Propagation constants acrylic derivatives

In relation to the mechanism of polymerization, the cobalt octabromo derivative (7b) is also an effective initiator for controlled free-radical polymerization of acrylic esters, where the apparent first-order rate constant of propagation (kapp) at 50 °C is more than 30 times larger than kapp using 7a under identical conditions. This is due to a higher concentration of radicals resulting from greater dissociation of the dormant organocobalt species. 

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