranjith, S.; Sudhakar, S.; Srinivasan, P.; Ponnuswamy, M. N.

    2015-01-01

    The asymmetric unit of the title salt, C4H12N2 2+·2C6H6NO3S−, consists of half a piperazindiium dication, located about an inversion centre, and a 4-amino­benzene­sulfonate anion. The piperazine ring adopts a chair conformation. In the crystal, the cations and anions are linked via N—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional framework. Within the framework there are C—H⋯π inter­actions and the N—H⋯O hydrogen bonds result in the formation of R 4 4(22) and R 3 4(13) ring motifs. PMID:26870510

  13. Novel Piperazine-based Compounds Inhibit Microtubule Dynamics and Sensitize Colon Cancer Cells to Tumor Necrosis Factor-induced Apoptosis*

    PubMed Central

    Chopra, Avijeet; Anderson, Amy; Giardina, Charles

    2014-01-01

    We recently identified a series of mitotically acting piperazine-based compounds that potently increase the sensitivity of colon cancer cells to apoptotic ligands. Here we describe a structure-activity relationship study on this compound class and identify a highly active derivative ((4-(3-chlorophenyl)piperazin-1-yl)(2-ethoxyphenyl)methanone), referred to as AK301, the activity of which is governed by the positioning of functional groups on the phenyl and benzoyl rings. AK301 induced mitotic arrest in HT29 human colon cancer cells with an ED50 of ≈115 nm. Although AK301 inhibited growth of normal lung fibroblast cells, mitotic arrest was more pronounced in the colon cancer cells (50% versus 10%). Cells arrested by AK301 showed the formation of multiple microtubule organizing centers with Aurora kinase A and γ-tubulin. Employing in vitro and in vivo assays, tubulin polymerization was found to be slowed (but not abolished) by AK301. In silico molecular docking suggests that AK301 binds to the colchicine-binding domain on β-tubulin, but in a novel orientation. Cells arrested by AK301 expressed elevated levels of TNFR1 on their surface and more readily activated caspases-8, -9, and -3 in the presence of TNF. Relative to other microtubule destabilizers, AK301 was the most active TNF-sensitizing agent and also stimulated Fas- and TRAIL-induced apoptosis. In summary, we report a new class of mitosis-targeting agents that effectively sensitizes cancer cells to apoptotic ligands. These compounds should help illuminate the role of microtubules in regulating apoptotic ligand sensitivity and may ultimately be useful for developing agents that augment the anti-cancer activities of the immune response. PMID:24338023

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

    PubMed

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

    2013-01-30

    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

  15. HEAT OF DISSOLUTION MEASUREMENTS FOR CO2 IN MIXED ALKANOLAMINE SOLVENTS

    SciTech Connect

    Vinayak N. Kabadi

    2004-04-27

    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.

  16. Heat of Dissolution Measurements for CO2 in Mixed Alkanolamine Solvents

    SciTech Connect

    Vinayak N. Kabadi

    2006-09-30

    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.

  17. HEAT OF DISSOLUTION MEASUREMENTS FOR CO2 IN MIXED ALKANOLAMINE SOLVENTS

    SciTech Connect

    Vinayak N. Kabadi

    2005-05-23

    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.

  18. Heat of Dissolution Measurements for CO2 in Mixed Alkanolamine Solvents

    SciTech Connect

    Vinayak N. Kabadi

    2006-05-29

    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.

  19. Heat of Dissolution Measurements for CO2 in Mixed Alkanolamine Solvents

    SciTech Connect

    Vinayak N. Kabadi

    2005-12-01

    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.

  20. HEAT OF DISSOLUTION MEASUREMENTS FOR CO2 IN MIXED ALKANOLAMINE SOLVENTS

    SciTech Connect

    Vinayak N. Kabadi

    2004-11-15

    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.

  1. Heat of Dissolution Measurements for CO2 in Mixed Alkanolamine Solvents

    SciTech Connect

    Vinayak N. Kabadi

    2007-03-31

    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.

  2. Carbon capture and sequestration: an exploratory inhalation toxicity assessment of amine-trapping solvents and their degradation products.

