PPh<sub>3</sub>
/Selectfluor-Mediated Transformation of Carboxylic Acids into Acid Anhydrides and Acyl Fluorides and Its Application in Amide and Ester Synthesis
An efficient synthesis of acid anhydrides or acyl fluorides mediated by PPh3/Selectfluor synstem is reported. Mechanistic studies show that the reaction proceeds through active species of acyloxyphosphonium ions, which can be quickly converted into the final products in situ by a second carboxylicacid or F–.
Oxidative esterification of benzylic alcohols with a catalytic amount of HBr-H2O2 in aqueous medium under mild conditions is reported with a wide range of substrate scope for both benzylic and aliphatic alcohols. The conditions are also suitable for selective mono-esterification of ethylene glycol and glycerol. With catalytic amounts of HBr (20 mol%) and H2O2, the generation of reactive intermediate species BrOH has been ascertained by UV-visible spectra.
Esterification of free fatty acids (Biodiesel) using nano sulfated-titania as catalyst in solvent-free conditions
作者:Mona Hosseini-Sarvari、Esmat Sodagar
DOI:10.1016/j.crci.2012.10.016
日期:2013.3
Résumé Nano sulfated titania was tested as catalyst for esterification of free fatty acids, specially methanolic and ethanolic esterification of stearic acid (biodiesels). Factorial design evidenced a positive effect of reaction temperature, amount of catalyst, and solvents on ester conversion. This nano-sized sulfated titania has been prepared by a sol-gel hydrothermal process. This prepared sulfated titania showed high catalytic activity in direct esterification of fatty acids as well as benzoic acids with various alcohols and phenols under solvent-free conditions. This method is of great value because of its environmentally benign character, easy handling, high yields, convenient operation, and green. FT-IR studies are shown that the catalyst can be reused for acylation without loss of catalytic activity.
were tested for one-pot selective synthesis of esters fromnitriles and alcohols. Ceria (CeO2) showed more than two orders of magnitude higher activity than the other oxides. CeO2 acted as a reusable and effective catalyst for the ester synthesisfrom various nitriles and alcohols under neutral and solvent-free conditions at 160 °C. This method provides a rare example for the synthesis of heteroaromatic
Sodium cyanide‐promoted copper‐catalysed aerobic oxidative synthesis of esters from aldehydes
作者:Najmeh Nowrouzi、Mohammad Abbasi、Maryam Bagheri
DOI:10.1002/aoc.3766
日期:2017.11
A simple and efficient copper‐catalysed procedure for oxidativeesterification of aldehydes with alcohols and phenols mediated by sodium cyanide, using air as a clean oxidant, is described. A variety of aromaticaldehydes and structurally different alcohols and phenols reacted efficiently, and the product esters were obtained in good to excellent yields under normal atmospheric and solvent‐free conditions