Names | |
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Preferred IUPAC name
Hexadecanoic acid | |
Other names
Palmitic acid
C16:0 (Lipid numbers) | |
Identifiers | |
3D model (JSmol)
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ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.000.284 |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C16H32O2 | |
Molar mass | 256.430 g/mol |
Appearance | White crystals |
Density | 0.852 g/cm3 (25 °C)[2] 0.8527 g/cm3 (62 °C)[3] |
Melting point | 62.9 °C (145.2 °F; 336.0 K)[7] |
Boiling point | 351–352 °C (664–666 °F; 624–625 K)[8] 271.5 °C (520.7 °F; 544.6 K), 100 mmHg[2] 215 °C (419 °F; 488 K), 15 mmHg |
4.6 mg/L (0 °C) 7.2 mg/L (20 °C) 8.3 mg/L (30 °C) 10 mg/L (45 °C) 12 mg/L (60 °C)[4] | |
Solubility | Soluble in amyl acetate, alcohol, CCl4,[4] C6H6 Very soluble in CHCl3[3] |
Solubility in ethanol | 2 g/100 mL (0 °C) 2.8 g/100 mL (10 °C) 9.2 g/100 mL (20 °C) 31.9 g/100 mL (40 °C)[5] |
Solubility in methyl acetate | 7.81 g/100 g[4] |
Solubility in ethyl acetate | 10.7 g/100 g[4] |
Vapor pressure | 0.051 mPa (25 °C)[3] 1.08 kPa (200 °C) 28.06 kPa (300 °C)[6] |
Acidity (pKa) | 4.75 [3] |
−198.6·10−6 cm3/mol | |
Refractive index (nD)
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1.43 (70 °C)[3] |
Viscosity | 7.8 cP (70 °C)[3] |
Thermochemistry | |
Heat capacity (C)
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463.36 J/(mol·K)[6] |
Std molar
entropy (S⦵298) |
452.37 J/(mol·K)[6] |
Std enthalpy of
formation (ΔfH⦵298) |
−892 kJ/mol[6] |
Std enthalpy of
combustion (ΔcH⦵298) |
10030.6 kJ/mol[3] |
Hazards | |
GHS labelling: | |
[2] | |
Warning | |
H319[2] | |
P305+P351+P338[2] | |
NFPA 704 (fire diamond) | |
Flash point | 206 °C (403 °F; 479 K)[2] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.[9][10] Its chemical formula is CH3(CH2)14COOH, and its C:D ratio (the total number of carbon atoms to the number of carbon-carbon double bonds) is 16:0. It is a major component of palm oil from the fruit of Elaeis guineensis (oil palms), making up to 44% of total fats. Meats, cheeses, butter, and other dairy products also contain palmitic acid, amounting to 50–60% of total fats.[11]
Palmitates are the salts and esters of palmitic acid. The palmitate anion is the observed form of palmitic acid at physiologic pH (7.4). Major sources of C16:0 are palm oil, palm kernel oil, coconut oil, and milk fat.[12]