Polymerization of Diphenylacetylenes with Polar Functional Groups by the Grubbs–Hoveyda Ru Carbene Catalyst

Abstract

AbstractSummary: Polymerization of various diphenylacetylene derivatives was investigated by using Grubbs–Hoveyda catalyst (1). Owing to excellent tolerance for polar functional groups, catalyst 1 polymerized diphenylacetylene (2) and diphenylacetylene derivatives bearing silyl (3), siloxy (4 and 5), ester (6 and 7), amide (8–10), and carbamate (11) groups. It is noteworthy that polymerization of monomers 6–11, which have polar functional groups, has been impossible until now due to the deactivation of well‐known Ta catalysts. Although monomers having ester groups (6 and 7) hardly polymerized, their copolymerization with trimethylsilyl group‐containing diphenylacetylene (3) afforded copolymers, which incorporated ester moieties more than the monomer feed ratio. While polymers with relatively nonpolar groups [poly(3)–poly(5)] were soluble in hydrocarbon solvents such as cyclohexane and hexane, polar group‐bearing homo‐ and copolymers (poly(10), poly(11), etc.) dissolved in polar solvents (e.g., DMF and acetone). Polymerization of 1‐(4‐tert‐butyldimethylsiloxy)phenyl‐2‐(4‐fluorophenyl)acetylene (5) gave a high molecular weight polymer ($\overline M _{\rm n}$ = 178 000) suitable for membrane fabrication, and the membrane of this polymer showed higher gas permeability and permselectivity than that of the Ta‐based polymer.Polymerization of various diphenylacetylenes by the Ru Grubbs–Hoveyda catalyst.magnified imagePolymerization of various diphenylacetylenes by the Ru Grubbs–Hoveyda catalyst.