Polymeric Reagents. 3. Poly[vinyl(pyridinium chlorochromate)]: A New Recyclable Oxidizing Agent

Poly[vinyl(pyridinium chlorochromate)] is prepared easily from cross-linked poly(vinylpyridine) resins by reaction with chromic anhydride and hydrochloric acid. The insoluble reagent, which has a capacity of 3.5-3.9 mmol of chlorochromate per gram, is useful in the oxidation of alcohols to carbonyl compounds. The oxidation has a high efficiency, as less than 1 molar equiv of the reagent is consumed in the reaction. Other advantages of the reagent are associated with its insolubility and that of its byproduct which facilitates the workup of reaction mixtures and allows for the quantitative recovery and regeneration of the spent resin. After several regenerations, the reagent is still as reactive as the original material.