Studies on the kinetics of tripropylammonium fluorochromate oxidation of some aromatic alcohols in non-aqueous media

The oxidation of benzyl alcohol (BnOH) and a few para-substituted benzyl alcohols by tripropylammonium fluorochromate (TriPAFC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding aldehydes. The reaction is first order each in TriPAFC and the alcohols. The reaction is catalysed by hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b[H+]. The oxidation of α α′-dideuterio benzyl alcohol exhibited a substantial primary kinetic isotope effect (kH/kD = 5.45 at 303 K). Oxidation of benzyl alcohol was studied in 19 different organic solvents. The solvent effect has been analysed using Kamlet's and Swain's multiparametric equation. A mechanism involving a hydride ion transfer via chromate ester is proposed.