Phosphomolybdic Acid: Mild and Efficient Catalyst for Acetylation of Alcohols, Phenols, and Amines under Solvent-Free Conditions
作者:Sung Kim、Santosh Kadam
DOI:10.1055/s-2007-1000859
日期:2008.1
simple and efficient catalyst for the acetylation of alcohols, phenols, and amines. Acetylation reactions with aceticanhydride (1.0 equiv) proceed in excellent yield in the presence of a catalytic amount (0.2 mol%) of PMA at ambient temperature within a relatively short reaction time (<10 min). Structurally diverse alcohols, phenols, and amines undergo acetylationunder solvent-free conditions.
Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
作者:Ying-Pong Lam、Xinyan Wang、Fei Tan、Wing-Hin Ng、Ying-Lung Steve Tse、Ying-Yeung Yeung
DOI:10.1021/acscatal.9b01959
日期:2019.9.6
organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic
carbodiimides in hydroxylic solvents containing hydrogenperoxide with mildly basic or acidic catalysts have been found to promote the epoxidation of olefins. A commercially available 30% aqueous solution of hydrogenperoxide serves as the oxidant for this process. The presumed reactive species is a peroxyisourea generated in situ by the addition of hydrogenperoxide to the carbodiimide.
ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
申请人:The Chinese University of Hong Kong
公开号:US20210023539A1
公开(公告)日:2021-01-28
An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
Epoxidation of Olefins with a Silica-Supported Peracid
作者:Rossella Mello、Ana Alcalde-Aragonés、María Elena González Núñez、Gregorio Asensio
DOI:10.1021/jo300533b
日期:2012.8.3
Anhydrous [2-percarboxyethyl] functionalized silica (2a) is an advantageous oxidant for performing the epoxidation of olefins 1. Epoxides 3 do not undergo the ring-opening reactions catalyzed by the acidic silica surface, except for particularly activated cases such as styrene oxide. The hydrophilic and acidic character of the silica surface does not interfere with the directing effects exerted by