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Carboxylic Acids

Industrial Importance

Carboxylic acids are also very important industrially. Perhaps one of the most important industrial applications of compounds with carboxyl groups is the use of fatty acids (which are carboxyl groups attached to long carbon chains) in making soaps, detergents, and shampoos. In some such compounds, the hydrogen atom in the carboxyl group is replaced with some metal cation. The modified carboxyl group is soluble in water, while the long chain of carbons remains soluble in fats, oils, and greases. This double solubility allows water to wash out the fat- and oil-based dirt. Many shampoos are based on lauric, palmitic, and stearic acids, which have long chains of 12, 16, and 18 carbon atoms, respectively. To make other cleansing agents, three molecules of fatty acid are combined with one molecule of a compound called glycerin in a reaction called saponification. This reaction also makes a soap molecule which has one end soluble in water and the other soluble in fat or grease or oil. Various fatty acids are used to make soaps and detergents that have different applications in society. Carboxylic acids are also important in the manufacture of greases, crayons, and plastics.

Compounds with carboxyl groups are relatively easily converted to compounds called esters, which have the hydrogen atom of the carboxyl group replaced with a group containing carbon and hydrogen atoms. Such esters are considered derivatives of carboxylic acids. Esters are important because many of them have characteristic tastes and odors. For example, methyl butyrate, a derivative of butyric acid, smells like apples. Benzyl acetate, from acetic acid, has a jasmine odor. Carboxylic acids are thus used commercially as raw materials for the production of synthetic odors and flavors. Other esters, derived from carboxylic acids, have different uses. For example, the ester ethyl acetate is a very good solvent and is a major component in nail polish remover.



Loudon, G. Mark. Organic Chemistry. Oxford: Oxford University Press, 2002.

Snyder, Carl H. The Extraordinary Chemistry of Ordinary Things. New York: John Wiley & Sons, 1992.


Murray, Frank. "Hydroxycitric Acid." Better Nutrition for Better Living 56 (1994): 34–39.

David W. Ball


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Amino acid

—An organic compound whose molecules contain both an amino group (-NH2) and a carboxyl group (-COOH). One of the building blocks of a protein.

Carboxyl group

—The —COOH group of atoms, whose presence defines a carboxylic acid.


—A derivative of a carboxylic acid, where an organic group has been substituted for the hydrogen atom in the acid group. Esters contribute to tastes and smells.

Fatty acid

—A carboxylic acid which is attached to a chain of at least 8 carbon atoms. Fatty acids are important components in fats, and are used to make soaps.

Lactic acid

—A carboxylic acid formed during the metabolism of sugar in muscle cells. A buildup of lactic acid leads to a feeling of fatigue.

Mineral acid

—An acid that is not organic. Examples include hydrochloric acid and sulfuric acid.


—A chemical reaction involving the breakdown of triglycerides to component fatty acids, and the conversion of these acids to soap.

Additional topics

Science EncyclopediaScience & Philosophy: Calcium Sulfate to Categorical imperativeCarboxylic Acids - Biological Importance, Industrial Importance