Isothermal solubility in supercritical carbon dioxide of solid derivatives of 2,3-dichloronaphthalene-1,4-dione (dichlone): 2-(Benzylamino)-3-chloronaphthalene-1,4-dione and 2-chloro-3-(phenethylamino)naphthalene-1,4-dione

Abstract

Two solid derivatives of dichlone (2,3-dichloronaphthalene-1,4-dione), 2-(benzylamino)-3-chloronaphthalene-1,4-dione and 2-chloro-3-(phenethylamino)naphthalene-1,4-dione were synthetized by replacing the chlorine atom with the amine substituent by means of a substitution reaction, with a purity grade of 98% mol mol−1. The solubility expressed as molar fraction of each solid derivative in the supercritical carbon dioxide rich-phase was measured at (313, 323 and 333) K and pressures ranged from (8.59 to 32.51) MPa, using a recirculation method with direct determination of the solubility in a high performance liquid chromatography. Results indicated that the measured solubility ranges were between (23·10−6 and 114·10−6) mol mol−1 for solid 2-(benzylamino)-3-chloronaphthalene-1,4-dione. For the second solid derivative, 2-chloro-3-(phenethylamino)naphthalene-1,4-dione measured solubilities were between (57·10−6 and 161·10−6) mol mol−1. Experimental measured solubility values were analyzed by using a procedure that included the estimation of the combined expanded uncertainty for each solubility data point and the evaluation of the thermodynamic consistency utilizing a test based on the Gibbs-Duhem equation. In addition, the self-consistency was verifying by correlating the experimental solubility data with a semi-empirical model as a function of temperature, pressure and pure carbon dioxide density.