New mechanistic aspects on the formation of poly(isothianaphthene) from P4S10 and phthalic anhydride derivatives: carbon–carbon bond formation and cleavage via a cyclic reaction mechanism

Abstract

Mechanistic studies on the formation of poly(isothianaphthene) (PITN) from phthalic anhydride and a thionating reagent (phosphorus pentasulphide or Lawessons' reagent) have shown that the thionating reagent is not crucial in the polymerization reaction itself; it only plays a role in the synthesis of the actual monomer, the tristhiophthalic anhydride. The polymerization process is not a classical polycondensation, but a process by which the very reactive tristhiophthalic anhydride monomer repeatedly attaches to the growing chain under expulsion of sulphur. We present new results obtained in studies on low molecular models, and we will focus on additional reactions induced by the thionating agent. A generalized mechanism will be proposed.