Two system have been developed for studying the configuration of stereoisomres.

i) Relative configuration (D, L-nomenclature): The configuration of various stereoisomers were studied with respect to glyceraldehydes. Glyceraldehyde having the –OH group on the right and hydrogen atom on the left was arbitrarity given the configurational symbol ‘D’ and its mirror image with –OH group on the left and hydrogen atom on the right was given the configuration symbol ‘L’.

Any stereoisomer which can be obtained from or converted into D-glyceraldehyde will belong to D-series. Similarly, any stereoisomer which can be obtained from or converted into L-glyceraldehyde will belong to L-series. The sign (+) or (-) added after D-and L-letters indicates the direction of the optical rotation.

ii) Absolute configuration (R and S systems of nomenclature):

1.

2.