Novel Catalyst Systems for the Polymerization of Substituted Acetylenes

Abstract

This article reviews two types of novel catalyst systems for the polymerization of substituted acetylenes; i.e., i) MoOl₄-based catalysts and ii) metal carbonyl-based catalysts. The MoOCl₄–n-Bu₄Sn–EtOH(1:1:1) catalyst achieves living polymerization of 1 -chloro-1-octyne, tert-butylacetylene, and phenylacetylenes having bulky ortho substituents. The initiator efficiency for the polymerization of o-CF₃-phenylacetylene reaches about 40% in anisole. Et₃Al, Et₂Zn, and n-BuLi also work as useful cocatalysts in the MoOCl₄-based system; the polydispersity ratios of poly(o-CF₃-phenylacetylene) are as small as 1.06 to 1.02. The binary MoOCl₄–n-BuLi system serves without ethanol. Block copolymers of o-CF₃- and o-Me₃Si-phenylacetylenes can be obtained by using MoOCl₄–Et₃Al–EtOH(1:1:4). Whereas CCl₄ is used as solvent in the polymerization of phenylacetylene by W(CO)₆–CCl₄–hn, only a few equivalents of Ph₂CCl₂ to tungsten is needed in the W(CO)₆–Ph₂CCl₂–hn system. A tungsten complex, WCl₂(CO)₃-(AsPh₃)₂ by itself induces the polymerization of phenylacetylenes.