IUPAC Names of simple monocyclic hydrocarbons

A saturated MONOCYCLIC hydrocarbon (a single-ring, fully saturated compound) is named simply by attaching the prefix 'cyclo-' to the name of the OPEN-CHAIN alkane with the same number of carbon atoms -- so a three-carbon ring is cyclopropane and a five-carbon ring is cyclopentane, directly parallel to propane and pentane. An UNSATURATED monocyclic hydrocarbon is named the same way, except that '-ane' is replaced by '-ene', '-yne', etc. exactly as for open-chain compounds -- so a six-carbon ring with one double bond is cyclohexene, and a five-carbon ring with one double bond is cyclopentene. Once side chains (substituents) are attached to such a ring, the SAME branching/locant/alphabetical rules already given for open-chain alkanes, alkenes and alkynes apply in full -- with the one extra rule that numbering of the ring's own carbons always STARTS from whichever ring carbon actually carries a side chain (rather than starting arbitrarily); this is illustrated by 1-ethyl-3-methylcyclohexane (a ring bearing one ethyl and one methyl substituent, numbered starting from the ethyl-bearing carbon) and 3-ethyl-1,1-dimethylcyclohexane (a ring bearing one ethyl and two methyls on the same carbon, numbered starting from the doubly-methylated carbon so that carbon gets locant '1,1'). There is one further, important exception to the whole 'ring is the parent' approach: if an attached ALKYL chain itself contains MORE carbon atoms than the ring does, the compound is instead named as a derivative of that open CHAIN, with the ring itself now treated merely as a substituent hanging off the chain -- for example 3-cyclopropylhexane (a six …