Effect of molecular structure on the thermodynamics of nitromethane plus butanol isomers near the upper critical point

Densities, isentropic compressibilities, and isobaric molar heat capacities were determined over the whole composition range fbr nitromethane + (2-but anol or isobutanol) at atmospheric pressure and at the temperatures 288.15, 293.15, 298.15, and 308.15 K. These results allowed us to obtain isobaric thermal expansivities, isothermal compressibilities, and isochoric molar he at capacities at the temperature 298.15 K. The excess quantities for the gi ven properties were obtained. In addition, liquid-liquid phase separation t emperatures were also determined, locating upper critical solution temperat ures near the experimental temperatures. The variation of the properties am ong isomers is discussed. Also, the effect of the nonrandomness of the mixt ures expected near the critical point is discussed.