How many stereoisomers are possible for 1,2-dichlorocyclopentane?
There are three stereoisomers for 1,2-dichlorocyclopentane.
Here's the procedure I would follow.
- Draw the bond-line structure.
- Identify the chiral centres.
- Calculate the maximum number of possible stereoisomers.
- Draw them.
- Eliminate any meso compounds.
1. Bond-line structure
The bond-line structure is
2. Chiral centres
3. Maximum number of stereoisomers
There are two chiral carbons, so the maximum number of stereoisomers is
4. Possible stereoisomers
Draw "UpUp" and its mirror image, then "UpDown" and its mirror image.
5. Identify meso compounds
Hence there are only three stereoisomers of 1,2-dichlorocyclopentane.