Reduction of azides: practice and mechanism
H₂ with Pd/C reduces the azide: N₂ escapes and the primary amine R–NH₂ remains on the same carbon.
Example
During catalytic hydrogenation N₂ is released and the azide group becomes a primary amino group. Together with the SN2 reaction with azide this is a clean route from haloalkane to primary amine (same chain length).
Mechanism step by step
- 1
The alkyl azide adsorbs on the palladium surface, where H₂ is split into H atoms.
- 2
Hydrogen is transferred to the N atom on carbon; N₂ is released and escapes.
- 3
The primary amine R–NH₂ remains; the configuration at carbon is retained.
Practice tasks
Which product forms, which reagent is needed? After each answer you see the explanation.
Which main product forms?
Typical mistakes
- The nitrogen is not lost completely. Only N₂ escapes; one N atom stays on the carbon as the NH₂ group.
- No hydrazine (N–N) remains. On reduction two N atoms leave as N₂ and a single N stays behind.
- The reduction gives an amine, not an imine. H₂ and Pd/C would reduce an imine further to the amine at once anyway.
Often confused with: SN2 with azide
Frequently asked questions
Which other reducing agents work?
LiAlH₄ or PPh₃/H₂O (Staudinger reduction). All give the primary amine.
Why go via the azide?
SN2 with azide followed by reduction cleanly gives a primary amine, without the overalkylation that occurs with NH₃.