Mechanism of free radical formation in metal carbonyl and halide systems. Solvent effects, part 3.—Manganese carbonyl

Abstract

The free-radical polymerization of methyl methacrylate initiated by manganese carbonyl and carbon tetrachloride has been studied in the presence of benzene and ethyl acetate. To explain the kinetics it is necessary to postulate that initiation results from an S_N1 type reaction, viz., dissociation of the carbonyl, with scission of carbon monoxide without intervention of monomer, followed by reaction with carbon tetrachloride. This differs from the corresponding process for molybdenum carbonyl, which follows as S_N2 course. Kinetic parameters have been evaluated from equations derived for steady state relationships.