Solubility of selected esters in supercritical carbon dioxide

Solubility measurement and thermodynamic modeling of pantoprazole sodium sesquihydrate in supercritical carbon dioxide

Knowing the solubility data of pharmaceutical compounds in supercritical carbon dioxide (ScCO₂) is essential for nanoparticles formation by using supercritical technology. In this work, solubility of solid pantoprazole sodium sesquihydrate in ScCO₂ is determined and reported at 308, 318, 328 and 338 K and at pressures between 12 and 27 MPa. The solubilities are ranged between 0.0301 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times$$\end{document}× 10^–4 and 0.463 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times$$\end{document}× 10^–4 in mole fraction. The determined solubilities are modelled with a new model using solid–liquid equilibrium criteria and the required activity coefficient is developed using regular solution theory. The measured solubilities data are also modelled with three recent and four conventional empirical models. The recent models used are, Alwi-Garlapati (AARD = 13.1%), Sodeifian et al. (14.7%), and Tippana-Garlapati (15.5%) models and the conventional models used are Chrastil (17.54%), reformulated Chrastil (16.30%), Bartle (14.1%) and Mendenz Santiago and Teja (MT) (14.9%) models. The proposed model is correlating the data with less than 14.9% and 16.23% in terms of AARD for temperature dependent and independent cases. Among exiting models, Mendez Santiago and Teja (MT) and Alwi-Garlapati models correlate the data better than other models (corresponding AARD% and AIC_c are 14.9, 13.1 and −518.89, −504.14, respectively). The correlation effectiveness of the models is evaluated in terms of Corrected Akaike’s Information Criterion (AIC_c). Finally, enthalpy of solvation and vaporization of pantoprazole sodium sesquihydrate are calculated and reported. The new model proposed in this study can be used for the combination of any complex compound with any supercritical fluid.

Supercritical carbon dioxide extraction of lutein from yellow maize (Zea mays) kernels: process optimization based on lutein content, antioxidant activity, and ω-6/ω-3 fatty acid ratio

Yellow maize kernels were subjected to supercritical carbon dioxide (SC-CO2) extraction to obtain a lutein-rich extract with potential nutraceutical properties. SC-CO2 extraction parameters (pressure and temperature) were optimized by employing a full-factorial (32) design of experiments and response surface methodology, based on yield of lutein, antioxidant activity, and ω-6/ω-3 fatty acid ratio of the extracts. A Chrastil equation was also developed for predicting the solubility of lutein in SC-CO2 under different extraction conditions. The optimized extraction condition was obtained at 500 bar, 70 °C for 90 min, at which the extract was found to possess a unique combination of the highest lutein yield (275.00 ± 3.50 μg/g of dry weight), along with a well-balanced ω-6/ω-3 fatty acid ratio (3:1). Moreover, the total phenol content and antioxidant activity were also found to be the highest at this condition. This lutein-rich extract is a promising nutraceutical or dietary supplement in the food industry.

Solubility of caffeine from green tea in supercritical CO2: a theoretical and empirical approach

Decaffeination of fresh green tea was carried out with supercritical CO2 in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO2 varied from 44.19 × 10(-6) to 149.55 × 10(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO2 was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 × 10(-3) mol fraction was obtained with chloroform.

A NEW SIMPLE CORRELATION FOR CALCULATING SOLUBILITY OF DRUGS IN SUPERCRITICAL CARBON DIOXIDE

During the past 20 years, supercritical fluid (SCF) based technologies have been gaining an increasing attention through the academic and industrial communities due to its advantages. One of the most important parameter for any supercritical-based technologies is the knowledge of the solute solubility at different pressures and temperatures. But, due to several concerns e.g. time and expense, measuring the solubility of all compounds in wide ranges of temperature and pressure is not possible. Respect to this, a new empirical correlation with four fitting parameters has been proposed to correlate the solubility of pharmaceuticals in different temperatures and pressures. The obtained results compared with four widely used density based correlations including Mendez-Santiago and Teja (MST), Bartle et al., Chrastil, Kumar and Johnston (KJ) revealed rather good capability of the proposed simple correlation for predicting the solubility of solutes in supercritical carbon dioxide (SC- CO 2). At last, the obtained results compared with the results of three Equations of State (EoS's) with three different mixing rules.

Synthesis of carbonated fatty methyl esters using supercritical carbon dioxide

The two-step syntheses of the cyclic carbonates carbonated methyl oleate (CMO) and carbonated methyl linoleate (CML) are reported. First, synthesis of epoxides through well-precedented chemical reactions of unsaturated fatty methyl esters with hydrogen peroxide and formic acid was accomplished. Next, a carbonation reaction with a simple tetrabutylammonium bromide catalyst was performed, allowing the direct incorporation of carbon dioxide into the oleochemical. These syntheses avoid the use of the environmentally unfriendly phosgene. The carbonated products are characterized by IR, 1H NMR, and 13C NMR spectroscopy and studied by thermogravimetric analysis (TGA). Also reported is the synthesis of a similar cyclic carbonate from the commercially available 2-ethylhexyl epoxy soyate. These carbonates show properties that may make them useful as petrochemical replacements or as biobased industrial product precursors.