Arrange the following groups in decreasing order of their activating power towards electrophilic aro — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

The activating power depends on the ability to donate electrons via resonance. Nitrogen is less electronegative than oxygen, making $-NH_2$ a stronger $+M$ donor than $-OH$. The $-NHCOCH_3$ group is moderately activating because its lone pair is cross-conjugated with the carbonyl group, reducing its availability to the aromatic ring. Alkyl groups like $-CH_3$ activate weakly only via hyperconjugation and $+I$ effects.