Chemical and phase transformations of thiophene at high pressures

Abstract

Phase transformations of thiophene (C4H4S) and deuterated thiophene (C4D4S) were studied by visual observations and Fourier‐transform infrared spectroscopy up to 30 GPa. At room temperature, thiophene freezes at 0.4 GPa and undergoes a solid‐to‐solid transition around 6 GPa and probably another one at 20 GPa. It is shown that an irreversible incomplete transition occurs at 16 GPa. The product of the reaction, a white solid, can be recovered at atmospheric pressure. The infrared analysis of the recovered product gives evidence of a polymer formed by coupling between rings derived from thiophene, but with saturated bonds. Physicochemical arguments suggest the formation of a fibrous compound.