Identify "Y" in the following reaction:

$ROH$

The correct answer is Option (3) → $ROH$

The given reaction involves a primary aliphatic amine (R–NH₂) reacting with nitrous acid (HNO₂).

Nitrous acid is usually generated in situ by the reaction:

NaNO₂ + HCl → HNO₂ + NaCl

Step 1: Formation of diazonium intermediate

The primary aliphatic amine reacts with nitrous acid to form an unstable aliphatic diazonium salt (R–N₂⁺Cl⁻).

R–NH₂ + HNO₂ → R–N₂⁺Cl⁻ + H₂O

Step 2: Decomposition

Aliphatic diazonium salts are very unstable and immediately decompose in water, producing an alcohol, nitrogen gas, and HCl.

R–N₂⁺Cl⁻ + H₂O → ROH + N₂ + HCl

Thus, the final product Y is an alcohol (ROH).

Option-wise Explanation

Option 1: R–CONH₂

Incorrect. This represents an amide, which is not formed in this reaction.

Option 2: R–COCl

Incorrect. This represents an acid chloride, not produced from this reaction.

Option 3: ROH

Correct. Primary aliphatic amines react with nitrous acid to form alcohols with evolution of nitrogen gas.

Option 4: R–NO₂

Incorrect. Nitro compounds are formed through nitration reactions, not through this reaction.