Determination of l-Valine Solubility in 12 Monosolvent Systems at Multiple Temperatures from 283.15 to 323.15 K

The solubility data of l-valine were measuredby the staticgravimetric method in 12 pure solvents (water, methanol, acetonitrile,1,4-dioxane, n-propanol, isopropanol, ethanol, acetone,methyl acetate, ethyl acetate, n-butanol, and isobutanol)at 283.15-323.15 K (except for 1,4-dioxane at 288.15-328.15K) and 101.2 kPa. The increasing temperature shows a positive effecton l-valine solubility in all the solvents. In addition,the solubility sequence of l-valine at 298.15 K is water> methanol > ethanol >1,4-dioxane > isobutanol > acetone> n-butanol > ethyl acetate > acetonitrile> methyl acetate> isopropanol > n-propanol. The polymorphismof l-valine was investigated by the powder X-ray diffractiontest,and the patterns show that there is no crystal transformation in theprocess of solubility measurement. The main factors influencing thesolubility behavior include solvent polarity (E (T)(30)), hydrogen bond, cohesive energy density, and Hansensolubility parameters (HSPs). Two mathematical models, i.e., the modifiedApelblat model and the Yaws model, were applied to correlate the measuredsolubility data. The ARDs, RMSDs, AIC, and Akaike weights were calculatedto evaluate the fitting results.