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Acetylene

"HCCH" redirects here. For other uses, see HCCH (disambiguation).
"ethyne" redirects here. Not to be confused with ethane or ethene.

Acetylene
Acetylene
Acetylene
Acetylene – space-filling model
space-filling model of solid acetylene
Names
Preferred IUPAC name
Acetylene[1]
Systematic IUPAC name
Ethyne[2]
Identifiers
3D model (JSmol)
906677
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.743 Edit this at Wikidata
EC Number
  • 200-816-9
210
KEGG
RTECS number
  • AO9600000
UNII
UN number 1001 (dissolved)
3138 (in mixture with ethylene and propylene)
  • InChI=1S/C2H2/c1-2/h1-2H checkY
    Key: HSFWRNGVRCDJHI-UHFFFAOYSA-N checkY
  • InChI=1/C2H2/c1-2/h1-2H
    Key: HSFWRNGVRCDJHI-UHFFFAOYAY
  • C#C
Properties
C2H2
Molar mass 26.038 g·mol−1
Appearance Colorless gas
Odor Odorless
Density 1.1772 g/L = 1.1772 kg/m3 (0 °C, 101.3 kPa)[3]
Melting point −80.8 °C (−113.4 °F; 192.3 K) Triple point at 1.27 atm
−84 °C; −119 °F; 189 K (1 atm)
slightly soluble
Solubility slightly soluble in alcohol
soluble in acetone, benzene
Vapor pressure 44.2 atm (20 °C)[4]
Acidity (pKa) 25[5]
Conjugate acid Ethynium
−20.8×10−6 cm3/mol [6]
Thermal conductivity 21.4 mW·m−1·K−1 (300 K) [6]
Structure
Linear
Thermochemistry[6]
44.036 J·mol−1·K−1
200.927 J·mol−1·K−1
227.400 kJ·mol−1
209.879 kJ·mol−1
1300 kJ·mol−1
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation mark
Danger
H220, H336
P202, P210, P233, P261, P271, P304, P312, P340, P377, P381, P403, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
1
4
3
300 °C (572 °F; 573 K)
Explosive limits 2.5–100%
NIOSH (US health exposure limits):
PEL (Permissible)
 none[4]
REL (Recommended)
 C 2500 ppm (2662 mg/m3)[4]
IDLH (Immediate danger)
 N.D.[4]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Acetylene (systematic name: ethyne) is the chemical compound with the formula C2H2 and structure H−C≡C−H. It is a hydrocarbon and the simplest alkyne.[7] This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution.[8] Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.[8][9]

As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond. The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°.[10]

  1. ^ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 375. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. The name acetylene is retained for the compound HC≡CH. It is the preferred IUPAC name, but substitution of any kind is not allowed; however, in general nomenclature, substitution is allowed, for example fluoroacetylene [fluoroethyne (PIN)], but not by alkyl groups or any other group that extends the carbon chain, nor by characteristic groups expressed by suffixes.
  2. ^ Acyclic Hydrocarbons. Rule A-3. Unsaturated Compounds and Univalent Radicals Archived 10 October 2000 at the Wayback Machine, IUPAC Nomenclature of Organic Chemistry
  3. ^ Record of Acetylene in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  4. ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0008". National Institute for Occupational Safety and Health (NIOSH).
  5. ^ "Acetylene – Gas Encyclopedia Air Liquide". Air Liquide. Archived from the original on 4 May 2022. Retrieved 27 September 2018.
  6. ^ a b c CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data. William M. Haynes, David R. Lide, Thomas J. Bruno (2016-2017, 97th ed.). Boca Raton, Florida. 2016. ISBN 978-1-4987-5428-6. OCLC 930681942. Archived from the original on 4 May 2022. Retrieved 4 May 2022.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  7. ^ R. H. Petrucci; W. S. Harwood; F. G. Herring (2002). General Chemistry (8th ed.). Prentice-Hall. p. 1072.
  8. ^ a b Pässler, Peter; Hefner, Werner; Buckl, Klaus; Meinass, Helmut; Meiswinkel, Andreas; Wernicke, Hans-Jürgen; Ebersberg, Günter; Müller, Richard; Bässler (2008). "Acetylene Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_097.pub3. ISBN 978-3527306732.
  9. ^ Compressed Gas Association (1995) Material Safety and Data Sheet – Acetylene Archived 11 July 2012 at the Wayback Machine
  10. ^ Whitten K. W., Gailey K. D. and Davis R. E. General Chemistry (4th ed., Saunders College Publishing 1992), pp. 328–329, 1046. ISBN 0-03-072373-6.