The WCl6–e−–Al–CH2Cl2 catalyzed polypentenamer formation via ring-opening metathesis polymerization (ROMP)

The synthesis of polypentenamer by an electrochemically generated metathesis polymerization catalyst from methylene chloride solution of WCl6 was investigated. The active species formed by electroreduction of this salt under controlled potential of +900 mV at a platinum cathode with an aluminum anode were found to catalyze the ring-opening metathesis polymerization (ROMP) of cyclopentene, monocyclic olefin of relatively low strain, in high yield (89%) and at short period (32 min) under mild conditions. The effect of reaction parameters, e.g., olefin/catalyst ratio, reaction time, electrolysis time, catalyst aging, on the polymerization yield have been studied. The resulting polymer has been characterized by 1H and 13C NMR, IR and gel permeation chromatography (GPC) techniques. Analysis of the polypentenamer microstructure by means of 13C NMR spectroscopy indicates that the polymer contains a mainly trans stereoconfiguration of the double bonds (σc = 0.31) and a slightly blocky distribution (rtrc > 1) of cis and trans double bond dyads (rtrc = 1.44). However, this electrochemical system is reluctant to facilitate the competing vinyl type addition polymerization reactions.