Question

Which of the two, $O+2NCH_2CH_2O^- \,or \,CH_3CH_2O^–$is expected to be more stable and why?

Answer 1

NO2 group is an electron-withdrawing group. Hence, it shows -I effect. By withdrawing the electrons toward it, the NO2 group decreases the negative charge on the compound, thereby stabilizing it. On the other hand, the ethyl group is electron-releasing. Hence, the ethyl group shows the +I effect. This increases the negative charge on the compound, thereby destabilizing it. Hence, O2NCH2CH2O- is expected to be more stable than CH3CH2O-.