Question

When C₆H₅CHO reacts with the mixture of HNO₃ and H₂SO₄ at 273-283K, it gives

• A. o-Nitrobenzaldehyde
• B. m-Nitrobenzaldehyde
• C. p-Nitrobenzaldehyde
• D. Toluene
• E. Nitrobenzene

Hint:

The formyl group (-CHO) in benzaldehyde directs electrophilic substitution to the ortho position due to its electron-withdrawing nature.

Answer 1

The Correct Option is A

This reaction is known as the nitration of benzaldehyde. When benzaldehyde (C₆H₅CHO) is treated with a mixture of nitric acid (HNO₃) and sulfuric acid (H₂SO₄), a nitration reaction takes place. In this reaction, the nitronium ion (NO₂⁺) is generated, which then attacks the aromatic ring of benzaldehyde.

- o-Nitrobenzaldehyde (A): This is the correct product. In nitration reactions, the nitronium ion typically adds to the ortho position (relative to the formyl group) because the formyl group (-CHO) is an electron-withdrawing group that deactivates the ring, making the ortho position more reactive.

- m-Nitrobenzaldehyde (B): This is incorrect. The meta position is less reactive for nitration when an electron-withdrawing group like the formyl group is present.

- p-Nitrobenzaldehyde (C): This is also incorrect because the para position is generally less reactive than the ortho position in such cases.

- Toluene (D): Toluene is the methylated form of benzene and will not form in this reaction because no methyl group is involved.

- Nitrobenzene (E): Nitrobenzene would only form if the nitronium ion attacked the benzene ring directly without the presence of a formyl group.

Thus, the correct product is o-Nitrobenzaldehyde.