What is the Zaitsev's rule?

Zaitsev's rule: The major product in elimination reaction has a more substituted double bond.

example: 2-bromo-2-methylpentane

now we eliminate HBr

our double bond can form in one of two places: A 1-2 double bond or a 2-3 double bond.

If we look at the 1-2 double bond, we can see we will have two substituents, a ##CH_3## and a propyl group

If we look at the 2-3 double bond, we can see will will have three substituents, two ##CH_3##'s and a ethyl group

According to Zaitsev's rule, the major product would be the 2-methylpent-2-ene. and the minor product would be 2-methylpentene

hope this helps:)