Benzoic Acid - Overview, Structure, Preparation, Properties & Uses, FAQs

Benzoic acid is an organic compound with C₆H₅COOH as its chemical formula. It consists of a benzene ring and a carboxylic group. The compound exists in normal conditions as a colourless crystalline solid. Benzoic acid is an organic compound that is used in our daily life for various food and cosmetic products. It is used in many products such as pickles, jams, lipsticks, wash creams, among others. In addition, it is an essential precursor in many organic combination syntheses.

Benzoic acid structure :

The Benzoic acid is also known as Benzene carboxylic acid. There are 7 carbon atoms, 2 oxygen atoms and 6 hydrogen atoms in its structure. It consists of a six-carbon ring with alternate single and double bands, as well as the group of –COOH attached to the ring that makes it benzoic acid.

Benzoic acid formula: C₆H₅COOH

The benzoic acid structure is given below:

Preparation of benzoic acid

In the process of preparation of benzoic acid, we convert Phenol to benzoic acid.

First we convert phenol to benzene using zinc dust and then we convert benzene to Tolune using the CH₃Cl+AlCl₃, here aluminum trichloride acts as lewis acid catalyst.

Then Toluene is converted into benzoic acid by oxidation.

Resonating structure of benzoic acid or Resonance structure of benzoic acid (Resonating structure of benzaldehyde)

Physical properties of benzoic acid

1. In its solid state of crystalline nature, benzoic acid reaction has an uncoloured appearance. It is nonclinical in its crystal structure.
2. This compound is slightly pleasant because of the aromatic ring.
3. This compound's density decreases to 1,075 gram per cubic centimeter at a temperature of 130^oC.
4. Benzoic acid melting point of benzoic acid is 122.3⁰C.
5. Benzoic acid molar mass - 122.12 g/mol.

Chemical properties of benzoic acid

1. The solubility is 3.44 g/L and 56.31 g/l, respectively, at a temperature range of 25^oC and 100^oC.

2. Benzene, carbon tetrachloride, acetone and alcohol are soluble.

3. The benzoic acid p^ka dissociation constant is 4.2.

4. The carboxyl group or even the aromatic Ring may experience its reactions.

NCERT Chemistry Notes :

Uses of benzoic acid

It is used in an acidic medium, but it has lost preservation activity in an alkaline medium because it divides into ions in an alkaline medium.

• The use of benzoic acid as a preservative does not affect the odour or taste of food products.

• It delays the reproduction of microorganisms by preserving the quality.

• The benzoic acid sodium salt sodium benzoate reduces the blood level of glycine because it is an amide bond between the benzoate and glycine that is excreted by the urinary tract.

• Some benzoic acid esters act as plasticizers.

• For many foodstuffs such as soda, barbecue sauces, pickle, and dressings which prevent the growth of bacteria and fungi, benzoic acid and its sodium salt are used as food preservatives.

• Benzoic acid is used to treat skin irritation, sunburns, insect bites, fungal infections. This is used specifically in cosmetics.

• It is used as a pH adjuster in the preparation of fragrances.

• It is mostly used in acidic foods because even at very low pH it has more anti-food and antibacterial properties.

Also read -

• NCERT Solutions for Class 11 Chemistry
• NCERT Solutions for Class 12 Chemistry
• NCERT Solutions for All Subjects