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

Mechanistic studies on the formation of poly(isothianaphthene) (PITN) from phthalic anhydride and a thionating reagent (phosphorus pentasulphide or La wessons' reagent) have shown that the thionating reagent is not crucial in the polymerization reaction itself; it only plays a role in the synthesis o f the actual monomer, the tristhiophthalic anhydride. The polymerization pr ocess is not a classical polycondensation, but a process by which the very reactive tristhiophthalic anhydride monomer repeatedly attaches to the grow ing chain under expulsion of sulphur. We present new results obtained in st udies on low molecular models, and we will focus on additional reactions in duced by the thionating agent. A generalized mechanism will be proposed. (C ) 2000 Elsevier Science Ltd. All rights reserved.