Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Tungsten oxychloride alone and in combination with Ph₄Sn were found to induce a polymerization of phenylacetylene (PhA) totrans-rich poly(phenylacetylene) (PPhA). The binary catalyst has a narrow maximum of the activity at the molar ratio [Ph₄Sn]_o =y = 2, so that two molecules of Ph₄Sn are necessary for a conversion of one molecule of WOCl₄ to the most active precursor specie. An identical excess of Ph₄Sn acts as a noncompetitive inhibitor (retarder) of the overall polymerization. The order of reaction with respect to catalyst (for y = 2) varies with a concentration of the catalyst. It has value 1 for [WOCl₄]_o from 0.1 to ca 4 mmol.dm^-3 and gradually increases over this concentration limit. Mutual interactions of partially associated growing species, eliminating inhibitive effects of monomer and organotin compounds, are supposed as a reason of this uncommon behaviour. The self inhibitive effect of polymerizing PhA was deduced from the dependence of the initial rate of polymerization on the concentration of PhA. This inhibition takes part most probably in both, the initiation and the propagation. The attempts to determine molecular weights of PPhA by VPO method failed because of a rapid degradation of polymer in diluted solution exposed to atmospheric oxygen.