Sodium stearate
Encyclopedia
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 deodorant
s, rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.
. 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 micelle
s, 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 form.
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:3C3H5 + 3 NaOH → C3H5(OH)3 + 3 C17H35CO2Na
Purified sodium stearate can be made by neutralizing stearic acid
with sodium hydroxide.
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
salt of stearic acid
Stearic acid
Stearic acid is the 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 CH316CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates...
. It is the major component of some types of soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
, especially those made from animal fat. It is found in many types of solid deodorant
Deodorant
Deodorants are substances applied to the body to affect body odor caused by bacterial growth and the smell associated with bacterial breakdown of perspiration in armpits, feet and other areas of the body. A subgroup of deodorants, antiperspirants, affect odor as well as prevent sweating by...
s, rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.
Use
Sodium stearate is one component of soapSoap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
. 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 micelle
Micelle
A micelle is an aggregate of surfactant molecules dispersed in a liquid colloid. A typical micelle in aqueous solution forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single tail regions in the micelle centre. This phase is...
s, 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
Surfactant
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
to aid the solubility of hydrophobic compounds in the production of various mouth form.
Production
Sodium stearate is produced as one component of soap upon saponificationSaponification
Saponification is a process that produces soap, usually from fats and lye. In technical terms, saponification involves base hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. In addition to soap, such traditional saponification processes...
of oils and fats. The percentage of the sodium stearate depends on the ingredient fats. Tallow
Tallow
Tallow is a rendered form of beef or mutton fat, processed from suet. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.In industry,...
is especially high in stearic acid content (as the triglyceride
Triglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
), 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:3C3H5 + 3 NaOH → C3H5(OH)3 + 3 C17H35CO2Na
Purified sodium stearate can be made by neutralizing stearic acid
Stearic acid
Stearic acid is the 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 CH316CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates...
with sodium hydroxide.