Illustrated Glossary of Organic Chemistry

Substituent: An atom or group other than hydrogen on a molecule. (The atom or group has substituted for the missing hydrogen.)

Cyclohexane has no substituents.


In phenylcyclohexane the benzene ring (or phenyl group) is a substituent on the cyclohexane ring and the cyclohexane ring (or cyclohexyl group) is a substituent on the benzene ring.


In (3-iodo-5-methylphenyl)cyclohexane the benzene ring (or aryl group) is a substituent on the cyclohexane ring. The cyclohexane ring (or cyclohexyl group), methyl group, and iodine atom are substituents on the benzene ring.