In aqueous acidic acetonitrile solution cerium{IV) oxidizes diphenylmethane (Ph 2CH2 ) to produce diphenylmethanol (Ph 2CHOH) first and then benzophenone (Ph 2eO). With the organic reductant in great excess, both theCe(IV)-Ph 2CH2 and Ce(IV)-Ph 2CHOH reactions follow second-order kinetics. The rates of both reactions increase nonlinearly with increasing [W] or with decreasing [H 20]. Both kinetic and spectrophotometric results indicate that replacement of water molecules by complex formation through the phenyl or hydroxyl group plays an important role in activating the reaction. Under similar conditions, the order of relative reactivities toward Ce(IV) oxidation is PhCH 2 0 H > CH 3CH20H > Ph 2CHOH > Ph 2CH2 > PhCH 3 » (Ph 2CO, C 6 H 6 ) . Mechanistic interpretations of the kinetic results are presented. 519