Vinylacetylene

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Vinylacetylene
Vinylacetylene-2D.png
Vinylacetylene-2D-skeletal.png
Vinylacetylene-3D-vdW.png
Identifiers
CAS number 689-97-4 YesY
PubChem 12720
ChemSpider 12197 YesY
ChEBI CHEBI:48088 YesY
Jmol-3D images Image 1
Properties
Molecular formula C4H4
Molar mass 52.07456 g/mol
Appearance colourless gas
Boiling point 0–6 °C
Solubility in water low
Hazards
Main hazards flammable
Flash point < -5 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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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.

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

Synthesis[edit]

Vinylacetylene was first by Hofmann elimination of the related quaternary ammonium salt:[3]

[(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.[4] It also arises via the dimerization of acetylene or dehydrogenation of 1,3-butadiene.

Application[edit]

At one time, chloroprene (2-chloro-1,3-butadiene), an industrially important monomer, was produced via the intermediacy of vinyl acetylene.[5] 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:[6]

H2C=CH-C≡CH + HCl → H2ClC-CH=C=CH2
H2ClC-CH=C=CH2 → H2C=CH-CCl=CH2

References[edit]

  1. ^ Ritzert and Berthol, Chem Ing Tech 45(3), 131-136, Feb 1973, reproduced in Viduari, J Chem Eng Data 20(3), 328-333, 1975.
  2. ^ Carver, Chemical Process Hazards V, Paper F
  3. ^ Richard Willstätter, Theodor Wirth "Über Vinyl-acetylen" Ber., volume 46, p. 535 (1913). doi:10.1002/cber.19130460172
  4. ^ G. F. Hennion, Charles C. Price, and Thomas F. McKeon, Jr. (1963), Monovinylacetylene, Org. Synth. ; Coll. Vol. 4: 683 
  5. ^ 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. 
  6. ^ 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