Stearic Acid (C₁₈H₃₆O₂)
Octadecanoic Acid
What is Stearic Acid?
Stearic Acid (C₁₈H₃₆O₂); is the most common 18-carbon saturated fatty acid found in nature. It is odorless and appears as a white-cream colored powder. Its chemical structure is expressed by the formula CH₃(CH₂)₁₆COOH.
Stearic acid is naturally found in vegetable and animal fats and is widely used in industry for the production of soap, candles, detergents, plastics, cosmetics, food, and pharmaceuticals. Stearates (stearic acid salts) in particular play an important role in the chemical industry.
Stearic Acid Properties
| Feature | Value |
|---|---|
| Physical Appearance | Creamy white powder |
| Chemical Formula | C₁₈H₃₆O₂ |
| Molecular Weight | 284.48 g/mol |
| Packaging Type: | Bag |
| Other Names | Stearic Acid, Octadecanoic Acid |
⚠️ Note: Although stearic acid is a safe ingredient, its purity levels may vary depending on the application, such as food, cosmetics, or industrial use.
In Which Industries Is Stearic Acid Used?
Stearic acid is a versatile chemical widely used in many industries. Some of the main sectors are:
- Cosmetics industry: Stearic acid is a widely used ingredient in creams, lotions, shampoos, soaps, and other personal care products. Its emollient and thickening properties give these products a better texture and feel.
- Food industry: Stearic acid is used in the food processing industry as an emulsifier, thickener, and fat substitute. For example, it can be used in chocolate production.
- Plastics industry: It is used in the production of thermoplastic materials such as stearic acid, polyethylene, and PVC. It improves the quality and workability of plastics, making them more durable, moldable, and workable.
- Pharmaceutical industry: Stearic acid is used in pharmaceuticals as an emulsifier, thickener, and substitute for oil.
- Other industries: Stearic acid is also used in the paint industry, paper and cardboard production, candle manufacturing, detergents, the textile industry, and the leather processing industry.
How is Stearic Acid Produced?
Stearic acid is a saturated fatty acid obtained from fats through hydrolysis. As its name suggests, its natural sources include beef tallow and vegetable oils. Industrially, a series of processes such as hydrolysis, hydrogenation, and distillation are used to obtain stearic acid, also known as stearin, from vegetable oils. The processes begin with the hydrolysis of fats, followed by the removal of unsaturated fatty acids through hydrogenation, and finally purification through distillation.
The hydrolysis process is carried out by boiling the fats and injecting steam. This process causes the production of free fatty acids from the fats. Subsequently, the unsaturated fatty acids are hydrogenated through the hydrogenation process, yielding saturated fatty acids. Finally, stearic acid is purified through distillation and brought to the desired thickness and purity.
Stearic acid can also be obtained as a by-product. In some industries, particularly in soap production, animal sources such as tallow, also known as stearin oil, can be used.