Click the structures and reaction arrows in sequence to view the 3D models and animations respectively
In an E2 eliminations, the new π bond is formed by overlap of the C-H σ bond with the C-X σ* anti-bonding orbital. The two orbitals have to lie in the same plane for best overlap. E2 elimination takes place from the anti-periplanar conformation, as this is the most stable conformation due to its staggered nature.
As you can see from the reaction below, when 2-bromobutane undergoes an E2 reaction, two possible stereoisomers are formed. This is because 2-bromobutane has two conformations with H and Br anti-periplanar, but the one that is less hindered forms the major product, so the E-alkene predominates.
The “Animated Molecular Orbital” is present to highlight the anti-periplanar nature of the leaving groups.
We are sorry that this page was not useful for you!
Let us improve this page!
Tell us how we can improve this page (in your own language if you prefer)? If you would like a response, please include your email address e.g. [email protected]