Question

Given below are two statements:
Statement I:
The acidic strength of monosubstituted nitrophenol is higher than phenol because of electron withdrawing nitro group.
Statement II:
$o-$nitrophenol, $m-$nitrophenol and $p-$nitrophenol will have same acidic strength as they have one nitro group attached to the phenolic ring.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Statement I is incorrect but Statement II is correct
• B. Both statement I and Statement II are correct
• C. Statement I is correct but Statement II is incorrect
• D. Both Statement I and Statement II are incorrect

Answer 1

The correct option is C Statement I is correct but Statement II is incorrect

Acidic strength $\propto \text{EWG}\propto \frac{1}{\text{EDG}}$

nitrophenol will be more acidic as compared to phenol because the phenoxide ion will be stabilized to some extent by the $e^{-}$ withdrawing effect of the $-N{O}_2$ group.

Nitro group has both −I and −R effect with the −R effect being more dominant than the −I effect. Since −R effect does not affect the meta position, only the weaker −I effect is responsible for withdrawing electron in the meta position. Hence m-nitrophenol is the weakest acid among the following.

Among ortho and para-nitrophenol, due to intramolecular hydrogen bonding, the loss of proton becomes more difficult in case of o-nitrophenol making it a weaker acid than p-nitrophenol.
Statement I is correct, Statement II incorrect.