Preparative separation of amino acid enantiomers as N-TFA, O-isopropyl derivatives by continuous countercurrent gas-liquid chromatography

Preparative separation of derivatives of amino acid enantiomers was carried out by a countercurrent gas–liquid chromatography (CCGLC) with chiral liquid phases, N‐stearoyl‐L‐valine tert‐butylamide and/or N‐stearoyl‐L‐leucine tert‐butylamide. In order to make effective use of these phases and also to lower the viscosity, Apiezon C was added as diluent. Through a repeated operation of a temperature gradient, purities more than 99% of leucine and α‐amino butyric acid derivatives were proved to be obtained. © 1993 Wiley‐Liss, Inc.