Potassium pthalimide on reaction with (A) followed by hydrolysis forms isopentyl amine.
Compound (A) is

Options

A. `CH_(3)-CH_(3)underset(|)(C)Hoverset(Br)overset(|)(C)HCH_(2)`
B. `CH_(3)-underset(CH_(3))underset(|)overset(Br)overset(|)(C)-CH_(2)CH_(3)`
C. `Coverset(Br_(2))overset(|)(H_(2))-underset(CH_(3))underset(|)(C)H-CH_(2)-CH_(3)`
D. `CH_(3)-underset(CH_(3))underset(|)(C)H-CH_(2)CH_(2)Br`

Answer

To solve the question, we need to identify compound (A) that reacts with potassium phthalimide to ultimately yield isopentyl amine after hydrolysis. Here’s the step-by-step solution:

### Step 1: Understand the Reaction
Potassium phthalimide is used in the Gabriel synthesis, which is a method for synthesizing primary amines. In this reaction, potassium phthalimide reacts with an alkyl halide (compound A) to form an intermediate.

### Step 2: Identify the Product
The product of the reaction is isopentyl amine, which has the structure:
- Isopentyl amine: \( \text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_2\text{NH}_2 \)

### Step 3: Determine the Structure of Compound A
To determine compound (A), we need to identify the alkyl halide that would lead to the formation of isopentyl amine. The structure of isopentyl amine suggests that the corresponding alkyl halide should have the same carbon skeleton but with a halogen (Br, Cl, etc.) instead of the amine group.

### Step 4: Write the Alkyl Halide Structure
The isopentyl group can be represented as:
- Isopentyl group: \( \text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_2- \)

Thus, the alkyl halide (compound A) would be isopentyl bromide:
- Isopentyl bromide: \( \text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_2\text{Br} \)

### Step 5: Conclusion
Therefore, compound (A) is isopentyl bromide, which can be written as:
- \( \text{C}_5\text{H}_{11}\text{Br} \)

### Final Answer
Compound (A) is isopentyl bromide.

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