COSMO‐RS Calculations of Partition Coefficients: Different Tools for Conformation Search

This work is encouraged by the growing interest and recent success of quantum mechanics‐based methods in modeling of thermodynamic properties in the field of chemical engineering and life sciences. Among those, the COSMO‐RS model has become one of the most popular methods to predict phase equilibria in complex bio‐related systems. Recently, we have shown that the quality of predictions of n‐octanol/water and micelle/water partition coefficients is improved when the weighted mixtures of conformers are used to represent molecules, thereby demanding that the conformation analysis is performed for each component of the system. In this paper, different methods for performing the conformational search are evaluated. Micelle/water partition coefficients of solutes from different homologous series in aqueous solutions of Triton X100 as well as the n‐octanol/water partitioning of three common drugs (aminopinicillanic acid, ampicillin, and penicillin G) are calculated and compared with experimental data. Conformational analysis is made by the HyperChem program for the molecules placed in vacuum as well as by using the molecular dynamics simulation in a solvent medium (n‐octanol and water). It is demonstrated that molecular dynamics simulation is a promising tool to conduct conformational analysis. Along with the possibility of providing the conformers for large surfactant and pharmaceutical molecules, the method accounts for the solvent in a realistic manner. The results for micelle/water partition coefficients illustrate that n‐octanol is a reasonable approximation for the “micelle‐like” medium in molecular dynamics (MD) simulations. Predicted n‐octanol/water partition coefficients of three penicillins are in a good agreement with literature data and values calculated by a common quantitative structure‐activity relationship (QSAR).     

Direct Extraction of Propionic Acid from Propionibacterium acidipropionici Broths with Tri‐n‐octylamine

The direct reactive extraction of propionic acid from Propionibacterium acidipropionici broths with solutions of tri‐n‐octylamine in dichloromethane, n‐butyl acetate or n‐heptane underlined the strong negative influence of the cells, due to the blockage of the interface by their adsorption. The magnitude of this effect <#>depends on the affinity of the cells for the organic phase, which is more important for n‐heptane, but only at biomass concentrations below 18 g L^–1 d.w. (dry weight). Moreover, the interfacial mass transfer of the acid is also controlled by the solvent polarity, and is accelerated from n‐heptane to dichloromethane and by the addition to the organic phase of 1‐octanol as a phase modifier. The influences of the biomass concentration, the rotation speed and the solvent dielectric constant were included in a mathematical model describing the solute mass flow from the aqueous to the organic phase.     

Intensification of enzymatic conversion of glucose to lactic acid by reactive extraction

Lactic acid is an important commercial product and extracting this out of aqueous solution is a growing requirement in fermentation-based industries and recovery from waste streams. The design of an amine extraction process requires (i) equilibrium and (ii) kinetic data for the acid-amine (solvent) system used. Equilibria and kinetics for lactic acid extraction by Alamine 336 in octanol as a diluent have been determined and compared with other diluents studied earlier. An approach for extracting the lactic acid by a long-chain tertiary amine, which is in the dispersed phase as a liquid ion exchanger (LIX), is presented. A mathematical model for slurry phase reactor with glucose in the continuous aqueous phase, the amine with a diluent in the dispersed phase and the immobilized enzyme as the solid catalyst, has been developed using equilibrium and kinetic data for reactive extraction. Effects of various parameters affecting the conversion of glucose have been discussed. The model has been solved for batch and semi-batch modes. It has been shown that the semi-batch mode yields approximately five times higher productivity than batch mode.     

