893.
Improved methods for the synthesis of linear and cyclic poly(diphenylacetylene)s by polymerization of the corresponding diphenylacetylenes using MoCl
5- and WCl
4-based catalytic systems have been developed. MoCl
5 induces migratory insertion polymerization of diphenylacetylenes in the presence of arylation reagents such as Ph
4Sn and ArSn
nBu
3 to produce
cis-stereoregular linear poly(diphenylacetyelene)s with high molecular weights (number-average molar mass (
Mn)=30,000–3,200,000) in good yields (up to 98 %). On the other hand, WCl
4 induces ring expansion polymerization of diphenylacetylenes in the presence of Ph
4Sn or reducing reagents to produce
cis-stereoregular cyclic poly(diphenylacetylene)s with high molecular weights (
Mn=20,000–250,000) in moderate to good yields (up to 90 %). Both catalytic systems are applicable to the polymerization of various diphenylacetylenes having polar functional groups such as esters that are not efficiently polymerized by conventional methods using WCl
6-Ph
4Sn and TaCl
5-
nBu
4Sn systems.
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