Solubilities in the system comprising acetonitrile (1) and decane (2) have been reported in four publications. Francis¹ reported the upper critical solution temperature. Schmid et al.² determined the upper critical solution temperature by the synthetic method. McLure et al.³ measured of the upper critical temperature solution and critical solution composition of components (1) and (2) during as study of solubilities of acetonitrile with alkanes (C₅-C₁₈). Antosik et al.⁴ studied the mutual solubility of (2) and (1) between 295 to 380 K by an synthetic method.
The upper critical solution temperature has been reported as 380.46 K,⁴ 380.7 K,^1,2 and 381.7 K,³ these data are in reasonable agreement and thus their average value: UCST = 380.9 ±0.5 K and is recommended. The corresponding critical solution composition has been reported as x_cl = 0.7143⁴ and x_cl = 0.75.³
All experimental values reported⁴ have been approximated by an equation based on the scaling law (described in the introduction to this volume) for which the following parameters have been derived:

a₁ = 0.8399, a₂= -0.1090, b₁ = 3.9660, b₂ = -4.1114

(mean standard error of estimate was 0.0173).
For approximation x_cl and UCST from Antosik et al.⁴ have been used. In the opinion of the evaluators, the mutual solubilities calculated by this equation may be treated as tentative. The results of calculations for the selected temperatures are presented in the following table. This relationship, together with experimental results,⁴ are also presented in Fig. 11.