Analyzing the hydrocyanation reaction: chiral HPLC and the synthesis of racemic cyanohydrins

A method to directly analyze unprotected cyanohydrins (with regard to enantiomeric purity and conversion) via chiral HPLC is described. The influence of the solvent composition on the stability of the unprotected cyanohydrins is investigated. By acidifying the solvent during HPLC analysis, hydrocyanation reactions can be directly followed in time. For many chiral cyanohydrins it is possible to determine both conversion and enantiomeric purity without prior protection of the cyanohydrin. Using a special aqueous-organic two-phase system racemic cyanohydrins can be synthesized in excellent yields.