S

Stearic acid

IUPAC: octadecanoic acid

C18H36O2 Acids CAS 57-11-4
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Quick Reference
Formula / NotationC18H36O2
CAS Number57-11-4
Molecular Weight284.5
Melting Point156.7 °F (NTP, 1992)
Boiling Point721 °F at 760 mmHg (NTP, 1992)
Density0.86 at 68 °F (USCG, 1999) - Less dense than water; will float
Solubility1 to 10 mg/mL at 73 °F (NTP, 1992)
AppearanceStearic acid is a white solid with a mild odor. Floats on water. (USCG, 1999)
Also Known Asoctadecanoic acid; Octadecanoic acid; 57-11-4; n-Octadecanoic acid; Stearophanic acid; Stearex Beads; Cetylacetic acid; 1-Heptadecanecarboxylic acid; Pearl stearic; Industrene R
CategoryAcids

What is Stearic acid?

Octadecanoic acid is a C18 straight-chain saturated fatty acid component of many animal and vegetable lipids. As well as in the diet, it is used in hardening soaps, softening plastics and in making cosmetics, candles and plastics. It has a role as a plant metabolite, a human metabolite, a Daphnia magna metabolite and an algal metabolite. It is a long-chain fatty acid, a saturated fatty acid and a straight-chain saturated fatty acid. It is a conjugate acid of an octadecanoate. It derives from a hydride of an octadecane.

Formula & Notation

C18H36O2

IUPAC Name: octadecanoic acid

Other Names / Synonyms: octadecanoic acid; Octadecanoic acid; 57-11-4; n-Octadecanoic acid; Stearophanic acid; Stearex Beads; Cetylacetic acid; 1-Heptadecanecarboxylic acid; Pearl stearic; Industrene R

Properties & Characteristics

Appearance: Stearic acid is a white solid with a mild odor. Floats on water. (USCG, 1999). Molecular formula: C18H36O2. Molecular weight: 284.5 g/mol. Boiling point: 721 °F at 760 mmHg (NTP, 1992). Melting point: 156.7 °F (NTP, 1992). Density: 0.86 at 68 °F (USCG, 1999) - Less dense than water; will float. Solubility: 1 to 10 mg/mL at 73 °F (NTP, 1992). Vapor pressure: 1 mmHg at 344.7 °F ; 5 mmHg at 408.2 °F (NTP, 1992). LogP: 7.4.

Physical Data

PropertyValue
Melting Point156.7 °F (NTP, 1992)
Boiling Point721 °F at 760 mmHg (NTP, 1992)
Density0.86 at 68 °F (USCG, 1999) - Less dense than water; will float
Molecular Weight284.5
Solubility1 to 10 mg/mL at 73 °F (NTP, 1992)
AppearanceStearic acid is a white solid with a mild odor. Floats on water. (USCG, 1999)

Uses & Applications

Used in industrial chemical synthesis, fertilizer production, battery electrolytes, metal processing, and laboratory acid-base reactions.

Safety Information

Corrosive. Causes severe burns to skin, eyes, and respiratory tract. Wear appropriate PPE including gloves, goggles, and lab coat. Consult SDS before use.

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

Key Facts

Term Stearic acid
Formula C18H36O2
CAS Number 57-11-4
Molecular Weight 284.5
Category Acids
Synonyms octadecanoic acid; Octadecanoic acid; 57-11-4; n-Octadecanoic acid; Stearophanic acid; Stearex Beads; Cetylacetic acid; 1-Heptadecanecarboxylic acid; Pearl stearic; Industrene R

Frequently Asked Questions

Octadecanoic acid is a C18 straight-chain saturated fatty acid component of many animal and vegetable lipids. As well as in the diet, it is used in hardening soaps, softening plastics and in making cosmetics, candles and plastics. It has a role as a plant metabolite, a human metabolite, a Daphnia magna metabolite and an algal metabolite. It is a long-chain fatty acid, a saturated fatty acid and a straight-chain saturated fatty acid. It is a conjugate acid of an octadecanoate. It derives from a hydride of an octadecane.

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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.