Carbonyl‐olefin exchange reaction. A new route to conjugated polymers, 6. Low‐molecular‐weight products

Abstract

The processes which take place with the α,β-unsaturated compound 1,2,3,3-tetraphenyl-2-propen-1-one (1) under the influence of WCl6 were investigated. Special attention was paid to the low-molecular-weight products. It was established that beside polydiphenylacetylene and benzophenone also benzil, tetraphenylethylene and molecular oxygen are present in the product mixture. Their formation is explained as a result of a redistribution of the atoms connected with double bonds according to olefin metathesis (OM), carbonyl-olefin exchange reaction (COER) and reductive coupling (RC) of carbonyl compounds, accompanied by molecular oxygen evolution. The yields of products insoluble in methanol are sometimes higher than a simple stoichiometry would allow. This can be attributed to the participation of both the inner double bonds of the polymer and the low-molecular-weight products.