Cycloalkanes just means "cyclic alkanes" - ring systems formed of only
C-C and C-H bonds.
Such structures are commonly encountered in natural compounds such as steroids,
with cyclopentanes and cyclohexanes being the most common.
Other than cyclopropane (which must be planar), cycloalkanes are "puckered"
to relieve some of the ring strain by lowering angle and torsional strains.
Ring strain : cyclopropane > cyclobutane > cyclopentane > cyclohexane
The structures of some of the smaller cycloalkanes are shown below with
the planar structures for contrast. In each case, manipulate the CHIME
images to look for the deviation from planarity and the effect this has
on the eclipsing interactions of adjacent H atoms and C-C bonds.
In order to be able to compare the strain in each member of the cycloalkane
series, the heat of combustion per
methylene (i.e. -CH2-) is also given. The smaller this number
is the less ring strain there is.
