Question

A primary amine, \[\ce{RNH2}\] can be reacted with \[\ce{CH3-X}\] to get secondary amine, \[\ce{R-NHCH3}\] but the only disadvantage is that 3° amine and quaternary ammonium salts are also obtained as side products. Can you suggest a method where \[\ce{RNH2}\] forms only 2° amine?

Answer 1

\[\ce{\underset{1° Amine}{R - NH2} + CHCl3 + 3KOH -> \underset{Alkyl isocyanide}{R - NC} ->[H2/Pd][(Reduction)] \underset{2° Amine}{R - NH - CH3}}\]

Carbylamine reaction is shown by 1° amine only which result in the replacement of two hydrogen atoms attached to N atom of –NH₂ group by one carbon atom to form isocyanide. On catalytic reduction, the isocyanide will give a secondary amine with one methyl group.