Stearic acid
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| Names | |
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Preferred IUPAC name
Octadecanoic acid
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| Other names
Stearic acid
C18:0 (Lipid numbers) |
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| Identifiers | |
57-11-4 
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| 3D model (Jmol) | Interactive image |
| ChEMBL |
ChEMBL46403 
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| ChemSpider |
5091
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| DrugBank |
DB03193
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| ECHA InfoCard | 100.000.285 |
| EC Number | 200-313-4 |
| 3377 | |
| PubChem | 5281 |
| RTECS number | WI2800000 |
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| Properties | |
| C18H36O2 | |
| Molar mass | 284.48 g·mol−1 |
| Appearance | White solid |
| Odor | Pungent, oily |
| Density | 0.9408 g/cm3 (20 °C) 0.847 g/cm3 (70 °C) |
| Melting point | 69.3 °C (156.7 °F; 342.4 K) |
| Boiling point | 361 °C (682 °F; 634 K) decomposes 232 °C (450 °F; 505 K) at 15 mmHg |
| 0.003 g/L (20 °C) 0.34 g/L (25 °C) 1 g/L (37 °C) |
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| Solubility | Soluble in alkyl acetates, alcohols, HCOOCH3, phenyls, CS2, CCl4 |
| Solubility in dichloromethane | 3.58 g/100 g (25 °C) 8.85 g/100 g (30 °C) 18.3 g/100 g (35 °C) |
| Solubility in ethanol | 0.9 g/100 mL (10 °C) 2 g/100 mL (20 °C) 4.5 g/100 mL (30 °C) 13.8 g/100 mL (40 °C) |
| Solubility in acetone | 4.96 g/100 g |
| Solubility in chloroform | 18.4 g/100 g |
| Solubility in toluene | 15.75 g/100 g |
| Vapor pressure | 0.01 kPa (158 °C) 0.46 kPa (200 °C) 16.9 kPa (300 °C) |
| -220.8·10−6 cm3/mol | |
| Thermal conductivity | 0.173 W/m·K (70 °C) 0.166 W/m·K (100 °C) |
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Refractive index (nD)
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1.4299 (80 °C) |
| Structure | |
| B-form = Monoclinic | |
| B-form = P21/a | |
| B-form = Cs 2h |
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a = 5.591 Å, b = 7.404 Å, c = 49.38 Å (B-form)
α = 90°, β = 117.37°, γ = 90°
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| Thermochemistry | |
| 501.5 J/mol·K | |
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Std molar
entropy (S |
435.6 J/mol·K |
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Std enthalpy of
formation (ΔfH |
−947.7 kJ/mol |
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Std enthalpy of
combustion (ΔcH |
11290.79 kJ/mol |
| Hazards | |
| NFPA 704 | |
| Flash point | 113 °C (235 °F; 386 K) |
| Lethal dose or concentration (LD, LC): | |
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LD50 (median dose)
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21.5 mg/kg (rats, intravenous) |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is ?) |
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| Infobox references | |
Stearic acid (/ˈstɪərɪk/ STEER-ik, /ˈstɪ.æ.rɪk/ stee-ARR-ik) is a saturated fatty acid with an 18-carbon chain and has the IUPAC name octadecanoic acid. It is a waxy solid and its chemical formula is C17H35CO2H. Its name comes from the Greek word στέαρ "stéar", which means tallow. The salts and esters of stearic acid are called stearates. As its ester, stearic acid is one of the most common saturated fatty acids found in nature following palmitic acid. The triglyceride derived from three molecules of stearic acid is called stearin.
Stearic acid is obtained from fats and oils by the saponification of the triglycerides using hot water (above 200 °C). The resulting mixture is then distilled. Commercial stearic acid is often a mixture of stearic and palmitic acids, although purified stearic acid is available.
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