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 (b)) were synthesized and added to vinylic monomer polymerizations. These olefins are activated towards free radical addition and contain a homolytic leaving group i n the allylic position. Thus, they exhibit chemical transfer propertie s in free radical polymerization. The compounds studied include bromid e, iodide, sulfone, mercaptan and peroxide derivatives. Cinnamic iodid e, however, exhibits degradative chain transfer activity. These compou nds have an advantage over simple thiols in that they permit a good co ntrol of molar mass by an addition-fragmentation mechanism involving d ifunctionalization of the resulting telomers. The methods of synthesis of ethyl 2-(substituted)cinnamates (b)) are discussed through the nuc leophilic substitution of various anions toward the allylic bromo deri vative prepared from ethyl 2-(alpha-hydroxybenzyl)propenoate.