    PubMed

    McDonald, Jacob D; Kracko, Dean; Doyle-Eisele, Melanie; Garner, C Edwin; Wegerski, Chris; Senft, Al; Knipping, Eladio; Shaw, Stephanie; Rohr, Annette

    2014-09-16

    Carbon dioxide (CO2) absorption with aqueous amine solvents is a method of carbon capture and sequestration (CCS) from flue gases. One concern is the possible release of amine solvents and degradation products into the atmosphere, warranting evaluation of potential pulmonary effects from inhalation. The CCS amines monoethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PIP) underwent oxidative and CO2-mediated degradation for 75 days. C57bl/6N mice were exposed for 7 days by inhalation of 25 ppm neat amine or equivalant concentration in the degraded mixture. The aqueous solutions were nebulized to create the inhalation atmospheres. Pulmonary response was measured by changes in inflammatory cells in bronchoalveolar lavage fluid and cytokine expression in lung tissue. Ames mutagenicity and CHO-K1 micronucleus assays were applied to assess genotoxicity. Chemical analysis of the test atmosphere and liquid revealed complex mixtures, including acids, aldehydes, and other compounds. Exposure to oxidatively degraded MEA increased (p < 0.05) total cells, neutrophils, and lymphocytes compared to control mice and caused inflammatory cytokine expression (statistical increase at p < 0.05). MEA and CO2-degraded MEA were the only atmospheres to show statistical (p < 0.05) increase in oxidative stress. CO2 degradation resulted in a different composition, less degradation, and lower observed toxicity (less magnitude and number of effects) with no genotoxicity. Overall, oxidative degradation of the amines studied resulted in enhanced toxicity (increased magnitude and number of effects) compared to the neat chemicals. PMID:25167095

  3. 3,3′-(Piperazine-1,4-diium-1,4-di­yl)di­propionate dihydrate

    PubMed Central

    Jin, Shouwen; Huang, Yanfei; Fang, Hao; Wang, Tianyi; Ding, Liangliang

    2012-01-01

    During the recrystallization of 3-[4-(2-carb­oxy­eth­yl)piperazin-1-yl]propionic acid, the carb­oxy­lic acid H atoms were transferred to the piperazine N atoms, forming the title compound, C10H18N2O4·2H2O, in which the zwitterion lies about an inversion center. In the crystal, bifurcated N—H⋯(O,O) hydrogen bonds connect the zwitterions into a two-dimensional framework parallel to (-102) forming R 4 4(30) rings. O—H⋯O hydrogen bonds involving the solvent water mol­ecules connect the two-dimensional framework into a three-dimensional network. In addition, weak C—H⋯O hydrogen bonds are observed. PMID:23125633

  4. 2-[2-(4-Methyl­piperazin-1-yl)eth­yl]iso­indoline-1,3-dione

    PubMed Central

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

    2014-01-01

    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 π–π inter­actions also occur [centroid–centroid distances = 3.556 (1)–3.716 (1) Å]. PMID:24764996

  5. Structural analysis of complexes formed by ethyl 4-phenylthiocarbamoyl piperazine-1-carboxylate with Ni(II), Zn(II) and Cd(II) through spectroscopic and DFT techniques

    NASA Astrophysics Data System (ADS)

    Prakash, Om; Gautam, Priyanka; Dani, R. K.; Nandi, Abhisikta; Singh, N. K.; Singh, Ranjan K.

    2014-04-01

    A piperazine derivative, ethyl 4-phenylthiocarbamoyl piperazine-1-carboxylate and its Ni(II), Zn(II) and Cd(II) complexes have been synthesized and characterized by elemental analyses, magnetic susceptibility measurement, UV-Visible, FTIR, Raman spectroscopic and DFT methods. The Ni(II) and Zn(II) bind through the N and S sites of the two ligand Heptpc and N site of two pyridine molecules. However, the Cd(II) binds through the only N sites of the two ligand Heptpc and N site of two pyridine molecules. On the basis of various techniques used for the characterizations of the complexes, we found that the most possible geometry of the Ni(II) and Zn(II) complexes are distorted octahedral and of the Cd(II) complex is distorted tetrahedral.

  6. (Z)-1-Di­phenyl­methyl-4-(3-phenyl­prop-2-en­yl)piperazine

    PubMed Central

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

    2014-01-01

    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⋯π inter­actions link the mol­ecules into [100] chains. PMID:24860379

  7. Synthesis and bioactivities of novel piperazine-containing 1,5-Diphenyl-2-penten-1-one analogues from natural product lead.

    PubMed

    Xu, Gaofei; Yang, Xinling; Jiang, Biaobiao; Lei, Peng; Liu, Xili; Wang, Qingmin; Zhang, Xuebo; Ling, Yun

    2016-04-01

    A series of novel 1,5-Diphenyl-2-penten-1-one analogues (7a-h, 8a-h) with piperazine moiety have been designed and synthesized on the basis of natural product 1,5-Diphenyl-2-penten-1-one (I). All the synthesized compounds were evaluated in vitro for anti-plant pathogenic fungi activities and insecticidal activities. The results indicated that most of these analogues exhibited moderate antifungal activities and moderate to good insecticidal activities. Amongst them, the most potent 7c, 7e and 7h keep a mortality of 100% against larva of mosquito at the concentration of 1mg/L. Initial structure-activity relationship (SAR) analysis showed that, a methyl group can influence the biological activities of these compounds significantly, the compounds with N'-unsubstituted piperazine showed much better antifungal activities and larvicidal activity against mosquito than the compounds with N'-methylated piperazine. In addition, the larvicidal activity against mosquito had sharply decline when the substituent on benzene ring was changed from 4-position to 2 or 3-position. PMID:26906636

  8. Development of a high-performance liquid chromatography with fluorescence detection method for quantification of piperazine in animal products by using precolumn derivatization.

