Key words: molecular association, solubility, supercritical fluid, methylxanthine
Experimental data on solubility of methylxanthines (theophylline and theobromine) in
the system «supercritical (SC) CO2-methanol» at various concentrations of methanol
is analyzed in the framework of the ASL (Associated Solution + Lattice) model based
on the molecular association theory and the simple lattice concept. 1H NMR
spectroscopy is applied to investigate hetero-association of methylxanthines with
methanol at 313 K. The contribution of molecular association to the solubility of
methylxanthines in a mixed SC CO2-methanol solvent is discussed. It is shown that the
presence of NH groups in methylxanthine molecule (i.e. theobromine and theophylline
vs. caffeine) leads to the increasing contribution of solubility component related to the
molecular association.
doi:10.1134/S1990793116070083