| Sodium stearate | |
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sodium octadecanoate |
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| Identifiers | |
| CAS number | 822-16-2 |
| PubChem | 2724691 |
| ChemSpider | 12639 |
| UNII | QU7E2XA9TG |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C18H35NaO2 |
| Molar mass | 306.46 g mol−1 |
| Appearance | white solid |
| Melting point |
245 - 255 C |
| Solubility in water | soluble |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Sodium stearate, or sodium octadecanoate, is the sodium salt of stearic acid. It is the major component of some types of soap, especially those made from animal fat. It is found in many types of solid deodorants, rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.
Contents |
Sodium stearate is one component of soap.[1] The salt has both hydrophilic and hydrophobic parts, the carboxylate and the long hydrocarbon chain, respectively. These two chemically different components induce the formation of micelles, which present the hydrophilic heads outwards and their hydrophobic (hydrocarbon) tails inwards, providing a lipophilic environment for hydrophobic compounds. It is also used in the pharmaceutical industry as a surfactant to aid the solubility of hydrophobic compounds in the production of various mouth foams.
Sodium stearate is produced as one component of soap upon saponification of oils and fats. The percentage of the sodium stearate depends on the ingredient fats. Tallow is especially high in stearic acid content (as the triglyceride), whereas most fats only contain a few percent. The idealized equation for the formation of sodium stearate from stearin (the triglyceride of stearic acid) follows:
Purified sodium stearate can be made by neutralizing stearic acid with sodium hydroxide.