• Grunwald–Winstein equation;
  • solvolysis;
  • solvent nucleophilicity;
  • solvent ionizing power;
  • aromatic ring parameter


Available specific rates of solvolysis at 25 °C of benzoyl chloride and four para-substituted derivatives for which both NT and YCl values are tabulated were analyzed using the extended (two-term) Grunwald–Winstein equation. The ionization pathway with appreciable nucleophilic solvation of the incipient carbocation observed for the p-methoxy derivative is accompanied by increasingly important regions of dominant operation of an addition–elimination pathway as the Hammett σ value for the substituent increases. Accordingly, for the p-nitro derivative only the 97% HFIP data point deviates from the addition–elimination correlation. Correlations of the specific rates of solvolysis of 2,6-dimethylbenzoyl chloride are improved by incorporation of a term governed by the aromatic ring parameter (I). Copyright © 2002 John Wiley & Sons, Ltd.