Optical Isomerism
Carbonyls & Optical Isomerism Worksheet
Because these questions benefit from being able to write on them, I have included a copy of the printable worksheet here.
1. Definitions
1. State what is meant by the term chiral carbon.
A carbon atom that has four unique groups attached to it, so that it has no plane of symmetry.
2. Identifying Chirality
2. For the following molecules, decide whether they contain any chiral carbons. If they do, circle the chiral carbon.
Answers:
3. Explaining Isomerism
3. Explain why butan-2-ol experiences optical isomerism whereas butan-1-ol does not.
Butan-2-ol has a chiral centre. The second carbon atom is bonded to four unique groups: a methyl group, an ethyl group, an alcohol (-OH) group, and a hydrogen atom. Because these four groups are unique, it is chiral.
Butan-1-ol has no equivalent carbon. All the carbon atoms in butan-1-ol have at least two identical groups attached (e.g., two hydrogens), so it has no chiral centre and cannot exhibit optical isomerism.