Rearrangement of an oxime to an amide in the presence of a strong acid is called

Options

A. Curtius rearrangement
B. Frie's rearrangement
C. Beckmann's rearrangement
D. Aldol condensation

Answer

To solve the question regarding the rearrangement of an oxime to an amide in the presence of a strong acid, we will go through the following steps:

### Step-by-Step Solution:

1. **Understanding the Reactants**:
- An oxime is a compound that contains the functional group R1R2C=NOH. It is derived from the reaction of an aldehyde or ketone with hydroxylamine.
- The strong acid (H+) will facilitate the rearrangement process.

2. **Protonation of the Oxime**:
- When an oxime is treated with a strong acid (H+), the hydroxyl group (–OH) of the oxime gets protonated. This increases the electrophilicity of the carbon atom attached to the nitrogen.
- The reaction can be represented as:
\[ R1R2C=NOH \xrightarrow{H^+} R1R2C=N^+(OH_2) \]

3. **Formation of a Carbocation**:
- The protonation leads to the formation of a positively charged intermediate where the nitrogen is now bonded to a water molecule (–OH2+).
- The nitrogen can donate its lone pair to the carbon, resulting in a positive charge on the carbon atom.

4. **Loss of Water**:
- The positively charged intermediate can then lose a water molecule (–H2O), leading to the formation of an iminium ion (R1R2C=NH+).
- This step can be represented as:
\[ R1R2C=N^+(OH_2) \rightarrow R1R2C=NH + H2O \]

5. **Rearrangement to Amide**:
- The iminium ion can rearrange to form an amide. The nitrogen atom can attack the carbonyl carbon, leading to the formation of an amide (R1R2C(=O)NH2).
- This step can be summarized as:
\[ R1R2C=NH \rightarrow R1R2C(=O)NH2 \]

6. **Conclusion**:
- The overall process is known as the **Beckmann Rearrangement**, which specifically refers to the conversion of an oxime into an amide in the presence of a strong acid.

### Final Answer:
The rearrangement of an oxime to an amide in the presence of a strong acid is called **Beckmann Rearrangement**.