Synthesis and Purification of Diastereomers: Sodium Borohydride Reduction of a Chiral Ketone


Quite often a chemical reaction produces one or more chiral atoms. Such a reaction can lead to one or more diastereomers and/or enantiomers depending on the exact structure of the starting material and the selectivity of the reaction.

It should be recalled that enantiomers have identical physical and chemical properties, while diastereomers can have different chemical and physical properties. Consequently, it is relatively easy to detect the presence of multiple diastereomers during normal laboratory manipulations such as chromatography and spectroscopy. In contrast, the presence of two enantiomers is more difficult to detect and special laboratory supplies, such as chiral silica gel supports or chiral shift reagents, are needed to analyze for enantiomers.

In this experiment, you will attempt to reduce a ketone with sodium borohydride to form a diastereomeric mixture of alcohols. The mixture of diastereomers will be separated by chromatography and analyzed by 1H NMR.