《有机化学》课程PPT教学课件（Organic Chemistry, William A. Price, Ph.D. PPT, La Salle University, L.G.WADE, JR., 8th Edition）Chemistry of Aromatic Compounds

Chemistry of Aromatic Compounds Electrophilic Aromatic Substitution Directing Effects Side-chain Reactions Synthesis Nucleophilic Aromatic Substitution

Chemistry of Aromatic Compounds Electrophilic Aromatic Substitution Directing Effects Side-chain Reactions Synthesis Nucleophilic Aromatic Substitution

Electrophilic Aromatic Substitution E+ H H H B sigma complex substituted E :base + H-base ⑧

Electrophilic Aromatic Substitution H E E H E + H-base :base

EAS Reactions of Benzene NO2 CHO SO3H

EAS Reactions of Benzene Br NO2 SO3H CR O Cl R I CHO

Bromination /Chlorination H Br Br2,FeBr3 HBr C12,FeCl3 HCI

Bromination / Chlorination H Br Br2, FeBr3 + HBr H Cl C l2, FeCl3 + HC l

Bromination Mechanism Step 1:Formation of a stronger electrophile. :B-Br:FeBr :Br-Br-FeBr Br2FeBr,intermediate (a stronger electrophile than Br,) Step 2:Electrophilic attack and formation of the sigma complex. H B H :Br-CBr-FeBr H +FeBra H H H 人 sigma complex Step 3:Loss of a proton gives the products H FeBra Br H H H +FeBr3 bromobenzene

Bromination Mechanism

Reaction Profile rate-limiting transition state reactants H +Br2 Br-FeBr4 K3.Ioua +FeBr3 intermediate products Br+HBr 10.8 kcal/mol +FeBr3 reaction coordinate

Reaction Profile

Nitration HNO3,H2SO4 NO2 +H20 Formation of ele ctrophile HNO3 H2SO4 NO2+H2O+HSO4

Nitration HNO3 , H2 SO4 NO2 + H2 O HNO3 + H2 SO4 N O2 + + H2 O + HSO4 - Formation of electrophile

Nitration Mechanism Formation of the nitronium ion. H:0 H--N=+H0-S-0-H=H-95N=+s0=0=N=0+H,6: nitronium ion Step 1:Electrophilic attack. Step 2:Loss of a proton. H H :0: H H H NH HSO> H,SO H H 0 H H H H benzene nitronium sigma complex nitrobenzene ion (resonance-delocalized)

Nitration Mechanism

Nitration of Toluene CH; CH; CH; CH3 HNO3 H2SO NO2 O2N NO2 toluene o-nitrotoluene m-nitrotoluene p-nitrotoluene (60%) (4%) (36%)

Nitration of Toluene

Sulfonation is Reversible fuming sulfuric acid SO3,H2SO4 SO:H SO:H OSO3H

Sulfonation is Reversible H SO3, H2 SO4 SO3H fuming sulfuric acid S O O O H OSO3H SO3H H OSO3H