The Amino Group Aniline,like anisole,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 3Br2 H,O HBr NaHCO (to neutralize HBr) Br aniline 2,4,6-tribromoaniline => (100%) 16 Copyright 2005 Pearson Prentice Hall,Inc
Chapter 17 16 The Amino Group Aniline, like anisole, reacts with bromine water (without a catalyst) to yield the tribromide. Sodium bicarbonate is added to neutralize the HBr that’s also formed. =>
Summary of Activators Groups: R -:>-N-R>-9-H>-0-R>-N-C-R>-R (no lone pairs) Compounds: R :0: OH :0-R :N-C-R phenoxides anilines phenols phenyl ethers anilides alkylbenzenes > Chapter 17 17
Chapter 17 17 Summary of Activators =>
Deactivating Meta- Directing Substituents Electrophilic substitution reactions for nitrobenzene are 100,000 times slower than for benzene. The product mix contains mostly the meta isomer,only small amounts of the ortho and para isomers. Meta-directors deactivate all positions on the ring,but the meta position is less deactivated. Chapter 17 18
Chapter 17 18 Deactivating MetaDirecting Substituents • Electrophilic substitution reactions for nitrobenzene are 100,000 times slower than for benzene. • The product mix contains mostly the meta isomer, only small amounts of the ortho and para isomers. • Meta-directors deactivate all positions on the ring, but the meta position is less deactivated. =>
Ortho Substitution on Nitrobenzene Ortho attack +charges adjacent ortho especially unstable => Chapter 17 19
Chapter 17 19 Ortho Substitution on Nitrobenzene =>