Redox polymerization of acrylonitrile‐kinetics of the reaction initiated by the redox system dimethyl sulfoxide–Mn(III)

The kinetics of oxidation of dimethyl sulfoxide by tervalent manganese was investigated in sulfuric and perchloric acid media at 40–45°C. A mechanism involving prior complexation between reactants followed by a reversible electron‐transfer step was shown to be consistent with the kinetics. The radical ion thus produced initiates polymerization of acrylonitrile, the termination being effected by the oxidant. Rates of polymerization vary directly as the sulfoxide concentration and are proportional to the square of the monomer concentration and being independent of the oxidant. Oxidation as well as polymerization is retarded by Mn(II). Average degrees of polymerization lend support to the proposed mechanism. Rate parameters have been evaluated in the two media, and their significance is discussed.