What are important electron withdrawing groups and electron donating groups should be remembered for NEET examination point of view?

The important electron withdrawing groups should be remembered for NEET examination point of view are halogens (F, Cl), nitriles CN, carbonyls RCOR’ and nitro groups NO₂. The electron donating groups are alkyl groups, alcohol groups and amino groups.

EWGs (electron withdrawing groups) are highly affine to electrons. When a molecule contains such a group, the majority of the charge density is partially displaced in the direction of EWG. For instance, the EWG is present and the Nitro group (NO2) is present in nitromethane. As a result of drawing the charge density to its side, NO2 has a partial negative charge in this molecule. Since CH3 experiences partial loss of charge density, it has a partial positive charge.

EDGs are an entirely new kind of situation. Alkyl groups and alkoxy groups fall under this heading. The methyl group is an electron-donor in the case of toluene (a methyl group is connected to benzene). It gives the benzene ring an electron density donation.

In aromatic substitution processes, EWG and EDG have differing directing properties. The electrophilic substitution reactions of substituted benzene reveal that EWG, such as NO2, deactivate the ring and result in the meta product. For instance, the major product of the nitration of nitrobenzene is metadinitrobenzene. If EDG had been the substitute present, however, this would not be the case.

The ortho- or para-substituted product is created when the EDG substituent initiates electrophilic aromatic substitution in benzene.

Toluene, for instance, can be nitrated to produce orthonitro and paranitro toluene.

A reaction center’s electrons are drawn away by an electron withdrawing group, or EWG. The electron-withdrawing substituent stabilises the centre when it is an electron-rich carbanion or an alkoxide anion.