    PubMed

    Park, Jin-A; Zhang, Dan; Kim, Dong-Soon; Kim, Seong-Kwan; Cho, Sang-Hyun; Jeong, Daun; Kim, Jin-Suk; Shim, Jae-Han; Abd El-Aty, A M; Shin, Ho-Chul

    2016-04-01

    A new high-performance liquid chromatography with ​fluorescence detection (HPLC-FLD) method was developed for determination of piperazine residues in food animal products. Samples were extracted with formic acid in water and purified using the PCX cartridge. Following purification, the samples were derivatized using dansyl chloride, and the analyte was separated using water/acetonitrile as a mobile phase. The calibration curves showed good linearity over a concentration range of 20-120 ng/g with coefficient of determination (R(2))⩾0.996. The intra-day accuracy (presented as recovery %) and precision (presented as relative standard deviation, RSD %) were 81-97.3% and 0.83-6.87%, whereas, the inter-day values were 80.5-96.8% and 1.7-6.8%, respectively. The limit of quantification (LOQ) was 20 ng/g, which was considerably lower than the maximum residue limit (MRL). The developed method was used to monitor market samples, and piperazine was not detected in any of the samples. To our knowledge, this is the first study in which the detection of piperazine in various food and animal products by using a sensitive and reliable analytical method has been described. PMID:26593624

  9. Click-based synthesis and antitubercular evaluation of novel dibenzo[b,d]thiophene-1,2,3-triazoles with piperidine, piperazine, morpholine and thiomorpholine appendages.

    PubMed

    Pulipati, Lokesh; Yogeeswari, Perumal; Sriram, Dharmarajan; Kantevari, Srinivas

    2016-06-01

    A series of novel piperidine, piperazine, morpholine and thiomorpholine appended dibenzo[b,d]thiophene-1,2,3-triazoles were designed and synthesized utilizing azide-alkyne click chemistry in the penultimate step. The required azide building block 6a-e was synthesized from commercial dibenzo[b,d]thiophene in good yields following five step reaction sequence. All the new analogues 8a-f, 9a-f, 10a-f, 11a-f &12a-f were characterized by their NMR and mass spectral analysis. Screening all thirty new compounds for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, resulted 8a, 8f and 11e as potent analogues with MIC 0.78μg/mL, 0.78μg/mL & 1.56μg/mL, respectively, and has shown lower cytotoxicity. Interestingly, all six piperazine appended dibenzo[b,d]thiophene-1,2,3-triazoles 11a-f exhibited Mtb inhibition activity with MIC 1.56-12.5μg/mL. To some extent, the data observed here indicated Mycobacterium tuberculosis inhibition among the appendages is in the order, piperazine>thiomorpholine>morpholine. PMID:27101894

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

    SciTech Connect

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

    1994-12-01

    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.

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

    SciTech Connect

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

    1981-01-01

    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.

  12. Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands

    PubMed Central

    El-Sherif, Ahmed A.; Shehata, Mohamed R.; Shoukry, Mohamed M.; Barakat, Mohammad H.

    2012-01-01

    Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO3) using a potentiometric technique. The order of –ΔG0 and –ΔH0 was found to obey Co2+ < Ni2+ < Cu2+ > Zn2+, in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K. PMID:23226992

  13. The antidepressant- and anxiolytic-like activities of new xanthone derivative with piperazine moiety in behavioral tests in mice

    PubMed Central

    Pytka, Karolina; Żmudzka, Elżbieta; Lustyk, Klaudia; Rapacz, Anna; Olczyk, Adrian; Gałuszka, Adam; Waszkielewicz, Anna; Marona, Henryk; Sapa, Jacek; Barbara, Filipek

