The effect of the end group, molecular weight and size on the solubility of compounds in supercritical carbon dioxide

Abstract

End groups of bis(2-hydroxyethyl)ether (compound 1) and tetraethylene glycol (compound 2) were modified with methyl malonyl chloride to produce two new compounds: malonic acid 2-[2-(2-methoxycarbonyl-acetoxy)-ethoxy]-ethyl ester methyl ester (compound 3) and Malonic acid 2-(2-{2-[2-(2-methoxycarbonyl-acetoxy)-ethoxy]-ethoxy}-ethoxy)-ethyl ester methyl ester (compound 4). And then the solubility of compounds 1–4 were investigated and compared in supercritical carbon dioxide (scCO2) at a temperature range of 313–363K and in the pressure range of 9.2–25.7MPa. The effect of the end group, molecular weight and size for the solubility of the compounds were discussed. In addition, the tested solubility data were calculated and correlated with a semiempirical model at different pressures and temperatures, which showed satisfactory agreement with each other and the average absolute relative deviation was in the range of 2.61% and 33.25%. The Chrastil model also showed satisfactory agreement with each other and the average absolute relative deviation was in the range of 1.69% and 11.53%.