Collect. Czech. Chem. Commun. 1991, 56, 351-367

Kinetics and mechanism of the phenylacetylene metathesis polymerization catalyzed with WOCl4/Ph4Sn in benzene

Jiří Vohlídal, Andreas Holländer, Markéta Jančálková, Jan Sedláček and Irena Sargánková

Department of Physical and Macromolecular Chemistry, Charles University, Albertov 2030, CS-128 40 Prague 2


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 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.