Kinetics and mechanism of the oxidation of aliphatic alcohols by benzyltrimethylammonium dichloroiodate

The oxidation of a series of aliphatic alcohols by benzyltrimethylammonium dichloroiodate (BTMACI), in glacial acetic acid in the presence of zinc chloride, leads to the formation of the corresponding carbonyl compounds. The reaction is first order each with respect to the alcohol, zinc chloride and BTMACI. Addition of the benzyltrimethylammonium chloride enhances the rate slightly. The oxidation of deuteriated ethanol indicates the presence of a substantial kinetic isotope effect. [PhCH2Me3N](+)[IZn2Cl6](-) is postulated to be the reactive oxidizing species. The reaction is susceptible to both polar and steric effects of the substituents. A mechanism involving transfer of a hydride ion from the alcohol to the oxidant has been proposed.