In the following reactions, which one is NOT correct?
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Answer
(3) [figure]
Solution
(1) Correct. Hypophosphorous acid reduces the diazonium salt to benzene:
C6H5N2+Cl- + H3PO2 + H2O C6H6 + N2 + H3PO3 + HCl
(2) Correct. Sandmeyer reaction: CuCN/KCN replaces the diazo group by –CN, giving benzonitrile.
(3) NOT correct. As per NCERT, ethanol is a mild reducing agent: it reduces the diazonium salt to benzene and is itself oxidised to ethanal; ethoxybenzene is not formed.
C6H5N2+Cl- + CH3CH2OH C6H6 + N2 + CH3CHO + HCl
(4) Correct. Iodide ion replaces the diazo group directly, giving iodobenzene.
Answer: (3)