Research On The Solid-liquid Equilibrium Of Naphthoic Acid Derivatives In Binary And Ternary Systems

Crystallization technology can efficiently purify a variety of chemical products and intermediates.The solid-liquid equilibrium theory and the solubility curve are the theoretical basis for the operation of the crystallization.Naphthoic acid derivatives are important raw materials and intermediates in the field of fine chemicals which are widely used in industries such as pharmaceuticals,pesticides,organic dyes and photosensitive materials.Therefore,the solid-liquid equilibrium of 2-hydroxy-3-naphthoic acid(2,3-HNA),a-naphthoic acid and ?-naphthoic acid were studied,which can be used to fill a database of solid-liquid equilibrium and provide a theoretical basis for the industrial application of naphthoic acid derivatives.In this study,at atmospheric pressure and temperature from 293.15?333.15 K,the solubility of 2,3-HNA,a-naphthoic acid and?-naphthoic acid in methanol,ethanol,n-propanol,isopropanol,n-butanol,isobutanol,acetone,acetic acid,methyl acetate,ethyl acetate,as well as 2,3-HNA in ethanol+n-propanol,a-naphthoic acid in ethanol+isobutanol,?-naphthoic acid in ethanol+methanol was determined by gravimetric method.The solubility curves of three solutes were plotted.The dissolution law,influencing factors and the co-solvent effect were analyzed.According to the modified Van't Hoff model,the thermodynamics of three solutes dissolved in ten pure solvents and mixed solvents were calculated,which are endothermic and non-spontaneous processes.The solubility of the three solutes in ten pure solvents and mixed solvent was correlated by Wilson,NRTL,UNIQUAC,Apelblat,Van't Hoff,and ?h models,respectively.The Apelblat model has the best accordance with measured data with the average ARD less than 1%.The average ARD of the UNIQUAC,Van't Hoff and ?h equations is less than 2%,which agree well with the experimental data.The average ARD of the NRTL equation is within 4%,which is within an acceptable range.The average ARD of the Wilson model correlating the solubility of 2,3-HNA and ?-naphthoic acid in the mixed solvents ranges from 4%to 7%,which has poor applicability to system compared with other models.The part of the Jouyban-Acree model that needs to use the solubility of the target solute in the corresponding pure solvent is improved by combining the simple Apelblat equation.The new model named JA-Apleblat model contains ten parameters and the applicability is improved.In addition,the new model was used to correlate the solubility of 2,3-HNA,a-naphthoic acid and ?-naphthoic acid in mixed solvents.The average ARD is less than 2%,showing good applicability.