2 Nitroaniline

Synthesis

One method of preparing o-nitroaniline is via acetanilide. First, aniline acetylated with acetic anhydride.

C₆H₅NH₂ + (CH₃CO)₂O → C₆H₅NHC(O)CH₃ + CH₃CO₂H

In the next step, the acetanilide is nitrated:

C₆H₅NHC(O)CH₃ + HNO₃ → O₂NC₆H₄NHC(O)CH₃ + H₂O

Finally, the nitroacetanilide is hydrolyzed:

O₂NC₆H₄NHC(O)CH₃ + H₂O → O₂NC₆H₄NH₂ + CH₃CO₂H

Uses

2-Nitroaniline is the main precursor to phenylenediamines, which are converted to benzimidazoles, a family of heterocycles that are key components in pharmaceuticals.

Reactions

One of the factors contributing to the reactivity of 2-nitroaniline is the relative positioning of the nitro and amine groups and their activating/deactivating properties. The nitrogroup is an electron withdrawing group deactivating ortho and para positions. This leaves meta position with electron density and more likely to undergo substitution. Reinforcing this reactivity, the amino group activates ortho and para with respect to the amine. The net effect is that these sites, which are also meta to the nitro group undergo reactions.