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

Options

A. R-configuration
B. S-configuration
C. racemic mixture
D. meso-form

Explanation

To solve the problem regarding the Hoffmann rearrangement of primary amides with an optically active group having S-configuration, we can break down the process step-by-step.

### Step-by-Step Solution:

1. **Understanding the Starting Material**:
- We start with a primary amide of the form R-C(=O)-NH2, where R is an optically active group with S-configuration.

2. **Reagents Used**:
- The reagents for the Hoffmann rearrangement include a halogen (like Br2) and a strong base (like NaOH or KOH).

3. **Formation of N-haloamide**:
- The primary amide reacts with the halogen to form an N-haloamide. This involves the substitution of the hydrogen atom on the nitrogen with a halogen atom (Br in this case).
- The structure now is R-C(=O)-NBr.

4. **Base-Induced Rearrangement**:
- The presence of a strong base facilitates the rearrangement. The base abstracts a hydrogen atom from the nitrogen, generating a negative charge on nitrogen.
- The R group migrates from the nitrogen to the carbonyl carbon, leading to the formation of an isocyanate intermediate.

5. **Formation of the Product**:
- The isocyanate then hydrolyzes in the presence of water (from the base), leading to the formation of a carbamic acid intermediate.
- The carbamic acid can then decompose to form the final amine product and carbon dioxide (CO2).

6. **Retention of Configuration**:
- Importantly, during the migration of the R group, the stereochemistry of the original optically active group is retained. Since the original configuration was S, the product amine will also have S-configuration.

7. **Conclusion**:
- Therefore, the product amine resulting from the Hoffmann rearrangement of a primary amide with an optically active group having S-configuration will also have S-configuration.

### Final Answer:
The product amine has S-configuration.