| As important synthetic intermediates,o-nitrophenylacetic acid and p-nitrophenylacetic acid have been widely employed in chemical production,drug synthesis and agricultural production.It is well-known that nitrophenylacetic acid is also an essential intermediate for the syntheses of nonsteroidal anti-inflammatory drug felbinac,high efficiency antihypertensive drug atenolol and antitumor drug niraparib.The mixtures of o-nitrophenylacetic acid and p-nitrophenylacetic acid are generally obtained through nitration of phenylacetic acid,or nitration of phenylacetonitrile,followed through hydrolysis in aqueous sulfuric acid solutions,with the low selectivity.Also,the nitrophenylacetic acid isomers are difficult to separate by means of distillation operation due to their similar physicochemical properties,especially the boiling points.Solvent crystallization as a low-energy separation method can effectively compelete the unsolvable problems of distillation and obtain green safe separation.Therefore,the solid-liquid equilibrium of o-nitrophenylacetic acid and p-nitrophenylacetic acid in different systems was studied.The results provide the basis for the separation processes of o/p-nitrophenylacetic acid.The solubility data of o/p-nitrophenylacetic acid in water,methanol,ethylene glycol(EG),acetonitrile,ethyl acetate,n-propanol,ethanol,n-butanol,cyclohexane,isopropanol,N,N-dimethylformamide(DMF)and isobutanol were determined by static method ranging from 283.15 to 328.15 K.The solubility of o/p-nitrophenylacetic acid increased with the increase of temperature in the above solvents.The mole fraction solubility of o-nitrophenylacetic acid presented the subsequence in the studied solvents:DMF>methanol>ethanol(ethyl acetate)>n-propanol>n-butanol>isopropanol>EG>acetonitrile>isobutanol>water>cyclohexane and the mole fraction solubility of p-nitrophenylacetic acid presented the subsequence in the studied solvents:DMF>methanol>ethanol>n-propanol>n-butanol>ethyl acetate>isopropanol>isobutanol>acetonitrile>EG>water>cyclohexane.Moreover,the determined solubility was mathematically correlated by the Apelblat model,Wilson model,?h model and NRTL model.The maximum values of root-mean-square deviation(RMSD)rand elative average deviation(RAD)acquired with the four models were no more than 5.677×10-3 and 3.27%,respectively.The values of relative average deviation were lower via the Apelblat equation than via the other model for a certain neat solvent.In addition,the solubility was correlated to KAT parameters and cavity term based on linear solvation energy relationships concept to investigate on the solvent effectThe equilibrium solubilities of o/p-nitrophenylacetic acid in(DMF+water),(isopropanol+ water),(ethanol+water)and(methanol+ water)solvent mixtures were measured by using static method.The solubility of o/p-nitrophenylacetic acid increased with increasing temperature as well as mass fraction of organic solvent for the binary systems studied.The solute-solvte and solvte-solvte interactions was studied based on the KAT-LSER equation,and the influence of solvent effect on the solubility variation of solute in mixed solvent was investigated.Moreover,the Apelblat-Jouyban-Acree model,Jouyban-Acree model,Van't Hoff-Jouyban-Acree model and Wilson model were used to correlate the solubility data that obtained the corresponding model parameters.For the binary solvent mixtures,the maximum values of root-mean-square deviation and relative average deviation were 6.04×10-3 and 4.67%,respectively;In the meanwhile,the standard enthalpy of dissolution and transfer properties of o-nitrophenylacetic acid and p-nitrophenylacetic acid in mixed solvents were calculated.The solid-liquid phase equilibria of p-nitrophenylacetic acid+o-nitrophenylacetic acid+ethyl acetate/n-butanol at 308.15 K,318.15 K and 328.15 K were measured by Schreinemaker's method,and the ternary phase diagrams were obtained.The co-crystallization regions were decreased with rising temperature.The crystallization region of o-nitrophenylacetic acid was lager than that of p-nitrophenylacetic acid at a given temperature,especially in n-butanol.The nutual solubility data for ternary systems was correlated by NRTL model and Wilson model.The RMSD were 5.09×10-3 and 4.835×10-3,respectively,which illustrated that the Wilson model could better correlate p-nitrophenylacetic acid+o-nitrophenylacetic acid+ethyl acetate/n-butanol ternary systems. |
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