Vinylacetylene is the organic compound with the formula or . The colourless gas was once used in the polymer industry. It is composed of both alkyne and alkene groups and is the simplest enyne.
Safety Vinylacetylene is extremely dangerous because in high enough concentrations (typically > 30 mole percent, but pressure dependent) it can auto-detonate (explode without air being present) especially at elevated pressures, such as those seen in chemical plants processing C4 hydrocarbons (hydrocarbons with 4 carbon atoms).Ritzert and Berthol, Chem Ing Tech 45(3), 131-136, Feb 1973, reproduced in Viduari, J Chem Eng Data 20(3), 328-333, 1975. An example of such an explosion occurred at a Union Carbide plant in Texas City in 1969.Carver, Chemical Process Hazards V, Paper F
Synthesis Vinylacetylene was first synthesized by Hofmann elimination of the related quaternary ammonium salt:
It is usually synthesized by dehydrohalogenation of 1,3-dichloro-2-butene .
It also arises via the dimerization of acetylene, which is catalyzed by copper(I) chloride.
Dehydrogenation of 1,3-butadiene is yet another route.
Application At one time, chloroprene (2-chloro-1,3-butadiene), an industrially important monomer, was produced via the intermediacy of vinyl acetylene. In this process, acetylene is dimerized to give vinyl acetylene, which is then combined with hydrogen chloride to give 4-chloro-1,2-butadiene via 1,4-addition. This allene derivative then, in the presence of cuprous chloride, rearranges to 2-chloro-1,3-butadiene:Manfred Rossberg, Wilhelm Lendle, Gerhard Pfleiderer, Adolf Tögel, Eberhard-Ludwig Dreher, Ernst Langer, Heinz Rassaerts, Peter Kleinschmidt, Heinz Strack, Richard Cook, Uwe Beck, Karl-August Lipper, Theodore R. Torkelson, Eckhard Löser, Klaus K. Beutel, "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, 2006 John Wiley-VCH: Weinheim.
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