NMR Study of the Protolysis Kinetics in Methanol and Ethanol

Abstract

Measurements by the nuclear magnetic resonance technique of the hydrogen exchange kinetics in methanol and ethanol are reported. The exchange reaction is both acid and base catalyzed. The observed kinetics can be interpreted as a simple proton transfer between a neutral alcohol molecule and an alcoxonium, or alcoxyde ion, respectively. In methanol a third mechanism, not involving ions, was also observed. In ethanol this reaction is presumably too slow for detection by the NMR technique. The hydrogen exchange was also studied in alcohol‐water mixtures. Possible exchange mechanisms are discussed and values for their respective rate constants are given.