Sodium stearate (IUPAC: Sodium Octadecanoate) is the sodium salt of stearic acid. This white solid is the most common soap. It is found in many types of solid , rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.[Klaus Schumann, Kurt Siekmann, "Soaps" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. ]
Use
Having the characteristics of
, sodium stearate has both
hydrophilic and
hydrophobic parts, a
carboxylate and a long hydrocarbon chain. These two chemically different components induce the formation of
, 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.
- C17H35COOH+NaOH→C17H35COONa+H2O
External links
