Solubility and thermodynamic parameters of 5-Fluoro-2-oxindole in nine pure solvents and binary solvent mixtures at T = (278.15–323.15) K

In this research, we employed a static equilibrium method to measure the solubility of 5-Fluoro-2-oxindole in nine pure solvents (n-hexane, n-propanol, tetrahydrofuran, isopropanol, methanol, ethyl acetate, N,N-dimethylformamide, acetonitrile, acetone) and three binary solvents (n-hexane+ tetrahydrofuran, ethyl acetate + tetrahydrofuran, acetonitrile + tetrahydrofuran) from 278.15 K to 323.15 K. The results demonstrate that as the temperature increases, the solubility of 5-Fluoro-2-oxindole increases in nine solvents selected. The modified Apelblat model and the λh model were adopted to correlate the solubility in pure solvents; meanwhile, we employed the CNIBS/R–K model and the Jouyban–Acree model to correlate the solubility in binary solvent mixtures. The maximum RAD values of modified Apelblat model and λh model are 0.64% and 0.71%; respectively; the maximum RMSD values are 0.076% and 0.058%. The corresponding maximum RAD values of the CNIBS/R–K model and the Jouyban–Acree model are 1.27% and 2.22%. In general, these equations emerge an excellent fitting effect.