Given below are two statements: Statement I: The acidic strength of mono substituted nitrophenol is higher…

Given below are two statements:

Statement I: The acidic strength of mono substituted 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 :

  1. Both Statement I and Statement II are incorrect.
  2. Statement I is correct but Statement II is incorrect.
  3. Statement I is incorrect but Statement II is correct.
  4. Both Statement I and Statement II are correct.

Solution

The presence of the Nitro group in the ortho or para position decreases the electron density in the -OH bond. As a result, it is easier to lose a proton from mono substituted nitro phenol Hence, ortho and para nitrophenols are stronger acids than phenol.

The acidic nature of nitrophenols increases in the order: meta < ortho < para.

Meta position shows only -I effect. Hence, it is less acidic than the para and ortho isomers.

Between para and ortho nitrophenols, para is more acidic due to the presence of an intramolecular hydrogen bonding that locks hydrogen of -OH bond in ortho isomer.

Asked in: NEET 2022 (Phase 1)

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