Borderline mechanisms involving ion-molecule pairs for the nucleophilic substitution reactions of benzhydrol and its derivatives. Facile formation and cleavage of diphenylmethyl ethers for the protection of hydroxyl groups

Article abstract of DOI:10.1016/S0040-4039(98)00181-6

Nucleophilic substitution reactions of benzhydrol and its derivatives, in refluxing benzene in the presence of para-toluenesulfonic acid, took different routes depending on whether paratoluenesulfonic acid was used in excess or in catalytic amounts. In the first case the reactions took place via benzhydryl carbocations and in the second case they proceeded via intimate ion-molecule pairs. On the basis of this study, facile methods for introduction and removal of CHPh₂ as a protective group of alcohols are presented.