Mechanisms of By‐Product Formation in the Dehydrochlorination of 1,2‐Dichloroethane

The decomposition of 1,2‐dichloroethane (DCE) to vinyl chloride (VC) was studied in the temperature range 620–750 K at DCE partial pressures of 50–450 Torr. Initiation of the radical chain reaction by a XeCl laser allowed controlled degree of conversion which had a strong influence on the formation of the major by‐products acetylene and 2‐chlorobutadiene. Both compounds are formed via abstraction of olefinic hydrogen from vinyl chloride by Cl atoms. Analysis of the product distribution combined with calculations yielded kinetic data of these side reactions. The mechanism was confirmed by adding HCl and vinyl chloride to the substrate. Formation of other byproducts by homogeneous processes and the photolysis of vinyl chloride are discussed.