Relationship of Chemical Structure to Supercritical-Fluid Solubility and toCosolvent-Modifier Properties: A Literature Review

摘要

This report describes a literature review on solubility and cosolvent effects insupercritical fluid extraction (SFE). A cosolvent modifier is a second solvent that is added, usually in small (<10%) amounts, to a supercritical solvent to enhance the solubility of a solute in that solvent. In general, nonpolar solvents such as ethane tend to most efficiently dissolve nonpolar solutes such as hydrocarbons, while more polar solvents such as CHF3 tend to most efficiently dissolve more polar solutes. Supercritical carbon dioxide (SF-CO2) is a fairly good general solvent. With regard to cosolvent effects, the main correlation seems to be that in order for addition of a given cosolvent to cause a large increase in the solubility of a given solute, there should be a specific interaction (e.g., hydrogen bonding, charge transfer, dipole-dipole interaction, etc.) between the solute and the cosolvent involved. The behavior of HMX and RDX in supercritical fluid chromatography (SFC) and SFE behavior are also summarized. Finally, some suggestions are made as to possible ways of enhancing the extractability of HMX and RDX in supercritical solvents. jg.