Which of the following reaction leads to the formation of secondary alcohol?

Options

A. `CH_(3) MgBr+CH_(3)CHO`
B. Formic ester + 2 mol `C_(2) H_(5) MgBr`
C. Acetic ester + 2mol `C_(2) H_(5) Mg Br`
D. Both (1) & (2)

Answer

To determine which of the given reactions leads to the formation of a secondary alcohol, we need to analyze the structure of secondary alcohols and the reactions provided.

### Step-by-Step Solution:

1. **Understanding Secondary Alcohols**:
- A secondary alcohol has the general structure where the carbon bearing the hydroxyl group (–OH) is attached to one hydrogen atom and two alkyl groups (R1 and R2). This can be represented as R1R2C(OH)H.

2. **Analyzing the First Reaction**:
- The first reaction involves the nucleophile CH3MgBr (methyl magnesium bromide). The methyl group (CH3-) acts as a nucleophile and attacks a carbonyl compound (like CH3C(=O)H).
- The attack of CH3- on the carbonyl carbon leads to the formation of a compound with the structure CH3C(OH)(CH3) after protonation. This structure has one hydrogen and two methyl groups, confirming it is a secondary alcohol.

3. **Analyzing the Second Reaction**:
- The second reaction involves methyl formate (HCOOCH3) and two moles of C2H5MgBr (ethyl magnesium bromide).
- The ethyl group (C2H5-) acts as a nucleophile and attacks the carbonyl carbon of the methyl formate. After the reaction and subsequent protonation, the product will have the structure C2H5C(OH)(C2H5), which also confirms it is a secondary alcohol.

4. **Analyzing the Third Reaction**:
- The third reaction involves acetic ester (CH3C(=O)OCH3) and C2H5Br.
- The ethyl group (C2H5-) attacks the carbonyl carbon, but upon further analysis, the resulting structure will have two ethyl groups and no hydrogen on the carbon attached to the hydroxyl group, indicating it is a tertiary alcohol.

5. **Conclusion**:
- From the analysis, the first and second reactions lead to the formation of secondary alcohols, while the third reaction leads to a tertiary alcohol. Therefore, the correct options that lead to the formation of secondary alcohols are the first and second reactions.

### Final Answer:
The reactions that lead to the formation of secondary alcohols are the **first and second reactions**.