Solubility and Model Correlation of Amprolium Hydrochloride in Pure Solvent at the Temperature Range of 273.15-313.15 K

The solubility data of amprolium hydrochloride in 12 pure solvents including methanol, ethanol, n-propanol, isopropanol, n-butanol, i-butanol, n-octanol, acetone, ethyl acetate, 1,4-dioxane, acetonitrile, and cyclohexanone was determined at temperature range from T = 273.15 to 313.15 K. The maximum value was obtained in methanol (x = 12.99 x 10(-4) at T = 313.15 K, in mole fraction) and the minimum data in n-octanol (x = 2.0 x 10(-6) at T = 273.15 K, in mole fraction). As expected, it increased with rising temperature in all of the selected solvents. The values from high to low obeyed the following sequence: methanol > acetone > cyclohexanone > ethanol > 1,4-dioxane > n-propanol > ethyl acetate > n-butanol > isopropanol > i-butanol > acetonitrile > n-octanol. Moreover, the results of infrared spectrogram indicated that there was no polymorph transformation or solvate formation during the determination process. The modified Apelblat equation and lambda h equation were applied to correlate the solubility data. The maximum values of the root mean square deviation (RMSD) and relative average deviation (RAD) were 4.02 x 10(-5) (in methanol) and 4.77% (in ethanol), respectively. Moreover, two statistical values selected in modified Apelblat equation are significantly smaller than those in lambda h equation. Therefore, modified Apelblat equation is more suitable to correlate the solute solubility in selected solvents. More importantly, the solubility data will be significant to the engineers and researchers before recrystallization.