The nitrosation of N, N-dimethylaniline takes place through the attack of electrophile

Options

A. nitronium ion
B. protonated nitrous acid
C. nitrous acid
D. nitrosonium ion

Answer

To solve the question regarding the nitrosation of N,N-dimethylaniline and the electrophile responsible for the reaction, we can follow these steps:

### Step 1: Understand the Structure of N,N-Dimethylaniline
N,N-dimethylaniline is an aromatic amine where two methyl groups are attached to the nitrogen atom of the aniline. The structure can be represented as:
- A benzene ring (C6H5) with an NH group (amine) where the nitrogen is bonded to two methyl groups (–N(CH3)2).

### Step 2: Identify the Reaction Conditions
The nitrosation reaction typically involves the use of sodium nitrite (NaNO2) and a strong acid, such as hydrochloric acid (HCl). Under these conditions, nitrous acid (HNO2) is generated.

### Step 3: Determine the Electrophile
In the nitrosation process, the electrophile that attacks the aromatic ring is crucial. The electrophiles that can be formed from nitrous acid include:
- Nitronium ion (NO2+)
- Protonated nitrous acid (HNO2+)
- Nitrous acid (HNO2)
- Nitrosonium ion (NO+)

Among these, the nitrosonium ion (NO+) is the most relevant electrophile for the nitrosation of aromatic amines.

### Step 4: Mechanism of Electrophilic Attack
1. **Formation of the Electrophile**: When NaNO2 reacts with HCl, it generates nitrous acid, which can be protonated to form the nitrosonium ion (NO+).
2. **Electrophilic Attack**: The nitrosonium ion (NO+) is electron-deficient and can attack the electron-rich aromatic ring of N,N-dimethylaniline. The nitrogen atom of the amine group donates electron density to the ring, enhancing its reactivity towards electrophiles.
3. **Formation of the Nitroso Derivative**: The attack occurs primarily at the para position relative to the amine group, leading to the formation of the nitroso derivative of N,N-dimethylaniline.

### Conclusion
The electrophile responsible for the nitrosation of N,N-dimethylaniline is the nitrosonium ion (NO+). Therefore, the answer to the question is option D.

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