催化氧化邻羟基甲苯制备邻羟基苯甲醛的热力学分析

引言邻羟基苯甲醛(o-hydroxybenzaldehyde,OHBA)是重要的有机合成中间体,广泛应用于医药工业1-2]、农药3-5]、食品香料与香精、电镀6]、石油化工和合成纤维等领域。目前合成邻羟基苯甲醛的方法很多,从原料的角度主要可以分为以邻羟基苯甲醇、邻羟基苯甲酸、苯酚和邻羟基甲苯为原料的合成方法7]。其中由于邻羟基甲苯廉价易得,且以其为原料的空气/氧气直接氧化法8-12]环境污

Thermodynamic analysis of o-hydroxytoluene catalytic oxidation to prepare o-hydroxybenzaldehyde

Catalytic oxidation of o-hydroxytoluene(ONT)is the main process to synthesize o-hydroxybenzaldehyde(OHBA),but the key problem is how to improve selectivity and yield of target product.In order to make more effective use of resources,the thermodynamic properties of o-hydroxytoluene oxidation were analyzed.The basic thermodynamic data of the reaction products were estimated through several group-contribution methods.According to the basic thermodynamic principles,the relationships between reaction temperature and reaction enthalpy change,reaction Gibbs free energy change,and reaction equilibrium constant were established.The calculation results were as follows:R₁:Δ_rH₂₉₈^Θ＝-158.36 kJ·mol^-1,Δ_rG₂₉₈^Θ＝-170.93 kJ·mol^-1; R₂:Δ_rH₂₉₈^Θ＝-214.53 kJ·mol^-1,Δ_rG₂₉₈^Θ＝-163.56 kJ·mol^-1; R₃,Δ_rH₂₉₈^Θ＝-259.35 kJ·mol^-1,Δ_rG₂₉₈^Θ＝-260.27 kJ·mol^-1.In the researched reaction temperature range,all the reaction steps were exothermic reactions and could proceed spontaneously,and a higher reaction temperature went against the reaction procedure.The thermodynamic analysis results provided the basic data for research on improving selectivity of target product,and could guide optimizing reaction conditions and commercialization.