An alicyclic compound is an organic compound that is both aliphatic and cyclic. They contain one or more all-carbon rings which may be either saturated or unsaturated, but do not have aromatic character.[1] Alicyclic compounds may or may not have aliphatic side chains attached.
The simplest alicyclic compounds are the monocyclic cycloalkanes: cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, and so on. Bicyclic alkanes include bicycloundecane and decalin. Polycyclic alkanes include cubane, basketane, and housane.
Spiro compounds have two or more rings that are connected through only one carbon atom.
An exocyclic group is always shown outside the ring structure, take for instance the exocyclic double bond on the left:
See for an example isotoluene.
The placement of double bonds in many alicyclic compounds can be predicted with Bredt's rule.
The mode of ring-closing in the formation of many alicyclic compounds can be predicted by Baldwin's rules.
Monocyclic cycloalkenes are cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, and so on. Bicyclic alkenes include norbornene and norbornadiene.