POLYMERIZATION OF 3-ALKYLTHIOPHENES WITH FECL3

We report on the mechanism of direct oxidation of 3-alkylthiophenes us ing ferric chloride (FeCl3) as the polymerization oxidant/catalyst to produce high molecular weight poly (3-alkylthiophenes) (P3ATs), conjug ated polymers that have potential as electrically and optically active polymers. This study shows that the FeCl3 must exist in the solid sta te in the reaction mixture to be active as an oxidant in the polymeriz ation of P3AT. A feasible polymerization mechanism for 3-alkylthiophen e was developed on the basis of the crystal structure of FeCl3 and qua ntum chemical computations of thiophene derivatives. The polymerizatio n is hypothesized to proceed through a radical mechanism rather than a radical cation mechanism.