Chemistry Reference
In-Depth Information
Figure 4.4 Partial charges can be delocalized through unsaturated bonds.
Scheme 4.8 Comparison of S
N
2 and S
N
2
0
reactions as explained with arrow pushing.
In the case of the reaction illustrated in Scheme 4.8, the product is not dependent upon
which site the nucleophile is drawn to or which mechanism the reaction proceeds through.
However, when the double bond possesses an additional substituent, product mixtures can
form as illustrated in Scheme 4.9. In general, when predicting the outcome of reactions
where both S
N
2 and S
N
2
0
reactions are possible, the major product will be dependent
upon the steric constraints around the various reactive (or partially positively charged)
sites. In cases where the nucleophile has comparable accessibility to electrophilic sites,
product mixtures are usually the result.
Scheme 4.9 Competing S
N
2 and S
N
2
0
reaction mechanisms can lead to product mixtures.
