Synthesis and polymerization of ethynylthiophenes and ethynylfurans containing trifluoromethyl groups

Abstract

Fluorination of thiophenedicarboxylic acid with sulfur tetrafluoride in the presence of anhydrous hydrogen fluoride provided mono and bis(trifluoromethyl)thiophenes in moderate yields. Ethynylthiophenes and ethynylfurans containing trifluoromethyl groups were prepared via 2,2-dichloro-1-fluorovinyl compounds. In polymerizations using transition metal catalysts, 3-ethynylthiophenes gave polymers in high yields, which were soluble in THF and/or fluorocompounds, while 2-ethynylthiophenes polymerized in low yields. In γ-ray induced polymerization, only 2,5-bis(trifluoromethyl)-3-ethynylthiophene afforded the corresponding polymers. Thermal decomposition temperature of polymers obtained increased by introduction of the trifluoromethyl groups as well as the methyl groups.