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Active Hydrogen (active + hydrogen)
Selected AbstractsDiphenylboron Perchlorate as an Efficient Catalyst for Self- and Cross-Condensation Reactions of Aldehydes Having ,-Active Hydrogens.CHEMINFORM, Issue 17 2003Syun-ichi Kiyooka Abstract For Abstract see ChemInform Abstract in Full Text. [source] Copolymerization of carbon dioxide and propylene oxide with zinc glutarate as catalyst in the presence of compounds containing active hydrogenJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007L. J. Gao Abstract To enhance the catalytic copolymerization of CO2 and propylene oxide catalyzed by zinc glutarate, the influence of trace of water, ethanol, and propanal on the catalytic activity, the resulted copolymer structure, and the molecular weight and molecular weight distribution of the copolymer were investigated extensively. The experimental results showed that the catalytic activity decreased remarkably in the presence of either trace of ethanol or water, but increased in the presence of trace of propanal. Both 1H-NMR and 13C-NMR spectra suggested that the content of carbonate linkages of resulted copolymer was not effected obviously in the presence of above-mentioned impurities, giving completely alternating poly(propylene carbonate) (PPC). GPC results indicated that these impurities reduced the molecular weights but broadened the molecular weight distributions of resulted copolymers. Finally, the byproduct contents including both propylene carbonate determined by GC and polyether increased with the increase of three impurity concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Preparation of sorbitol from D -glucose hydrogenation in gas,liquid,solid three-phase flow airlift loop reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2004Jian-Ping Wen Abstract A new process for D -glucose hydrogenation in 50 wt% aqueous solution, into sorbitol in a 1.5 m3 gas,liquid,solid three-phase flow airlift loop reactor (ALR) over Raney Nickel catalysts has been developed. Five main factors affecting the reaction time and molar yield to sorbitol, including reaction temperature (TR), reaction pressure (PR), pH, hydrogen gas flowrate (Qg) and content of active hydrogen, were investigated and optimized. The average reaction time and molar yield were 70 min and 98.6% under the optimum operating conditions, respectively. The efficiencies of preparation of sorbitol between the gas,liquid,solid three-phase flow ALR and stirred tank reactor (STR) under the same operating conditions were compared. Copyright © 2004 Society of Chemical Industry [source] Negative ion electrospray ionization mass spectrometry of nucleoside phosphoramidate monoesters: elucidation of novel rearrangement mechanisms by multistage mass spectrometry incorporating in-source deuterium labellingRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2008Peng-Xiang Xu Several O-2,,3,-isopropylideneuridine-O-5,-phosphoramidate monoesters were synthesized and analyzed by negative ion electrospray ionization tandem mass spectrometry (ESI-MSn). Two kinds of novel rearrangement reactions were observed due to the difference in the amino acid in the nucleoside phosphoramidate monoesters, and possible mechanisms were proposed. One involves a five-membered cyclic transition state. The other is formation of a stable five-membered ring intermediate by Michael addition. Results were confirmed by tandem mass spectrometry and isotopically labeled hydrogen atoms. Furthermore, the internal hydrogen exchange between active hydrogen and methyl acrylate in the heated capillary of the mass spectrometer was found. The characteristic fragmentation behavior in ESI-MS may be used to monitor this kind of compounds in the biological metabolism. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||