Influence of the ortho effect in the solvolyses of dichlorobenzoyl chlorides

Abstract

The ortho-effect of substituents upon the kinetics of reactions taking place at a reaction center attached to an aromatic ring has long been a topic of interest. For benzoyl chloride solvolyses, it was shown by Bentley and coworkers that the 2,6-dimethyl-derivative followed an ionization pathway with characteristics very similar to those for the solvolyses of p-methoxybenzoyl chloride. We have carried out a GrunwaldWinstein equation treatment of the solvolyses of 2,6-dichlorobenzoyl chloride, with similar sized chlorines replacing the methyl groups but now with an overall electron-withdrawing influence of the ortho-substituents. In this way the reactivity is moderated and the study can be extended to the important fluoroalcohol-containing solvents. For the 30 solvents studied, an ionization pathway with a moderate nucleophilic solvation component is indicated. For comparison purposes, the treatment has also been applied to the 2,4-, 3,4-, and 3,5-dichloro- derivatives. For the 2,4-dichloro-derivative, the two reaction channels are clearly visible and the solvents included for each channel are consistent with their solvent properties. Copyright (C) 2011 John Wiley & Sons, Ltd.