THE MECHANISM OF SOLVOLYSIS OF 2,2-DIMETHYL-3-PENTYL AND 1-(1-ADAMANTYL)PROPYL SULFONATES

Solvolysis rates, alpha and beta deuterium isotope rate effects and pr oduct yields have been determined for some 1-(1-adamantyl) propyl sulf onate esters, 4, in some ethanol-water, trifluoroethanol-water and hex afluoroisopropyl alcohol-water mixtures. For comparison, similar measu rements have been made for solvolysis of 2,2-dimethyl-3-pentyl sulfona tes, 5. For the esters 5, the alpha-d and beta-d(2) effects vary littl e with solvent in the ranges of 1.164-1.165 and 1.215-1.241, respectiv ely, and only small yields of unrearranged products are formed; it is concluded that the mechanism involves rate determining formation of th e secondary cation-ion pair followed by rapid rearrangement. For the a damantyl analogs, 4, the alpha-d effects vary in the different solvent s from 1.162 to 1.213 and the beta-d(2) effects vary from 1.339 to 1.6 49; significant yields of unrearranged and Wagner-Meerwein rearranged (ring expansion) products are formed. The steady state treatment, whic h had been used previously to fit the results for 1-(1-adamantyl)ethyl esters, was applied to the results for 4; a mechanism which involves partially reversible ionization to the intimate ion-pair followed by c ompeting elimination and solvent separation, to give the substitution products, fits the results reasonably well.