Palladium Catalysis of Ditriflates for the Preparation of Soluble Poly(phenylene) Derivatives

Abstract

A new polymerization reaction for the preparation of alkyl-substituted poly(phenylene)s is described based on the coupling of alkyl-substituted aromatic bis(trifluoromethanesulfonate) (triflate) with 1,4-bis(trimethylstannyl)benzene in the presence of a palladium catalyst. Aromatic triflates, readily prepared from the corresponding hydroquinone, were discovered to be excellent substrates in the preparation of soluble poly(phenylene) derivatives with alkyl substituents on alternating aromatic rings. Analysis of the poly(phenylene) derivatives by SEC revealed a near-Gaussian molecular weight distribution curve with degree of polymerization of 11 and polydispersity from 1.3 to 1.7. Analysis by 31 P-NMR revealed the presence of phosphorus, the presence of which limits the catalytic efficiency of palladium leading to a decrease in the degree of polymerization.