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Review date: July 24, 2003
PNNL-SA-27883

Solution Dynamics of Perfluorobenzene, Benzene, and Perdeuterobenzene in Carbon Dioxide as a Function of Pressure and Temperature

.R. Yonker. 1999. J. Phys. Chem.A, 104, 685-691.

Abstract: The ¹⁹F, ¹H, and ²H relaxation times of perfluorobenzene, benzene, and perdeuterobenzene were measured in carbon dioxide using capillary high-pressure NMR spectroscopy. The pressure range for the measurement of the ¹⁹F, ¹H, and ²H nuclear relaxation times was between 400 and 2300 atm over a temperature range of 298-423 K. The density regime of the solvent, carbon dioxide, over these conditions was between 0.55 to 1.27 g/cm³. Over this wide range of solvent conditions, the contributions to the molecular relaxation processes for both ¹H and ¹⁹F in CO2 were determined. These conditions were chosen to address the occurrence of specific molecular interactions between CO2 and fluorine. From the comparison of the relaxation processes for ¹⁹F and ¹H in CO2, especially at high densities, any interaction between fluorine and carbon dioxide should be prevalent. No specific interaction between fluorine and CO2 that contributed to the molecular relaxation of these nuclei was noted over the temperature and pressure range investigated in this study.