Sep 26, 2017 · Examples are NO 2, carbonyl groups (C=O), sulfonyl, cyano (CN) among others. These groups are universally deactivating, slowing the rate of electrophilic aromatic substitution.

Electron donating groups are generally ortho/para directors for electrophilic aromatic substitutions, while electron withdrawing groups (except the halogens) are generally meta directors. The selectivities observed with EDGs and EWGs were first described in 1892 and have been known as the Crum Brown–Gibson rule. [4]

EWG remove electron density from the π system making it less nucleophilic.

The reactivity of aromatic pi bonds in S E Ar reactions is very sensitive to the presence of electron-donating groups (EDG) and electron-withdrawing groups (EWG) on the aromatic ring.

Jan 4, 2012 · The N in NO 2 is positively charged and has a pi-bond to O, so it's a slammin' EWG (by resonance and the inductive effect both). That N has no lone pair of electrons, so it can't be an EDG.

Answer: Substituents with pi bonds to electronegative atoms (e.g. -C=O, -NO2) adjacent to the pi system are electron withdrawing groups (EWG) - they deactivate the aromatic ring by decreasing the electron density on the ring through a resonance withdrawing effect.

Because the element directly attached to ring is a carbon with no partial charge on it, the electronegativity difference between it and the ring carbon is small and hence the inductive effect is almost zero. Thus alkyl groups should be mildly activating.

Apr 5, 2023 · The main difference between EDG and EWG is their effect on the electron density of a molecule. EDGs increase electron density in the molecule, while EWGs decrease electron density.

In this lesson, we will learn: To recall the definitions of electron-withdrawing group (EWG) and electron-donating groups (EDG). To understand the effects of EWGs and EDGs on nucleophile and electrophile strength. To understand the underlying …

Because NO2 is an electron withdrawing group, looking at the resonance structures reveals that the positive charge concentrates at the ortho-para positions. As a result, these positions are deactivated in favor of an electrophilic aromatic substitution.