Acetophenone is prepared by

Options

A. heating benzoyl chloride with dimethyl cadmium
B. treating benzoyl chloride with excess of `CH_3 MgI`followed by hydrolysis
C. treating benzene with excess acetyl chloride in presence of anhydrous `AICI_3`
D. reducing benzoyl chloride with `H_2` in the presence of Lindlar catalyst

Answer

To prepare acetophenone, we can utilize several methods. Here’s a step-by-step breakdown of the options provided in the question:

### Step 1: Analyzing the Options
We have four options to consider for the preparation of acetophenone:
1. Heating benzoic chloride with dimethyl cadmium.
2. Treating benzoic chloride with excess CH₃MgI followed by hydrolysis.
3. Treating benzene with excess acetyl chloride in the presence of anhydrous AlCl₃.
4. Reducing benzoyl chloride with H₂ in the presence of Lindlar catalyst.

### Step 2: Evaluating Each Option

**Option 1: Heating benzoic chloride with dimethyl cadmium**
- This reaction involves the formation of an organocadmium compound.
- The reaction can be represented as:
\[ \text{C}_6\text{H}_5\text{COCl} + \text{(CH}_3\text{)}_2\text{Cd} \rightarrow \text{C}_6\text{H}_5\text{COCH}_3 + \text{CdCl}_2 \]
- This results in the formation of acetophenone (C₆H₅COCH₃).
- **Conclusion**: This option is correct.

**Option 2: Treating benzoic chloride with excess CH₃MgI followed by hydrolysis**
- This reaction involves a Grignard reagent, CH₃MgI, which reacts with benzoic chloride.
- The initial reaction forms a tertiary alcohol after hydrolysis:
\[ \text{C}_6\text{H}_5\text{COCl} + \text{CH}_3\text{MgI} \rightarrow \text{C}_6\text{H}_5\text{C(OH)(CH}_3\text{)}_2 \]
- This does not yield acetophenone but rather a tertiary alcohol.
- **Conclusion**: This option is incorrect.

**Option 3: Treating benzene with excess acetyl chloride in the presence of anhydrous AlCl₃**
- This is a Friedel-Crafts acylation reaction.
- The reaction can be represented as:
\[ \text{C}_6\text{H}_6 + \text{CH}_3\text{COCl} \xrightarrow{\text{AlCl}_3} \text{C}_6\text{H}_5\text{COCH}_3 \]
- This results in the formation of acetophenone.
- **Conclusion**: This option is correct.

**Option 4: Reducing benzoyl chloride with H₂ in the presence of Lindlar catalyst**
- This reaction typically reduces benzoyl chloride to an aldehyde (benzaldehyde) rather than to acetophenone.
- The reaction can be represented as:
\[ \text{C}_6\text{H}_5\text{COCl} + \text{H}_2 \xrightarrow{\text{Lindlar catalyst}} \text{C}_6\text{H}_5\text{CHO} \]
- **Conclusion**: This option is incorrect.

### Final Conclusion
Based on the analysis, the correct methods for preparing acetophenone are:
- **Option 1**: Heating benzoic chloride with dimethyl cadmium.
- **Option 3**: Treating benzene with excess acetyl chloride in the presence of anhydrous AlCl₃.