Enthalpy‐entropy compensation effect in gas chromatographic enantiomeric separation

Abstract

In this paper, the enthalpy-entmpy compensation effect in the enantiorneric separation by modiGed cyclodextrins (CD) and diamide c h i d stationary phase ( G P ) gas chromatography was investigated using the method of plotting A(AH) versus A(AG) rhm combined with t-test statistic analysis. 'The investigated racemates cover a-phenylethylamine and its analogs, 2-alkylamines, c h i d acyclic alcohols, halogenated arylethanediol-1 , 2-dipe1fIuompropionates~ amino acid and its analogs, and two series of compounds containing chlom and b m substituents. Fmm the compensation analysis results, the effects of the diluent composition in the investigated chiral stationary phases, the size and the d i e d p u p s on investigated cyclodexbins, the derivatization mthods and the groups attached to the stemcentem on enantiomeric separation mechanisms were all discussed.

Entropy−Enthalpy Compensation in Chemical Reactions and Adsorption: An Exactly Solvable Model

“…The general phenomenon “enthalpy−entropy compensation” in essence refers to the experimental observation of a linear scaling between enthalpy (Δ h i ) and entropy (Δ s i ) for a set of related reactions (labeled by the index i ) normalΔ italich italici = normalα + βΔ italics italici where α and β are constants, with β called the “compensation” temperature, as well as a common isokinetic/isoequilibrium temperature for all van’t Hoff plots (see below). This compensation phenomenon has long been claimed to be observed in an extremely wide range of areas, such as thermal desorption kinetics, micellization, − chromatography, − Langmuir adsorption, water sorption, drug−receptor binding, − melting, , thermal transitions of peptides, protein and nucleic acid unfolding, , solution extraction, ion hydration, conformational transitions, dielectric relaxation, formation of supramolecular and van der Waals complexes, capsules, DNA, ligand solvation, thermal death of bacteria, viruses, and yeasts, evolutionary adaptation of proteins, viscous flow of simple and polymeric liquids at high temperatures, conductivity of organic substances, electrical conductivity of single crystals, plasticization−antiplasticization transition, , dispersion of quantum dots, dissociation of lipid complexes, thermal decomposition, thermal isomerization, oxidation and substitution reactions, proton and electron , transfer reactions, depolymerization, photoisomerization, hydrolysis, , cycloaddition, − …”