Question

Why does p-methoxybenzyl bromide react faster than p-nitrobenzyl bromide with ethanol to form an ether product?

Answer 1

p-Methoxybenzyl bromide reacts faster than p-nitrobenzyl bromide with ethanol due to the electronic effects of the substituents. The methoxy group is electron-donating via resonance, which stabilizes the benzyl carbocation intermediate formed during the reaction, thereby increasing the reaction rate. In contrast, the nitro group is strongly electron-withdrawing, which destabilizes the carbocation intermediate and slows down the reaction. 

Thus, electron-donating groups accelerate the reaction with ethanol to form ether products, while electron-withdrawing groups retard it.