Catalytic Chain Transfer Isomerization Reactions Involving 2-Phenylallyl Alcohol

Abstract

A catalytic chain transfer agent, bis[(difluoroboryl)dimethylglyoximato]cobalt(II) (COBF), was utilized in free radical polymerizations involving 2-phenylallyl alcohol (PAA). In homopolymerization only oligomers were formed, and the predominant product was 2-phenylpropanal consistent with a radical-induced isomerization reaction. In copolymerizations with methyl methacrylate (PAA included at 5 and 10 mol %) the chain transfer constants increased significantly (compared to those obtained for methyl methacrylate homopolymerization). NMR analyses of the co-oligomer chains confirmed PAA incorporation into the copolymers and provided evidence for the presence of an aldehyde group resulting from chain transfer isomerization. Further analyses by matrix-assisted laser desorption ionization (MALDI) mass spectrometry indicated conclusively that a PAA monomer unit was incorporated into copolymer chains. The thermal degradation behavior of the oligomers was measured using thermogravimetric analysis (TGA). The thermograms clearly indicate that the PAA is situated at the chain ends of the majority of the polymer chains even at low concentrations of PAA in the initial monomer feed.