P

Propylene glycol

IUPAC: propane-1,2-diol

C3H8O2 Organic Compounds CAS 57-55-6
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Quick Reference
Formula / NotationC3H8O2
CAS Number57-55-6
Molecular Weight76.09
Melting Point-76 °F (NTP, 1992)
Boiling Point370.8 °F at 760 mmHg (NTP, 1992)
Density1.04 at 68 °F (USCG, 1999) - Denser than water; will sink
Solubilitygreater than or equal to 100 mg/mL at 70 °F (NTP, 1992)
AppearanceThick odorless colorless liquid. Mixes with water. (USCG, 1999)
Also Known Aspropane-1,2-diol; 1,2-propanediol; 57-55-6; 1,2-Propylene glycol; 1,2-dihydroxypropane; 2-Hydroxypropanol; Isopropylene glycol; Dowfrost; Sirlene; Methylethyl glycol
CategoryOrganic Compounds

What is Propylene glycol?

Propane-1,2-diol is the simplest member of the class of propane-1,2-diols, consisting of propane in which a hydrogen at position 1 and a hydrogen at position 2 are substituted by hydroxy groups. A colourless, viscous, hygroscopic, low-melting (59C) and high-boiling (188C) liquid with low toxicity, it is used as a solvent, emulsifying agent, and antifreeze. It has a role as a protic solvent, an allergen, a mouse metabolite and a human xenobiotic metabolite. It is a glycol and a member of propane-1,2-diols.

Formula & Notation

C3H8O2

IUPAC Name: propane-1,2-diol

Other Names / Synonyms: propane-1,2-diol; 1,2-propanediol; 57-55-6; 1,2-Propylene glycol; 1,2-dihydroxypropane; 2-Hydroxypropanol; Isopropylene glycol; Dowfrost; Sirlene; Methylethyl glycol

Properties & Characteristics

Appearance: Thick odorless colorless liquid. Mixes with water. (USCG, 1999). Molecular formula: C3H8O2. Molecular weight: 76.09 g/mol. Boiling point: 370.8 °F at 760 mmHg (NTP, 1992). Melting point: -76 °F (NTP, 1992). Density: 1.04 at 68 °F (USCG, 1999) - Denser than water; will sink. Solubility: greater than or equal to 100 mg/mL at 70 °F (NTP, 1992). Vapor pressure: 0.08 mmHg at 68 °F ; 0.13 mmHg at 77 °F (NTP, 1992). LogP: -0.9.

Physical Data

PropertyValue
Melting Point-76 °F (NTP, 1992)
Boiling Point370.8 °F at 760 mmHg (NTP, 1992)
Density1.04 at 68 °F (USCG, 1999) - Denser than water; will sink
Molecular Weight76.09
Solubilitygreater than or equal to 100 mg/mL at 70 °F (NTP, 1992)
AppearanceThick odorless colorless liquid. Mixes with water. (USCG, 1999)

Uses & Applications

Used as an industrial feedstock, solvent, pharmaceutical intermediate, flavoring agent, or chemical building block.

Safety Information

Flammable or irritant. Many organic compounds are flammable liquids or vapours. Keep away from ignition sources. Consult SDS for specific hazard data.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Propylene glycol
Formula C3H8O2
CAS Number 57-55-6
Molecular Weight 76.09
Synonyms propane-1,2-diol; 1,2-propanediol; 57-55-6; 1,2-Propylene glycol; 1,2-dihydroxypropane; 2-Hydroxypropanol; Isopropylene glycol; Dowfrost; Sirlene; Methylethyl glycol

Frequently Asked Questions

Propane-1,2-diol is the simplest member of the class of propane-1,2-diols, consisting of propane in which a hydrogen at position 1 and a hydrogen at position 2 are substituted by hydroxy groups. A colourless, viscous, hygroscopic, low-melting (59C) and high-boiling (188C) liquid with low toxicity, it is used as a solvent, emulsifying agent, and antifreeze. It has a role as a protic solvent, an allergen, a mouse metabolite and a human xenobiotic metabolite. It is a glycol and a member of propane-1,2-diols.

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Editorial standards: Chemical data is sourced from peer-reviewed literature, CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA, and IAEA. For educational purposes only — always consult official SDS documentation and qualified professionals before handling chemicals.