Stearic acid (octadecanoic acid) is an aliphatic monobasic carboxylic acid corresponding to the formula C 17 H 35 COOH (one can also see the entry in the form of the molecular formula (gross formula) C 18 H 36 O 2 or other variants of the rational formula - CH 3 (CH 2 ) 16 COOH or C 17 H 35 CO 2 H). White crystals, insoluble in water and soluble in diethyl ether . Stearic acid was discovered in lard in 1816 by the French chemist Chevrel.
| Stearic acid | |
|---|---|
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| Octadecanoic acid (stearic) .png | |
| Are common | |
| Chem. formula | C 17 H 35 COOH |
| Physical properties | |
| Molar mass | 284.48 g / mol |
| Density | 0.94 g / cmΒ³ |
| Thermal properties | |
| T. melt. | 69.6 Β° C |
| T. bale. | 376.1 Β° C |
| Classification | |
| Reg. CAS number | 57-11-4 |
| PubChem | |
| Reg. EINECS number | 200-313-4 |
| Smiles | |
| Inchi | |
| Chebi | and |
| ChemSpider | |
Content
Physical Properties
Chemically pure stearic acid has the form of colorless crystals. Stearic acid is insoluble in water, but soluble in ether. It is odorless.
Chemical Properties
Reacts with alkalis (with the formation of stearates):
C 17 H 35 COOH + NaOH β C 17 H 35 COONa + H 2 O
Getting
Stearic acid is obtained by hydrogenation of oleic acid:
C 17 H 33 COOH + H 2 β C 17 H 35 COOH
Stearic acid is also synthesized by oxidation of saturated hydrocarbons with manganese compounds [1] .
Biological Importance
Stearic acid is one of the most common fatty acids in nature, which is a part of lipids in the form of glycerides , primarily triglycerides of animal fats , the latter serve as an energy depot. The content of stearic acid in animal fats is maximum in lamb fat (up to ~ 30%), in vegetable oils - up to 10% (palm oil).
It is synthesized in the body from palmitic acid under the action of enzymes - elongase, which are responsible for lengthening the aliphatic chain of fatty acids.
Production
The main industrial method for producing stearic acid is to extract it from stearin , a product of fat hydrolysis in the manufacture of soap . Although stearic acid can also be extracted from vegetable fats , animal fat is usually used for its production.
Industrial value and application
It is widely used in the cosmetic industry: sodium stearate is one of the main components of soap , stearic acid itself is part of many cosmetics. It is used in the manufacture of candles and as a softener in the production of rubber . Stearates of sodium , calcium , lead are used as components of greases. In the pharmaceutical industry, magnesium stearate is used as a filler.
Notes
- β A. E. Temirbulatova, N. N. Nurakhmetov, R. N. Zhumadilova, S. K. Alimzhanova. Translation by A. Tusupbekova. A textbook for 11 classes of the natural-mathematical direction of secondary schools. - Almaty: Mektep, 2011