Abstract
AbstractSolvolysis of 1,1‐diphenyl‐1‐X‐ethane (1‐X) [X = 4‐nitrobenzoate (PNB), 3,5‐dinitrobenzoate (DNB), AcO, MeOH+, EtOH+ or H2O+] was studied in 20 vol% dimethyl sulphoxide in water, in which specific salt effects are very small, and in 25 vol% acetonitrile in water. Substrates with negatively charged leaving groups yield more elimination product 1,1‐diphenylethene (3) than those with uncharged groups, indicating the intermedicacy of ion pairs. Thus, three times more alkene is formed in the reactions of the substrates 1‐OAc and 1‐PNB than in the acid‐catalysed hydrolysis of 1‐OMe and 1‐OAc. The substitution products may be formed via the solvent‐equilibrated carbocation since the measured nucleophilic selectivities are very similar with different leaving groups.
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