Kinetics of Bromination of Acetophenones. Part I

The bimolecular rate constant (k) and activation energy(E) for bromination of twentyfour mono and disubstituted acetophenones in 87% acetic acid containing 0.838 (M) sodium perchlorate and 0.05 (M) perchloric acid have been determined. Ionic strength was maintained constant. Changes in rate with sub­stitution arc mainly due to changes in E. The changes in activation energy due to the effects of substituents were found to be additive. Linear plots were obtained by plotting log k against. the logarithm of dissociation constants of different acetophenones, and also by plotting the activation energies of different acetophenones against the corresponding dipole moments. The applicability of Hammett equation has been examined, the value oil p being found to be equal to —0.714. log k for different acetophenones have been plotted against the activation energy and the results are discussed