Quaternary ammonium ions can externally block voltage-gated K+ channels. Establishing a theoretical and experimental model that predicts KDs and the selectivity of K+ over Na+ ions
摘要:
The physicochemical basis for the high ion selectivity of potassium channels is poorly understood. In the present studies, external blockade of cloned voltage-gated potassium channels with alkyl quaternary ammonium ions are analyzed from a model derived from theory and experimental data. Atomic mass units, electrostatic potential residing on the nitrogen atom, the COSMO van der Waals solvent accessible surface, the Onsager solvation model, and the isodensity PCM solvation model are computed at the semi-empirical and the ab initio levels of theory. A structure-activity relationship (SAR) exists between the calculated values and the experimentally obtained K-D (mM). The SAR model gives us K-D predictions and when K+ and Na+ are incorporated into the model, it dramatically predicts the selectivity of K+ over Na+ ions. (C) 2001 Elsevier Science B.V. All rights reserved.
Describes a method for obtaining substantially pure chloromethyl chloroformate from a chloroformate mixture comprising chloromethyl chloroformate and methyl chloroformate by heating the chloroformate mixture in a reaction zone at temperatures ranging from at least 50° C. to the reflux temperature of the chloroformate mixture in the reaction zone while simultaneously removing volatile gaseous decomposition products from the reaction zone. Dichloromethyl chloroformate may also be present in the chloroformate mixture.
The invention provides a process for the preparation of an alkylene glycol from an alkylene oxide. Alkylene oxide reacts with carbon dioxide in the presence of a carboxylation catalyst to provide alkylene carbonate; alkylene carbonate reacts with water in the presence of a hydrolysis catalyst to provide alkylene glycol. An initial charge of the carboxylation catalyst and an initial charge of the hydrolysis catalyst are added, the degradation and activity of the hydrolysis catalyst are monitored, and when the activity of the hydrolysis catalyst has fallen below a minimum level, an additional charge of the hydrolysis catalyst is added.
Diol derived blocked mercaptofunctional silane compositions in which the silanes comprise cyclic and bridged alkoxy groups derived from hydrocarbon-based diols and processes for their preparation are provided. Also provided are rubber compositions comprising the cyclic diol-derived blocked mercaptofunctional silanes, processes for their preparation and articles of manufacture comprising the rubber compositions, in particular, automotive tires and components thereof.
[EN] PROCESS FOR THE PREPARATION OF THIOCARBOXYLATE SILANE<br/>[FR] PROCEDE DE PREPARATION DE SILANE THIOCARBOXYLATE
申请人:GEN ELECTRIC
公开号:WO2005007661A1
公开(公告)日:2005-01-27
An aqueous process is described in which thiocarboxylate silane is produced from haloalkyl silane by reaction of the haloalkyl silane with an aqueous solution of thiocarboxylate salt. Also described is a process for the preparation of aqueous thiocarboxylate salt from a sulfide and/or hydrosulfide and an acid chloride and/or acid anhydride.
METHYL-IODIDE-FREE CARBONYLATION OF AN ALCOHOL TO ITS HOMOLOGOUS ALDEHYDE AND/OR ALCOHOL
申请人:EASTMAN CHEMICAL COMPANY
公开号:US20160185700A1
公开(公告)日:2016-06-30
Disclosed is a process for the reductive carbonylation of a low molecular weight alcohol to produce the homologous aldehyde and/or alcohol. The process includes conducting the reaction to produce the aldehyde in the presence of a single component catalyst complex composed of cobalt, an onium cation and iodide in a ratio of 1:2:4 without additional promoters. A ruthenium co-catalyst is used in the production of the homologous alcohol. The reductive carbonylation reaction does not require an additional iodide promoter and produces a crude reductive carbonylation product substantially free of methyl iodide.