THE USE OF HIGH-PRESSURE NMR FOR THE DETERMINATION OF PHASE-BEHAVIOR FOR SELECT BINARY SOLVENT SYSTEMS

High pressure NMR has proven itself to be a valuable technique for the study of supercritical fluid solutions. In this manuscript, we descri be the extension of high pressure NMR to the investigation of the phas e behavior for two binary solvent systems; ethylene-methanol and propa ne-methanol. The phase behavior was investigated as a function of pres sure and temperature, with the molar composition of both phases being determined simultaneously, in situ, in a high pressure capillary NMR c ell. The hydrogen bonding behavior of the alcohol in both phases deter mined in these experiments, provides important physicochemical informa tion regarding solvent interactions occurring in both the liquid and v apor phase. High pressure NMR proves to be an efficient method for obt aining vapor liquid equilibrium data and critical conditions of binary solvent systems. This methodology should also be applicable to ternar y systems as well as to more extreme solvent systems, such as, supercr itical water. (C) 1998 Elsevier Science B.V. All rights reserved.