E+ Sigma Complex Ortho attack CH, CH CH NO NO H H Intermediate is more 3°(favorable) 2 29 Para attack stable if CH3 CH; CH; CH3 nitration occurs at H H NO. H NO2 H NO the ortho 3°(avorable】 or para Meta atack CH3 CH CH position. NO H H NO 2 > Chapter 17 11
Chapter 17 11 Sigma Complex Intermediate is more stable if nitration occurs at the ortho or para position. =>
Energy Diagram H benzene meta CH3 ortho,para NO CH3 NO2 H NO2 ++NO2 reaction coordinate > Chapter 17 12
Chapter 17 12 Energy Diagram =>
Activating,O-,P- Directing Substituents Alkyl groups stabilize the sigma complex by induction,donating electron density through the sigma bond. Substituents with a lone pair of electrons stabilize the sigma complex by resonance. OCH3 -NO2 -NO2 => H Chapter 17 13
Chapter 17 13 Activating, O-, PDirecting Substituents • Alkyl groups stabilize the sigma complex by induction, donating electron density through the sigma bond. • Substituents with a lone pair of electrons stabilize the sigma complex by resonance. OCH3 H NO2 + OCH3 H NO2 + =>
Nitration of Anisole Ortho attack Meta attack Para attack > Chapter 17 14
Chapter 17 14 Nitration of Anisole Ortho attack Meta attack Para attack =>
The Amino Group Aniline reacts with bromine water(without a catalyst)to yield the tribromide.Sodium bicarbonate is added to neutralize the HBr that's also formed. NH2 :NH2 Br Br 3 Br2 H2O,NaHCO3 Br Chapter 17 15
Chapter 17 15 The Amino Group Aniline reacts with bromine water (without a catalyst) to yield the tribromide. Sodium bicarbonate is added to neutralize the HBr that’s also formed. NH2 3 Br 2 H2O, NaHCO3 NH2 Br Br Br =>