Sunday, May 22, 2011

Ortho/Meta/Para Directors

Electron Donating = Activating (Ortho, Para) (HAS LONE PAIR OF ELECTRONS, FORMS RESONANCE STRUCTURES!)
- participates in electrophilic substitution reactions
EX: -NH2, -OH, -OR (there's lone pair on the nitrogen/oxygen)
Strong: Anything that has lone pair w/o a group of carbonyl.
EX: -OR
Moderate: They have a C=O (carbonyl)
EX: -NHCOR
Weak: All alkyl group because they donate in electron density.
Electron Withdrawing = Deactivating (Meta, Halogens) (USUALLY POSITIVE, NO LONE PAIR ELECTRONS)
- removes electron density from the benzene ring, making electrophilic aromatic substitution reactions slower and more complex relative to benzene
-NO2, -NH3+ (there's no lone pair on the nitrogen)
STRONG: there's no lone pair, no carbonyl group
EX: -CN, -NO2
MODERATE: carbonyl, but no lone pair
Ex: -COH, -CO2H
WEAK:
Deactivating: o,p directors
These are all HALOGENS.

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