The halogen atom in haloarenes, being o, p-directing, directs further substitution to the ortho- and para-positions with respect to itself due to resonance, resulting in increased electron density at these positions.
How does the halogen atom in haloarenes influence the position of further substitution in electrophilic reactions?
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The halogen atom in haloarenes influences the position of further substitution in electrophilic reactions through its directing effect. Halogens, being electron-withdrawing groups, deactivate the benzene ring towards electrophilic attack. However, they also exhibit a directing effect based on their position. Ortho-para directing halogens (like -Cl and -Br) direct incoming electrophiles to the ortho and para positions due to resonance stabilization and increased electron density at those positions. In contrast, meta-directing halogens (like -F) direct electrophiles to the meta position. This directing effect is crucial for predicting and understanding the regioselectivity of electrophilic aromatic substitution reactions in haloarenes.