Question

Increasing order of acidic strength among p-methoxy phenol (I), p-methyl phenol (II) and p-nitrophenol (III) is

• A. III, I, II
• B. II, I, III
• C. III, II, I
• D. I, II, III

Answer 1

The Correct Option is C

Nitro group is an electron-withdrawing group, so increase the acidic character of phenol whereas \(-CH_3\) and \(-OCH_3\) both are electron releasing groups, so it decrease the acidic character of phenol but \(-CH_3\) group is less electron donating or releasing, so p-methyl phenol is slightly more acidic than p-methoxy phenol and p-nitro phenol is most acidic.
So the order of acidic character is p-methoxy phenol < p-methyl phenol \(50mm\) < p-nitro phenol.

Answer 2

The correct option is C.

Since \(−NO_2\)​ show strong −I and −M effect, so it is the strongest acid. Between I and II, II is a stronger acid than I because although \(−CH_3\)​ shows +I effect and \(−OCH_3\)​ show −I effect, but the inductive effect is less relevant in the para positioning. Also, the group \(−O−CH_3​\) is the group, which destabilizes the phenolate ions through a strong +M effect. So, p−methoxy phenol is less acidic in nature.