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This summary covers the four categories of directing effects in electrophilic aromatic substitution reactions, highlighting activating and deactivating groups and their impact on reaction outcomes. It also discusses steric effects and synthetic strategies with aromatic compounds.
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Summary of Directing Effects FOUR CATEGORIES: I. Strongly activating, ortho/para-directing (eg. –OMe, I, R) II. Weakly activating, ortho/ para-directing (eg. –CH3I) III. Weakly deactivating, ortho/ para-directing (eg. –CI, I, R) IV. Deactivating, meta-directing (eg. -NO2, I) I. Strongly activating, ortho/para directing (LP electrons) (eg. -OMe, Inductive and Resonance effects)
I. Strongly activating, ortho/para directing (eg. -OMe, inductive, resonance) Reaction Coordinate II. Weakly activating, ortho/para directing (eg. -CH3 inductive)
Stability of Sigma Complex Defines Outcome Intermediate is more stable if nitr atior occurs at the ortho or para position. II. Weakly activating, ortho/para directing (eg. -CH3 inductive)
III. Weakly deactivating, ortho/para directing (eg. -Cl, Inductive/Resonance) Chlorobenzene III. Weakly deactivating, ortho/para directing (eg. -Cl, Inductive/Resonance)
IV. Deactivating, meta directing (eg. -NO2 , inductive) IV. Deactivating, meta directing (eg. -NO2 , inductive) Positive or partial positive charge on substituent very unfavorable in σcomplex.
SYNTHETIC STRATEGIES WITH AROMATIC COMPOUNDS Steric Effects in Electrophllic Aromatic Substitution
STERIC EFFECTS IN ELECTROPHILIC AROMATIC SUBSTITUTION Reaction with Br2/FeBr3 to afford monobrominated derivative Statistically 66%ortho/33%para)