Spectroscopic probes for hydrogen bonding, extraction impregnation and reaction in supercritical fluids

Abstract

Spectroscopy is used for monitoring a number of processes relevant to solution, extraction and impregnation in supercritical CO₂(scCO₂). Examples include: a combined infrared (IR) and ultraviolet study of the interaction between para-hydroquinone (HQ) and tributyl phosphate in scCO₂, which reveals hydrogen bonding, detected by the characteristic v(O–H) IR bands; IR measurement of the solubility of CpMn(CO)₃(Cp =η⁵–C₅H₅) in scCO₂ as a function of temperature and pressure; an investigation of the uniformity of supercritical impregnation of CpMn(CO)₃ into 4 mm diameter pellets of polyethylene (PE) using Fourier-transform infrared (FTIR) microscopy and FTIR depth profiling by photoacoustic detection; and an IR study of the photochemical reaction of CpMn(CO)₃ with N₂ with PE film.