Polymerization of 3‐methyl‐2,5‐dibromothiophene utilizing n‐butyl lithium and copper(II) chloride

Abstract : In recent years, there have been extensive research activities focussed on macromolecules with extended pi-electron system. Among the many macromolecules studied, conjugated olefinic compounds (polyenes), have been given much attention. Various methods for their synthesis have been reported. In the heterocyclic category, there are four reports on the synthesis of poly(3-substituted-2,5-thienylene) (substituent = H, CH3) via coupling of 3-substituted-2,5-dibromothienylmagnesium by nickel salt promoters. Recently Afanas'ev, et al. reported also about the preparation of poly(2,5-thienylene) by an electrochemical method. The ability for charge transport through the thiophene polymer chain is an important criterion for achieving high conductivity. For that reason the synthesis of polyenes was studied. The present investigation was undertaken to improve the synthesis of poly(3-methyl-2,5-thienylene) and to obtain a magnesium free material. n-Butyl lithium was used as dehaloginating agent. Cu(II) chloride was utilized to serve as catalyst.