Question

Benzoic acid to Benzene

Hint:

Soda lime decarboxylation removes –COOH as CO\(_2\) → gives hydrocarbon.

Answer 1

Step 1: Understanding the Reactants.
Benzoic acid (\( \text{C}_6\text{H}_5\text{COOH} \)) is an aromatic carboxylic acid that contains a benzene ring attached to a carboxyl group (\( \text{-COOH} \)). Benzene (\( \text{C}_6\text{H}_6 \)) is an aromatic hydrocarbon composed only of a benzene ring.

Step 2: Reaction Type.
To convert benzoic acid to benzene, we need to remove the carboxyl group (\( \text{-COOH} \)) from benzoic acid. This process is known as reduction, specifically decarboxylation.

Step 3: Decarboxylation of Benzoic Acid.
Benzoic acid can be converted to benzene by heating it with soda lime (a mixture of sodium hydroxide \( \text{NaOH} \) and calcium oxide \( \text{CaO} \)) or with potassium hydroxide (\( \text{KOH} \)). The carboxyl group (\( \text{-COOH} \)) is removed as carbon dioxide (\( \text{CO}_2 \)), resulting in the formation of benzene.
The reaction can be written as:
\[ \text{C}_6\text{H}_5\text{COOH} \xrightarrow{\text{soda lime}} \text{C}_6\text{H}_6 + \text{CO}_2 \] This reaction is known as decarboxylation of benzoic acid.

Step 4: Conclusion.
To convert benzoic acid to benzene, a decarboxylation reaction using soda lime (NaOH + CaO) is carried out, which removes the carboxyl group as carbon dioxide, producing benzene as the product.