CBSE Class 12 · 2000 · All India Compartment · Compounds Containing NitrogenShort Answer

Show how p-aminoazobenzene can be obtained from aniline.

Answer: Diazotise part of the aniline, then couple C₆H₅N₂⁺Cl⁻ with aniline (mildly acidic) → p-H₂N–C₆H₄–N=N–C₆H₅.

Solution

Step 1:

C_{6} H_{5} N H_{2} + NaN O_{2} + 2HCl 273 - 278K C_{6} H_{5} N_{2}^{+} C l^{-}

Step 2 — coupling at aniline's para position:

C_{6} H_{5} N_{2}^{+} C l^{-} + C_{6} H_{5} N H_{2} \to C_{6} H_{5} - N = N - C_{6} H_{4} - N H_{2} (p) + HCl

(p-aminoazobenzene, a yellow dye).

CBSE Class 12 Board · 2000 · All India Compartment · Subjective