`(A) overset(NH_3)to(B) underset(KOH//Br_2)overset(KOBr)to CH_3 - overset(CH_3)overset(|)(CH) -NH_2`.
structure of (A) is

Options

A.
B.
C.
D.

Answer

To determine the structure of compound (A) based on the provided reactions, let's break down the steps systematically.

### Step 1: Analyze the Final Product
The final product is given as CH₃-CH(CH₃)-NH₂. This indicates that the final compound has a branched structure with an amine functional group (NH₂) attached to a carbon that is also connected to two methyl groups (CH₃).

### Step 2: Identify the Preceding Reactions
The reaction sequence starts with compound (A) reacting with NH₃ (ammonia) to form an intermediate compound. This intermediate is then treated with KOH and Br₂, leading to the formation of the final product.

### Step 3: Determine the Intermediate Structure
The intermediate structure that leads to the final product can be deduced from the final product. Since we know that the final product has an amine group, it suggests that (A) must have a carbonyl group (C=O) that can react with ammonia to form an amide.

### Step 4: Propose the Structure of (A)
Given that the final product has a branched structure, we can propose that compound (A) is likely a carbonyl compound (specifically an acyl chloride) that can lead to the formation of the amide upon reaction with ammonia. The most plausible structure for (A) is:

**(A) - CH₃-CH(CH₃)-C(=O)Cl**

This structure has a carbonyl group attached to a carbon that is also bonded to two methyl groups, which aligns with the requirements for the reaction.

### Step 5: Confirm the Reaction Pathway
1. **First Reaction**: The acyl chloride reacts with ammonia (NH₃) to form an amide:
\[ CH₃-CH(CH₃)-C(=O)Cl + NH₃ \rightarrow CH₃-CH(CH₃)-C(=O)NH₂ + HCl \]

2. **Second Reaction**: The amide then undergoes a reaction with KOH and Br₂ (bromination) to yield the final product:
\[ CH₃-CH(CH₃)-C(=O)NH₂ + KOH + Br₂ \rightarrow CH₃-CH(CH₃)-NH₂ \]

### Conclusion
Thus, the structure of compound (A) is:
\[ \text{(A) - } CH₃-CH(CH₃)-C(=O)Cl \]