DPPH (2,2-DiphenyM-picrylhydrazyl) as a Diagnostic Tool in Mechanistic Studies Related to Polymerization

Abstract

The reactions of DPPH with azobisisobutyronitrile in benzene and in methyl methacrylate have been studied. The reactions are complex, and the previously-assumed initiator radical-DPPH adduct, l-(4-cyanoisopropylphenyl)-l-phenyl-2-picrylhydrazine, is only one component in a mixture of products which include diphenyl, diphenylamine, l,l-diphenyl-2-picrylhydrazine and aminophenylphenyl-picrylhydrazine derivatives, and nitrile-rich polymeric species. The reactions of DPPH with aliphatic mercaptans are also more complex than previously assumed, and although the corresponding aliphatic disulfides are usually the major products, the reactions apparently do not involve free radical intermediates. © ..