Vinyl chloride reactions with metal cations

Gold(III) was identified as the most active catalyst for that process in 1985, when Hutchings recognized that the efficiency in catalyzing the hydrochlorination of ethyne to vinyl chloride (a very important industrial process that previously used mercury salts as catalysts) correlated with the standard reduction potential of the supported metal cation. That meant that the metal could be found as a transient species in the reaction [10]. 

Simpler p-halide eliminations occur from late transition metal catalysts for olefin polymerization (Equations 10.25 and 10.26). Reactions of the cationic palladium-alkyl complexes occur in a similar fashion to the reactions of the cationic group 4 complexes, despite the softer nature of these species. In this case, propylene and the metal chloride are formed. Even a neutral nickel-hydrocarbyl complex (the salicaldimine complex in Equation 10.26) undergoes reactions with vinyl chloride that involve insertion followed by P-chloride elimination. 

The reaction of acetophenone oxime with acetylene (100°C, 3 h) is well catalyzed by all alkali metal hydroxides (taken in 10%-30% from the oxime weight), but Ca(OH)2 is inactive nnder these conditions [160]. Tetrabutylammonium hydroxide exerts weak catalytic action on the reaction only at harsher conditions (120 C). Potassium, zinc, and cadmium acetates as well as zinc, copper (I and II), and cobalt chlorides do not show catalytic activity in this reaction (starting acetophenone oxime is recovered almost completely [160]), though several cations of the aforementioned salts are known [95,162] to be catalysts of direct vinylation of NH-heterocycles with acetylene. 

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