Sodium stearate

Sodium stearate

Names
IUPAC name sodium octadecanoate
Other names sodium octadecanoate
Identifiers
CAS Number	822-16-2
ChemSpider	12639
EC Number	212-490-5
Jmol interactive 3D	Image
PubChem	2724691
UNII	QU7E2XA9TG
InChI InChI=1S/C18H36O2.Na/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h2-17H2,1H3,(H,19,20);/q;+1/p-1 Key: RYYKJJJTJZKILX-UHFFFAOYSA-M InChI=1/C18H36O2.Na/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h2-17H2,1H3,(H,19,20);/q;+1/p-1 Key: RYYKJJJTJZKILX-REWHXWOFAA
SMILES [Na+].[O-]C(=O)CCCCCCCCCCCCCCCCC
Properties
Chemical formula	C18H35NaO2
Molar mass	306.47 g·mol^−1
Appearance	white solid
Odor	slight, tallow-like odor
Density	1.02 g/cm^3
Melting point	245 to 255 °C (473 to 491 °F; 518 to 528 K)
Solubility in water	soluble
Solubility	slightly soluble in ethanediol
Hazards
NFPA 704	1 2 0
Flash point	176 °C (349 °F; 449 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium stearate is the sodium salt of stearic acid. This white solid is the most common soap. 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.^[1]

Use

Characteristic of soaps, sodium stearate 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.The tail part dissolves the grease (or) dirt and forms the micelle. 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.

Production

Sodium stearate is produced as a major 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:

(C₁₈H₃₅O₂)₃C₃H₅ + 3 NaOH → C₃H₅(OH)₃ + 3 C₁₈H₃₅O₂Na

Purified sodium stearate can be made by neutralizing stearic acid with sodium hydroxide.

References

1. Klaus Schumann, Kurt Siekmann, "Soaps" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a24_247

External links

• Safety Data