Peroxy esters thermal decomposition

Peroxy esters of malonic and succinic acids have been subjected to thermal decomposition and the kinetic data are given in Table 110. A two-bond homolysis... 

THERMAL DECOMPOSITION OF PEROXY ESTERS OF MALONIC AND SUCCINIC ACIDS AT... 

Radical trapping by a nitroxide was used to determine the ratio between (3-fragmentation and hydrogen abstraction by alkoxy radicals generated by thermal decomposition of peroxy pivalate esters.The ratio of fragmentation hydrogen abstraction increased sharply with radical substitution and stability. 

These peroxy esters undergo smooth thermal decomposition at temperatures around 75 °C and are useful initiators of radical chain reactions. 

The choice of the proper peroxy initiator largely depends on its decomposition rate at the reaction temperature of the polymerization. BPO is the major initiator for bulk polymerization of polystyrene or acrylic ester polymers, where temperatures from 90°C to 220°C are encountered. Dilau-royl, dicaprylyl, diacecyl, and di- err-butyl peroxides are also used. In the case of suspension polymerization of styrene, where temperatures between 85°C and 120 C are applied, the initiators also range in activity from BPO to di-tm-butyl peroxide. In suspension polymerization of vinyl chloride (reaction temperatures of 45-60°C for the homopolymer), thermally very labile peroxides such as diisopropyl peroxydicarbonate and rm-butyl peroxy-pavilate are used. 

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