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Vinylacetylene
Names
	Preferred IUPAC name But-1-en-3-yne
	Other names Butenyne, normal isomer; 3-Butene-1-yne, Vinyl acetylene
Identifiers
CAS Number	689-97-4 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:48088 ;
ChemSpider	12197 ;
ECHA InfoCard	100.010.650
PubChem CID	12720;
UNII	VW72FM10OQ ;
CompTox Dashboard (EPA)	DTXSID4029199 ;
	InChI InChI=1S/C4H4/c1-3-4-2/h1,4H,2H2 Key: WFYPICNXBKQZGB-UHFFFAOYSA-N ; InChI=1/C4H4/c1-3-4-2/h1,4H,2H2 Key: WFYPICNXBKQZGB-UHFFFAOYAE;
	SMILES C#CC=C;
Properties
Chemical formula	C4H4
Molar mass	52.07456 g/mol
Appearance	colourless gas
Boiling point	0 to 6 °C (32 to 43 °F; 273 to 279 K)
Solubility in water	low
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	flammable
NFPA 704 (fire diamond)	2 4 3 W
Flash point	< −5 °C (23 °F; 268 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Vinylacetylene is the organic compound with the formula C₄H₄. The colourless gas was once used in the polymer industry. It is composed of both alkyne and alkene groups and is the simplest enyne.

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.^[2] An example of such an explosion occurred at a Union Carbide plant in Texas City in 1969.^[3]

Synthesis

Vinylacetylene was first synthesized by Hofmann elimination of the related quaternary ammonium salt:^[4]

[(CH₃)₃NCH₂CH=CHCH₂N(CH₃)₃]I₂ → 2 [(CH₃)₃NH]I + HC≡C-CH=CH₂

It is usually synthesized by dehydrohalogenation of 1,3-dichloro-2-butene.^[5]

It also arises via the dimerization of acetylene, which is catalyzed by copper(I) chloride.^[6]

Dehydrogenation of 1,3-butadiene is yet another route.^{[citation needed]}

Application

At one time, chloroprene (2-chloro-1,3-butadiene), an industrially important monomer, was produced via the intermediacy of vinyl acetylene.^[7] 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 which, in the presence of cuprous chloride, rearranges to 2-chloro-1,3-butadiene:^[8]

H₂C=CH-C≡CH + HCl → H₂ClC-CH=C=CH₂

H₂ClC-CH=C=CH₂ → H₂C=CH-CCl=CH₂

References

^ "New Environment Inc. - NFPA Chemicals".
^ Ritzert and Berthol, Chem Ing Tech 45(3), 131-136, Feb 1973, reproduced in Viduari, J Chem Eng Data 20(3), 328-333, 1975.
^ Carver, Chemical Process Hazards V, Paper F
^ Willstätter, Richard; Wirth, Theodor (1913). "Über Vinyl-acetylen". Berichte der Deutschen Chemischen Gesellschaft. 46: 535–538. doi:10.1002/cber.19130460172.
^ G. F. Hennion, Charles C. Price, Thomas F. McKeon, Jr. (1958). "Monovinylacetylene". Organic Syntheses. 38: 70. doi:10.15227/orgsyn.038.0070.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Trotuş, Ioan-Teodor; Zimmermann, Tobias; Schüth, Ferdi (2014). "Catalytic Reactions of Acetylene: A Feedstock for the Chemical Industry Revisited". Chemical Reviews. 114 (3): 1761–1782. doi:10.1021/cr400357r. PMID 24228942.
^ Wallace H. Carothers, Ira Williams, Arnold M. Collins, and James E. Kirby (1937). "Acetylene Polymers and their Derivatives. II. A New Synthetic Rubber: Chloroprene and its Polymers". J. Am. Chem. Soc. 53 (11): 4203–4225. doi:10.1021/ja01362a042.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ 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.doi:10.1002/14356007.a06_233.pub2