Question

The major product formed in the following reaction is : 

• A. A
• B. B
• C. C
• D. D

Hint:

$SOCl_2$ and an alcohol convert acids to esters while simultaneously converting free amines to their hydrochloride salts.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The reaction of a carboxylic acid with thionyl chloride ($SOCl_2$) in the presence of an alcohol ($CH_3OH$) is a standard method for esterification. If an amine group is present, it will react with the HCl byproduct to form an ammonium salt.
Step 2: Detailed Explanation:
The reactant is a derivative of tryptophan (an amino acid containing an indole ring, an amine group, and a carboxylic acid group).
1. $SOCl_2$ reacts with the $-COOH$ group to form the highly reactive acid chloride ($R-COCl$).
2. The acid chloride then reacts with methanol ($CH_3OH$) to form the methyl ester ($R-COOCH_3$).
3. During these steps, hydrogen chloride ($HCl$) is produced as a byproduct.
4. The basic amine group ($-NH_2$) reacts with $HCl$ to form the hydrochloride salt ($-NH_2 \cdot HCl$ or $-NH_3^+Cl^-$).
The indole nitrogen is less basic due to delocalization and typically does not form a stable salt under these mild conditions compared to the aliphatic amine.
Step 3: Final Answer:
The major product is the methyl ester of the amino acid in its hydrochloride salt form.