Solubility of Triphenylphosphine, Tris(p-fluorophenyl)phosphine, Tris(pentafluorophenyl)phosphine, and Tris(p-trifluoromethylphenyl)phosphine in Liquid and Supercritical Carbon Dioxide

The solubility of the solid substances triphenylphosphine P(C 6 H 5 ) 3, tris( p -fluorophenyl)phosphine P(C 6 H 4 F) 3, tris(pentafluorophenyl)phosphine P(C 6 F 5 ) 3, and tris( p -trifluoromethylphenyl)phosphine P[4-(CF 3 )C 6 H 4 ] 3 in CO 2 was measured as a function of pressure at 300.0 K, 310.0 K, 320.0 K, and, in the case of triphenylphosphine, at 330.0 K. For this purpose, a new recirculation view cell apparatus coupled to a high-performance liquid chromatograph was constructed. The solubility S of triphenylphosphine was measured up to 30.3 MPa and up to a maximum of 0.119 mol/L, tris(pentafluorophenyl)phosphine up to 12.0 MPa and 0.246 mol/L, tris( p -fluorophenyl)phosphine up to 18.9 MPa and 0.468 mol/L, and tris( p -trifluoromethylphenyl)phosphine up to 12.0 MPa and 0.470 mol/L. The increasing degree of fluorination in these four substances led to an increase of their solubility in carbon dioxide.