| In this paper,the synthetic technology,kinetics and thermodynamic properties of ethyl p-aminobenzoate(EPAB)were studied.EPAB is synthesized with p-aminobenzoic acid(PABA)and ethanol as raw materials,p-toluenesulfonic acid(PTSA)as catalyst.The effects of reaction time,the amount of catalyst and ethanol on the yield of product were investigated by using orthogonal experimental method and single factor experimental method.The results showed that the effect of factors satisfied the following sequence:reaction time>the amount of catalyst>the quantity of ethanol.The optimal condition is displayed as follows:the reaction time is 2.5h,n(PABA):n(ethanol):n(PTSA)=1:17.63:21.60,and the yield of EPAB is 72.48%.The kinetic data of above esterification were measured in different temperature(354.15K?360.15K?365.15K?370.15K),Based on the power function model and the influence of the inverse reaction,the kinetic equation of the reaction is obtained by the optimal fitting.The melting point and melting enthalpy of EPAB were measured by DSC method.The solubility of EPAB in methanol,ethanol,n-propanol,n-butanol,isobutanol,isoamyl alcohol was measured by the dynamic method within(283.15 to 327.15)K.Modified Apelblat equation,?h model,NRTL and Wilson model were used to correlate the solubility of EPAB.The results showed that modified Apelblat equation,NRTL and Wilson model could describe the relationship between the solubility of EPAB and temperature well.The thermodynamic functions of EPAB in dissolution process were calculated based on the above works.The heat capacity of p-aminobenzoic acid(298.15-540.15)K and EPAB(298.15-423.15)K were determined by adiabatic calorimeter,and then the relationship between Cp and T was also obtained.The standard enthalpy of formation and standard entropy of EPAB were obtained by theoretical estimation and the results were verified by designing a thermodynamic cycle.The results showed the estimated values are reliable. |
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