Polymerization of phenylacetylene by WCl6·Ph4Sn: Synthesis of high polymer achieved by selection of solvents

Phenylacetylene was polymerized by WCl6·Ph4Sn (1:1) in 1,4‐dioxane to provide in high yield a polymer whose molecular weight reached 1 × 105. The polymerization also proceeded in other oxygen‐containing solvents (ethers, esters, and ketones) but the polymer molecular weights were lower than 1 × 104. Certain hydrocarbon solvents such as cyclohexene, tetralin, and indan also afforded high‐molecular‐weight polyphenylacetylene [Mn = (5–8) × 104], as compared with those (Mn ≤ 1.5 × 104) obtained in conventional aromatic hydrocarbons like benzene. A high polymer (Mn = 1.6 × 105) was also formed from β‐naphthylacetylene in 1,4‐dioxane. It was inferred that the active hydrogens of these solvents prevent the formed polymer from being decomposed by a radical mechanism and/or modify the nature of active species.