An axis about which a set of
ligands is held so that it results in a spatial arrangement which is not superposable on
its mirror image. For example with an allene
abC=C=Ccd
the
chiral axis is defined by the
C=C=C
bonds; and with an
ortho-substituted biphenyl the atoms C-1, C-1', C-4 and C-4' lie on the
chiral axis.
Source:
PAC, 1996, 68, 2193
(Basic terminology of stereochemistry (IUPAC Recommendations 1996))
on page 2203