Characteristics of the SN2 Reaction

Methyl, 1 prime or 2 prime alkyl halide

For the substrate, ______ are preferred

3 prime

_____ substrates are too bulky AND WON’T WORK!

Inversion

The stereochemistry, the reaction proceeds with an ____ of stereochemistry at the reactive center: partial positive carbon

2nd

The kinetics - ___ order (bimolecular) aka the rate depends on [Nu] and [RX]

k[Nu][RX]

rate =

Transition state

A non-hindered needs to be used. Large substrates prevent the nucleophile from being able to attack. They will raise the energy of the ______\

Methyl and 1 prime alkyl halides

Undergo SN2 reactions with ease

2 prime alkyl halides

React more slowly

3 prime alkyl halides

DO NOT UNDERGO SN2 reactions. This order of reactivity can be explained by steric effects. Steric hinderance caused by bulky R groups makes Nucleophilic attack from the backside more difficult, slowing the reaction rate.

Vinyl and aryl halides

Do not undergo SN2 displacement

Nucleophile

Appears in the rate expression; the strength of the ______ will affect the rate of the reaction

Polar Aprotic solvent

Preferred for an SN2 reaction; has strong dipoles but no -OH or -NH groups

Protic solvents

Stabilize the nucleophile by lowering its energy, therefore slowing down the SN2 reaction; examples are ROH and NH2

Weaker base

The better leaving group is the ______ (except TsO- due to resonance)