Preparation Equations

$\text{RCONH}_2 + \text{Br}_2 + 4\text{NaOH} \rightarrow \text{RNH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O} \quad \text{(Hoffmann; –1 carbon)}$

$\text{RNH}_2 + \text{CHCl}_3 + 3\text{KOH} \rightarrow \text{R-NC} + 3\text{KCl} + 3\text{H}_2\text{O} \quad \text{(Carbylamine test; 1° only)}$

$\text{ArNH}_2 + \text{NaNO}_2 + 2\text{HCl} \xrightarrow{0\text{–}5°C} \text{ArN}_2^+\text{Cl}^- + \text{NaCl} + 2\text{H}_2\text{O} \quad \text{(Diazotization)}$

$\text{ArN}_2^+\text{Cl}^- + \text{HBF}_4 \rightarrow \text{ArN}_2^+\text{BF}_4^- \xrightarrow{\Delta} \text{ArF} + \text{BF}_3 + \text{N}_2 \quad \text{(Schiemann; only ArF route)}$

pKb Values (Approximate, Aqueous)

$pK_b: (CH_3)_2NH \approx 3.27 < CH_3NH_2 \approx 3.38 < (CH_3)_3N \approx 4.19 < NH_3 \approx 4.74 \ll C_6H_5NH_2 \approx 9.38$ (Lower pKb = stronger base)

Basicity Equilibrium

$\text{RNH}_2 + \text{H}_2\text{O} \rightleftharpoons \text{RNH}_3^+ + \text{OH}^- \quad K_b = \frac{[\text{RNH}_3^+][\text{OH}^-]}{[\text{RNH}_2]}$

Diazonium Reactions Summary

• $ArN_{2}^{+}$ + CuCl/HCl → ArCl (Sandmeyer)
• $ArN_{2}^{+}$ + CuBr/HBr → ArBr (Sandmeyer)
• $ArN_{2}^{+}$ + CuCN/KCN → ArCN (Sandmeyer)
• $ArN_{2}^{+}$ + Cu°/HCl → ArCl (Gattermann)
• $ArN_{2}^{+}$ + $HBF_{4}$ →$\Delta$ ArF (Schiemann)
• $ArN_{2}^{+}$ + $H_{3}PO_{2}$ → ArH (Deamination)

Key SMILES

• Aniline: Nc1ccccc1
• Benzenediazonium chloride: [N+]#Nc1ccccc1.[Cl-]
• Fluorobenzene: Fc1ccccc1
• p-Hydroxyazobenzene: Oc1ccc(/N=N/c2ccccc2)cc1