The major product formed on nitration of N, N - dimethylaniline with conc. `H_2SO_4,NHO_3` mixture is

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Answer

To determine the major product formed on the nitration of N,N-dimethylaniline with a concentrated H₂SO₄ and HNO₃ mixture, we can follow these steps:

### Step 1: Understand the Structure of N,N-Dimethylaniline
N,N-Dimethylaniline is an aniline derivative where the two hydrogen atoms on the nitrogen atom of aniline are replaced by methyl groups. The structure can be represented as:

```
CH3
|
CH3 - N - H
|
C6H5 (benzene ring)
```

### Step 2: Identify the Nitrating Mixture
The nitrating mixture consists of concentrated sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The role of this mixture is to generate the nitronium ion (NO₂⁺), which is the active electrophile in the nitration reaction.

### Step 3: Reaction Mechanism
In the presence of this strong acidic medium, the lone pair of electrons on the nitrogen atom of N,N-dimethylaniline can be protonated, leading to the formation of a positively charged species. This makes the nitrogen atom more electrophilic, which can withdraw electron density from the benzene ring.

### Step 4: Electrophilic Substitution
Due to the electron-withdrawing effect of the protonated nitrogen, the electron density at the ortho and para positions of the benzene ring decreases. Thus, the most favorable position for the electrophilic attack by the nitronium ion (NO₂⁺) will be the meta position, as it is less affected by the withdrawing effect of the nitrogen.

### Step 5: Formation of the Major Product
When the nitronium ion attacks the meta position of the benzene ring, the structure of the product becomes:

```
CH3
|
CH3 - N - H
|
C6H4 - NO2 (meta position)
```

Thus, the major product formed is **meta-nitro-N,N-dimethylaniline**.

### Final Answer
The major product formed on nitration of N,N-dimethylaniline with concentrated H₂SO₄ and HNO₃ mixture is **meta-nitro-N,N-dimethylaniline**.

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