snrxns - -> Cl-Leaving Groups Favored by better leaving...

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Summary of Nucelophilic Substitution Reactions S N 1 S N 2 Mechanism Two Steps R L R + Nu: R Nu One Step R L + Nu: R Nu Kinetics 1st order (unimolecular) rate= k[R-L] Ionization= rate determining step (1st step), 2nd step does not effect the rate 2nd Order (bimolecular) rate= k[R-L] [Nu:] Stereochemistry Racemization Inversion Carbon (sp 3 ) Electrophile Favored by electrophiles which can best stabilize a carbocation. 3°> benzylic ~ allylic ~ 2°>> 1° Steric hinderance controlled CH 3 > 1°> 2 (3°= no reaction) Nucleophile Nature of the nucleophile has no effect on rate Favored by better nucleophiles RS - > NC - > I - > RO - > HO
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Unformatted text preview: -> Cl-Leaving Groups Favored by better leaving groups-N 2 > -OTos > -I > -Br > -Cl >-OH 2 Favored by better leaving groups-N 2 > -OTos > -I >- Br > -Cl > Solvent Effect Favored by polar, ionizing solvents. Solvolysis: polar protic (H-bonding) solvents act as the nucleophile H 2 O > H 2 O/ROH (mixed solvent) > ROH Favored by polar aprotic solvents. HMPA > CH 3 CN > DMF > DMSO > THF Disfavored by polar protic (H-bonding) solvents Competative Reactions Elimination (E1) Rearrangements Elimination (E2) by strongly basic nucleophiles...
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This note was uploaded on 03/11/2012 for the course CHEM 220A taught by Professor Sulikowski during the Fall '08 term at Vanderbilt.

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