Acetylene

Acetylene
Names
	Preferred IUPAC name Acetylene
	Systematic IUPAC name Ethyne
Identifiers
CAS Number	74-86-2 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	906677
ChEBI	CHEBI:27518 ;
ChEMBL	ChEMBL116336 ;
ChemSpider	6086 ;
ECHA InfoCard	100.000.743
EC Number	200-816-9;
Gmelin Reference	210
KEGG	C01548 ;
PubChem CID	6326;
RTECS number	AO9600000;
UNII	OC7TV75O83 ;
UN number	1001 (dissolved); 3138 (in mixture with ethylene and propylene)
CompTox Dashboard (EPA)	DTXSID6026379 ;
	InChI InChI=1S/C2H2/c1-2/h1-2H Key: HSFWRNGVRCDJHI-UHFFFAOYSA-N ; InChI=1/C2H2/c1-2/h1-2H Key: HSFWRNGVRCDJHI-UHFFFAOYAY;
	SMILES C#C;
Properties
Chemical formula	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)
Melting point	−80.8 °C (−113.4 °F; 192.3 K) Triple point at 1.27 atm
Sublimation; conditions	−84 °C; −119 °F; 189 K (1 atm)
Solubility in water	slightly soluble
Solubility	slightly soluble in alcohol ; soluble in acetone, benzene
Vapor pressure	44.2 atm (20 °C)
Acidity (pKa)	25
Conjugate acid	Ethynium
Magnetic susceptibility (χ)	−20.8×10−6 cm3/mol
Thermal conductivity	21.4 mW·m−1·K−1 (300 K)
Structure
Molecular shape	Linear
Thermochemistry
Heat capacity (C)	44.036 J·mol−1·K−1
Std molar; entropy (S⦵298)	200.927 J·mol−1·K−1
Std enthalpy of; formation (ΔfH⦵298)	227.400 kJ·mol−1
Gibbs free energy (ΔfG⦵)	209.879 kJ·mol−1
Std enthalpy of; combustion (ΔcH⦵298)	1300 kJ·mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H220, H336
Precautionary statements	P202, P210, P233, P261, P271, P304, P312, P340, P377, P381, P403, P405, P501
NFPA 704 (fire diamond)	1 4 3
Autoignition; temperature	300 °C (572 °F; 573 K)
Explosive limits	2.5–100%
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	C 2500 ppm (2662 mg/m3)
IDLH (Immediate danger)	N.D.
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Acetylene (systematic name: ethyne) is a chemical compound with the formula C₂H₂ and structure HC≡CH. It is a hydrocarbon and the simplest alkyne.^[8] 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.^[9] Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.^[9]^[10]

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°.^[11] The triple bond in acetylene results in a high energy content that is released when acetylene is burned.^[12]

^ Favre, Henri A.; Powell, Warren H. (2014). Nomenclature of Organic Chemistry. IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. p. 375. doi:10.1039/9781849733069. 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.
^ Moss, G.P. (web version). "P-14.3 Locants". Nomenclature of Organic Chemistry. IUPAC Recommendations and Preferred Names 2013. London: Queen Mary University. Section P-14.3.4.2 (d). Retrieved 24 August 2024.
^ Acyclic Hydrocarbons. Rule A-3. Unsaturated Compounds and Univalent Radicals Archived 10 October 2000 at the Wayback Machine, IUPAC Nomenclature of Organic Chemistry
^ Record of Acetylene in the GESTIS Substance Database of the Institute for Occupational Safety and Health
^ ^a ^b ^c ^d NIOSH Pocket Guide to Chemical Hazards. "#0008". National Institute for Occupational Safety and Health (NIOSH).
^ "Acetylene – Gas Encyclopedia Air Liquide". Air Liquide. Archived from the original on 4 May 2022. Retrieved 27 September 2018.
^ ^a ^b ^c William M. Haynes; David R. Lide; Thomas J. Bruno (2016). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (2016-2017, 97th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4987-5428-6. OCLC 930681942.
^ R. H. Petrucci; W. S. Harwood; F. G. Herring (2002). General Chemistry (8th ed.). Prentice-Hall. p. 1072.
^ ^a ^b Pässler, Peter; Hefner, Werner; Buckl, Klaus; Meinass, Helmut; Meiswinkel, Andreas; Wernicke, Hans-Jürgen; Ebersberg, Günter; Müller, Richard; Bässler, Jürgen; Behringer, Hartmut; Mayer, Dieter (2008). "Acetylene Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_097.pub3. ISBN 978-3527306732.
^ Compressed Gas Association (1995) Material Safety and Data Sheet – Acetylene Archived 11 July 2012 at the Wayback Machine
^ 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.
^ Cite error: The named reference Myers was invoked but never defined (see the help page).

[iupac2013-1] Favre, Henri A.; Powell, Warren H. (2014). Nomenclature of Organic Chemistry. IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. p. 375. doi:10.1039/9781849733069. 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.

[P-14.3.4.2-2] Moss, G.P. (web version). "P-14.3 Locants". Nomenclature of Organic Chemistry. IUPAC Recommendations and Preferred Names 2013. London: Queen Mary University. Section P-14.3.4.2 (d). Retrieved 24 August 2024.

[3] Acyclic Hydrocarbons. Rule A-3. Unsaturated Compounds and Univalent Radicals Archived 10 October 2000 at the Wayback Machine, IUPAC Nomenclature of Organic Chemistry

[GESTIS-4] Record of Acetylene in the GESTIS Substance Database of the Institute for Occupational Safety and Health

[NIOSH-5] NIOSH Pocket Guide to Chemical Hazards. "#0008". National Institute for Occupational Safety and Health (NIOSH).

[airliquide-6] "Acetylene – Gas Encyclopedia Air Liquide". Air Liquide. Archived from the original on 4 May 2022. Retrieved 27 September 2018.

[CRC97-7] William M. Haynes; David R. Lide; Thomas J. Bruno (2016). CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data (2016-2017, 97th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4987-5428-6. OCLC 930681942.

[8] R. H. Petrucci; W. S. Harwood; F. G. Herring (2002). General Chemistry (8th ed.). Prentice-Hall. p. 1072.

[Ullmann-9] Pässler, Peter; Hefner, Werner; Buckl, Klaus; Meinass, Helmut; Meiswinkel, Andreas; Wernicke, Hans-Jürgen; Ebersberg, Günter; Müller, Richard; Bässler, Jürgen; Behringer, Hartmut; Mayer, Dieter (2008). "Acetylene Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_097.pub3. ISBN 978-3527306732.

[msds-10] Compressed Gas Association (1995) Material Safety and Data Sheet – Acetylene Archived 11 July 2012 at the Wayback Machine

[11] 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.

[Myers-12] Cite error: The named reference Myers was invoked but never defined (see the help page).

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