The ortho substituted aniline are less basic than aniline and ortho substituted benzoic acids are more acidic than benzoic acid.

 Ortho effect is valid only for benzoic acid and aniline.
 

Ex.1 Compare the basic strength of the following:

Sol. a > b > d > c

* Due to ortho effect d > c
If c is less basic than d then it will be certainly less than b as b is more basic than d.

Ex.2 Compare the basic strength of the following:

Sol. Do your selves

S.I.PSteric inhibition of Protonation (ortho effect)

After protonation, repulsion increases therefore ortho substituted aniline is less basic than aniline S.I.RSteric inhibition of resonance

 

Therefore a > b (basic character)

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