    2016-01-01

    Objectives: Xanthones are flavonoids with numerous activities, including antioxidant, antidepressant., or anxiolytic-like. Therefore, the aim of our study was to determine antidepressant- and anxiolytic-like properties of four xanthone derivatives (3-chloro-5-[(4-methylpiperazin-1-yl)methyl]-9H-xanthen-9-one dihydrochloride [HBK-5], 6-methoxy-2-[(4-methylpiperazin-1-yl) methyl]-9H-xanthen-9-one dihydrochloride, 2-[(4-benzylpiperazin-1-yl) methyl]-6-methoxy-9H-xanthen-9-one dihydrochloride, 2-{[4-(2-methoxyphenyl) piperazin-1-yl] methyl}-9H-xanthen-9-one hydrochloride), as well as the influence on cognitive and motor function of active compounds, using animal models. Materials and Methods: To determine the antidepressant-like activity, we used forced swim test (FST) and tail suspension test (TST) in mice. We evaluated anxiolytic-like properties in the four-plate test in mice. We studied the influence on cognitive and motor function in passive avoidance step-through and chimney tests, respectively. Results: The antidepressant-like activity (in both FST and TST) showed only HBK-5. Moreover, the compound was also active in the four-plate test, which suggests that it possessed anxiolytic-like properties. HBK-5 did not cause any cognitive and motor deficits in mice at antidepressant- and anxiolytic-like doses. Conclusions: HBK-5 may have potential in the treatment of depression or anxiety disorders, but this issue needs further studies. PMID:27298499

  14. Synthesis and Structure-Activity Relationship Analysis of 5-HT₇ Receptor Antagonists: Piperazin-1-yl Substituted Unfused Heterobiaryls.

    PubMed

    Strekowski, Lucjan; Sączewski, Jarosław; Raux, Elizabeth A; Fernando, Nilmi T; Klenc, Jeff; Paranjpe, Shirish; Raszkiewicz, Aldona; Blake, Ava L; Ehalt, Adam J; Barnes, Samuel; Baranowski, Timothy C; Sullivan, Shannon M; Satała, Grzegorz; Bojarski, Andrzej J

    2016-01-01

    A series of piperazin-1-yl substituted unfused heterobiaryls was synthesized as ligands of the 5-HT₇ receptors. The goal of this project was to elucidate the structural features that affect the 5-HT₇ binding affinity of this class of compounds represented by the model ligand 4-(3-furyl)-2-(4-methylpiperazin-1-yl)pyrimidine (2). The SAR studies included systematical structural changes of the pyrimidine core moiety in 2 to quinazoline, pyridine and benzene, changes of the 3-furyl group to other heteroaryl substituents, the presence of various analogs of the 4-methylpiperazin-1-yl group, as well as additional substitutions at positions 5 and 6 of the pyrimidine. Substitution of position 6 of the pyrimidine in the model ligand with an alkyl group results in a substantial increase of the binding affinity (note a change in position numbers due to the nomenclature rules). It was also demonstrated that 4-(3-furyl) moiety is crucial for the 5-HT₇ binding affinity of the substituted pyrimidines, although, the pyrimidine core can be replaced with a pyridine ring without a dramatic loss of the binding affinity. The selected ethylpyrimidine (12) and butylpyrimidine (13) analogs of high 5-HT₇ binding affinity showed antagonistic properties in cAMP functional test and varied selectivity profile-compound 12 can be regarded as a dual 5-HT₇/5-HT2AR ligand, and 13 as a multi-receptor (5-HT₇, 5-HT2A, 5-HT₆ and D₂) agent. PMID:27043518

  15. Dithiocarbamate/piperazine bridged pyrrolobenzodiazepines as DNA-minor groove binders: synthesis, DNA-binding affinity and cytotoxic activity.

    PubMed

    Kamal, Ahmed; Sreekanth, Kokkonda; Shankaraiah, Nagula; Sathish, Manda; Nekkanti, Shalini; Srinivasulu, Vunnam

    2015-04-01

    A new series of C8-linked dithiocarbamate/piperazine bridged pyrrolo[2,1-c][1,4]benzodiazepine conjugates (5a-c, 6a,b) have been synthesized and evaluated for their cytotoxic potential and DNA-binding ability. The representative conjugates 5a and 5b have been screened for their cytotoxicity against a panel of 60 human cancer cell lines. Compound 5a has shown promising cytotoxic activity on selected cancer cell lines that display melanoma, leukemia, CNS, ovarian, breast and renal cancer phenotypes. The consequence of further replacement of the 3-cyano-3,3-diphenylpropyl 1-piperazinecarbodithioate in 5b and 5c with 4-methylpiperazine-1-carbodithioate yielded new conjugates 6a and 6b respectively. In addition, the compounds 5c and 6a,b have been evaluated for their in vitro cytotoxicity on some of the selected human cancer cell lines and these conjugates have exhibited significant cytotoxic activity. Further, the DNA-binding ability of these new conjugates has been evaluated by using thermal denaturation (ΔTm) studies. The correlation between structure and DNA-binding ability has been investigated by molecular modeling studies which predicted that 6b exhibits superior DNA-binding ability and these are in agreement with the experimental DNA-binding studies. PMID:25665519

