Primary Applications for the Carboxylic Acids

Compounds containing the carboxyl group (abbreviated –COOH o CO2H) are known as carboxylic acids. The carboxyl group is the source of a number of organic compounds, among which can be found the acid halides (RCOCl), acid anhydrides ((RC(O))2O), esters (RCO2R'), and amides (RC(O)NH2).

 

Some carboxylic acids that are widely used in the industry include:

Acrylic acid is the common name for propenoic acid with the formula CH2=CHCO2H. This organic compound is colorless, flammable, caustic with a pungent odor and a boiling temperature of 142 º C. Acrylic acid is the simplest unsaturated carboxylic acid; its salts and esters are known as acrylates. Its main reaction is polymerization: resulting polyacrylates are often transparent but brittle. To modify its physical and chemical properties, acrylic acid can be combined with other components (copolymerization). Therefore, it is the starting material to make plastics, varnishes, adhesives, elastic and transparent resins. For more information, click here

Solid with the formula C6H5COOH, benzoic acid is slightly soluble in water and has a slightly higher acidity than simple aliphatic acids. Used as a food preservative, it has low toxicity and is nearly tasteless. It is combined with salicylic acid to form an ointment form with antifungal properties. It can be safely applied to the skin. For more information, click here

Trans-butanedioic or fumaric acid is a colorless, crystalline compound, with the formula HO2CCH=CHCO2H. It has a melting point at 200°C and is found in certain fungi and some plants, unlike its cis (Z) isomer, maleic acid (cis butanedioic), which does not occur naturally.

 

Fumaric acid is used in processing and preserving food because of its strong antimicrobial action, and to make paints, varnishes and synthetic resins. For more information, click here

Linoleic acid is a colorless or pale yellow oily liquid with the formula CH3(CH2)4(CH=CHCH2)2(CH2)6CO2H, which has double bonds in its cis configuration. It is soluble in organic solvents and is easily polymerized, giving it drying properties. Linoleic acid is an essential fatty acid, meaning that it is a necessary element in the diet of mammals as one of the precursors to prostaglandins and other hormone-like components.

 

Linoleic acid is found as an ester of glycerin in many vegetable seed oils such as linseed, soybean, sunflower and cotton. It is used in the manufacture of paints and varnishes. For more information, click here

A colorless, oily liquid, oleic acid has the formula CH3(CH2)7CH=CH(CH2)7COOH in its cis configuration (meaning that the carbon chain continues on the same side of the double bond). It is an unsaturated fatty acid that quickly turns yellow in contact with air. Saturated stearic acid is obtained by the hydrogenation of oleic acid. It is not soluble in water, but is soluble in benzene, alcohol, ether and many organic solvents. Oleic acid solidifies when cooled and melts at 14° C. Its trans isomer (elaidic acid) is solid and melts at 51° C which can be obtained by heating oleic acid in the presence of a catalyst.

 

Together with stearic acid and palmitic acid, oleic acid is found in an ester form in most natural fats and oils, especially olive oil. It is obtained by hydrolysis of the ester and purified by distillation. It is used in the manufacture of soaps and cosmetics, in the textile industry, and in metal cleaning. For more information click here

Salicylic acid is a white, crystalline solid with the formula C6H4(OH)COOH. It is found in many plants (especially fruit), in the form of methyl salicylate, and is obtained commercially from phenol. Salicylic acid tastes slightly sweet and is less soluble in water than in alcohol, ether or chloroform. It has a melting point of 159 ° C and is used primarily to prepare certain important salts and esters.

 

Sodium salicylate, which is obtained by treating sodium phenolate with carbon dioxide under pressure, is used to preserve food and to a greater extent to develop mild antiseptic preparations such as toothpaste and mouthwash. Salicylic medicinal compounds include analgesics from acetylsalicylic acid and antipyretics from phenyl salicylate, sold under the trade names of aspirin and salol, respectively. Methyl salicylate is the main component of wintergreen oil or essence of wintergreen, and is produced synthetically in large quantities by the reaction of salicylic acid and methanol. For more information, click here

A yellow liquid with the formula CH3(CH2)4COOH, caprylic acid has a characteristically rancid odor and fungicidal activity that is used against various fungi. Caprylic acid and its salts are also used for dermatological treatments. For more information, click here