# What are the major and minor products obtained in the reaction of (E)-3-methyl-2-pentene and HBr?

Jun 28, 2015

The major product by far is 3-bromo-3-methylpentane; there may be a small amount of 2-methyl-3-bromopentane.

#### Explanation:

The structure of ($E$)-3-methylpent-2-ene is

According to Markovnikov's rule, the ${\text{H}}^{+}$ from $\text{HBr}$ will add to $\text{C-2}$ of the alkene and form a 3° carbocation at $\text{C-3}$.

The ${\text{Br}}^{-}$ will add to $\text{C-3}$ and form 3-bromo-3-methylpentane

There may be a small amount of product formed when the ${\text{H}}^{+}$ adds to $\text{C-3}$ of the alkene to form the less stable 2° carbocation at $\text{C-2}$.

The ${\text{Br}}^{-}$ will then add to $\text{C-2}$ and form 2-bromo-3-methylpentane.