Dichloroacetylene

Dichloroacetylene
Names
IUPAC name
Dichloroethyne
Other names
DCA, dichloroethyne
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.149.197
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 94.92 g·mol−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
Thermochemistry[2][3]
272.0 ± 13 J·K−1·mol−1 (gas)[2]
  • 209.6 ± 42 kJ·mol−1 (gas)[2]
  • 233.39 ± 0.95 kJ·mol−1 (gas)[3]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 explosive, potential carcinogen[1]
GHS labelling:
H200, H319, H330, H335, H351, H370, H372, H373
P260, P264, P270, P271, P280, P284, P304+P340, P310, P312, P320, P321, P337+P313, P403+P233, P405, P501
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
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dichloroacetylene (DCA) is an organochlorine compound with the formula C2Cl2.[4] It is a colorless, pyrophoric, explosive liquid that has a sweet and "disagreeable" odor.[5] Dichloroacetylene is neurotoxic, hepatotoxic, nephrotoxic and possibly carcinogenic.[6]

History and production

Dichloroacetylene was first synthesized via the thermal decarboxylation of barium trichloroacrylate by Jacob Böeseken and J. F. Carriére in 1914:[7][8]

Ba(Cl2C=C(Cl)COO)2 → BaCl2 + ClC≡CCl + 2CO2

Dichloroacetylene was discovered as an intermediate in the synthesis of diphenylacetylene with calcium carbide, chlorine and benzene in 1918.[9] It was first synthesized from trichloroethylene by Erwin Ott, W. Ottemeyer and K. Packendorff in 1930.[4]

Ether solutions of up to 50 mol% dichloroacetylene are relatively stable, and such solutions can be safely generated by the dehydrochlorination of trichloroethylene. A popular procedure uses potassium hydride as the base:[10][11]

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[12] as well as potassium hydroxide.[13]

Adventitious routes

It is a by-product in the production of vinylidene chloride.[14] For instance, it can be formed from trichloroethylene.[15][16] 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.[17]

Stability

Pure dichloroacetylene is explosive, igniting or detonating spontaneously upon contact with air.[18] Products of this reaction include phosgene, carbon monoxide, and carbon dioxide:[18][17]

ClC≡CCl + O2 → Cl2C=O + CO

When heated to 130 °C in the absence of air, it explosively decomposes to the elements:[7]: 330, 336 

ClC≡CCl → 2C + Cl2

Dichloroacetylene has been reported to trimerize to hexachlorobenzene upon heating, as well as perhaps on exposure to light.[18]: 705 [7]: 334  While it does not undergo heat-induced polymerization, molybdenum pentachloride catalyzes its room-temperature polymerization to cis-polydichloroacetylene.[19]

Like other haloalkynes, dichloroacetylene is a strong halogen bond donor.[20] It forms an air-stable azeotrope with ether, boiling at 32 °C, that contains 55.4 wt% DCA, corresponding to a 1:1 molar ratio.[18][21]

Stabilizers such as trichloroethylene can support dichloroacetylene concentrations of up to 200 parts per million in air without significant decomposition.[6][22]

Reactions

Dichloroacetylene, being electrophilic, adds nucleophiles, such as amines:[11]: 356 

ClC≡CCl + R2NH → Cl(H)C=CCl(NR2)

It forms pi-complexes with tungsten, such as [WCl5(C2Cl2)]−.[23]

Biological role and toxicity

Dichloroacetylene causes severe neurological disorders,[14] among other problems.[1][24] Main route of human exposure to dichloroacetylene has been the breakdown of trichloroethylene in presence of alkali hydroxides, historically during trichloroethylene anaesthesia when soda lime was used. Humans exposed to dichloroacetylene showed symptoms such as nausea, vomiting, loss of appetite, headache, facial nervous and muscular issues, and formation of herpes-like lesions on the face. Some people reported itching around the eyes and pain around the jaw. It affects the trigeminal nerve in particular and over-exposure could be fatal.[22]

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.[14] It also causes weight loss in animals.[1] 3.5% of a dose of dichloroacetylene remains in the corpses of male Wistar rats.[14] 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.[17] 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, its nephrotoxicity in humans is not well-understood.[6][5]

Dichloroacetylene has mutagenic effects on Salmonella typhimurium.[14]

Like trichloroethylene, dichloroacetylene is metabolized to S-(1,2-dichlorovinyl)-L-cysteine (DCVC) in vivo.[25][26]

The maximum safe concentration of dichloroacetylene in air is 0.1 parts per million.[27] It is unsafe to store dichloroacetylene in close proximity to potassium, sodium, or aluminium powder. According to the Department of Transportation, it is forbidden to ship dichloroacetylene.[5]

Additional reading

  • Trifu, Roxana Melita (1999), "Dichloroacetylene", Homopolymers of Dihaloacetylenes (Ph.D. Thesis), p. 57, Bibcode:1999PhDT.......149T, ISBN 978-0-549-39503-4

