Solubility and Hansen Solubility Parameters of N-Benzyloxycarbonyl-l-serine in 12 Monosolvents from 283.15 to 323.15 K

The solid–liquid equilibrium solubility and solvent effects of N-benzyloxycarbonyl-l-serine in 12 monosolvent systems (water, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, acetonitrile, 2-butanone, acetone, methyl acetate, and ethyl acetate) were reported in this work. All of the solubility data were measured at 283.15–323.15 K (5 K interval) by the static gravimetric method at a pressure of 101.2 kPa. Among the 12 monosolvents, the solubility increased with the increase of absolute temperature; the order is acetone > isopropanol > n-propanol > sec-butanol > n-butanol > 2-butanone > isobutanol ≈ n-pentanol > methyl acetate > ethyl acetate > acetonitrile > water. The solubility is the largest in acetone (0.2055 mol·mol–1 at 323.15 K) and the smallest in water (9.737 × 10–4 mol·mol–1 at 283.15 K). According to the solubility data analysis results, the solubility of N-benzyloxycarbonyl-l-serine is positively correlated with the polarity of the solvent. However, its solubility could be affected by other factors, such as propensity for hydrogen bonding acceptor for isopropanol, structural similarity for acetone, cohesive energy density for water, acetonitrile, and sec-butanol, which lead to different dissolution behavior. In addition, the Hansen solubility parameters (HSPs) were used to further analyze its solubility behavior. The Yaws model and the modified Apelblat model were employed to correlate the experimental solubility, and the fitting results of the two models were both well. In addition, through the comparison of the AIC values and Akaike weights of the two models, the modified Apelblat model yielded a more satisfactory correlation result. The results may provide a theoretical basis for the preparation and application of N-benzyloxycarbonyl-l-serine.