Aromaticity is a property of cyclic, planar molecules with delocalized -electrons that follow the 4n+2 rule Hückel's rule , where n is an integer. Aromatic compounds are known for their stability and resistance to reactions that would disrupt their aromaticity. This stability arises from the delocalization of -electrons across the ring, which creates a lower energy state compared to non-aromatic compounds.The reactivity of aromatic compounds towards electrophilic substitution reactions is influenced by their aromaticity. Electrophilic substitution reactions involve the replacement of a substituent on the aromatic ring by an electrophile. Since aromaticity provides stability, aromatic compounds are generally less reactive towards electrophilic substitution reactions compared to non-aromatic compounds with localized double bonds. However, they are more reactive than fully saturated compounds, as the delocalized -electrons can still interact with electrophiles.The reactivity of an aromatic compound towards electrophilic substitution can also be affected by the presence of substituents on the ring. Substituents can be classified as either electron-donating or electron-withdrawing groups. Electron-donating groups EDGs increase the electron density on the aromatic ring, making it more nucleophilic and thus more reactive towards electrophiles. Examples of EDGs include alkyl groups e.g., methyl, ethyl and hydroxyl groups OH . In contrast, electron-withdrawing groups EWGs decrease the electron density on the aromatic ring, making it less nucleophilic and less reactive towards electrophiles. Examples of EWGs include nitro groups NO2 and carbonyl groups C=O .For example, consider the electrophilic substitution reaction of bromination. In the presence of a catalyst, bromine Br2 reacts with benzene to form bromobenzene. However, if a methyl group is present on the benzene ring toluene , the reaction occurs more rapidly due to the electron-donating effect of the methyl group. On the other hand, if a nitro group is present on the benzene ring nitrobenzene , the reaction is slower due to the electron-withdrawing effect of the nitro group.In summary, the aromaticity of a compound affects its reactivity towards electrophilic substitution reactions by providing stability through delocalized -electrons. Aromatic compounds are generally less reactive than non-aromatic compounds with localized double bonds but more reactive than fully saturated compounds. The presence of electron-donating or electron-withdrawing substituents on the aromatic ring can further influence the reactivity of the compound towards electrophilic substitution reactions.