  16. A potent new class of kappa-receptor agonist: 4-substituted 1-(arylacetyl)-2-[(dialkylamino)methyl]piperazines.

    PubMed

    Naylor, A; Judd, D B; Lloyd, J E; Scopes, D I; Hayes, A G; Birch, P J

    1993-07-23

    The synthesis of 4-substituted 1-(arylacetyl)-2-[(alkylamino)methyl]piperazines (10-22, 26, 27, and 30-33) and their activities as kappa-opioid receptor agonists are described. This includes a range of 4-acyl and 4-carboalkoxy derivatives with the latter series showing the greatest kappa-agonist activity. In particular, methyl 4-[(3,4-dichlorophenyl)acetyl]-3-[(1-pyrrolidinyl) methyl]-1-piperazinecarboxylate (18) displays exceptional potency and selectivity. It showed the following activities in functional in vitro assays: rabbit vas deferens (kappa-specific tissue) IC50 = 0.041 nM, rat vas deferens (mu-specific tissue) IC50 > 10,000 nM, and hamster vas deferens (delta-specific tissue) IC50 > 10,000 nM. Compound 18 is also a highly potent antinociceptive agent, as determined in the mouse acetylcholine-induced abdominal constriction test: ED50 = 0.000 52 mg/kg, sc. The activity of 18 resides solely in its 3(R)-enantiomer. The kappa-agonist activity in both the 4-acyl and the 4-carbamate series is sensitive to the size of the 4-substituent. In addition, it would appear that an appreciable negative electrostatic potential in this region of the molecule is an important requirement for optimal potency. PMID:8393489

  17. Formation of Diastereoisomeric Piperazine-2,5-dione from uc(dl)-Alanine in the Presence of Olivine and Water

    NASA Astrophysics Data System (ADS)

    Fuchida, Shigeshi; Naraoka, Hiroshi; Masuda, Harue

    2016-04-01

    uc(dl)-Alanine (Ala) was heated with/without powdered olivine and water at 120 °C for 8 days to investigate the formation of the diastereoisomers of piperazine-2,5-dione (diketopiperazine, DKP). When only uc(dl)-Ala was heated with a small amount of water, 3.0 % of uc(dl)-Ala changed to cis- and trans-DKP after 8 days. DKPs were not detected after heating when no water was added. The presence of a small amount of water is important factor controlling peptide production rates under thermal conditions. When DL-Ala was heated with olivine powder for 8 days, the yields of cis- and trans-DKP were 6.8 and 4.9 %, respectively. The high yield of cis-DKP compared with trans-DKP was attributed to greater thermal stability of cis-DKP. After heating for 8 days, the diastereoisomeric excess of cis-DKP without olivine was 7.3 %, whereas a much higher value of 16.3 % was obtained in the presence of olivine. Taken together, these results show that olivine is not only an efficient catalyst for the formation of DKPs but that it also play a significant role in determining the diastereoisomer selectivity of these cyclic dipeptides.

  18. Pharmacological and pharmacokinetic characterization of 2-piperazine-alpha-isopropyl benzylamine derivatives as melanocortin-4 receptor antagonists.

    PubMed

    Chen, Chen; Tucci, Fabio C; Jiang, Wanlong; Tran, Joe A; Fleck, Beth A; Hoare, Sam R; Wen, Jenny; Chen, Takung; Johns, Michael; Markison, Stacy; Foster, Alan C; Marinkovic, Dragan; Chen, Caroline W; Arellano, Melissa; Harman, John; Saunders, John; Bozigian, Haig; Marks, Daniel

    2008-05-15

    A series of 2-piperazine-alpha-isopropylbenzylamine derivatives were synthesized and characterized as melanocortin-4 receptor (MC4R) antagonists. Attaching an amino acid to benzylamines 7 significantly increased their binding affinity, and the resulting compounds 8-12 bound selectively to MC4R over other melanocortin receptor subtypes and behaved as functional antagonists. These compounds were also studied for their permeability using Caco-2 cell monolayers and metabolic stability in human liver microsomes. Most compounds exhibited low permeability and high efflux ratio possibly due to their high molecular weights. They also showed moderate metabolic stability which might be associated with their moderate to high lipophilicity. Pharmacokinetic properties of these MC4R antagonists, including brain penetration, were studied in mice after oral and intravenous administrations. Two compounds identified to possess high binding affinity and selectivity, 10d and 11d, were studied in a murine cachexia model. After intraperitoneal (ip) administration of 1mg/kg dose, mice treated with 10d had significantly more food intake and weight gain than the control animals, demonstrating efficacy by blocking the MC4 receptor. Similar in vivo effects were also observed when 11d was dosed orally at 20mg/kg. These results provide further evidence that a potent and selective MC4R antagonist has potential in the treatment of cancer cachexia. PMID:18417348

  19. 2-Benzazolyl-4-Piperazin-1-Ylsulfonylbenzenecarbohydroxamic Acids as Novel Selective Histone Deacetylase-6 Inhibitors with Antiproliferative Activity

