question_answer 99)

  A colourless substance 'A'  is sparingly soluble in water and gives a water soluble compound ?B? on treating with mineral acid. On reacting with  and alcoholic potash 'A' produces an obnoxious smell due to the formation of compound 'C'. Reaction of 'A' with benzenesulphonyl chloride rives compound 'D' which is soluble in alkali. With  and HCl, 'A' forms compound 'E' which reacts with phenol in alkaline medium to give an orange dye 'F'. Identify compounds 'A' to 'F'.

Answer:

                  (i) Since compound A  is sparingly soluble in water and gives a water soluble substance (B), on treatment with mineral acid, therefore, compound (A) must be an amine. (ii) Since compound (A) with m.p. reacts with  to form a compound (E) which reacts with phenol in alkaline medium to give an orange dye (F), therefore, compound (A) must be a aromaticamine, i.e., aniline, . If A is aniline, then E must be benzenediazonium chloride and the orange dye (F) must be p-hydroxyazobenzene. (iii) Since compound (A), i.e., aniline reacts  in presence of alcoholic KOH to form a compound (C) having obnoxious smell, therefore, compound (C) must be benzene isonitrile. (iv) Since compound (A), i.e., aniline reacts with benzenesulphonyl chloride to form compound (D) which is soluble in alkali, therefore, (D) must be N-phenylbenzenesulphonamide. (vi) Since compound (A), i.e., aniline reacts with mineral acids (say HCl) to form water soluble en (B), therefore, (B) must be anilinium chloride