# Why is o-nitroaniline not more basic than aniline? [closed]

We know from SIR effect (Steric Inhibition of Resonance) that in o-nitroaniline, the nitrogen's p-orbitals will change their plane, causing the conjugation/resonance of its lone pairs to stop. So, the only effect acting on it now is −I effect from the $$\ce{NO2}$$ group.

Comparing with just aniline, the $$\ce{NH2}$$ lone pairs are in constant resonance with the benzene ring making them unavailable for donation. Thus, aniline should be less basic than o-nitroaniline. But it isn't as per experimental values. So what's going on? What's the logic behind this?

• Oh, do we know that? No, it's your misunderstanding - in such cases it's ortho-effect not SIR. Mar 31 '20 at 15:16

• How can resonance of Lone Pairs of Nitrogen of$NH2$ occur in ortho case?? Resonance completely stops due to SIR effect. Mar 31 '20 at 8:08