Question

An organic compound (A) on catalytic hydrogenation with \( \mathrm{H_2/Pt} \) gives tetralin, and on oxidation with hot alkaline \( \mathrm{KMnO_4} \) followed by acidification gives phthalic acid. Identify compound (A).

• A. Option a
• B. Option b
• C. Option c
• D. Option d

Hint:

Fused aromatic hydrocarbons like naphthalene: \begin{itemize} \item Give phthalic acid on strong oxidation \item Give tetralin on partial catalytic hydrogenation \end{itemize} These reactions are commonly used for identification.

Answer 1

The Correct Option is A

To identify the organic compound (A), we need to consider the reactions it undergoes: 

1. Catalytic Hydrogenation: Compound (A) reacts with \( \mathrm{H_2/Pt} \) to give tetralin. Tetralin is also known as tetrahydronaphthalene, which has a fully saturated cyclohexane ring fused to a benzene ring.
2. Oxidation Reaction: Compound (A) on oxidation with hot alkaline \( \mathrm{KMnO_4} \) followed by acidification yields phthalic acid, which is a benzene ring with two adjacent carboxylic acid groups.

From the information given, compound (A) needs to have a naphthalene structure with a partial unsaturation that hydrogenates to form tetralin and oxidizes to form phthalic acid. This corresponds to 1,2-dihydronaphthalene.

Hence, option a is correct. Compound (A) is 1,2-dihydronaphthalene.