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Unformatted text preview: deactivating o/p-directors A) Deactivate all ring positions (inductive withdrawal dominates over resonance donation) B) Are o/p-directors because they can stabilize resulting intermediates by resonance Fig. 18.7: Effect of substituents on benzene reactivity Limitations in EAS of Substituted Benzenes (18.10) A) Polyhalogenation of strongly activated rings (OH, OR, NH 2 , NR 2 ) B) Limitations in FC reactions i) EWGs prevent reaction ii) NH 2 groups prevent reaction iii) Polysubstitution a problem in FC alkylations Another key limitation of Friedel-Crafts Reactions CO 2 H and CHO cannot be added by FC acylation! Synthesis of Benzene Derivatives (18.12) You have already seen how to prepare some monosubstituted benzene derivatives via EAS If more than one substituent, synthetic strategy must take directing effects into account...
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This note was uploaded on 10/24/2011 for the course CHEMISTRY 623 taught by Professor Benson during the Spring '11 term at Kansas.
- Spring '11
- Organic chemistry