Compound (A) racts with `SOCl_2` to give compound (B). The compound (B) reacts with Mg metal give Grignard's reagent , which is treated with acetone and product is hydrolysed to give 2-methyl-2-butanol . What is (A)?

Options

A. `CH_3CH_2OH`
B. `CH_3CH_2CH_2OH`
C. `CH_3OH`
D. `CH_3COOH`

Explanation

To determine the compound (A) that reacts with SOCl₂ to yield compound (B), which subsequently forms a Grignard reagent and leads to the production of 2-methyl-2-butanol, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Final Product**: The final product given is 2-methyl-2-butanol. This is a tertiary alcohol, which means it has a carbon atom bonded to three other carbon atoms.

2. **Understand the Grignard Reaction**: The Grignard reagent is formed by the reaction of an alkyl halide (compound B) with magnesium metal. The Grignard reagent then reacts with acetone to produce the tertiary alcohol.

3. **Determine the Structure of Compound B**: Since the final product is 2-methyl-2-butanol, we can deduce that the Grignard reagent must have come from an alkyl halide that, when reacted with acetone, would yield this product. The alkyl halide should be ethyl chloride (C2H5Cl), which is the result of the reaction of compound A with SOCl₂.

4. **Identify the Reactant for SOCl₂**: To produce ethyl chloride (C2H5Cl) from SOCl₂, the starting compound (A) must be an alcohol. The alcohol that would yield ethyl chloride upon reaction with SOCl₂ is ethanol (C2H5OH).

5. **Confirm the Reaction Sequence**:
- Ethanol (C2H5OH) reacts with SOCl₂ to produce ethyl chloride (C2H5Cl).
- Ethyl chloride then reacts with magnesium to form the Grignard reagent (C2H5MgCl).
- The Grignard reagent reacts with acetone (CH3COCH3) to yield 2-methyl-2-butanol after hydrolysis.

6. **Conclusion**: Therefore, the compound (A) is ethanol.

### Final Answer:
**Compound (A) is ethanol (C2H5OH).**