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
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 G¡Æfor 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.
CHIRALCEL OD|RH, CHIRALPAK AD|RH, enthalpy|entropy compensation, vanft Hoff plot