Ethyne

The simplest alkyne, with a linear carbon–carbon triple-bond unit.

Formula
C2H2
Molar mass
26.04 g/mol
Also known as
acetylene, Narcylen, Ethine, Acetylen, Vinylene, OC7TV75O83

Overview

The simplest alkyne, with a linear carbon–carbon triple-bond unit.

Both carbons bear a terminal hydrogen. These hydrogens are more acidic than those of ordinary alkenes and alkanes, although ethyne is not an ordinary aqueous acid. Reduction can remove one or both degrees of triple-bond unsaturation depending on the reaction system.

Identifiers

Formula
C2H2
Molar mass
26.04 g/mol
Also known as
acetylene, Narcylen, Ethine, Acetylen, Vinylene, OC7TV75O83
Chemical identifiers
SMILES
C#C
InChI
InChI=1S/C2H2/c1-2/h1-2H
PubChem CID
6326

Properties

Melting Point
-80.7 °C (triple point)
Sublimation
BP: -84 °C sublimes
Density
0.377 g/cu cm (pressure >1 atm)
Water solubility
In water, 1200 mg/L at 25 °C

Related compounds

  • Alkynes

    Ethyne is a specific member of the alkynes family.

References

  1. PubChem Compound Summary: Ethyne (CID 6326)National Center for Biotechnology Information · PubChem

    Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.

  2. OpenStax Organic Chemistry: Alkyne acidity: formation of acetylide anionsJohn McMurry · OpenStax · 2023

    Supports the qualitative structure and reactivity context; identity and numerical measurements retain their original references.

  3. OpenStax Organic Chemistry: Reduction of alkynesJohn McMurry · OpenStax · 2023

    Supports the qualitative structure and reactivity context; identity and numerical measurements retain their original references.

  4. Hazardous Substances Data Bank (HSDB): Ethyne — melting pointHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6326#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Lide, D.R. CRC Handbook of Chemistry and Physics 86TH Edition 2005-2006. CRC Press, Taylor & Francis, Boca Raton, FL 2005, p. 3-6

  5. Hazardous Substances Data Bank (HSDB): Ethyne — boiling pointHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6326#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Verschueren, K. Handbook of Environmental Data on Organic Chemicals. Volumes 1-2. 4th ed. John Wiley & Sons. New York, NY. 2001, p. V1: 117

  6. Hazardous Substances Data Bank (HSDB): Ethyne — densityHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6326#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 94th Edition. CRC Press LLC, Boca Raton: FL 2013-2014, p. 3-6

  7. Hazardous Substances Data Bank (HSDB): Ethyne — solubilityHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6326#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 20