Study of the mechanism of enantioseparation.: Part XII.: Comparison study of thermodynamic parameters on separation of phenylcarbamic acid derivatives by HPLC using macrocyclic glycopeptide chiral stationary phases

Four macrocyclic glycopeptide chiral stationary phases ( CSPs) based on native teicoplanin ( Chirobiotic T), methylated teicoplanin aglycone ( Chirobiotic m-TAG), teicoplanin aglycone ( Chirobiotic TAG), and vancomycin ( Chirobiotic V) were compared for the high performance liquid chromatographic ( HPLC) separation of enantiomers of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4- alkoxyphenylcarbamic acid ( potential local anaesthetic drugs). The enthalpies (Delta H-i), entropies (Delta S-i), and Gibbs energies ( Delta G(i)) of transfer were evaluated for the separation of these compounds. The enantiomers were separated isothermally in the range of 0-50 degrees C with 10 degrees C increments, in the polar organic mode. The thermodynamic parameters were calculated in order to gain an understanding of the driving forces for retention in this chromatographic system. From these results, it is evident that the elongation of the alkoxy-chain has major influence on the values of (Delta S-i) when using the vancomycin CSP and on the values of (Delta H-i) using the teicoplanin-type CSPs.