Exams › JEE Advanced › Chemistry
Which of the following substituents, when attached to phenol, will increase its acidity?
- -NO2
- -CN
- -CHO
- -CH3
Correct answer: -NO2
Solution
-NO2, -CN, and -CHO are all electron-withdrawing groups that stabilize the phenoxide anion, thereby increasing acidity of phenol. -CH3 is an electron-donating group that destabilizes the anion and decreases acidity. Among the EWG options, -NO2 is the strongest acid-promoter.
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