Test: Method of Preparation of Diazonium Salts (March 1) - NEET MCQ

p-amino azo benzene is obtained by treating diazonium chloride with aniline. The reactions are specifically acid catalyzed and involve pre‐equilibrium formation of amine and diazonium salt followed by rate‐limiting attack of the diazonium ion at a C‐atom (C‐coupling) to give the corresponding amino azo compounds.

The correct answer is option A

Hypophosphorous acid when treated with diazonium salts is reduced to arenes.
ArN₂Cl + H₃PO₂ + H₂O ⟶ ArH + N₂ + H₃PO₃ +HCl

The correct answer is Option A.
Aromatic Primary amine will form the most stable diazonium salt because it releases water when it reacts with nitronium ions. If aliphatic primary amine reacts with nitrosonium ion it Also releases water but in this case water reacts with alkyl diazonium salt and it forms alcohol while benzene diazonium salt does not react with water at this temperature.

Replacement of diazo group by other group is helpful in preparing compounds which are not/ cannot be produced by direct nucleophilic substitution reaction.This is because,to substitute in aromatic ring, the nucleophilic should leave the partial double bond, which is more energy required than in haloalkane.

This reaction is called Gattermann reaction. In this reaction, Cl, Br and CN can be introduced into the benzene ring by simply treating diazonium salts with HCl, HBr, KCN. Respectively in presnce of copper powder instead of using Cu(I) salts.

C₆H₅NH₂ reacts with HNO₂ to forms diazonium salts, the reaction are as follows,
C₆H₅NH₂ + HNO₂ ------> C₆H₅OH + H₂O + N₂

The correct answer is option D
By treating diazonium salts with cuprous cyanide or KCN and copper powder it forms aryl nitrile. Illustrative is the preparation of benzonitrile using the reagent cuprous cyanide:

The correct answer is option A
When C₂H₅OH (ethanol) is treated with C₆H₅N₂Cl it forms benzene.
Some mild reducing agents like C₂H₅OH themselves get oxidized to ethanol after reducing C₆H₅N₂Cl to benzene.

The process of conversion of primary aromatic amines into its diazonium salt is called diazotization. Diazonium salts are important synthetic intermediates that can undergo coupling reactions to form azo dyes and electrophilic substitution reactions to introduce functional groups.