Helix-Sense-Selective Polymerization of 1-Phenyldibenzosuberyl Methacrylate by Free Radical Mechanism.

Abstract

Free radical polymerization of 1-phenyldibenzosuberyl methacrylate was carried out in toluene at 40 or 50°C under chiral reaction conditions based on the use of (-)-dimenthyl peroxydicarbonate as an initiator, (-)- and (+)-menthol as a reaction solvent (additive), and (+)- and (-)-neomenthanethiol as a chain transfer agent. The obtained polymers had a highly isotactic and helical structure; there was an excess of right- or left-handed helicity by the influence of the above chiral materials and consequently, the polymers were optically active. The mechanism of chiral induction for the polymerization using the chiral initiator involved helix-sense-selective primary radical termination, i.e., the reaction between a polymer radical and an initiator radical. In the polymerization using menthol and neomenthanethiol, hydrogen transfer from these chiral compounds to the growing radical appeared to take place in a helix-sense-selective manner.