NMR study of solid naphthalene solubilities in supercritical carbon dioxide near the upper critical end point

Solid solubilities of naphthalene in supercritical carbon dioxide have been measured near the upper critical end point of the binary mixture by using a novel, in situ NMR technique. Solubility data were obtained at 50.0, 55.0, and 58.5°C over a pressure range of 120-500 bar. The pressure-temperature trace of the solid-liquid-gas phase line that terminates at the upper critical end point was also determined. The solubility results are discussed in terms of the supercritical solubility theory of Gitterman and Procaccia. This approximative analysis gives the location of the upper critical end point as T_c = 60.1°C and P_c = 226 bar.