Advertisements
Advertisements
प्रश्न
Write a short note on coupling reactions.
उत्तर
The reaction involves the retention of diazo groups.
- Arenediazonium salts when treated with certain reactive aromatic compounds such as phenols or aromatic amines, give azo compounds.
- These have extended conjugated system of double bonds in which two aromatic rings are joined through the azo group \[\ce{- N = N -}\]. This reaction is called azo coupling.
- Azo compounds are brightly coloured and are used as dyes.
- This is an example of an electrophilic aromatic substitution reaction. Here, the electrophiles are positively charged diazonium ions.
- Substitution usually occurs para to the ring activating group.
e.g. Benzenediazonium chloride reacts with phenol in mild alkaline medium to give p-hydroxyazobenzene (orange dye).
- Azo coupling with β-naphthol in NaOH is used as a confirmatory test for primary aromatic amines.
- Benzenediazonium chloride reacts with aniline in mild alkaline medium to give p-aminoazobenzene (yellow dye.)
APPEARS IN
संबंधित प्रश्न
Answer the following
Complete the following reaction :
`"C"_6"H"_5"N"_2^+"Cl"^-` + C2H5OH →
The reaction in which diazonium salt is used
Draw resonance structures of aryl diazonium salts.
Write the use of aryl diazonium salts.
Explain the following reaction with a suitable example.
Gatterman reaction
Explain the following reaction with a suitable example.
Sandmeyer reaction
Which of the following reaction of diazonium salt involves retention of diazonium group?
When a quaternary ammonium hydroxide is strongly heated, an alkene and a tertiary amine are formed as the products. This reaction is known as ____________.
The reagent used in Gatterman reaction is ____________.
Benzenediazonium chloride on reaction with 'X' gives benzene. Identify X.
Which of the following reaction does NOT involve replacement of diazonium group?
Which of the following is a Gattermann reaction?
Replacement of diazo group by Cl using cuprous chloride is known as ____________.
Formation of p-hydroxyazobenzene from benzene diazonium chloride and phenol in mild alkaline medium is a ______.
Identify compound 'A' in the following reaction.
What is the product X obtained in the following reaction?
\[\ce{C6H5N2Cl ->[(i) HBF4, (ii) NaNO2/Cu][\Delta] X + N2 + NaBF4}\]
The reaction in which copper (I) salt is used to replace nitrogen in diazonium salt is called, ____________.
In the following reaction the reagent A is,
\[\ce{Ar - N^+_2 X^- ->[A] Ar - N^+_2 BF^-_4 ->[\Delta] Ar - F + BF3 + N2 ^}\]
Benzene diazonium chloride on reaction with ethanol forms ____________.
Fluorobenzene (C6H5F) can be synthesized in the laboratory ______.
Which of the following reactions is used to prepare aryl fluorides from diazonium salts and fluoroboric acid?
