60 likes | 186 Views
CH 6-2: SN2 Reaction-II Stereochemistry in The SN2 Reaction: A Stereospecific Reaction. (S). (R). “Inversion of Configuration”……..Why?. Example: SN2 Reaction?. (R). (S). What is the configuration at the chiral center in reactant and product?. Is there an “Inversion of Configuration”?.
E N D
CH 6-2: SN2 Reaction-II Stereochemistry in The SN2 Reaction:A Stereospecific Reaction (S) (R) “Inversion of Configuration”……..Why?
Example: SN2 Reaction? (R) (S) • What is the configuration at the chiral center in reactant and product? • Is there an “Inversion of Configuration”? • Is this an SN2 reaction?
Re-cap: The SN2 Substitution Reaction • A bimolecular, concerted mechanism • Energy Diagram: minimum of one step (one T.S.) • “Pentavalent Carbon” in the T.S.; crowded T.S. • Nuc “grabs” the electrophilic carbon 180o opposite the Lg. • Stereospecific reaction; inversion of configuration
Alkyl Halide Structure in SN2 Reactions • What was the significance of the SN2 Transition State? CROWDED! • How would large “R” groups effect the reaction? • Rank the following substrates in order of SN2 reactivity: Methyl >>> 1o > 2o >>>>> 3o (NR)
Alkyl Halide Structure in SN2 Reactions Methyl >>> 1o > 2o >>>>>>>>>>>>> 3o (NR)
Alkyl Halide Structure in SN2 Reactions • Halogens bonded to sp2 carbon (vinyl and phenyl halides) do not undergo substitution: WHY NOT?