The Kinetics and Mechanism of the Reaction of Diphenyldiazomethane and Benzoic Acid in Ethanol1

Abstract

The reactions of substituted diazomethanes with carboxylic acids have been studied mainly in nonhydroxylic solvents. In one of the earliest papers published on this subject, Staudinger and Gaule reported that a variety of diazomethane derivatives reacted with substituted acetic acids in cumene at rates which depended on the strengths of the acids. Similar observations were later made by Norris and Strain with di-p-tolyldiazomethane and substituted benzoic acids in benzene, toluene and ethyl acetate solutions. The reaction of diazoacetic ester in aprotic solvents with various carboxylic acids has also been investigated and found to be roughly second-order in acid in contrast to the reaction of di-p-tolyldiazomethane with benzoic acid in toluene, which has been reported to be accurately first-order in acids. In non-hydroxylic solvents, the principal (if not the exclusive) reaction products are the carboxylic esters. Thus, diphenyldiazomethane reacts with benzoic acid in ether to give a 92% yield of benzhydryl benzoate' and recently Hardegger, El Heweihi and Robinet found that a large variety of carboxylic acids react similarly in non-hydroxylic solvents to form the corresponding benzhydryl esters in high yields.