Question

When considering electrophilic
aromatic substitution reactions
electron withdrawing substituents
(e.g. nitro) are described as...

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Answer 1

Answer:

Pi Acceptor Groups Are Strongly Deactivating

Examples are NO2, carbonyl groups (C=O), sulfonyl, cyano (CN) among others. These groups are universally deactivating, slowing the rate of electrophilic aromatic substitution

Answer 2

When considering electrophilic aromatic substitution reactions

electron withdrawing substituents (e.g. nitro) are described as deactivating groups

Explanation:

• Electrophiles are electron-deficient species. These species are found to attack the benzene ring, due to the presence of pi-electron clouds above and below the plane of the benzene ring.
• If benzene molecule has electron-withdrawing groups like nitro, due to their -I effect, they tend to pull the electron density from the benzene ring, making it electron deficient.
• Hence, the reactivity of the benzene ring decreases towards an electrophile.
• Such groups are termed deactivating groups.