See also

References

  1. ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0188". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b c Chase, Malcolm W. Jr., ed. (1998). NIST-JANAF thermochemical tables (4th ed.). Washington, DC : New York: American Chemical Society ; American Institute of Physics for the National Institute of Standards and Technology. p. 664. ISBN 1563968312.
  3. ^ a b Ruscic, Branko; Bross, David H. "Dichloroacetylene Enthalpy of Formation". Active Thermochemical Tables (ATcT). Retrieved 11 March 2026.
  4. ^ 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.
  5. ^ a b c Pohanish, Richard P. (2011), Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, William Andrew, pp. 908–910, ISBN 9781437778694
  6. ^ a b c Valacchi, Giuseppe; Davis, Paul A., eds. (January 1, 2008), Oxidants in Biology: A Question of Balance, Springer Science+Business Media, pp. 217–218, ISBN 9781402083990
  7. ^ a b c Smirnov, K M; Tomilov, Andrei P; Shchekotikhin, A I (31 May 1967). "Haloacetylenes". Russian Chemical Reviews. 36 (5): 326–338. doi:10.1070/RC1967v036n05ABEH001627.
  8. ^ Böeseken, J. [at Wikidata]; Carriére, J. F. (1914). "Over het dichlooracetyleen (tevens een waarschuwing)" [On dichloroacetylene (furthermore, a warning)]. Versl. Wis. Nat. Afd. K. Akad. Wet. (in Dutch). 22. Amsterdam: 1186–1188.
  9. ^ Clinton Davidson: Tolane chlorides from calcium carbide, chlorine and benzene. In: Journal of the American Chemical Society. 40, Nr. 2, 1918, S. 397–400, doi:10.1021/ja02235a009.
  10. ^ 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.
  11. ^ a b Udmark, J. [at Wikidata]; Nielsen, M. Brøndsted [at Wikidata] (11 June 2014). "Bis[heteroatom-functionalized] Acetylenes (Update 2014)". Science of Synthesis Knowledge Updates: Houben-Weyl methods of molecular transformations. Vol. 2014/3. Stuttgart: Thieme. p. 354. ISBN 978-3-13-176281-8.
  12. ^ "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.
  13. ^ 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.
  14. ^ 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
  15. ^ 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
  16. ^ 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, Bibcode:1984ArTox..56...74G, doi:10.1007/bf00349074, PMID 6532380, S2CID 19576314
  17. ^ 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
  18. ^ a b c d Delavarenne, Serge Y.; Viehe, Heinz Günter (1969). "1-Halogenoacetylenes". In Viehe, Heinz Günter [in German] (ed.). Chemistry of Acetylenes. pp. 674–675. ISBN 9780783709321. LCCN 69010275.
  19. ^ Gould, George L.; Eswara, Veena; Trifu, Roxana M.; Castner, David G. (1 April 1999). "Polydifluoroacetylene, Polychlorofluoroacetylene, and Polydichloroacetylene". Journal of the American Chemical Society. 121 (15): 3781–3782. doi:10.1021/ja983840a.
  20. ^ Cavallo, Gabriella; Metrangolo, Pierangelo; Milani, Roberto; Pilati, Tullio; Priimagi, Arri; Resnati, Giuseppe; Terraneo, Giancarlo (24 February 2016). "The Halogen Bond". Chemical Reviews. 116 (4): 2478–2601. doi:10.1021/acs.chemrev.5b00484. hdl:11311/996019.
  21. ^ Ott, Erwin; Packendorff, Kurt (10 June 1931). "Über das Dichloracetylen (II.) und den Einfluß der Reaktionsgeschwindigkeit auf den stereochemischen Verlauf der Halogen‐Addition an die Acetylen‐Bindung". Chem. Ber. (in German). 64 (6): 1324–1329. doi:10.1002/cber.19310640619. Diese Molekülverbindung ist zwar vollig unempfindlich gegen Sauerstoff, sie ist aber locker, besitzt den charakteristischen Geruch beider Komponenten und zerfällt beim Mischen mit Wasser, in dem sich der Äther sehr viel leichter löst und sich das nunmehr abgeschiedene Dichlor-acetylen entzündet. [This molecular compound is completely insensitive to oxygen, but it is loose, possesses the characteristic odor of both components, and decomposes when mixed with water, in which the ether dissolves much more readily and the now-separated dichloroacetylene ignites.]
  22. ^ a b Saunders, Raymond Arthur (December 1966). "A dangerous closed atmosphere toxicant, its source and identity" (PDF). Proceedings of the 2nd Annual Conference on Atmospheric Contamination in Confined Spaces, 4 and 5 May 1966 (Report). Aerospace Medical Research Laboratory. pp. 55–56.{{cite report}}: CS1 maint: year (link)
  23. ^ Stahl, Karlheinz; Weller, Frank; Dehnicke, Kurt (1986). "Dichloracetylen als stabiler Komplexligand die Kristallstruktur von PPh4[WCL5(C2Cl2)] · 0,5 CCL4". Zeitschrift für Anorganische und Allgemeine Chemie. 533 (2): 73–82. doi:10.1002/zaac.19865330210.
  24. ^ Dichloroacetylene, retrieved July 3, 2013
  25. ^ Purich, Daniel L., ed. (September 15, 2009), Advances in Enzymology and Related Areas of Molecular Biology, Amino Acid Metabolism, John Wiley & Sons, ISBN 9780470123973
  26. ^ 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.
  27. ^ Hazardous Material Fact Sheet (PDF), April 1997, retrieved July 4, 2013
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