    PubMed Central

    Wang, Lei; Kofler, Marina; Brosch, Gerald; Melesina, Jelena; Sippl, Wolfgang; Martinez, Elisabeth D.; Easmon, Johnny

    2015-01-01

    We have screened our compound collection in an established cell based assay that measures the derepression of an epigenetically silenced transgene, the locus derepression assay. The screen led to the identification of 4-[4-(1-methylbenzimidazol-2-yl)piperazin-1-yl]sulfonylbenzenecarbohydroxamic acid (9b) as an active which was found to inhibit HDAC1. In initial structure activity relationships study, the 1-methylbenzimidazole ring was replaced by the isosteric heterocycles benzimidazole, benzoxazole, and benzothiazole and the position of the hydroxamic acid substituent on the phenyl ring was varied. Whereas compounds bearing a para substituted hydroxamic acid (9a-d) were active HDAC inhibitors, the meta substituted analogues (8a-d) were appreciably inactive. Compounds 9a-d selectively inhibited HDAC6 (IC50 = 0.1–1.0μM) over HDAC1 (IC50 = 0.9–6μM) and moreover, also selectively inhibited the growth of lung cancer cells vs. patient matched normal cells. The compounds induce a cell cycle arrest in the S-phase while induction of apoptosis is neglible as compared to controls. Molecular modeling studies uncovered that the MM-GBSA energy for interaction of 9a-d with HDAC6 was higher than for HDAC1 providing structural rationale for the HDAC6 selectivity. PMID:26698121

  20. Complexation, thermal and catalytic studies of N-substituted piperazine, morpholine and thiomorpholine with some metal ions

    NASA Astrophysics Data System (ADS)

    Kacan, Mesut; Turkyilmaz, Murat; Karabulut, Ferhat; Altun, Ozlen; Baran, Yakup

    2014-01-01

    Several Cu(II), Pt(II) and Ni(II) complexes of N-substituted, piperazine (NN donor), morpholine (NO donor) and thiomorpholine (NS donor) derivatives were synthesized and their thermal behavior and catalytic activity in epoxidation reaction of cis-diphenylethylene were studied using oxygen sources NaOCl. The coordination compounds of Cu(II), Pt(II) and Ni(II) having general formula [MLCl]Cl, [ML2l]Cl2 or [ML]Cl2 with tetra coordinated geometry around metal ions have been isolated as solid. All the ligands and complexes were identified by spectroscopic methods and elemental analysis, magnetic measurements, electrical conductance and thermal analysis. A square planer structures have been proposed for all complexes. The thermal stability of the complexes discussed in terms of ligands donor atoms, geometry and central metal ions. The complexes have a similar thermal behavior for the selected metal ions. The thermogravimetric analyses suggest high thermal stability for most complexes followed by thermal decomposition in different steps. The decomposition processes were observed as water elimination, chloride anion removal and degradation of the organic ligands. Catalytic ability of the complexes were examined and found that all the complexes can effectively catalyze the epoxidation of cis-stilbene with NaOCl.

  1. Selective gas treating produces better claus feeds

    SciTech Connect

    Goar, B.G.

    1980-01-01

    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.

  2. N-Aryl Piperazine Metabotropic Glutamate Receptor 5 Positive Allosteric Modulators Possess Efficacy in Preclinical Models of NMDA Hypofunction and Cognitive Enhancement

    PubMed Central

    Gregory, K.J.; Herman, E.J.; Ramsey, A.J.; Hammond, A.S.; Byun, N.E.; Stauffer, S.R.; Manka, J.T.; Jadhav, S.; Bridges, T.M.; Weaver, C.D.; Niswender, C.M.; Steckler, T.; Drinkenburg, W.H.; Ahnaou, A.; Lavreysen, H.; Macdonald, G.J.; Bartolomé, J.M.; Mackie, C.; Hrupka, B.J.; Caron, M.G.; Daigle, T.L.; Lindsley, C.W.; Conn, P.J.

