Question

What alkenes are formed from each alkyl halide by an E1 reaction? Use the Zaitsev rule to predict the major product.

a.

b.

Short answer

The alkenes formed from each halide by an E1 reaction are shown below:-

Step-by-step solution

Zaitsev Rule

Zaitsev's rule states that the more substituted products are considered to be the major product.This is because due to the presence of electron-donating alkyl groups, which through the +I effect increases the stability of the compound.

The stability increases in the following order:$\mathbf{\text{Tetrasubstituted>Trisubstituted>Disubstituted>Monosubstituted}}$

Types of β hydrogens

The presence of different types of$\text{β}$ hydrogens results in different products. The products formed are considered to be constitutional isomers. In those constitutional isomers, only one is considered to be major according to the Zaitsev rule.

Representation of different hydrogens

By all explanations, the alkenes formed from each halide by an E1 reaction are shown below:-

Formation of products from a

Two possible products are formed where only one is considered to be a major product.

Formation of products from b

The reaction yields two different products where one of them is the major product.