Benzoic Acid
Overview
Benzoic acid (ben-ZO-ik AS-id) is the simplest of the aromatic carboxylic acids, a family of organic compounds containing the carboxyl (-COOH) group. It occurs in the form of white crystalline needles or thin plates. Many naturally occurring plants contain benzoic acid, including most types of berries and the natural product called gum benzoin, a plant common to the islands of Java, Sumatra, and Borneo. Gum benzoin may contain up to 20 percent benzoic acid. Benzoic acid is also excreted by most animals (except fowl) in the form of a related compound called hippuric acid (C6H5CONHCH2COOH).
Key Facts
Other Names:
Carboxybenzene, benzenecarboxylic acid, phenylformic acid
Formula:
C6H5COOH
Elements:
Carbon, hydrogen, oxygen
Compound Type:
Organic acid
State:
Solid
Molecular Weight:
122.12 g/mol
Melting Point:
122.35°C (252.23°F)
Boiling Point:
249.2°C (480.6°F)
Solubility:
Slightly soluble in water; soluble in alcohol, ether, and acetone
How It Is Made
Some benzoic acid is prepared from gum benzoin and other natural compounds containing high concentrations of the compound. Three methods are available for making benzoic acid commercially. In one method, toluene (C6H5CH3) is oxidized at high temperature and pressure over a cobalt catalyst. In a second procedure, phthalic anhydride (C6H4(CO)2O) is heated to remove carbon dioxide, with the formation of benzoic acid. In the third method, toluene is first converted to benzotrichloride (C6H5Cl3), which is then hydrolyzed to obtain benzoic acid.
Common Uses and Potential Hazards
More than half of all the benzoic acid produced in the United States is used in the manufacture of various polymeric products, primarily the family of plastics known as the polyvinyl acetates (PVAs). The PVAs, in turn, are used as adhesives, caulks, sealants, and coatings for paper, film, and plastic foil. About a quarter of all benzoic acid is converted to its sodium and potassium salts, sodium benzoate (C6H5COONa) and potassium benzoate (C6H5COOK), for use as food preservatives. Sodium benzoate and potassium benzoate are now the most widely used food preservatives in the world. They are added to a host of products, such as soft drinks and fruit juices, jams and jellies, baked goods, and salad dressings. They are also added to a number of non-food products such as mouthwashes, toothpastes, cosmetic creams, and deodorants.
Other uses of benzoic acid include:
- As an additive to antifreezes, where is acts to prevent corrosion of engine parts;
- As a seasoning agent in the processing of tobacco products;
- As a stabilizing agent in the processing of photographs; and
- For the treatment of fungal infections.
Benzoic acid and its sodium and potassium salts pose moderate health hazards to people who work directly with them. They may cause skin, nose, and eye problems if inhaled or deposited on the body. In the form of finely divided dust, they may also pose a fire or explosive risk. Most people do not encounter any of these compounds in a form in which they pose a health risk. All three compounds are considered safe by the U.S. Food and Drug Administration as food additives provided their concentration in foods does not exceed 0.1 percent. Other nations have set a safe level for the three compounds as food additives as high as 1.25 percent.
Words to Know
A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure. The process by which a compound reacts with water to form two new compounds. A compound consisting of very large molecules made of one or two small repeated units called monomers.For Further Information
"Benzoic Acid." Chemical Land 21. http://www.chemicalland21.com/arokorhi/industrialchem/organic/BENZOIC%20ACID.htm (accessed on September 22, 2005).
"Benzoic Acid and Sodium Benzoate." International Programme on Chemical Safety. http://www.inchem.org/documents/cicads/cicads/cicad26.htm (accessed on September 22, 2005).
"Benzoic Acid (CASRN 65-85-0)." U.S. Environmental Protection Agency. http://www.epa.gov/iris/subst/0355.htm (accessed on September 22, 2005).
See Also
Denatonium Benzoate
This is the complete article, containing 590 words
(approx. 2 pages at 300 words per page).
