Osmium(VIII) catalyzed oxidation of tellurium(IV) by periodate in aqueous alkaline medium

Osmium(VIII) catalyzed oxidation of tellurium(IV) by periodate in alkaline medium is found to occur via oxidant-catalyst complex formation in a slow s tep followed by the interaction of substrate and complex in the fast step t o yield the products with regeneration of catalyst. One of the products, Te (VI), considerably retards the rate of reaction. The reaction shows zero or der in [tellurium(IV)], first order each in [IO4-] and [Os(VIII)] and an in verse fractional order dependence on [OH-]. A plausible mechanism is propos ed and the reaction constants involved in the mechanism are derived.