Détermination des paramètres thermodynamiques de transfert eau/ n-octanol de barbituriques : application aux relations quantitatives

Abstract

Thermometric titrimetry allows the determination of the three thermodynamic parameters of transfer ( ΔG 0 T , ΔH 0 T , and ΔS 0 T ) from water to n-octanol for barbiturates. The transfer is entropy driven when the substituents are saturated; when one is unsaturated, this entropy effect is less marked. For phenobarbital, enthalpy and entropy effects are cooperative. Quantitative structure—activity relationships analyzed with these data show no improvement when transfer enthalpy or entropy is used instead of transfer free energy (log P).