Beckmann rearrangement.

Explanation

### Step-by-Step Solution for Beckmann Rearrangement

**Step 1: Formation of Oxime**
- The Beckmann rearrangement begins with the formation of an oxime from a ketone or aldehyde. The reaction involves the condensation of a carbonyl compound (R1C=O) with hydroxylamine (NH2OH) to form an oxime (R1C=N-OH).

**Step 2: Protonation of the Oxime**
- In an acidic medium, the oxime is protonated. The nitrogen atom in the oxime has a lone pair of electrons, which can be protonated to form a positively charged oxime (R1C=N^+(OH2)).

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