Local chain‐configuration dependence of the mechanisms of the chemical reaction of poly(vinyl chloride). IX. Novel results on stereoselectivity of chlorination reaction

Abstract

A poly(vinyl chloride) (PVC) sample was chlorinated in solution in the presence of 2,2Ј-azobisisobutyronitrile and by the fluid-bed method. The aim was to evaluate the scope of the stereoselectivity of the chlorination reaction. The quantitative microstructural analysis of the residual PVC with a degree of chlorination was followed by 13 C NMR spectroscopy. From the evolution of the content of isotactic (mm), heterotactic (mr), and syndiotactic (rr) triads and of mmmm, mmmr, and rmmr isotactic pentads in the unchlorinated parts of the polymer, it was unambiguously inferred that the chlorination reaction proceeds by a stereoselective mechanism in that the mr heterotactic triads are the most reactive structures followed by the isotactic triad at mmmr and rmmr pentads. This conclusion was confirmed on the basis of the Fourier transform infrared results. The results provide valuable information regarding the effect of tacticity and related local conformations in the chemical reactions of PVC.

UV‐Enhanced Gas‐Solid Chlorination of Polyvinyl Chloride for Cleaner Production of Chlorinated Polyvinyl Chloride

“…Allen et al first reported the influence of local conformation on selective substitution of chlorine radical [8]. Martinez et al then pointed out that heterotactic triads are the most reactive structures in polymers [9]. However, it is worth mentioning that in a series of articles Lucas et al reported that the chlorination using an aqueous method follows two kinds of reaction mechanisms: the substitution route and the elimination-addition route [10][11][12][13][14][15].…”