Polydienes singlet oxygen

Polydienes also can undergo oxidation with singlet oxygen. The present consensus is that the oxidation of polydienes with singlet oxygen occurs via a so-called ene-mechanism ... 

In the case of polydienes Kaplan and Kelleher (63 64) have shown addition of singlet o ygen to two nearest neT bour double bonds with the formation of two allylic hydroperoxides. Further addition of singlet oxygen to double bonds followed the formation of cyclo-peroxide rings ... 

Since 1971 our department is Involved in study of photodegradation, sensitized photooxidation and photostabilization of polymers. A big effort is made in the study of singlet oxygen oxidation of several important polymers, such as polydienes, poly(vinyl chloride), polystyrene and polyesters, reactions of atomic oxygen and ozone with polydienes and photostabilization of these polymers. 

Breck at al (68) have recently examined the reactivities of a number of saturated and unsaturated polymers towards singlet oxygen generated by microwave generator. The saturated chain polymers as polystyrene,polyurethane and polyethyle-ne were found to be inert within the experimental conditions with singlet oxygen,while the unsaturated polymers as polydienes were found to react quite readily.In this paper concentration of hydroperoxide groups has been measured. 

It is generally accepted that singlet oxygen ( O2) can react with polymers which contain unsaturated bonds as elements of their structures e.g. polydienes, or in the form of abnormal structures (internal impurities), e.g. polyolefins and poly(vinyl chloride). 

Polydienes (polybutadiene, polyisoprene and their copolymers and analogues) react very effectively with singlet oxygen CO2) generated in the gaseous phase by microwave discharge or in photosensitized (dye) reactions. Reaction of 02 with polyisoprene leads to the formation of three polymeric hydroperoxides [800, 1569, 1571, 1572, 1787, 2095, 2096] ... 

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