Dichloroacetylene
Structure of dichloroacetylene

Dichloroacetylene
(with tetrachloroethylene as the stabiliser)
Names
IUPAC name
Dichloroethyne
Other names
DCA, dichloroethyne
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.149.197 Edit this at Wikidata
RTECS number
  • AP1080000
UNII
  • InChI=1S/C2Cl2/c3-1-2-4
    Key: ZMJOVJSTYLQINE-UHFFFAOYSA-N
  • InChI=1/C2Cl2/c3-1-2-4
    Key: ZMJOVJSTYLQINE-UHFFFAOYAO
  • C(#CCl)Cl
Properties
C2Cl2
Molar mass 94.927[1]
Appearance colorless oily liquid[1]
Odor disagreeable, sweetish
Density 1.26 g/cm3
Melting point −66 to −64 °C (−87 to −83 °F; 207 to 209 K)
Boiling point 33 °C (91 °F; 306 K) explodes
insoluble
Solubility soluble in acetone, ethanol, ether
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 explosive, potential carcinogen[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[1]
REL (Recommended)
 Ca C 0.1 ppm (0.4 mg/m3)[1]
IDLH (Immediate danger)
 Ca (N.D.)[1]
Related compounds
Other anions
 Acetylene, Dibromoacetylene, Difluoroacetylene, Diiodoacetylene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Dichloroacetylene (DCA) is an organochlorine compound with the formula C2Cl2.[2] It is a colorless, explosive liquid that has a sweet and "disagreeable" odor.[3]

Production

Dichloroacetylene was first synthesized in 1930.[2]

Ether solutions of dichloroacetylene are relatively stable, and such solution can be safely generated by dehydrochlorination of trichlorethylene. A popular procedure uses potassium hydride as the base:[4]

Cl2C=CHCl + KH → ClC≡CCl + KCl + H2

A trace of methanol is required.

It has also been generated (and used in situ) using lithium diisopropylamide under anhydrous conditions[5] as well as potassium hydroxide.[6] Dichloroacetylene can occur and be stable in air at concentrations of up to 200 parts per million if certain other compounds, such as ether, with which it forms an azeotrope (boiling point of 32 °C), and trichloroethylene,[7] are also present.[8]

Adventitious routes

It is a by-product in the production of vinylidene chloride.[9] For instance, it can be formed from trichloroethylene.[10][11] It is also possible to produce dichloroacetylene from trichloroethylene at low concentrations by running the trichloroethylene through nitrogen at 120 °C in the presence of dry potassium hydroxide.[12]

Reactions

Dichloroacetylene reacts with oxygen to give phosgene:[12]

ClC≡CCl + O2 → Cl2CO + CO

Dichloroacetylene, being electrophilic, adds nucleophiles, such as amines:

ClC≡CCl + R2NH → Cl(H)C=CCl(NR2)

Biological role and toxicity

Dichloroacetylene causes neurological disorders,[9] among other problems.[13][14] Studies on male rats and rabbits have shown that inhalation of dichloroacetylene can cause tubular necrosis, focal necrosis, and other nephrotoxic effects. Additionally, the rabbits that were given dichloroacetylene experienced hepatotoxic and neuropathological effects. Inhalation of dichloroacetylene also causes benign tumors of the livers and kidneys of rats. The chemical also caused increased instances of lymphomas.[9] It also causes weight loss in animals.[13] 3.5% of a dose of dichloroacetylene remains in the corpses of male Wistar rats.[9] The LC50s of mice exposed to dichloroacetylene are 124 parts per million for a 1-hour exposure by inhalation and 19 parts per million for a 6-hour exposure by inhalation.[12] The chemical is ingested primarily through glutathione-dependent systems. Glutathione also reacts with it. Hepatic and renal glutathione S-transferases serve as catalysts to this reaction. While dichloroacetylene is nephrotoxic in rats, it does not show any signs of nephrotoxicity in humans.[7]

Dichloroacetylene has mutagenic effects on Salmonella typhimurium.[9]

