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How to synthesize p-nitrobenzoic acid and m-nitrobenzoic acid starting from benzene?

Mechanism of nitrification reaction: propose a synthetic pathway for synthesis of p-nitrobenzoic acid and m-nitrobenzoic acid if you are starting from benzene.

1 Answer
Apr 25, 2017


How about these?


I. The Nitration Mechanism

(a) Formation of nitronium ion

(i) The sulfuric acid protonates the nitric acid.


(ii) The protonated nitric acid loses a molecule of water to form nitronium ion

(b) Nitration of toluene

(i) Nitronium ion attacks the aromatic ring

Attack occurs at all possible positions to form resonance stabilized carbonation.


However, the cations formed by ortho and para attack are more stable than those formed by meta attack.

They put the positive charge next to the methyl group, which is electron-donating and adds to the stabilization.

(ii) The hydrogen sulfate ion formed in Step (a) (i) removes a proton from the intermediate, regenerating the aromatic ring and the sulfuric acid catalyst.

II. Synthesis of 4-Nitrobenzoic acid

(a) Friedel-Crafts alkylation of benzene

Benzene to toluene

(b) Nitration of toluene

Toluene to 4-nitrotoluene

(c). Oxidation of the alkyl side-chain

4-Nitrotoluene to 4-nitrobenzoic acid

III. Synthesis of 3-Nitrobenzoic acid

(a) Friedel-Crafts alkylation of benzene

Benzene to toluene

(b) Oxidation of toluene to benzoic acid


(c) Nitration of benzoic acid