Photosensitized oxidation of unsaturated polymers

Abstract

The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1