Solubilities in the system comprising nitromethane and hexane have been reported in three publications, all using the synthetic method.Mulliken and Wakeman1 determined the upper critical solution temperature, while Malesinska2 and Rolla et al.3 measured the mutual solubilities of the components between 366 and 376 K and between 357 and 376 K respectively.
Values obtained by the graphical interpolation or extrapolation from the data sheets are presented in the following table. Data are "recommended" if two or more apparently reliable studies are in reasonable (± 5 % relative) agreement. All other data are regarded as tentative only.
Recommended and Tentative values for the mutual solubilities of nitromethane and hexane
The upper critical solution temperature has been reported as 375.4 K3, 375.55 K2 and 379 K1. The UCST of Mulliken and Wakeman,1 is rejected. The remaining values are in good agreement and their average, (375.5 ± 0.1) K is recommended.
The corresponding critical solution composition has been reported as xc1 = 0.6225 (Malesinska2) and xc1 = 0.585 (Rolla et al.3). Their average value, xc1 = (0.604 ± 0.018), is recommended.
The recommended UCST and xc1 are consistent with the values calculated on the basis of critical evaluation of all experimental critical solution compositions in the nitromethane - n -alkane series and discussed at the beginning of this volume. The numerical values reported in the above tables have been approximated by the
equation based on scaling law (described in the Introduction material to this volume "Relations of Solubility Data in Binary Systems Containing Nitromethane") and the following parameters have been adjusted:
a1 = 0.89257, a2= 0.19671, b1 = 3.20560, b2 = -3.07772(mean standard error of estimate was 0.0049).
For approximation the recommended value of UCST and xc1 have been used. This relationship is presented in Fig. 12 together with experimental data reported in Malesinska2 and Rolla et al.3