What is Another Name for Stearic Acid?
Stearic acid, a name derived from the Greek word stéar meaning tallow, is a common saturated fatty acid with a variety of technical and trade names. The most scientifically precise and universally accepted alternative name is octadecanoic acid, which follows the official naming conventions of the IUPAC. This name is critical for chemists and researchers to ensure clear and unambiguous communication about the substance.
Other Synonyms and Common Names
While octadecanoic acid is the primary systematic name, several other synonyms may be encountered, depending on the context. Some of these include:
- Stearophanic acid: An alternative chemical name sometimes used, particularly in older literature.
- Cetylacetic acid: A less common but occasionally used name.
- 1-Heptadecanecarboxylic acid: Describes the acid based on its structure, starting from the heptadecane chain.
- C18:0: This notation is widely used in lipid and fatty acid chemistry to indicate a fatty acid with 18 carbon atoms and zero double bonds.
Where Stearic Acid is Found Naturally
Stearic acid is widespread in nature and exists as a glyceride in many fats and oils. Its presence varies significantly between animal and vegetable sources:
- Animal Sources: It is most abundant in animal fats like tallow, where it can comprise up to 30% of the fat content. This high concentration explains its original name. It is also present in fish oil.
- Vegetable Sources: While generally less common in vegetable fats (typically less than 5%), it is an important component in specific plant-based oils. Notable exceptions include cocoa butter and shea butter, which have remarkably high concentrations of stearic acid, ranging from 28–45%.
Production and Industrial Uses
Industrially, stearic acid is produced by treating animal and vegetable fats and oils with hot water at high pressure, a process that hydrolyzes the triglycerides. The resulting mixture is then distilled to separate the fatty acids. Commercial stearic acid is often a mixture of stearic and palmitic acids. Its unique properties make it invaluable across numerous industries.
Comparison of Stearic Acid and Palmitic Acid
| Property | Stearic Acid (Octadecanoic Acid) | Palmitic Acid (Hexadecanoic Acid) |
|---|---|---|
| Chemical Formula | CH₃(CH₂)₁₆CO₂H | CH₃(CH₂)₁₄CO₂H |
| Number of Carbons | 18 | 16 |
| Chain Length | Longer | Shorter |
| Melting Point | 69.3 °C | 63.1 °C |
| Natural Sources | Tallow, cocoa butter, shea butter | Palm oil, animal fat |
| IUPAC Name | Octadecanoic acid | Hexadecanoic acid |
Applications in Modern Industry
Stearic acid is a versatile chemical with a wide range of applications, many of which stem from its nature as a fatty acid with both polar and non-polar properties.
- Soaps and Cosmetics: It is a key ingredient in many soaps, shampoos, and other cosmetics. Its esters, like glycol stearate, are used to produce a pearly effect in products.
- Candle Making: Historically, stearic acid was a primary component in candles, which is reflected in the origin of its name.
- Pharmaceuticals: Used as a lubricant in the manufacture of tablets and capsules. Magnesium stearate, a derivative, is a common excipient.
- Plastics and Rubber: It acts as a lubricant and release agent during the molding and pressing of plastic and rubber products.
- Pyrotechnics: Utilized as a coating for metallic powders to prevent oxidation, improving their storage life.
Conclusion
In summary, while the question asks for another name, the most scientifically accurate and important alternative name for stearic acid is octadecanoic acid. Other synonyms like stearophanic acid exist, but octadecanoic acid is the standard. This saturated fatty acid's diverse applications, from cosmetics to pharmaceuticals, demonstrate its vital role in modern industry. Its prevalence in both animal and vegetable sources ensures its continued utility, showcasing its importance far beyond its original association with tallow. For more detailed information on fatty acid chemistry, you can consult resources from the American Oil Chemists' Society.
