Chemistry Reference
In-Depth Information
Figure 6.4 When a carbon-hydrogen (or carbon-alkyl) bond is aligned with an empty p orbital,
1,2-hydride
/
alkyl shifts and E1 eliminations are favorable.
Figure 6.5 When a carbon-hydrogen bond is aligned trans-periplanar with a carbon-leaving group
bond, E2 eliminations are favorable.
Figure 6.5, require alignment of a carbon-hydrogen bond with an adjacent carbon-leaving
group bond. Furthermore, as shown in Figure 6.5, the relationship between these bonds is
critical for elimination to occur. Specifically, the relevant bonds must adopt a trans relation-
ship within the same plane. This relationship is referred to as trans-periplanar.
Scheme 6.5 Rates and reactivity of substrates for potential E2 eliminations are influenced by
the presence of trans-periplanar relationships.