THE SYNERGISTIC SOLVENT EXTRACTION OF RADIUM FROM ALKALINE NITRATE MEDIA BY DICYCLOHEXANO-21-CROWN-7 COMBINED WITH 2-METHYL-2-HEPTYL NONANOIC ACID EQUtUBRIUM REACTIONS AND METAL ION COMPETITION∗

The equilibria in the solvent extraction of radium from aqueous sodium nitrate/sodium hydroxide solutions by toluene solutions of dicyclohexano-21-crown-7 (DC21C7). 2-methyl-2-heptylnonanioc acid (HMHN). and mixtures of the two reagents are examined. The mixed reagents are synergistic in the extraction of radium and selective for radium over other alkali and alkaline earth elements. The dependencies of the extraction on pH and reagent concentration were utilized in computer modeling to estimate the stochiometry of the extracted complexes and equilibria involved the extraction. Three organic-phase species were identified in the extraction under basic (pH 11-13) conditions. With A = MHN^?. B = DC21C7 and assuming NaA is a 10-fold aggregate they are. RaA₂B.NaA. Log K = 3.57: RaA NaA. Log K = 0.99: and B 2NaA. Log K = ? 0.41. The effect of the presence of various concentrations of sodium     

高纯度仲辛醇试制技术

阐述由粗仲辛醇加氢制得高纯的技术。     

Polymer induced structures in cetylpyridinium chloride–octanol micellar system

The effect of octanol on the interaction of polyethylene glycol (PEG) and cetylpyridinium chloride (CPC) were investigated by viscosity, conductivity, differential scanning calorimetry (DCS), polarizing microscopy, Fourier transform infrared spectroscopy (FTIR) and rheology analysis. The aggregation of polymer-surfactant micelles takes place at a surfactant concentration higher than the critical micelle concentration. The long chain aliphatic alcohol (n-octanol) induced rapid structural transformation in the mixed micellar system by unusual cooperative micellization. The rheological behavior of the viscoelastic system reveals the presence of giant aggregates in this system. The lyotropic nature of the giant aggregates was monitored by DSC and polarizing microscopic studies, and which was confirmed by cryo-TEM.     

Determination of K ow of Substituted Polycyclic Aromatic Compounds

Octanol-water partition coefficients (K _ow s) of substituted polycyclic aromatic compounds (PACs), anthracene-, pyrene- and quinoline-derivatives, have been determined using HPLC. The determined K _ow s have been compared with results from theoretical fragment methods, developed by Rekker and Mannhold [1] and by Hansch and Leo [2]. The results showed that if these theoretical methods are to be useful with simple substituted PAHs they must be applied differently than normally supposed, due to intramolecular steric conditions. Comparison of the determined K _ow s with measured K _oc values showed that the relationship between K _oc and K _ow is not straightforward, and that prediction of K _oc from K _ow alone will not give results applicable for substituted polycyclic aromatic compounds.     

DF石墨浮选剂的合成

为能更好地利用有限的资源,在DF煤浮选剂的基础上,研制开发DF石墨浮选剂,该制剂兼有起泡和捕集两种作用,具有浮选速度快,刺激气味小,无毒无害,节约药剂用量等特点。     

辛醇废碱液除油工艺研究

简要介绍了聚结除油工艺机理及研究进展,通过酸化破乳试验及聚结填料的优选试验,确定了聚结除油的最佳pH值、最佳填料及工艺条件。在此基础上进行了辛醇废碱液的聚结除油试验,结果表明,辛醇废碱液中C8以上有机相去除率高达80%以上,COD去除率可达50%左右,说明该工艺适合用于辛醇废碱液中C8以上有机相的去除。     

Zur physikalisch‐chemischen Charakterisierung von 5‐Amino‐1‐aryl‐1H‐tetrazolen: Charakterisierung von Wasserlöslichkeiten und ihre Beziehungen zu Octan‐1‐ol/Wasser‐Verteilungskoeffizienten

The aqueous solubilities (logS) of a set of 27 5‐amino‐1‐aryl‐1H‐tetrazoles with known biological activity were determined photometrically and correlated with their octan‐1‐ol/water partition coefficients (logP). The otained linear relationship between logS and logP can be significantly improved by a melting point term, an electronic term and several indicator variables describing the deviating solubility behaviour of compounds with hydrogen bonding groups and the dependence on substituent position. The calculated moreparameter equations allow the reliable prediction of aqueous solubilities for 5‐amino‐1‐aryl‐1H‐tetrazoles not yet synthesized or investigated.