Organolithium Catalysis of Olefin and Diene Polymerization

Abstract

Publisher Summary This chapter discusses the organolithium catalysis of olefin and diene polymerization. The lithium and alkyllithium initiation of diene polymerization has, from the earliest times, remained in the shadow of other, apparently more important, initiator systems. The earliest mention of lithium initiation of diene polymerization was in 1910–1913. The development of organometallic initiators, both of the lithium type and of the transition-metal coordination type, occurred rapidly in the decade following the late 1950s. The coordination catalysts were quickly extended to dienes and found to produce the long-sought objective of a “synthetic” natural rubber. Alkyllithium compounds have solubility and stability because of their ability to associate to form aggregates of definite structure. A somewhat different form of delocalization occurs in the case of allylic lithium compounds. The insertion of olefins and conjugated dienes between carbon-bound metals has been well documented in the literature. There are reports in the literature that the higher molecular weight alkyllithium compounds, such as polystyryl- or polyisopropyllithium may be dimeric. Organolithium reagents have been used to prepare random, block, and graft copolymers. When butadiene and styrene are mixed in the presence of an organolithium initiator, the resulting copolymerization process and product will be governed by the reaction conditions.