The liquid-liquid coexistence curve and the heat capacity for binary solution of (2-propanol + 1-octyl-3-methylimidazolium hexafluorophosphate) have been precisely measured. The values of the critical exponents alpha and beta, characterizing the critical anomalies of the heat capacity and the coexistence curve respectively, were deduced and found to be consistent with theoretical predictions. The asymmetric behavior of the diameter of the coexistence curve was studied in the frame of the complete scaling theory, demonstrating that the heat capacity related term is of importance. Furthermore, the restricted primitive model (RPM) was used to calculate the reduced upper consolute temperature and density, which together with a comparative larger value of A(+) indicated a character of solvophobic criticality. (C) 2016 Elsevier Ltd.