Illustrate the following reactions with an example in each case: Coupling reaction Balz-Schiemann…
Illustrate the following reactions with an example in each case:
(a)
Coupling reaction
(b)
Balz-Schiemann reaction
Answer
Answer (a)
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Coupling reaction: Benzenediazonium chloride reacts with phenol in mild alkaline medium to form p-hydroxyazobenzene:
$\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{C}_6\text{H}_5\text{OH} \xrightarrow{\text{OH}^-,\ 273-278\text{ K}} p-\text{HOC}_6\text{H}_4-\text{N}=\text{N}-\text{C}_6\text{H}_5 + \text{HCl}$
Answer (b)
AIWritten by AI (gemini) - it can contain mistakes.
Balz-Schiemann reaction: Benzenediazonium chloride reacts with fluoroboric acid ($\text{HBF}_4$) to precipitate benzenediazonium fluoroborate, which upon heating yields fluorobenzene:
$\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{HBF}_4 \rightarrow \text{C}_6\text{H}_5\text{N}_2^+\text{BF}_4^- \xrightarrow{\Delta} \text{C}_6\text{H}_5\text{F} + \text{BF}_3 + \text{N}_2$
From ISC 2027 Specimen Chemistry Paper 1, question 9(i).