Abstract:

The shifts of stretching vibration frequency of the radicals in salicylic acid and the interaction of entrainer and solute in supercritical CO₂ with the addition of entrainer by using infrared spectroscopy were studied. The stretching vibration frequency of both radicals C=Oand O—Hshifted towards a lower frequency with ethanol as entrainer, while the stretching vibration frequency of radical C=Oshifted towards a higher frequency with acetone as entrainer. The results showed that the solubility of salicylic acid in supercritical CO₂ with ethanol as entrainer was much higher than that with acetone as entrainer. The influence of the action of hydrogen bond was much stronger than the action of solvent polarity on the increase of solute solubility.