Question

P-Nitrophenol is a stronger acid than phenol while p-cresol is a weaker acid. This can be explained as

• A. $- CH_{3}$group decreases the electron density on oxygen of $O - H$ group making p-cresol a weaker acid
• B. $- NO_{2}$ group decreases electron density on oxygen of $O - H$ group making p-nitrophenol a stronger acid.
• C. $- CH_{3}$ group increases the electron density on oxygen of $O - H$ group making release of $H^{+}$ easier.
• D. $- NO_{2}$ group increase the electron densti yon oxyen of $O - H$ group making release of $H^{+}$ easier

Answer 1

Answer: (B)

$- NO_{2}$ group decreases electron density on oxygen of $O - H$ group making p-nitrophenol a stronger acid.

Answer 2

$- NO_{2}$ group being electron withdrawing group, decreases electron density on oxygen of $O - H$ group thus making the release of $H^{+}$ easier hence increasing the acidity of phenol $- CH_{3}$group increases the electron density on oxygen atom thus deceasing acidity than phenol.