Comparing the basicity of aniline and ortho anisidine

2018-03-20 21:32:09

In my worksheet there is a question that asks for the comparison of basicities of the three ansidines and anniline.

After my analysis using:

$\text{Basicity} \propto \text{+M effect (except for meta annisidine)} \propto \dfrac{1}{\text{-I effect}}$,

I could make the following conclusions:

m-Anisidine should be the least basic

p- Ansidine should be more basic than anniline.

But the real problem is comparing the baicity of anniline and o-Anisidine and arranging them with p-Anisidine. I doubt the presence of ortho effect in ortho isomer after seeing the ball and stick model which makes the interaction of lone pair of nitrogen and hydrogens of $\ce{-OCH3}$ improbable.

The answer given is:

p-Anisidine> Anniline > o-Anisidine > m-Anisidine (I have verified it with $\pu{pKa}$ values from The PubChem)