High-Pressure ~(19)F NMR Measurements of a Series of Fluorinated Benzenes in Supercritical Carbon Dioxide

摘要

The high-pressure and high-resolution NMR cell method has been developed for precise measurements of supercritical carbon dioxide solutions.~(19)F NMR chemical shifts of a series of fluorinated benzenes,C_6H_nF_m(n=6-m and m=1 ~ 6)in CO_2 at dilute concentrations were measured over a wide pressure range up to 35 MPa at 314.3 K.The density dependence of the corrected chemical shift,where the bulk magnetic susceptibility contribution was subtracted,was well represented by a cubic function of CO_2 density for any fluorinated benzene.The linear coefficients,arising from pairwise intermolecular interactions,were found to be dependent on the numbers and positions of fluorine atoms in the fiuorinated benzenes.The solute-solvent interaction between fluorine and CO_2 was discussed.