Solubility Measurement and Modeling of 5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (Y Form) in Pure and Binary Solvents

Abstract

5-Methyl-2-[(2-nitrophenyl) amino]-3-thiophenecarbonitrile, known as ROY for its red, orange, and yellow crystal colors, has attracted great attention for its rich polymorphism and has been widely adopted as a benchmark compound in crystallization studies. Form Y of ROY is the most stable polymorph at low temperature. Solubility of form Y in six pure solvents (methanol, ethanol, ethyl acetate, acetic acid, acetone, and DMSO) at different temperatures within a range of 292.15 to 334.15 K as well as in four organic (methanol, ethanol, acetone, DMSO) aqueous binary mixtures at different solvent compositions and a temperature of 301.15 K were determined via a UV spectrophotometric method. The experimental solubility data were modeled applying a state-of-the-art semi-predictive model: the PC-SAFT equation-of-state. Both the measured data and the proposed modeling tool could further facilitate studies on solvent screening and polymorphic control for the solution crystallization of ROY.