Types of dehydrohalogenation reactions

The -elimination of hydrogen halides HX from organic halogen compounds yields olefins or acetylenes, depending on the structure of the starting substance and the number of HX molecules which have split off, viz. 

The equilibrium of reaction (B) is less favourable for the formation of an alkyne and, in order to achieve equal conversion, much higher temperatures would be required than are necessary for the olefin-forming elimination (A). Therefore little attention has been paid to this type of reaction and this section will be devoted solely to type (A) dehydrohalogenation. 

A large variety of catalysts, both homogeneous and heterogeneous, has been found active for dehydrohalogenation. The catalysts include a number of Br nsted and Lewis acids (liquid or soluble, as well as solid), metal oxides, active carbon, carbides, nitrides and some metals. However, in the latter case, the actual catalysts are most probably surface metal halides 

Comparison of the activity of different catalysts for the dehydrochlorination of 1-chlorobutane [174] 

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