Propane

Overview

A three-carbon alkane with terminal methyl groups and a central methylene.

The terminal and middle carbons have different hydrogen environments. Rotation about either carbon–carbon bond changes conformation while preserving connectivity. Extending methane to propane increases molecular size without introducing the addition chemistry of a carbon–carbon double bond.

Identifiers

Formula

C3H8

Functional group

Alkanes

Molar mass

44.1 g/mol

Also known as

n-Propane, Dimethylmethane, Propyl hydride, Propyldihydride, Purifrigor p 3.5, HC 290

Properties

Melting Point

-187.6 °C

Boiling Point

-42.1 °C at 1 atm

Relative density (water = 1)

Relative density (water = 1): 0.5

Water solubility

In water, 62.4 ppm at 25 °C

Related compounds

• Alkanes

  A three-carbon alkane with terminal methyl groups and a central methylene.

References

1. PubChem Compound Summary: Propane (CID 6334)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: Alkanes and alkane isomersJohn McMurry · OpenStax · 2023

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

3. OpenStax Organic Chemistry: Conformations of other alkanesJohn McMurry · OpenStax · 2023

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

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

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6334#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 1397

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

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6334#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 1397

6. ILO-WHO International Chemical Safety Cards (ICSCs): Propane — densityILO-WHO International Chemical Safety Cards (ICSCs)

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6334#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred.

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

   Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/6334#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., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 77