Research on the 2-Chloro-4-amino-6,7-dimethoxyquinazoline Solubility in 12 Monosolvents at Various Temperatures: Experimental Measurement and Thermodynamic Correlation
The present study investigating the experimental equilibrium solubility of 2-chloro-4-amino-6,7-dimethoxyquinazoline (CADQ) dissolved in 12 kinds of neat organic solvents, including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutyl alcohol, ethyl acetate, toluene, N,N-dimethyl formamide (DMF), N-methylpyrrolidone (NMP), 1,4-dioxane, and cyclohexanone, was determined in an equilibrium state by means of the isothermal saturation method at temperature ranges of 273.15–313.15 K under normal atmospheric conditions of 101.2 kPa. The rising temperature showed the obvious positive effect on the increasing CADQ solubility gradually, and the maximum value (0.01370 at 313.15 K, in mole fraction) was observed in NMP for the studied temperature ranges. The equilibrated solid state of CADQ was characterized by applying the Fourier transform infrared (FT-IR) spectrometer, resulting in no existences of crystal transition, solvate formation, or polymorphic transformation in the experimental process. Results showed that the mole fraction solubility of CADQ abiding the order from high to low is as follows: NMP (0.01370, 313.15 K) > DMF (0.01157, 313.15 K) > cyclohexanone (3.847 × 10–3, 313.15 K) > ethyl acetate (1.010 × 10–3, 313.15 K) > n-butanol (9.288 × 10–4, 313.15 K) > isobutyl alcohol (8.408 × 10–4, 313.15 K) > n-propanol (7.692 × 10–4, 313.15 K) > ethanol (6.934 × 10–4, 313.15 K) > isopropanol (6.220 × 10–4, 313.15 K) > methanol (5.437 × 10–4, 313.15 K) > 1,4-dioxane (2.535 × 10–4, 313.15 K) > toluene (2.174 × 10–5, 313.15 K). Then, the achieved CADQ solubility values were correlated and calculated by mathematical models containing the modified Apelblat equation and λh equation, respectively. As a consequence, the largest root-mean-square deviation (RMSD) and average relative deviation (ARD) were 1.020 × 10–4 and 2.352%, respectively, which turned out to be that the calculated data agreed well with the experimental ones.
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