Ch 13 covers amines — derivatives of ammonia with one or more alkyl/aryl groups. Topics include classification (1°, 2°, 3°), preparation, basicity, chemical reactions, and diazonium salt chemistry.
Primary (R-NH₂), secondary (R₂NH), tertiary (R₃N). Basicity depends on electron availability on N. In aqueous solution: 2° > 1° > 3° (steric + solvation effects). Alkylamines > NH₃ > aniline. Aniline is weakly basic because the lone pair delocalises into the benzene ring.
Carbylamine test: only 1° amines give isocyanide (foul smell) with CHCl₃ + KOH. Hofmann bromamide: RCONH₂ → RNH₂ (one C less). Diazotisation: ArNH₂ + NaNO₂ + HCl (0-5°C) → ArN₂⁺Cl⁻. Coupling: ArN₂⁺ + phenol/aniline → azo dyes (coloured). Sandmeyer reaction: ArN₂⁺ → ArCl, ArBr, ArCN.
Download: https://ncert.nic.in/textbook/pdf/lech204.pdf | Part II: https://ncert.nic.in/textbook/pdf/lech2ps.zip
In aniline, the nitrogen lone pair delocalises into the benzene ring (resonance), making it less available for protonation. In cyclohexylamine, no such resonance is possible — the lone pair is fully available. Hence aniline (pKb ≈ 9.4) is much weaker base than cyclohexylamine (pKb ≈ 3.4).
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