Kinetic and Mechanistic Study on p-Quinodimethane Formation in the Sulfinyl Precursor Route for the Polymerization of Poly(p-phenylenevinylene) (PPV)

The kinetics of p-quinodimethane formation in the sulfinyl precursor route for the poly(p-phenylenevinylene) (PPV) polymerization was studied using stop-flow UV−vis spectroscopy and theoretical first principle calculations. Different sulfinyl monomers were studied by means of quantitative kinetic experiments regarding the p-quinodimethane formation in 2-butanol. The influence of the solvent, the nature of the aromatic moiety, and the substituents on the phenyl core was analyzed by means of qualitative experiments. Quantitative measurements, using pseudo-first-order reaction conditions, were performed in order to assess the effect of the polarizer and the leaving group on the reaction rates. To obtain additional fundamental insight into the pathway leading to p-quinodimethane formation, density functional theory calculations were performed and subsequent reaction rate coefficients were determined from a theoretical point of view, enabling a profound comparison with experiment. From all these data, an E2 mechanism is proposed for the p-quinodimethane formation in the sulfinyl precursor route.