The heating of oxime of acetone in presence of conc. `H_(2)SO_(4)` to form N - methyl ethanamide is called

Options

A. Bayer - Villger rearrangement
B. Beckmann rearrangement
C. Wolf - rearrangement
D. Hoffmann reaction

Answer

To solve the question regarding the heating of oxime of acetone in the presence of concentrated sulfuric acid to form N-methyl ethanamide, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Oxime of Acetone**:
The oxime of acetone is formed by the reaction of acetone (CH3COCH3) with hydroxylamine (NH2OH). The structure of the oxime is CH3C(=N-OH)CH3.

2. **Reaction with Concentrated H2SO4**:
When the oxime is heated with concentrated sulfuric acid (H2SO4), it acts as a dehydrating agent. The concentrated acid protonates the hydroxyl group (–OH) of the oxime, leading to the formation of a better leaving group (water).

3. **Formation of Carbocation**:
The protonation of the oxime leads to the formation of a carbocation intermediate. The nitrogen atom can now rearrange, and the methyl group (–CH3) migrates to the positively charged carbon atom.

4. **Rearrangement**:
This migration of the methyl group results in the formation of an intermediate with a double bond between carbon and nitrogen, specifically CH3C(=N^+)CH3.

5. **Nucleophilic Attack**:
Water (from the environment or the reaction medium) can then attack the positively charged carbon, leading to the formation of a hydroxylamine derivative.

6. **Dehydration**:
A proton is lost from the hydroxylamine derivative, resulting in the formation of N-methyl ethanamide (CH3CONHCH3).

7. **Naming the Reaction**:
The overall process is known as the **Beckmann rearrangement**, which involves the rearrangement of oximes to amides upon treatment with acid.

### Final Answer:
The heating of oxime of acetone in the presence of concentrated H2SO4 to form N-methyl ethanamide is called the **Beckmann rearrangement**.

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