Application of Grunwald-Winstein correlation analyses with Y-BnBr scales to the solvolysis of benzoyl bromides

The solvolysis of 4-methoxy-(1), 4-methyl-(2), unsubstituted (3) and 4-chlo ro-(4) benzoyl bromide in a variety of solvents was studied. The linear log k-Y-BnBr plots for 1 indicates limiting S(N)1 mechanism, whereas the split ting of lines for nucleophilic solvents and poorly nucleophilic solvents in the case of 2 suggests significant nucleophilic solvent participation. The mechanism for the solvolysis of 3 and 4 probably varies with solvents, sim ilar to that of the corresponding chlorides. Good linear Hammett log k-sigm a (+) plot could be found in a few solvents. A comparison of the solvolytic behavior for aromatic acyl bromides and chlorides will be discussed. (C) 2 001 Elsevier Science Ltd. All rights reserved.