The Experts below are selected from a list of 30 Experts worldwide ranked by ideXlab platform
Taha Mohamed - One of the best experts on this subject based on the ideXlab platform.
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Designing new mass-separating agents based on piperazine-containing good's buffers for separation of propanols and water azeotropic mixtures using COSMO-RS method
ELSEVIER SCIENCE BV, 2026Co-Authors: Taha MohamedAbstract:The isobaric vapor-liquid equilibria of the binary 1-propanol + water, 2-propanol + water, and 2-methyl-2-propanol (tert-butanol) + water systems were predicted using the conductor-like screening model for realistic solvation (COSMO-RS) method. The phase behavior of the 1-propano1/2-propanol/tert-butanol water + piperazine-based Good's buffer systems were predicted. The effect of piperazine-containing Good's buffers, 2-[4-(2-hydroxyethyl)piperazin-1-yl]Alkanesulfonic Acid, as mass-separating agents on the separation of proponals from water were discussed. The influence of alkyl chain length between the zwitterion end groups, R = methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl was evaluated. Further, the effect of 4-(2-hydroxyethyl)piperazine-1-(2-hydroxypropane sulfonic Acid) was also evaluated. Piperazine-based Good's buffers are expected to be effective mass separating agents to have practical application in the separation of propanol from water. (C) 2016 Elsevier B.V. All rights reserved
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Designing new mass-separating agents based on piperazine-containing good's buffers for separation of propanols and water azeotropic mixtures using COSMO-RS method
Elsevier, 2026Co-Authors: Taha MohamedAbstract:The isobaric vapor liquid equilibria of the binary 1 propanol þ water, 2 propanol þ water, and 2 methyl 2 propanol (tert butanol) þ water systems were predicted using the conductor like screening model for realistic solvation (COSMO RS) method. The phase behavior of the 1 propanol/2 propanol/tert butanol þ water þ piperazine based Good’s buffer systems were predicted. The effect of piperazine containing Good’s buffers, 2 [4 (2 hydroxyethyl)piperazin 1 yl]Alkanesulfonic Acid, as mass separating agents on the separation of proponals from water were discussed. The influence of alkyl chain length between the zwitterion end groups, R ¼ methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl was evaluated. Further, the effect of 4 (2 hydroxyethyl)piperazine 1 (2 hydroxypropane sul fonic Acid) was also evaluated. Piperazine based Good’s buffers are expected to be effective mass separating agents to have practical application in the separation of propanol from water
Wolfgang Lindner - One of the best experts on this subject based on the ideXlab platform.
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increments to chiral recognition facilitating enantiomer separations of chiral Acids bases and ampholytes using cinchona based zwitterion exchanger chiral stationary phases
IEEE Journal of Solid-state Circuits, 2012Co-Authors: Stefanie Wernisch, Reinhard Pell, Wolfgang LindnerAbstract:The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of Alkanesulfonic Acid chain length and flexibility on enantiomer separations of chiral Acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral stationary phases in comparison with structurally related anion and cation exchangers. Employing polar-organic elution conditions, we observed an intramolecular counterion effect for Acidic analytes which led to reduced retention times but did not impair enantiomer selectivities. Retention of amphoteric analytes is based on simultaneous double ion pairing of their charged functional groups with the Acidic and basic sites of the zwitterionic selectors. A chiral center in the vicinity of the strong cation exchanger site is vital for chiral separations of bases. Sterically demanding side chains are beneficial for separations of free amino Acids. Enantioseparations of free (un-derivatized) peptides were particularly successful in stationary phases with straight-chain Alkanesulfonic Acid sites, pointing to a beneficial influence of more flexible moieties. In addition, we observed pseudo-enantiomeric behavior of quinine and quinidine-derived chiral stationary phases facilitating reversal of elution orders for all analytes.
Qingze Jiao - One of the best experts on this subject based on the ideXlab platform.
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synthesis of polyoxymethylene dimethyl ethers catalyzed by bronsted Acid ionic liquids with Alkanesulfonic Acid groups
Industrial & Engineering Chemistry Research, 2014Co-Authors: Min Wang, Yu Hao, Yun Zhao, Qingze JiaoAbstract:Catalytic reaction of methylal (DMM) with trioxane (TOX) for preparation of polyoxymethylene dimethyl ethers (PODMEn, CH3O(CH2O)nCH3, where n > 1) was investigated in a series of Bronsted Acid ionic liquids with Alkanesulfonic Acid groups. The structures, Acidities, and properties of ionic liquids were experimentally characterized and theoretically analyzed. The Bronsted Acidity–activity correlation for the ionic liquids was studied. Among all these ionic liquids, 1-(4-sulfonic Acid) butylpyridinium hydrogen sulfate ([PY-BS][HSO4–]) exhibited the best catalytic performance, which was ascribed to its strong Bronsted Acidity. The influences of ionic liquid dosage, molar ratio of DMM to TOX, and reaction temperature on the catalytic reaction were explored using [PY-BS][HSO4–] as the catalyst. Under the optimal conditions of n(methylal):n(trioxane):n(ILs) = 180:60:1, 170 °C, and 10h, the conversion of trioxane and the selectivity of PODME3–8 were as high as 91.18% and 70.90%, respectively. The ionic liquid [P...
Yingwei Zhao - One of the best experts on this subject based on the ideXlab platform.
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metal free and recyclable route to synthesize polysubstituted olefins via c c bond construction from direct dehydrative coupling of alcohols or alkenes with alcohols catalyzed by sulfonic Acid functionalized ionic liquids
Advanced Synthesis & Catalysis, 2014Co-Authors: Lei Yang, Zhen Li, Yingwei ZhaoAbstract:A direct synthesis of polysubstituted olefins via construction of C-C bonds, which involves the direct dehydrative coupling of alcohols or alkenes with alcohols, was realized using a series of Alkanesulfonic Acid group-functionalized ionic liquids (SO 3 H-functionlization ILs) without additives. The metal-free and recyclable catalyst system avoided the disposal and neutralization of Acidic catalysts after reaction and tolerated a broad range of substrates, including benzylic, allyl, propargylic, aliphatic and aromatic or aliphatic olefins. Additionally, the catalytic system was suitable for a gram-scale preparation. Preliminary mechanistic studies indicated that the C-H bond cleavage in this reaction might be involved in the rate-determining step.
Stefanie Wernisch - One of the best experts on this subject based on the ideXlab platform.
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increments to chiral recognition facilitating enantiomer separations of chiral Acids bases and ampholytes using cinchona based zwitterion exchanger chiral stationary phases
IEEE Journal of Solid-state Circuits, 2012Co-Authors: Stefanie Wernisch, Reinhard Pell, Wolfgang LindnerAbstract:The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of Alkanesulfonic Acid chain length and flexibility on enantiomer separations of chiral Acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral stationary phases in comparison with structurally related anion and cation exchangers. Employing polar-organic elution conditions, we observed an intramolecular counterion effect for Acidic analytes which led to reduced retention times but did not impair enantiomer selectivities. Retention of amphoteric analytes is based on simultaneous double ion pairing of their charged functional groups with the Acidic and basic sites of the zwitterionic selectors. A chiral center in the vicinity of the strong cation exchanger site is vital for chiral separations of bases. Sterically demanding side chains are beneficial for separations of free amino Acids. Enantioseparations of free (un-derivatized) peptides were particularly successful in stationary phases with straight-chain Alkanesulfonic Acid sites, pointing to a beneficial influence of more flexible moieties. In addition, we observed pseudo-enantiomeric behavior of quinine and quinidine-derived chiral stationary phases facilitating reversal of elution orders for all analytes.