REACTIVITY-SELECTIVITY RELATIONSHIPS .9. IDENTIFICATION OF SOLVOLYTIC INTERMEDIATES IN SOLVOLYSIS OF SUBSTITUTED BENZYL DERIVATIVES

The selectivity of substituted benzyl derivatives toward ethanol and water during solvolysis was examined. The results provide a detailed description of the solvolytic intermediates formed during solvolysis. p-Chlorobenzyl and benzyl derivatives are found to undergo product formation via intimate ion pairs, p-methylbenzyl derivatives via intimate ion pairs at low solvent polarity but through increasing proportion of solvent separated ion pairs as the polarity of the medium is increased, and p-methoxybenzyl chloride predominantly through solvent separated ion pairs. A leaving group effect on selectivity is proposed as a new diagnostic tool for the identification of solvent separated ion pairs. Application of this tool leads to conclusions identical to those we obtain based on the study of solvent effects on selectivity.