EASdirecting - Nolta 2008 EAS on a SUBSTITUTED benzene ring...

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Once a benzene ring has a substituent, different regions are defined (i.e. regiochemistry!) S EAS on a SUBSTITUTED benzene ring - what happens in the NEXT EAS reaction? Directing or steering effcts! For most OP directors, the atom attached to the ring has a lone pair which can be delocalized INTO the ring (simple alkyl groups are also O/P directors, however, and they do not have a lone pair. They do allow for tertiary C+ stabilization in the EAS reaction) D Meta directing! slide fur INTO ring C N O O Generally these are considered "activating" on the ring, tending to increase the ring's reactivity (exception is halogens, which slightly deactivate). C O R Ortho/Para directing! When there is more than one substituent attached, they can direct the next electrophile together or they can be in conflict. When conflict arises, the O/P directors (typically activators) tend to have more power in regioselection S = some group that has already been placed on the ring ORTHO ORTHO META META PARA Ortho - two
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This note was uploaded on 01/28/2011 for the course CHEM 215 taught by Professor Koreeda during the Spring '07 term at University of Michigan.

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