Dicyclopentadiene Polymerization Using Well-Characterized Tungsten Phenoxide Complexes

Abstract

Pure WOCl 4 -x (OAr) x complexes (x = 1, 2, 3 and 4; and OAr = phenoxide) were prepared in essentially quantitative yield by reacting tungsten oxytetrachloride (WOCl4) with the requisite amount of phenol or metal phenoxide. The ring-opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) by WOCl 3 (OAr), WOCl 2 (OAr) 2 , and WOCl(OAr) 3 , in combination with trialkyltin hydride (R 3 SnH) was assessed. The tungsten catalysts produced are capable of bulk-polymerizing DCPD to very high polymer yields. The polymerization ability of a particular procatalyst was correlated with the reduction potential (W(VI)-->W(V)) of the complex and the charge on the oxygen of the di-or tri-substituted phenoxide ion. The effects of changing DCPD:W, Sn:W, and rate moderator:W ratios on residual monomer levels were studied.Transition metal-catalyzed ring-opening metathesis polymerization (ROMP) of cyclic olefins is an important application of the olefin metathesis reaction (Scheme 1) [7]. Polynorbornene, polyoctenamer, and polydicyclopentadiene are currently produced on an industrial scale using this process [2].