Which of the following statements is incorrect ?

Options

A. `p`-Nitrophenol is a stronger than `p`-chlorophenol
B. `2,4,6`-trinitrophenol is a stronger acid than `2,4`-dinitrophenol
C. `2,6`-dimethylphenol is a weaker acid than `2`-methylphenol
D. Ring deuteration of phenol increases the acidic strength.

Answer

D

Explanation

Ring deuteration of phenol lowers the acidic strength by about `12` percent (secondary isotope effect) because deuterium `(D)` is more electron releasing than protium `(H)`.
(1) `p`-Nitrophenol is a stronger acid because nitro group

with a positive charge on `N` has a greater electron withdrawing inductive effect than `Cl`. Even more significantly it has an effective electron -withdrawing resonance effect
(2) `2,4,6`-Trinitrophenol (picric acid), a moderate acid is more acidic because it has one more properly situated `NO_(2)`.Picric acid `(pK_(a) = 0.38)`, so exceptionally acidic that it more acidic than acetic acid `(pK_(a) = 4.75)`.
(3) `2,6`-Dimethylphenol is a weaker acid on account of additional electron releasing `Me` group.