Solid-liquid Phase Equilibrium Thermodynamics Of D(-)-Salicin In Pure And Binary Solvent Systems

As a raw material with important economic value,D(-)-salicin is widely used in the fields of food,cosmetics and medicine industries.Solubility is an important basic data for studying the solid-liquid phase equilibrium process of substances.However,there is no literature report on the solubility of D(-)-salicin in the existing literature,which can not directly reflect the dissolution behavior of D(-)-salicin,and is not enough to design the crystallization process.Therefore,the purpose of this paper is to systematically and comprehensively determine the solubility data of D(-)-salicin in different pure and binary mixed solvent systems.In this paper,the static weighing method is adopted under the conditions of P=101.3 k Pa and T=283.15 K?323.15 K,the solubility data of D(-)-salicin in 12monosolvents(methanol,ethanol,n-propanol,i-propanol,n-butanol,i-butanol,n-pentanol,acetone,acetonitrile,1,4-dioxance,ethyl acetate and water)and four binary solvents(water+ethanol,water+acetone,water+isopropanol,water+methanol)were determined.The experimental results show that the solubility of D(-)-salicin increases with the increase of temperature in all solvent systems.At constant temperature,the solubility of D(-)-salicin in four binary solvent systems first increased and then decreased with the increase of mole fraction of water.The order of D(-)-salicin in twelve pure solvents is:water>methanol>1,4-dioxane>ethanol>n-propanol>isopropanol>n-butanol>isobutanol>n-pentanol>acetone>acetonitrile>ethyl acetate.For the monosolvents,the solubility of D(-)-salicin may be affected by certain factors,such as polarity,hydrogen bond,viscosity,molecular structure,and so on.The solubility of D(-)-salicin was mathematically represented by the modified Apelblat,Jouyban-Acree,Apeblat-Jouyban-Acree,Yaws,Machatha,and Apelblat-Machatha models,respectively.The fitting results are good,indicating that these six models can be used to correlate and predict the solubility of D(-)-salicin.In order to further analyze the solute-solvent and solvent-solvent interactions,this paper uses KAT-LSER model and Hansen solubility parameters to analyze the solubility data of D(-)-salicin in many aspects.The KAT-LSER model carried out MLRA on pure solvent and found that the effects of the hydrogen bond donation ability(?),the hydrogen bond acceptance ability(?),the dipolarity-polarisability parameter(?*)and cavity terms(?_H)on the solubility of D(-)-salicin are 28.66%,22.30%,29.80%and 19.24%,respectively.For binary mixed solvent systems,the KAT-LSER model derives the two-parameter optimal MLRA conclusions that is the water+ethanol(methanol)system(consisting of?*and a cavity term)and the water+acetone(isopropanol)system(consisting of?and a cavity term),respectively.The Hansen solubility parameters can well explain the solubility sequence of D(-)-salicin alcohol solvents,and make reasonable predictions for the co-solvency phenomenon and the maximum peak position of the binary mixed solvent system.This paper can provide basic solid-liquid equilibrium data for the production and crystallization purification of D(-)-salicin in industry.