Thermal dehydrochlorination of poly(vinyl chloride) models in the liquid phase

Abstract

AbstractAn investigation was made of the kinetics of thermal dehydrochlorination of 8‐chlorohexadecane, 2,4‐dichloropentadecane, 4‐chloro‐2‐dodecene, 8‐chloro‐6‐tridecene, 6‐chloro‐2,4‐octadiene, and 7‐chloro‐3,5‐nonadiene in the liquid phase in an inert gas.The course of the reaction is accelerated by the presence of free hydrogen chloride and slowed down by conjugated dienes and trienes. Destruction of the model compounds leads to the formation of oligomers and telomers, some of which were isolated and their elementary composition and molecular weight determined. The reaction occurs much faster in nitrobenzene, compared with the dehydrochlorination of a model without solvent.With respect to its complicated mechanism, the dehydrochlorination reaction was characterized from the kinetic viewpoint by its initial rate kO. Parameters E and A were estimated from the temperature dependence kO = A exp(−E/RT).It follows from the experimental results and from the comparison of thermal dehydrochlorination reactions in the gas and liquid phases and in poly(vinyl chloride) that the reaction under investigation occurs by a ionic mechanism in the liquid phase, and most probably also in the polymer.