Question

What is the major E2 elimination product formed from each halide?

a.

b.

c.

Short answer

The major E2 elimination product formed from each halide are:

Step-by-step solution

Anti-periplanar orientation

The $\mathbf{\text{β}}$proton and the leaving group must be in an anti-periplanar position to undergo an elimination reaction. Anti-periplanar is the orientation where the proton is abstracted, and the leaving group removed must be in a trans position.

In some cases, the anti-periplanar position needs to be done by the bond rotation, which is observed for b. and c.

Removal of β hydrogens to form the elimination product

The$\text{β}$ proton is then abstracted by a base, followed by the removal of a leaving group. This is how an elimination reaction process in a Newman projection.

E2 elimination products

The major E2 elimination product formed from each halide are as follows:

a.

Representation of the major elimination products from a

b.

Representation of the major elimination products from b

c.

Representation of the major elimination products from c