Chain transfer by addition-fragmentation mechanism, 5 Investigation of the chain transfer activity of several ethyl 2-(substituted)cinnamates

A variety of ethyl 2-(substituted)cinnamates

1 Systematic name: ethyl 3-phenyl-2-(substituted)propenoate.

were synthesized and added to vinylic monomer polymerizations. These olefins are activated towards free radical addition and contain a homolytic leaving group in the allylic position. Thus, they exhibit chemical transfer properties in free radical polymerization. The compounds studied include bromide, iodide, sulfone, mercaptan and peroxide derivatives. Cinnamic iodide, however, exhibits degradative chain transfer activity. These compounds have an advantage over simple thiols in that they permit a good control of molar mass by an addition-fragmentation mechanism involving difunctionalization of the resulting telomers. The methods of synthesis of ethyl 2-(substituted)cinnamates are discussed through the nucleophilic substitution of various anions toward the allylic bromo derivative prepared from ethyl 2-(α-hydroxybenzyl)propenoate.