Friedal craft's acetylation of benzene ring involves the uses of :

Options

A. `CH_3Cl`
B. `CH_3COCl`
C. `(CH_3CO)_2O`
D. either (b) or (c)

Explanation

To solve the question regarding Friedel-Crafts acetylation of the benzene ring, we need to identify the reagents involved in this reaction. Here’s a step-by-step breakdown of the process:

### Step 1: Understand the Acetyl Group
The acetyl group is represented as CH3CO. In Friedel-Crafts acetylation, we aim to introduce this acetyl group onto the benzene ring by replacing one hydrogen atom.

**Hint:** Remember that Friedel-Crafts reactions involve the substitution of hydrogen atoms on the benzene ring with acyl or alkyl groups.

### Step 2: Identify the Role of Lewis Acids
Friedel-Crafts reactions require a Lewis acid catalyst to generate the electrophile necessary for the reaction. Common Lewis acids used include aluminum chloride (AlCl3) and iron(III) chloride (FeCl3).

**Hint:** Lewis acids are electron-deficient species that can accept electron pairs, facilitating the formation of electrophiles.

### Step 3: Determine the Electrophile Formation
When we use a reagent like acetyl chloride (CH3COCl) in the presence of a Lewis acid (e.g., AlCl3), the Lewis acid interacts with the acetyl chloride to form the electrophile CH3CO+.

**Hint:** The electrophile is crucial for the electrophilic aromatic substitution mechanism, which is the basis of Friedel-Crafts reactions.

### Step 4: Reaction with Benzene
Once the electrophile CH3CO+ is generated, it can react with the benzene ring. The benzene ring will undergo electrophilic aromatic substitution, resulting in the formation of acetophenone (C6H5COCH3).

**Hint:** The product of Friedel-Crafts acetylation is typically an aromatic ketone.

### Step 5: Alternative Reagents
Another reagent that can be used in Friedel-Crafts acetylation is acetic anhydride (CH3CO)2O. This reagent also generates the acetyl electrophile (CH3CO+) upon reaction with a Lewis acid.

**Hint:** Both acetyl chloride and acetic anhydride can serve as sources of the acetyl group in this reaction.

### Conclusion
Based on the above steps, the reagents that can be used for Friedel-Crafts acetylation of the benzene ring are:
1. Acetyl chloride (CH3COCl)
2. Acetic anhydride ((CH3CO)2O)

Thus, the correct answer to the question is that Friedel-Crafts acetylation of the benzene ring involves the use of acetyl chloride and acetic anhydride along with a Lewis acid catalyst.

**Final Answer:** Acetyl chloride (CH3COCl) and acetic anhydride ((CH3CO)2O) with a Lewis acid catalyst (like AlCl3 or FeCl3).