Kinetics of polymerization of thiophene by FeCl3 in choloroform and acetonitrile

The kinetics polymerization of thiophene (T) with FeCl3 was followed by gas chromatography and by calorimetry either in suspension in chloroform or in acetonitrile solution. At low monomer concentration in chloroform the polymerization rate follows a first order vs T and is proportional to Fecl3 surface. The polymerization rate decreases when the T concentration increases. With Fecl3 solutions in acetonitrile the polymerization yield is limited but the reaction takes place in absence of solid FeCl3 surface contrary to previous claims. Measurements of reaction heats as a function of monomer concentration, for T and for its non polymerizable homologue 2 Methylthiophene (2meT), show different behaviors upon the nature of the solvent. These results will be the basis of a further mechanism discussion.