  On the basis of empirical Fischer projections, we developed an algebraic
approach to central molecular chirality of tetrahedral molecules. The elements
of such an algebra are obtained from the 24 projections which a single chiral
tetrahedron can generate in S and R absolute configurations. They constitute a
matrix representation of the O(4) orthogonal group. According to this
representation, given a molecule with n chiral centres, it is possible to
define an index of chirality, where n is the number of stereogenic centres of
the molecule and p the number of permutations observed under rotations and
superimpositions of the tetrahedral molecule to its mirror image. The chirality
index, not only assigns the global chirality of a given tetrahedral chain, but
indicates also a way to predict the same property for new compounds, which can
be consistently built up
