which of the following reaction is used for the prepara-tion of IsopropyI 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 reaction is used for the preparation of isopropyl alcohol (also known as 2-propanol), we need to analyze the given options and understand the reaction mechanisms involved.

### Step-by-Step Solution:

1. **Identify the Structure of Isopropyl Alcohol**:
- Isopropyl alcohol has the molecular formula \( \text{C}_3\text{H}_8\text{O} \) or more specifically, \( \text{CH}_3\text{CHOHCH}_3 \). It is a secondary alcohol.

2. **Examine the First Option**:
- The first option is \( \text{CH}_3\text{MgBr} \) (Methylmagnesium bromide), which is a Grignard reagent.
- When \( \text{CH}_3\text{MgBr} \) reacts with an aldehyde (like \( \text{CH}_3\text{CHO} \)), the nucleophilic carbon from the Grignard reagent attacks the electrophilic carbonyl carbon of the aldehyde.

3. **Reaction Mechanism**:
- The nucleophile \( \text{CH}_3^- \) attacks the carbonyl carbon of \( \text{CH}_3\text{CHO} \), forming an alkoxide intermediate.
- The reaction can be summarized as follows:
\[ \text{CH}_3\text{CHO} + \text{CH}_3\text{MgBr} \rightarrow \text{CH}_3\text{C(OH)(CH}_3)\text{O}^- + \text{MgBr}^+ \]
- The alkoxide then gets protonated by water to yield isopropyl alcohol:
\[ \text{CH}_3\text{C(OH)(CH}_3)\text{O}^- + \text{H}_2\text{O} \rightarrow \text{CH}_3\text{C(OH)(CH}_3) + \text{OH}^- \]

4. **Examine the Second Option**:
- The second option involves formic acid and \( \text{C}_2\text{H}_5\text{MgBr} \).
- This reaction does not yield isopropyl alcohol but rather leads to products that do not match the desired structure.

5. **Examine the Third Option**:
- The third option involves acetic ester and \( \text{C}_2\text{H}_5\text{MgBr} \).
- Similar to the second option, this reaction does not lead to isopropyl alcohol.

6. **Conclusion**:
- The only reaction that leads to the formation of isopropyl alcohol is the first option involving \( \text{CH}_3\text{MgBr} \) and an aldehyde.

### Final Answer:
The reaction used for the preparation of isopropyl alcohol is the reaction of \( \text{CH}_3\text{MgBr} \) with an aldehyde (specifically \( \text{CH}_3\text{CHO} \)).

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