The Solid-liquid Phase Equilibrium Thermodynamics Of Sodium Naphthalene-1,5-disulfonate In Pure And Binary Solvent Systems

Naphthalene-1,5-disulfonate is an important monomer in solid-state chemical reaction of coordination polymer,which can be used to construct flexible three position layered structure.The crystallization of monomers has an important influence on the solid-state chemical reaction.The quality attributes of crystal purity,crystal habit,crystal size and distribution can be controlled by controlling the crystallization process of monomers,thus affecting the subsequent single crystal to single crystal transformation.However,the solubility data of naphthalene-1,5-disulfonate in common pure solvent and binary solvent system is essential in the optimization of crystallization process.However,the solubility of naphthalene-1,5-disulfonate in related solvents has not been reported so far.Therefore,it is necessary to study the dissolution behavior of naphthalene-1,5-disulfonate.In this paper,maltitol and xylitol are selected to verify the static weighing method,which proves that the static weighing method can be used to measure the solubility of naphthalene-1,5-disulfonate sodium.Then,the solubility of various pure solvents was determined by experiments.Finally,water was used as positive solvent and ethanol,isopropanol and acetone as counter solvent.On this basis,the solubility of naphthalene-1,5-disulfonate in three binary solvent systems was determined.The experimental results show that the solubility of naphthalene-1,5-disulfonate increases with the increase of water mole fraction and temperature.Through the X-ray powder diffraction(XRD)analysis of naphthalene-1,5-disulfonate crystals prepared in different solvents,it is found that complex polymorphic transformation can take place in the investigated solvent system,and there are three crystal types,named ?,?,? respectively,and the critical point of crystal transformation is determined.Through data analysis,it is found that the dissolving behavior of naphthalene-1,5-disulfonic acid sodium in pure solvent is mainly affected by solvent type and solvent properties.In addition,KAT LSER model was used to fit the solubility data of naphthalene-1,5-disulfonate in five pure solvents,and the improved Apelblat,Jouybana-Acree,van't Hoff-Jouybana-Acree and Apelbla-Jouybana-Acree models were used to fit the solubility data.The results show that the solubility of naphthalene-1,5-disulfonate can be predicted by four thermodynamic models.The best fitting effect of Apelbla-Jouybana-Acree model is determined by comprehensively considering ARD,RMSD and the number of model parameters.