Polymerization of vinyl compounds with heterocyclic groups. IV. Thermal polymerization of 2‐vinylthiophene

Abstract

Abstract2‐Vinylthiophene was found to undergo thermal polymerization. With benzene as diluent, the overall rate of polymerization was proportional to the 2.5 power of monomer concentration, suggesting that the thermal initiation is a termolecular process. The following Arrhenius equation was obtained from the polymerization data for the range 55–100°C: The activation energy of the thermal initiation was estimated to be 28.2 kcal/mole, which was similar to those values obtained for styrene and 2‐vinylfuran. When a dilute solution of the monomer in bromobenzene was heated in an ampoule at 151°C, a dimer, mp 82°C, was obtained in a good yield. The spectroscopic data indicated that the dimer was a Diels‐Alder type adduct. The initiation of the thermal polymerization was considered to involve hydrogen abstraction by monomer from the Diels‐Alder dimer, in common with the initiation of other vinylaromatic monomers.