Question

The structure of product C, formed by the following sequence of reactions is : 
\( CH_3COOH + SOCl_2 \to A \xrightarrow[\text{AlCl}_3]{\text{Benzene}} B \xrightarrow[\text{}^-OH]{\text{KCN}} C \) 

• A. A
• B. B
• C. C
• D. D

Hint:

Reaction of HCN/KCN with aldehydes or ketones always results in cyanohydrins, characterized by a \( -CN \) and an \( -OH \) group on the same carbon.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This is a multi-step synthesis involving functional group transformations and a Friedel-Crafts acylation followed by nucleophilic addition.
Step 2: Detailed Explanation:
1. Step 1 (Acid to Acid Chloride): Acetic acid reacts with thionyl chloride (\( SOCl_2 \)) to form acetyl chloride.
\[ CH_3COOH + SOCl_2 \to CH_3COCl \text{ (A)} + SO_2 + HCl \]
2. Step 2 (Friedel-Crafts Acylation): Acetyl chloride reacts with benzene in the presence of anhydrous \( AlCl_3 \) to form acetophenone.
\[ C_6H_6 + CH_3COCl \xrightarrow{AlCl_3} C_6H_5COCH_3 \text{ (B)} + HCl \]
3. Step 2 (Nucleophilic Addition): Acetophenone reacts with \( KCN \) in a basic medium (\( OH^- \)) to undergo nucleophilic addition to the carbonyl group, forming a cyanohydrin.
\[ C_6H_5COCH_3 + CN^- \to C_6H_5-C(OH)(CH_3)(CN) \text{ (C)} \]
The product is 2-hydroxy-2-phenylpropanenitrile.
Step 3: Final Answer:
The final product C is the cyanohydrin of acetophenone.