When benzene is heated with acetic anhydride in presence of anhydrous `AlCl_(3)`, is product formed is-

Options

A. Benzoin acid
B. Acetophenone
C. Ethylphenyl ketone
D. Benzophenone

Answer

To solve the question of what product is formed when benzene is heated with acetic anhydride in the presence of anhydrous AlCl₃, we can follow these steps:

### Step 1: Understand the Reactants
- **Benzene (C₆H₆)**: A simple aromatic hydrocarbon.
- **Acetic Anhydride (C₄H₆O₃)**: A reagent that can introduce an acyl group into an aromatic compound.
- **Anhydrous Aluminium Chloride (AlCl₃)**: A Lewis acid that acts as a catalyst in electrophilic aromatic substitution reactions.

### Step 2: Electrophile Formation
- When acetic anhydride is mixed with AlCl₃, it generates an acylium ion. The reaction can be represented as:
\[ \text{CH}_3\text{CO} - \text{O} - \text{C(O)CH}_3 + \text{AlCl}_3 \rightarrow \text{CH}_3\text{C}^+=\text{O} + \text{AlCl}_4^- \]
- The acylium ion (CH₃C^+=O) acts as the electrophile in the reaction.

### Step 3: Electrophilic Attack on Benzene
- The acylium ion attacks the benzene ring, leading to the formation of a carbocation intermediate:
\[ \text{C}_6\text{H}_5 + \text{CH}_3\text{C}^+=\text{O} \rightarrow \text{C}_6\text{H}_5\text{C}^+=\text{O}\text{CH}_3 \]
- This results in a resonance-stabilized carbocation.

### Step 4: Deprotonation
- The carbocation loses a proton (H⁺) to restore aromaticity:
\[ \text{C}_6\text{H}_5\text{C}^+=\text{O}\text{CH}_3 \rightarrow \text{C}_6\text{H}_5\text{C(O)CH}_3 + \text{H}^+ \]
- The product formed is **acetophenone (C₈H₈O)**.

### Step 5: Summary of Products
- The final product of the reaction is acetophenone, along with by-products such as HCl and AlCl₃.

### Final Answer
The product formed when benzene is heated with acetic anhydride in the presence of anhydrous AlCl₃ is **acetophenone (C₈H₈O)**.

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