Metathesis polymerization of monosubstituted acetylenes

In Table 10.1 are simimarized the alkylacetylenes that have been polymerized by metathesis catalysts. The halides NbCls, TaCls, M0CI5, and WCl can be used without a cocatalyst because acetylenes themselves react readily with the halide to generate an initiating metal carbene complex, perhaps through a sequence such as eqns. (23a) or (23b) (Weiss 1986b). 

Numerous other monosubstituted acetylenes can be polymerized with these catalysts as summarized in Table 10.2 for Si-containing monomers and in Table 10.3 for various non-aromatic monomers containing functional groups. 

Much work has also been carried out on phenylacetylene and its derivatives. Phenylacetylene itself can be polymerized by all types of catalyst for example, by 

SiMe Mo(CO)6/CCl4/Av X = 4 TaCI gives mainly cyclic trimers  

Mc3Si MoOCl4/Bu4Sn/EtOH Living system = 1.11 Masuda 1987c, 1993 

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