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Groups on a benzene ring

What determines whether a group on a benzene ring will be activating or deactivating and ortho para or meta directing?

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A. Directing effects
1. Ortho, para directors can stabilize a positive charge. As a result, the intermediates formed
when the electrophile reacts at the ortho or para position are relatively more stable than the
intermediates formed when the electrophile reacts at the meta position. The more stable
intermediates form at a faster rate (recall Hammond's postulate).
a. Alkyl groups are ortho, para directors because they can stabilize a positive charge through
hyperconjugation.
b. Groups in which the atom directly attached to the ring has a lone pair, are ortho, ...

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