# What is the major product of the addition reaction below?

## $C {H}_{3} C {H}_{2} C {H}_{2} C H = C {H}_{2} + H B r \to$

##### 1 Answer
Jun 24, 2016

$\text{2-bromopentane}$

#### Explanation:

The electron-rich olefin adds to the electrophile, the protium ion, as a first step in the reaction:

$R C H = C {H}_{2} + H B r \rightarrow R {C}^{+} H C {H}_{3} + B {r}^{-}$

The second step is of course bond formation between nucleophilic $B {r}^{-}$ and the carbocation to form the 2-substituted alkane. The 2""^@ carbocation as shown is stabilized with respect to the 1""^@ carbocation, $R C {H}_{2} - C {H}_{2}^{+}$, and the reaction tends to proceed thru this more stable intermediate. This is classic Markownikow addtion.