Reactivity of acetates in aqueous alcohols

A series of X,Y-substituted benzhydryl acetates (1-3) were subjected to solvolysis in various binary methanol/water and ethanol/water mixtures at 25 °C. The LFER equation log k = sf(Ef + Nf) was used to derive the nucleofuge-specific parameters (Nf and sf) for an SN1 type reaction in 60 % and 80 % aqueous methanol. It has been established that X,Y-substituted benzhydryl acetates produce almost parallel correlation lines, so the average sf = 0.9 has been taken for calculation of the nucleofugality parameters from a single rate constant in some solvent mixtures. In comparison with other leaving groups for which the nucleofugality has already been determined, acetates are the poorest nucleofuges