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← IIT-JEE 2011 · Paper 2
ChemistrySingle correct+3 / -1Question 6 of 60

IIT-JEE 2011 · Paper 2, Chemistry question 6

Amongst the compounds given, the one that would form a brilliant colored dye on treatment with NaNOX2\ce{NaNO2} in dil. HCl followed by addition to an alkaline solution of β-naphthol is

Choose one option
Answer and worked solution

Official answer: C

Azo dyes need an aryl diazonium salt, which only a primary aromatic amine gives with NaNOX2\ce{NaNO2}/HCl at 0-5 °C. The diazonium ion then couples with β-naphthoxide.

  • (A) is a tertiary amine and (B) a secondary amine (gives an N-nitrosamine).
  • (D) benzylamine is a primary aliphatic amine; its diazonium salt decomposes at once.
  • (C) p-toluidine is a primary aromatic amine and gives a red-orange azo dye.

(C)