V.A. Golubev, M.Yu. Nikiforov, G.A. Alper
Solubility of caffeine in a binary solvent supercritical CO2—methanol
The association constant caffeine—methanol at 313 K is determined using 1H NMR.
The caffeine solubility in a mixed solvent «supercritical carbon dioxide (SC-CO2) —
methanol» is calculated taking into consideration the experimentally measured value
of association constant in the framework of ASL model (Associated Solution + Lattice)
based on the theory of molecular association and a simple lattice model. Individual
contributions to the solubility are obtained and relative role of various factors
determining the solubility of caffeine in the mixed solvent are analyzed. The presence
of a maximum on the dependence of the solubility of caffeine versus the methanol
content in the system «SC-CO2 — methanol» is predicted.
Key words: molecular association, solubility, supercritical fluid, mixed solvent