Micellar electrokinetic capillary chromatography of thiocarbamoyl derivatives produced in reactions between isothiocyanates and amino acids

The reactions of amino acids and ammonia with the isothiocyanate derivatives: allyl-, benzyl-, but-3-enyl-, phenethyl- and phenylisothiocyanate have been investigated by UV spectroscopy, H-1-NMR, and micellar electrokinetic capillary chromatography (MECC). The influence of reaction time, media, temperature, and type of solvent used to dissolve the evaporated reaction mixture were investigated with respect to the formation and stability of substituted thiocarbamoyl (STC) derivatives of amino acids, produced in reactions with allylisothiocyanate. Long reaction time in 50% pyridine at ambient temperature resulted in the production of STC, substituted thiohydantoin derivatives and various oxidation products including dimers with net charge -2. Increased temperature speeded up the reaction, as did increment in pH. Too high pH (>11) resulted in decreased product stability, which however varied considerably both with respect to the individual amino acids used as precursors, and the solvating medium. Modification of the reaction conditions allowed selective production of allylthiocarbamoylated amino acids, neutral as well as acidic, which separated well in the developed MECC system using sodium cholate as surfactant. (C) 1999 Elsevier Science B.V. All rights reserved.