Question

How many stereoisomers are there for 1,2,3-tribromocyclopentane ?

Answer 1

There are four stereoisomers.

Explanation:

The structure of 1,2,3-tribromocyclopentane is

There are only two chiral carbons because `"C2"` lies on a plane of symmetry.

Thus, the maximum number of stereoisomers is `2^2 = 4`.

Let's draw the various possibilities.

This isomer is a meso-compound because it has an internal plane of symmetry.

This isomer is also a meso-compound because it has an internal plane of symmetry.

The two structures above are enantiomers (non-superimposable images of each other).

Thus, there are four stereoisomers: two meso-compounds and a pair of enantiomers.