The maximum safe concentration of dichloroacetylene in air is 0.1 parts per million.[15] It is unsafe to store dichloroacetylene in close proximity to potassium, sodium, or aluminium powder.[3]

Like trichloroethylene, dichloroacetylene is metabolized to S-(1,2-dichlorovinyl)-L-cysteine (DCVC) in vivo.[16][17]

According to the Department of Transportation, it is forbidden to ship dichloroacetylene.[3]

Additional reading

See also

References

  1. ^ a b c d e f NIOSH Pocket Guide to Chemical Hazards. "#0188". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b Henning Hopf; Bernhard Witulski (1995). "Functionalized Acetylenes in Organic Synthesis - The Case of the 1-Cyano- and the 1-Halogenoacetylenes". In Stang, Peter J.; Diederich, François (eds.). Modern Acetylene Chemistry. Weinheim: VCH. pp. 33–66. doi:10.1002/9783527615278.ch02. ISBN 9783527615261.
  3. ^ a b c Pohanish, Richard P. (2011), Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, William Andrew, ISBN 9781437778694[page needed]
  4. ^ Denis, Jean Noel; Moyano, Albert; Greene, Andrew E. (1987). "Practical synthesis of dichloroacetylene". The Journal of Organic Chemistry. 52 (15): 3461–3462. doi:10.1021/jo00391a059.
  5. ^ "Dichlorovinylation of an Enolate: 8-Ethynyl-8-Methyl-1,4-Dioxaspiro[4.5]Dec-6-Ene". Organic Syntheses. 64: 73. 1986. doi:10.15227/orgsyn.064.0073.
  6. ^ Siegel, J.; Jones, Richard Arvin.; Kurlansik, L. (1970). "Safe and Convenient Synthesis of Dichloroacetylene". The Journal of Organic Chemistry. 35 (9): 3199. doi:10.1021/jo00834a090.
  7. ^ a b Valacchi, Giuseppe; Davis, Paul A., eds. (January 1, 2008), Oxidants in Biology: A Question of Balance, Springer Science+Business Media, ISBN 9781402083990[page needed]
  8. ^ Proceedings, Aerospace Medical Research Laboratory, 1966[page needed]
  9. ^ a b c d e "Dichloroacetylene" (PDF), IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, 39: 369–78, 1986, PMID 3465694
  10. ^ John T. James; Harold L. Kaplan; Martin E. Coleman (1996), B5 Dichloroacetylene, doi:10.17226/5435, hdl:2060/19970023991, ISBN 978-0-309-05629-8, retrieved July 3, 2013
  11. ^ Greim, H; Wolff, T; Höfler, M; Lahaniatis, E (1984), "Formation of dichloroacetylene from trichloroethylene in the presence of alkaline material--possible cause of intoxication after abundant use of chloroethylene-containing solvents", Archives of Toxicology, 56 (2): 74–7, doi:10.1007/bf00349074, PMID 6532380, S2CID 19576314
  12. ^ a b c Reichert, D.; Ewald, D.; Henschler, D. (1975), "Generation and inhalation toxicity of dichloroacetylene", Food and Cosmetics Toxicology, 13 (5): 511–5, doi:10.1016/0015-6264(75)90004-8, PMID 1201833
  13. ^ a b Dichloroacetylene, November 18, 2010, retrieved July 3, 2013
  14. ^ Dichloroacetylene, retrieved July 3, 2013
  15. ^ Hazardous Material Fact Sheet (PDF), April 1997, retrieved July 4, 2013
  16. ^ Purich, Daniel L., ed. (September 15, 2009), Advances in Enzymology and Related Areas of Molecular Biology, Amino Acid Metabolism, John Wiley & Sons, ISBN 9780470123973[page needed]
  17. ^ Kanhai, Wolfgang; Dekant, Wolfgang; Henschler, Dietrich (January 1989). "Metabolism of the nephrotoxin dichloroacetylene by glutathione conjugation". Chemical Research in Toxicology. 2 (1): 51–56. doi:10.1021/tx00007a009. eISSN 1520-5010. ISSN 0893-228X. PMID 2519231.
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