1,4 polymerization of isoprene by titanate catalyst systems

Abstract

AbstractTitanates are versatile in the 1,4 polymerization of isoprene. The (R′O)4Ti/RAlCl2 catalyst gives either cis‐ or trans‐1,4‐polyisoprene, depending on the nature of both the titanate and the solvent. Primary titanates give cis‐1,4‐polyisoprene in both aliphatic and aromatic solvents. Secondary titanates give cis‐polyisoprene in aliphatic solvents, and trans‐1,4‐polyisoprene in aromatic solvents. Tertiary titanates give trans‐polyisoprene in both aliphatic and aromatic solvents. A mechanism is postulated which takes into consideration the role of the solvent. ESR studies of the various titanate–RAlCl2 catalysts were made; the paramagnetic structures are related to polymerization mechanisms.