Benzoic Acid - C<sub>6</sub>H<sub>5</sub>COOH

What is Benzoic Acid?

Benzoic acid is an organic compound which is described by the chemical formula C6H5COOH. It consists of a carboxyl group attached to a benzene ring. Therefore, benzoic acid is said to be an aromatic carboxylic acid. This compound exists as a crystalline, colorless solid under normal conditions. The term ‘benzoate’ refers to the esters and salts of C6H5COOH.

The commercial production of benzoic acid is done via the partial oxidation of toluene with oxygen, catalyzed by manganese or cobalt naphthenates. This chemical reaction is illustrated below.

Benzoic Acid

Another industrial method of preparing benzoic acid is by reacting tri-chlorotoluene with calcium hydroxide in the presence of water, and the treatment of the calcium benzoate product with hydrochloric acid.

Structure

The structure of a C6H5COOH molecule is illustrated below. This molecule consists of a benzene ring to which a carboxyl functional group is linked. The molecule consists of 7 carbon atoms, 6 hydrogen atoms, and 2 oxygen atoms.

Benzoic Acid Structure

Properties of Benzoic Acid

The physical and chemical properties of C6H5COOH are discussed in this subsection.

Chemical Data

Benzoic Acid Formula C7H6O2 or C6H5COOH
Molecular Weight/ Molar Mass 122.12 g/mol
Density 1.27 g/cm3 at 15oC
Boiling Point 523K
Melting Point 395 K

Physical Properties

  • Benzoic acid has a colorless appearance in its solid state, which is of a crystalline nature.
  • The crystal structure is monoclinic.
  • The presence of the aromatic ring gives this compound a faintly pleasant odor.
  • At a temperature of 130oC, the density of this compound reduces to 1.075 grams per cubic centimeter.

Chemical Properties

  • It is soluble in water, and the solubility at 25oC and 100oC is 3.44 g/L and 56.31 g/L respectively.
  • It is soluble in benzene, carbon tetrachloride, acetone, and alcohols.
  • The acid dissociation constant (pKa) of benzoic acid corresponds to 4.2
  • Its reactions can occur at the carboxyl group or even at the aromatic ring.

Uses of Benzoic Acid

Some important uses of C6H5COOH are listed below.

  • The production of phenol involves the use of benzoic acid.
  • This compound is used in ointments that prevent or treat fungal skin diseases.
  • C6H5COOH is used as a preservative in the food industry.
  • Benzoic acid is an ingredient in many cosmetic products, such as lipsticks.
  • It is also a precursor to benzoyl chloride.
  • One of the components of toothpaste, mouthwash, and facewash creams is C6H5
  • This compound is also used in the manufacture of dyes and in insect repellants.

To learn more about this compound and other aromatic compounds, such as pyridine, register with BYJU’S and download the mobile application on your smartphone.

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