CHROMATOGRAPHY, Vol. 24 (2003), No. 3, pp. 121-125
Enthalpy.entropy compensation for enantio.separation on cellulose and amylose tris (3, 5.dimethylphenylcarbamate) derivatives as stationary phases
Masato Kazusaki*, Toshiya Shoda and Hirofumi Kawabata
Chemical Analysis Research Group, Pharmaceutical Research & Technology Center, Dainippon Pharmaceutical Co., Ltd. 1-5-51 Ebie, Fukushima-ku, Osaka, 553-0001, Japan
The thermodynamics of enantioseparation on cellulose and amylose tris (3, 5dimethylphenylcarbamate) derivatives (CHIRALCEL OD RH and CHIRALPAK ADRH) was studied in the reversedphase mode. The differences of enthalpic and entropic changes of enantioselective adsorption are discussed with the aim to rationalize their possible contributions to the overall chiral recognition. On the cellulosederived ODRH column chiral recognition was completely enthalpydriven with a negative entropic contribution. However, positive entropic contribution for enantioseparation was observed on an amylosederived ADRH column. Enthalpyentropy compensation concerning enantio separation indicates that enthalpic gain/loss was substantially cancelled out by the entropic loss/gain on both columns. This relationship leaded to constant Gfor enantioseparation. It was also revealed that the entropic contribution caused the greater capability for enantio separation on an amylosederived ADRH column than on a cellulosederived ODRH column.
Keywords: CHIRALCEL OD|RH, CHIRALPAK AD|RH, enthalpy|entropy compensation, vanft Hoff plot