Question

10. Treatment of aromatic amine
with nitrous acid in presence of
acid to form diazonium salt is
known as
1)Coupling reaction
2)Dark reaction
3)Etard reaction
4)Sandymer's reaction​

Answer 1

Treatment of aromatic amine (aniline) with nitrous radical in acidic medium gives a diazonium salt. This reaction is Sandmeyer's reaction (option 4).

• Sandmeyer's reaction usually involves the replacement of the amino group of an aromatic molecule such as benzene with a halide from the copper-halide compound present in the medium.
• The aromatic amine first undergoes electrophilic attack by nitrosonium ion obtained from sodium nitrate. This forms a diazo radical which releases nitrogen gas and on reaction with copper halide gives a diazonium salt.
• Coupling reaction is a chemical reaction involving diazonium salts to form azo dyes. Etard reaction is a method of preparing aldehydes. Dark reaction occurs in plants during photosynthesis.

Answer 2

CORRECT OPTION IS 1)

1) COUPLING REACTION.

Explanation:

• In coupling reaction two species couple together. For example in Mc murry coupling reaction, in it a double bond is formed between carbonyl groups of two species.
• In diazotization reaction, amine reacts with nitrous acid at 0-5 °C to form diazonium salt.
• The diazotization reaction is a type of coupling reaction as it forms a azo dye when two aryl groups join together.
• In diazotization $N_{2} ^{+} Cl^{-}$ is formed which attacks the other aryl ring to form a azo compound through coupling reaction.
• Therefore, option (1) is correct.