Solubilities of C-Tetraalkylcalix[4]resorcinarenes in SCCO₂: Experimental Measurements, Characterization, and Correlation

Abstract

The solubilities of two C-tetraalkylcalix[4]-resorcinarenes, namely C-tetramethylcalix[4]resorcinarene and Ctetrapentylcalix[4]resorcinarene, in supercritical carbon dioxide (SCCO 2 ) were measured in a flow-type apparatus at a temperature range from (313.2 to 333.2) K and at pressures from (12.0 to 35.0) MPa. The C-tetraalkylcalix[4]resorcinarenes were synthesized applying our optimized procedure and fully characterized by means of gel permeation chromatography, infrared and nuclear magnetic resonance spectroscopy. The solubilities of the Ctetraalkylcalix[4]resorcinarenes in SCCO 2 were determined by analysis of the extracts obtained by HPLC with ultraviolet (UV) detection methodology adapted by our team. Four semiempirical density-based models, and the Soave−Redlich−Kwong cubic equation of state (SRK CEoS) with classical mixing rules, were applied to correlate the solubility of the calix[4]resorcinarenes in the SC CO 2 . The physical properties required for the modeling were estimated and reported.

Semi-Empirical Models and Cubic Equations of State for Correlation of Solids Solubility in scCO2: From Simple to Complex Substances

“…The solubilities of acrylamide and C-tetramethylcalix [4]resorcinarenein scCO 2 were experimentally measured and reported in the literature for the first time by the present authors and colleagues [18,19]. The data obtained is completely reliable and consistent even for such difficult compounds with very low solubility as calyx [4]resorcinarenes [19].…”

“…β-carotene) there are some scatter and uncertainties associated with the experimental solubility data reported by the different laboratories. In view of this, the performance of the models chosen for correlating the solubility of bixin and β-carotene in scCO 2 is examined on the basis of our experimental data only, [19,20,23] respectively.…”

“…Aside from the information that the melting point of this calixarene should be higher than 300 o C there are no other data available in the literature. The melting point was hence determined by DSC analysis using the Pyris software [19]. All other properties required should thus be estimated.…”