    2013-01-01

    Impaired transmission through glutamatergic circuits has been postulated to play a role in the underlying pathophysiology of schizophrenia. Furthermore, inhibition of the N-methyl-d-aspartate (NMDA) subtype of ionotropic glutamate receptors (NMDAR) induces a syndrome that recapitulates many of the symptoms observed in patients with schizophrenia. Selective activation of metabotropic glutamate receptor subtype 5 (mGlu5) may provide a novel therapeutic approach for treatment of symptoms associated with schizophrenia through facilitation of transmission through central glutamatergic circuits. Here, we describe the characterization of two novel N-aryl piperazine mGlu5 positive allosteric modulators (PAMs): 2-(4-(2-(benzyloxy)acetyl)piperazin-1-yl)benzonitrile (VU0364289) and 1-(4-(2,4-difluorophenyl)piperazin-1-yl)-2-((4-fluorobenzyl)oxy)ethanone (DPFE). VU0364289 and DPFE induced robust leftward shifts in the glutamate concentration-response curves for Ca2+ mobilization and extracellular signal-regulated kinases 1 and 2 phosphorylation. Both PAMs displayed micromolar affinity for the common mGlu5 allosteric binding site and high selectivity for mGlu5. VU0364289 and DPFE possessed suitable pharmacokinetic properties for dosing in vivo and produced robust dose-related effects in reversing amphetamine-induced hyperlocomotion, a preclinical model predictive of antipsychotic-like activity. In addition, DPFE enhanced acquisition of contextual fear conditioning in rats and reversed behavioral deficits in a mouse model of NMDAR hypofunction. In contrast, DPFE had no effect on reversing apomorphine-induced disruptions of prepulse inhibition of the acoustic startle reflex. These mGlu5 PAMs also increased monoamine levels in the prefrontal cortex, enhanced performance in a hippocampal-mediated memory task, and elicited changes in electroencephalogram dynamics commensurate with procognitive effects. Collectively, these data support and extend the role for the development of novel

  3. The 5-substituted piperazine as a novel secondary pharmacophore greatly improving the physical properties of urea-based inhibitors of soluble epoxide hydrolase.

    PubMed

    Li, Hui-Yuan; Jin, Yi; Morisseau, Christophe; Hammock, Bruce D; Long, Ya-Qiu

    2006-10-01

    The inhibition of the mammalian soluble epoxide hydrolase (sEH) is a promising new therapy in the treatment of hypertention and inflammation. The problems of limited water solubility and high melting points commonly displayed by the active 1,3-disubstituted ureas prevent the further development of potent urea-based sEH inhibitors. Therefore, a new class of potent inhibitors of sEH were designed and synthesized by the introduction of a polar constrained piperazino group in the right side of adasmantyl urea to increase the water solubility. A facile and general synthesis was established to prepare a series of 1-adamantan-1-yl-3-(2-piperazin-2-yl-ethyl)-ureas (1a-d) with various 5-substitutions on the 2-piperazino ring, which will advance the SAR study by the efficient making of structurally diverse analogs. The effect of the 5-substitution on the activity and the water solubility was examined. The best potency was exhibited by the 5-benzyl-substituted-piperazine-containing urea with an IC50 value of 1.37 microM against human sEH and good water solubility (S=7.46 mg/mL) and low melting point, in which the 5-substituted piperazine serves as a favorable secondary pharmacophore and a water-solubility enhancing group. Our present work provides a promising new template for the design of orally available therapeutic agents for the disorders that can be addressed by changing the in vivo concentration of the chemical mediators that contain an epoxide. PMID:16784862

  4. Strong effect of copper(II) coordination on antiproliferative activity of thiosemicarbazone-piperazine and thiosemicarbazone-morpholine hybrids.

    PubMed

    Bacher, Felix; Dömötör, Orsolya; Chugunova, Anastasia; Nagy, Nóra V; Filipović, Lana; Radulović, Siniša; Enyedy, Éva A; Arion, Vladimir B

    2015-05-21

    In this study, 2-formylpyridine thiosemicarbazones and three different heterocyclic pharmacophores were combined to prepare thiosemicarbazone–piperazine mPip-FTSC (HL1) and mPip-dm-FTSC (HL2), thiosemicarbazone–morpholine Morph-FTSC (HL3) and Morph-dm-FTSC (HL4), thiosemicarbazone–methylpyrrole-2-carboxylate hybrids mPyrr-FTSC (HL5) and mPyrr-dm-FTSC (HL6) as well as their copper(II) complexes [CuCl(mPipH-FTSC-H)]Cl (1 + H)Cl, [CuCl(mPipH-dm-FTSC-H)]Cl (2 + H)Cl, [CuCl(Morph-FTSC-H)] (3), [CuCl(Morph-dm-FTSC-H)] (4), [CuCl(mPyrr-FTSC-H)(H2O)] (5) and [CuCl(mPyrr-dm-FTSC-H)(H2O)] (6). The substances were characterized by elemental analysis, one- and two-dimensional NMR spectroscopy (HL1–HL6), ESI mass spectrometry, IR and UV–vis spectroscopy and single crystal X-ray diffraction (1–5). All compounds were prepared in an effort to generate potential antitumor agents with an improved therapeutic index. In addition, the effect of structural alterations with organic hybrids on aqueous solubility and copper(II) coordination ability was investigated. Complexation of ligands HL2 and HL4 with copper(II) was studied in aqueous solution by pH-potentiometry, UV–vis spectrophotometry and EPR spectroscopy. Proton dissociation processes of HL2 and HL4 were also characterized in detail and microscopic constants for the Z/E isomers were determined. While the hybrids HL5, HL6 and their copper(II) complexes 5 and 6 proved to be insoluble in aqueous solution, precluding antiproliferative activity studies, the thiosemicarbazone–piperazine and thiosemicarbazone–morpholine hybrids HL1–HL4, as well as copper(II) complexes 1–4 were soluble in water enabling cytotoxicity assays. Interestingly, the metal-free hybrids showed very low or even a lack of cytotoxicity (IC50 values > 300 μM) in two human cancer cell lines HeLa (cervical carcinoma) and A549 (alveolar basal adenocarcinoma), whereas their copper(II) complexes were cytotoxic showing IC50 values from 25.5 to 65.1

