Cyclic mechanism in the trapping of carbonyl oxides with alcohols and carboxylic acids

Abstract The reaction of diphenylcarbonyl oxide with alcohols and carboxylic acids, which has been classified as a nucleophilic trapping, is shown to be in the reactivity order: AcOH ≫ MeOH > CF 3 CH 2 OH > EtOH ≫  t -BuOH. A laser-flash spectroscopy indicated that the reaction of carboxylic acids is very fast, that is, one-tenth of the diffusion rate. These results suggest that the hydroxyl compounds react as an acid and a nucleophile at the same time and the major reaction is via the seven- and five-membered cyclic mechanism for RCO 2 H and ROH, respectively.