The following diagram show the different possibilities of stabilization of the positive charge in the transition state.

Note that the ortho and para-attack have one more resonance form that can contribute significantly if the attached

X-atom is electron-donating (e.g. has a lone pair).

Here are a few examples of how the first substituent can direct the incoming electrophil into a specific position.

75-84%


81-85%












Partial speed of nitration (in reference to benzene)




Directing effects

ortho/para directing, activating: R(alkyl), -NH₂, -NR₂, -NHCOR, -OH, -OR, OCOR

ortho/para directing, deactivating: halogene

meta directing, deactivating: -NO₂, -SO₃H, -CCl₃, -CF₃, -COOH, -COOR, -CHO, -COR


Nitration reagent

1. diluted or concentrated HNO₃
2. Mixture of concentrated HNO₃ and H₂SO₄
3. Nitronium salts (NO₂⁺BF_4^-, NO₂⁺PF₆^-)
4. N₂O₅ in CCl₄ (NO₂⁺ + NO₃^-)



Planning of a synthesis:



Question: How do you obtain the meta-nitroaniline?