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

    PubMed Central

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

    2014-01-01

    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⋯π inter­actions, producing a two-dimensional supramolecular architecture. PMID:24526973

  6. 3-(Adamantan-1-yl)-1-[(4-benzyl­piperazin-1-yl)meth­yl]-4-ethyl-1H-1,2,4-triazole-5(4H)-thione

    PubMed Central

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

    2013-01-01

    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. PMID:24454243

  7. Ethyl 4-{[3-(adamantan-1-yl)-4-phenyl-5-sulfanyl­idene-4,5-dihydro-1H-1,2,4-triazol-1-yl]meth­yl}piperazine-1-carboxyl­ate

    PubMed Central

    Al-Abdullah, Ebtehal S.; Asiri, Hanadi H.; El-Emam, Ali A.; Ng, Seik Weng

    2012-01-01

    The title mol­ecule, C26H35N5O2S, displays a chair-shaped piperazine ring, as well as a planar triazole ring whose phenyl substituent is perpendicular to the mean plane of the five-membered ring [dihedral angle = 90.00 (13)°]. The methyl­ene substituent on the piperazine ring occupies an equatorial site. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure. The crystal studied was a non-merohedral twin, with a 33.9 (3)% minor component. PMID:22347127

  8. 3-(Adamantan-1-yl)-1-[(4-benzyl­piperazin-1-yl)meth­yl]-4-phenyl-1H-1,2,4-triazole-5(4H)-thione

    PubMed Central

    Al-Abdullah, Ebtehal S.; Asiri, Hanadi H.; El-Emam, Ali; Ng, Seik Weng

    2012-01-01

    The title mol­ecule, C30H37N5S, displays a chair-shaped piperazine ring, as well as an approximately planar triazole ring [maximum deviation = 0.002 (2) Å] whose phenyl substituent is nearly perpendicular to the mean plane of the five-membered ring [dihedral angle = 80.4 (1)°]. The substit­uents on the piperazine ring occupy equatorial sites. Weak inter­molecular C—H⋯S hydrogen bonding is present in the crystal structure. PMID:22346973

  9. 3-(Adamantan-1-yl)-4-phenyl-1-[(4-phenyl­piperazin-1-yl)meth­yl]-1H-1,2,4-triazole-5(4H)-thione

    PubMed Central

    Al-Abdullah, Ebtehal S.; Asiri, Hanadi H.; El-Emam, Ali; Ng, Seik Weng

    2012-01-01

    The title mol­ecule, C29H35N5S, displays a chair-shaped piperazine ring, as well as an approximately planar triazole ring (r.m.s. deviation = 0.001 Å) whose phenyl substituent is nearly perpendicular to the mean plane of the five-membered ring [dihedral angle = 88.9 (1)°]. The substituents on the piperazine ring occupy equatorial sites. In the crystal, the adamantyl cage is disordered over two sets of sites with a major component of 67.8 (5)%. Weak inter­molecular C—H⋯S hydrogen bonding is present in the crystal. PMID:22346974

  10. Nippostrongylus brasiliensis infection in the rat: effect of iron and protein deficiency on the anthelmintic efficacy of mebendazole, pyrantel, piperazine, and levamisole.

    PubMed Central

    Duncombe, V M; Bolin, T D; Davis, A E; Fagan, M R; Kelly, J D

    1979-01-01

    The benzimidazole anthelmintics mebendazole and fenbendazole have been shown to be much less effective against Nippostrongylus brasiliensis infections in the rat on a combined iron and protein deficient diet. In the present experiments it was shown that the anthelmintic efficacy of mebendazole was significantly impaired in the rat on either an iron deficient or a protein deficient diet. Furthermore, iron and protein deficiency reduced the efficacy of the anthelmintics pyrantel and piperazine but not levamisole. The finding that nutritional deficiencies reduce anthelmintic efficacy may well be relevant to worm eradication programmes in iron deficient and protein calorie malnourished populations. PMID:447110