Which of the reacrion is used for preparing `2^(@)` alcohol ?

Options

A. `CH_(3) MgX+HCOOC_(2) H_(5)`
B. `HCOOC_(2)H_(5)+2 " Mol of " CH_(3) MgX`
C. `CH_(3)MgX+HCHO`
D. `CH_(3) COCH_(3) +CH_(3) MgX`

Answer

To determine which reaction is used for preparing a 2° alcohol, we can analyze the reactions provided in the question.

### Step-by-Step Solution:

1. **Understanding the Structure of 2° Alcohol**:
- A 2° alcohol has the general formula where the carbon atom attached to the hydroxyl group (–OH) is connected to one hydrogen atom and two alkyl groups (R1 and R2).

2. **Analyzing the First Reaction**:
- The first reaction involves a Grignard reagent (CH3MgX) reacting with an ether (HC=O-O-C2H5).
- The Grignard reagent acts as a nucleophile and attacks the carbonyl carbon of the ether, leading to the formation of an aldehyde.
- This reaction does not yield a 2° alcohol; instead, it leads to the formation of an aldehyde.

3. **Analyzing the Second Reaction**:
- The second reaction also involves the ether (HC=O-O-C2H5) and two moles of CH3MgX.
- The first mole of CH3MgX attacks the carbonyl carbon, forming an intermediate with a negative charge on the oxygen.
- The ether part (O-C2H5) acts as a leaving group, resulting in the formation of a carbonyl compound (aldehyde).
- The second mole of CH3MgX then attacks this carbonyl carbon, leading to the formation of a 2° alcohol (R1 = CH3, R2 = CH3).

4. **Analyzing the Third Reaction**:
- The third reaction involves formaldehyde (HCHO) reacting with CH3-.
- The nucleophile attacks the carbonyl carbon, resulting in the formation of a 1° alcohol, which does not meet our requirement for a 2° alcohol.

5. **Analyzing the Fourth Reaction**:
- The fourth reaction involves acetone (CH3C=OCH3) reacting with a Grignard reagent.
- The nucleophile attacks the carbonyl carbon, leading to the formation of a 3° alcohol, which is also not the desired product.

6. **Conclusion**:
- Based on the analysis, the second reaction is the correct one for preparing a 2° alcohol.

### Final Answer:
The reaction used for preparing a 2° alcohol is the second option involving two moles of Grignard reagent reacting with an ether.