NCEA Level 3 Organic Chemistry Reaction Schemes Practice Test

Anisole is strongly activated by the methoxy group, which donates electron density into the ring through resonance. That makes the ring highly susceptible to electrophilic aromatic substitution at the ortho and para positions relative to the methoxy group. During nitration, the nitronium ion adds to the ring to form a resonance-stabilized arenium ion; the positive charge can be delocalized onto the ortho and para carbons, so those positions are favored. Among them, the para position is less hindered by the methoxy group, so the transition state and final product experience less steric clash. This leads to a higher yield of para-nitroanisole compared with the ortho isomer, while the meta position remains largely unactivated. Hence the major product is para-nitroanisole.