Abstract:
Measurements are reported on the hydroxidc-catalyzed ionization of (d)-phenylmethylaceto-
phenone in the presence of varying amounts of dimethyl sulphoxide. The kinetic hydrogen isotope
effect (kn/kr) increases with increasing basicity until at a H_ value of 16.5 it reaches a maximum.
The value of the Bronsted exponent 3 is 0.49 ±0.02 for both isotopes. For several media, activation
energies and pre-cxponcntial factors have been determined. The difference Ey—Er reaches a
maximum at a H_ value of 16.8. The ratios of JrMt reflect the importance of solvent reorganization
contributions.
