Vinylacetylene

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

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 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:48088 Y
ChemSpider	12197 Y
ECHA InfoCard	100.010.650
PubChem CID	12720
UNII	VW72FM10OQ Y
CompTox Dashboard (EPA)	DTXSID4029199
InChI InChI=1S/C4H4/c1-3-4-2/h1,4H,2H2 Y Key: WFYPICNXBKQZGB-UHFFFAOYSA-N Y 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). Y verify (what is YN ?) Infobox references

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

1. "New Environment Inc. - NFPA Chemicals".
2. Ritzert and Berthol, Chem Ing Tech 45(3), 131-136, Feb 1973, reproduced in Viduari, J Chem Eng Data 20(3), 328-333, 1975.
3. Carver, Chemical Process Hazards V, Paper F
4. Willstätter, Richard; Wirth, Theodor (1913). "Über Vinyl-acetylen". Berichte der Deutschen Chemischen Gesellschaft. 46: 535–538. doi:10.1002/cber.19130460172.
5. 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)
6. 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.
7. 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)
8. 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