Kinetics of oxidation of acetophenones by diperiodatonickelate(IV) in the presence and absence of Os(VIII)

849-854The rate of oxidation of acetophenone(S) in the absence of Os(VIII) exhibits a pseudo-first order dependence in [DPN], (DPN, diperiodatonickelate(IV)) when [S] is in excess. The order in [S] is one. Increase in [OH-] increases the rate while added [periodate] decreases it. Added salts and change in dielectric constant of the medium do not affect the rate both in the absence and presence of Os(VIII). Added acrylamide does not produce any polymerisation in both the cases. The rate is independent of [DPN] in the presence of Os(VIII)and orders in [S]and [OH-] are found to be fractional. The order in [Os(VIII)] is one. The products of oxidation are the corresponding benzoic acid and formaldehyde in the presence as well as absence of Os(VIII). A suitable mechanism has been suggested and relevant rate law is derived