Question

In the Hofmann rearrangement of primary amides having optically active group with S-configuration, the product amine has

• A. R-configuration
• B. S-configuration
• C. Racemic mixture
• D. Meso form
• E. Achiral nature

Hint:

Hofmann rearrangement is a retention reaction. Always remember: configuration of migrating group does not change.

Answer 1

The Correct Option is B

Concept: The Hofmann rearrangement involves migration of an alkyl group from carbonyl carbon to nitrogen. This migration is intramolecular and stereospecific, meaning the configuration of the migrating group is retained.

Step 1: {Understand the reaction mechanism.}
Primary amide undergoes Hofmann rearrangement to give a primary amine with one less carbon: \[ RCONH_2 \rightarrow RNH_2 \] The \( R \)-group migrates from carbon to nitrogen without breaking its configuration.

Step 2: {Apply stereochemical rule.}
Since migration occurs without inversion: \[ \text{Configuration is retained} \]

Step 3: {Determine configuration of product.}
Given: \[ \text{Reactant has S-configuration} \] After rearrangement: \[ \text{Product also has S-configuration} \]

Step 4: {Final answer.}
\[ \boxed{\text{(B) S-configuration}} \]