`R-CNoverset(H_(3)O^(+))underset("Complete hydrolysis")to Xoverset(NH_(3))underset(Delta)toYoverset((i)Br_(2)+KOH)underset((ii)H_(3)O^(+))toZ`
Identify Z.

Options

A. `R-NH_(2)`
B. `R-CH_2NH_2`
C. `R-overset(O)overset(||)C-NH_2`
D. R-CN

Answer

To solve the question step-by-step, we will analyze the reactions mentioned in the problem and identify the final compound Z.

### Step 1: Complete Hydrolysis of Alkyl Cyanide (R-CN)
- When an alkyl cyanide (R-CN) undergoes complete hydrolysis in the presence of hydronium ions (H₃O⁺), it converts to a carboxylic acid.
- The reaction can be represented as:
\[ R-CN + H_3O^+ \rightarrow R-COOH \quad (\text{Carboxylic Acid}) \]
- **Hint**: Remember that hydrolysis of nitriles (cyanides) leads to carboxylic acids.

### Step 2: Reaction of Carboxylic Acid with Ammonia
- The carboxylic acid (R-COOH) formed in the previous step reacts with ammonia (NH₃) upon heating.
- This reaction results in the formation of an amide (R-C(=O)NH₂):
\[ R-COOH + NH_3 \xrightarrow{\Delta} R-C(=O)NH_2 \quad (\text{Amide}) \]
- **Hint**: Heating carboxylic acids with ammonia typically yields amides.

### Step 3: Treatment of Amide with Bromine and KOH
- The amide (R-C(=O)NH₂) is then treated with bromine (Br₂) and potassium hydroxide (KOH).
- This reaction is known as the Hofmann degradation or Hofmann bromamide reaction, which converts the amide to a primary amine (R-NH₂):
\[ R-C(=O)NH_2 + Br_2 + KOH \rightarrow R-NH_2 + K_2CO_3 + KBr + H_2O \]
- **Hint**: The Hofmann reaction is crucial for converting amides to amines.

### Step 4: Acidification
- After the reaction with Br₂ and KOH, the product is typically acidified (with H₃O⁺), but this step does not change the primary amine formed.
- Thus, the final product remains:
\[ Z = R-NH_2 \quad (\text{Primary Amine}) \]
- **Hint**: Acidification is often used to neutralize the reaction mixture but does not alter the primary amine.

### Conclusion
- The final compound Z, after all the reactions, is identified as R-NH₂, which is a primary amine.

### Final Answer
Z = R-NH₂