Thermodynamic characteristics of the sorption of adamantane derivatives in glycerol containing the additions of β-cyclodextrin under the conditions of equilibrium gas–liquid chromatography

Resumo

The thermodynamics of the sorption of adamantane and its derivatives, as well as of some derivatives of n-decane, in glycerol with the addition of β-cyclodextrine (β-CD) is studied under the conditions of gas–liquid chromatography. The constants of an infinitely dilute solution–vapor phase equilibrium (Ostwald coefficient, classical Henry coefficient), as well as equilibrium values of the sorption heat and entropy, are determined. It is shown that accomplishment of the macrocyclic effect associated with the formation of the sorbate–β-CD inclusion complexes significantly affects the thermodynamic characteristics of sorption. The formation of stable complexes between β-CD and adamantane derivatives causes noticeable differences in the sorption of linear and framework molecules. The influence of peculiarities of the molecular structure of adamantane derivatives on the character of their retention in the glycerol–β-CD sorbent is established. Conclusions regarding selective properties of the glycerol–β-CD system with regard to the structural isomers in the series of adamantane derivatives are made. For the first time, the limiting activity coefficients and excess thermodynamic functions of mixing for some adamantane derivatives in the state of infinitely dilute solutions in pure glycerol and glycerol with the additions of β-CD are determined by the chromatographic method.