# How many isomers does #C_4H_9Br# have?

##### 1 Answer

4

#### Explanation:

First we should consider the formula as

Then, how can we arrange the carbon atoms?

The first three, only can be arranged in a linear mode:

The fourth one can be allocated in the ends:

or in the middle carbon:

(isobutane)

Now, where can we put the Br atoms?

In butane we can put the Br in the first carbon (equivalent to the last)

giving bromobutane:

or in the second which is equivalent to the third:

(sec-butyl bromide)

In the case of isobutane, the external carbons are equivalent, giving:

(isobutyl bromide)

but we can also substitute in the carbon of the middle:

(ter-butyl bromide)

The remaining positions we add hydrogen atoms, making each carbon atom four bonds.

So there are four isomers of