Substituted Cycloalkanes

Basic IUPAC Organic Nomenclature

Substituted Cycloalkanes

Substituted cycloalkanes are named in an analogous fashion to regular alkanes (also referred to as acyclic alkanes, i.e. non-cyclic alkanes).

In principle, a substituted cycloalkane could be name in two ways, either as an alkyl substituted cycloalkane, or as a cycloalkyl substituted alkane

When the ring size (e.g. number of C atoms) is larger than the longest continuous chain, then the ring becomes the parent and hence the system is treated as a alkyl cycloalkane.

Other rules:

If a ring is monosubstituted then no locant is required since the substituent must be at C1.
If a ring is polysubstituted then each substituent requires a locant to unambiguously assign their relative positions.

Ring is smaller than the chain, so the chain is the parent. Functional group is an alkane, therefore suffix = -ane The longest continuous chain is C4 therefore root = but The branch is a C3 cycloalkyl group i.e. a cyclopropyl group The first point of difference rule requires numbering from the right as drawn, the substituent locant is 2- 2-cyclopropylbutane
Ring is larger than the chain, so the ring is the parent. Functional group is an alkane, therefore suffix = -ane The ring is C6 therefore root = cyclohex The branch is a C2 alkyl group i.e. a ethyl group Since it's monosubstituted, no locant is required since it is unambiguous (i.e. the ethyl group will define the C it is attached to as C1) ethylcyclohexane
Ring is larger than the chain, so the ring is the parent. Functional group is an alkane, therefore suffix = -ane The ring is C6 therefore root = cyclohex One branch is a C2 alkyl group i.e. an ethyl group The other branch is a C1 alkyl group, i.e. a methyl group Since the first point of difference doesn't resolve the numbering, the alphabetisation order is used. 1-ethyl-2-methylcyclohexane