Stearic Acid

Definition

Stearic acid is a long-chain saturated fatty acid that is commonly found in various fats and oils. It plays important roles in the context of functional groups, waxes, fats, and oils, soap, as well as the catabolism of triacylglycerols through β-oxidation.

5 Must Know Facts For Your Next Test

1. Stearic acid has the chemical formula CH$_{3}$(CH$_{2}$)$_{16}$COOH, making it a long-chain saturated fatty acid.
2. As a saturated fat, stearic acid is solid at room temperature and has a high melting point compared to unsaturated fats.
3. Stearic acid is found in various animal fats, such as beef tallow, and in some plant-based oils, like cocoa butter.
4. In the context of soap, stearic acid contributes to the hardness and cleansing properties of the soap.
5. During the β-oxidation of triacylglycerols, stearic acid is broken down into acetyl-CoA units to be used in the citric acid cycle for energy production.

Review Questions

• Explain the role of stearic acid as a functional group in organic chemistry.
  • As a carboxylic acid functional group, stearic acid has a polar carbonyl carbon and a hydroxyl group that can participate in various chemical reactions. This functional group allows stearic acid to be involved in esterification, saponification, and other processes that are important in the context of organic chemistry.
• Describe the significance of stearic acid in the composition and properties of waxes, fats, and oils.
  • Stearic acid is a common component of many natural fats and oils, including animal fats and some plant-based oils. Its long, saturated hydrocarbon chain and carboxylic acid functional group contribute to the physical and chemical properties of these lipids, such as melting point, viscosity, and susceptibility to oxidation. The presence of stearic acid influences the overall characteristics and behavior of waxes, fats, and oils in various applications.
• Analyze the role of stearic acid in the saponification process and the formation of soap.
  • During the saponification reaction, the carboxylic acid group of stearic acid reacts with a base, such as sodium hydroxide, to form a salt. This salt, known as a soap, has both hydrophilic (polar) and hydrophobic (nonpolar) regions, allowing it to effectively emulsify and remove dirt and grease from surfaces. The presence of stearic acid in the soap formulation contributes to the hardness, lathering, and cleansing properties of the final soap product.

Related terms

Fatty Acid: A carboxylic acid with a long hydrocarbon chain, which can be saturated or unsaturated.

Triacylglycerol: Also known as triglyceride, a lipid molecule composed of three fatty acid chains attached to a glycerol backbone.

β-Oxidation: The catabolic process by which fatty acids are broken down to generate acetyl-CoA for energy production.