Benzoic Acid
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
- CATALYST
- A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure.
- HYDROLYSIS
- The process by which a compound reacts with water to form two new compounds.
- POLYMER
- 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 AlsoDenatonium Benzoate
Benzoic acid
Benzoic acid
Benzoic acid is a derivative of benzene with the chemical formula C6 H5 COOH. It consists of a carboxyl group attached to a phenyl group, and is thus the simplest aromatic carboxylic acid. It is also known as carboxybenzene, benzene carboxylic acid, and phenylformic acid.
In its pure form, benzoic acid exists as white needles or scales with a strong characteristic odor. It melts at 252.3°F (122.4°C), although it may also sublime (go from a solid to a vapor) at temperatures around 212°F (100°C). It dissolves only sparingly in cold water (0.4 g/100 g at 77°F [(25°C)]), but more completely in hot water (6.8 g/100 g at 203°F [(95°C)]).
Benzoic acid occurs naturally in gum benzoin, also known as benzoin resin or Benjamin gum, a brown resin found in the benzoin tree of Southeast Asia. It is also found naturally in many kinds of berries, where its concentration may reach 0.05%.
One of the most common uses of benzoic acid is as a food preservative. Both the acid and its sodiumsalt, sodium benzoate (usually listed on labels as benzoate of soda), are used to preserve many different kinds of foods, including fruit juices, soft drinks, pickles, and salad dressings. In fact, it is the acid rather than the sodium salt that is toxic to bacteria. Thus, the two additives can be used only in acidic solutions, where the sodium salt is converted to the acid form.
The acid and the sodium salt are both considered to be safe for human consumption in limited amounts. In the United States, foods may contain a maximum of 0.1% benzoic acid or sodium benzoate, although the limit in other nations may be as high as 1.25% in some types of prepared foods. Benzoic acid is also used in the manufacture of artificial flavors and perfumes and for the flavoring of tobacco.
Benzoic Acid
Benzoic acid
Benzoic acid is a derivative of benzene with the chemical formula C6H5COOH. It consists of a carboxyl group attached to a phenyl group , and is thus the simplest aromatic carboxylic acid. It is also known as carboxybenzene, benzene carboxylic acid, and phenylformic acid.
In its pure form, benzoic acid exists as white needles or scales with a strong characteristic odor. It melts at 252.3°F (122.4°C), although it may also sublime at temperatures around 212°F (100°C). It dissolves only sparingly in cold water [0.4 g/100 g at 77°F (25°C)], but more completely in hot water [6.8 g/100 g at 203°F (95°C)].
Benzoic acid occurs naturally in gum benzoin, also known as benzoin resin or Benjamin gum, a brown resin found in the benzoin tree of Southeast Asia . It is also found naturally in many kinds of berries, where its concentration may reach 0.05%.
One of the most common uses of benzoic acid is as a food preservative. Both the acid and its sodium salt , sodium benzoate (usually listed on labels as benzoate of soda), are used to preserve many different kinds of foods, including fruit juices, soft drinks, pickles, and salad dressings. In fact, it is the acid rather than the sodium salt that is toxic to bacteria . Thus, the two additives can be used only in acidic solutions, where the sodium salt is converted to the acid form.
The acid and the sodium salt are both considered to be safe for human consumption in limited amounts. In the United States, foods may contain a maximum of 0.1% benzoic acid or sodium benzoate, although the limit in other nations may be as high as 1.25% in some types of prepared foods. Benzoic acid is also used in the manufacture of artificial flavors and perfumes and for the flavoring of tobacco.