The kinetics and mechanism of oxidation of aliphatic aldehydes by benzyltriethylammonium chlorochromate

Abstract

The oxidation of six aliphatic aldehydes by benzyltriethylammonium chlorochromate (BTEACC) in dimethyl sulfoxide (DMSO) leads to the formation of corresponding carboxylic acids. The reaction is first order each in BTEACC and the aldehyde. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form: k obs = a + b[H + ]. The oxidation of deuteriated acetaldehyde, MeCDO, exhibited a substantial primary kinetic isotope effect (k H / k D = 5.89 at 298 K). The oxidation of acetaldehyde has been studied in 19 different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The rate constants correlate well with Taft's σ* values; reaction constants being negative. A mechanism involving transfer of hydride ion has been suggested.