Diphenolic acid (DPA) is a renewable compound to produce polycarbonates and epoxy resins. Diphenolic acid is produced by acid-catalyzed condensation of levulinic acid with phenol to form monophenolic acid. Subsequently, monophenolic acid undergoes condensation with phenol to form two DPA isomers, ortho-diphenolic acid (o,p′-DPA) and para-diphenolic acid (p,p′-DPA). Here we describe a kinetic analysis of solvent-free levulinic acid-phenol condensation catalyzed by phosphotungstic acid at temperatures between 70 and 140°C. The reaction appeared to be pseudo-first-order with respect to levulinic acid when the levulinic acid:phenol molar ratio was four or higher. We determined the kinetic parameters (reaction rate constants, pre-exponential factors, and activation energies) by fitting experimental results to simulated data. Although the activation energies of o,p′-DPA, and p,p′-DPA formation were higher than their corresponding reverse reactions, the kinetic analyses revealed that a steric effect controls the reaction products. Our findings demonstrated a simple temperature-controlled strategy to achieve a p,p′:o,p′ DPA molar ratio of 28.3 with 87% conversion and 98% selectivity to total DPA. This work provides a potential production route for p,p′-DPA from biomass.

双酚酸 (DPA) 是一种可再生的化合物，可用于生产聚碳酸酯和环氧树脂。双酚酸是通过乙酰丙酸与苯酚在酸催化下缩合形成单酚酸而生产的。随后，单酚酸与苯酚缩合形成两种 DPA 异构体，邻二酚酸 ( o,p' -DPA) 和对二酚酸 ( p,p'-DPA）。在这里，我们描述了在 70 到 140°C 的温度下由磷钨酸催化的无溶剂乙酰丙酸-苯酚缩合的动力学分析。当乙酰丙酸:苯酚摩尔比为 4 或更高时，该反应似乎是关于乙酰丙酸的准一级反应。我们通过将实验结果与模拟数据拟合来确定动力学参数（反应速率常数、指前因子和活化能）。尽管o,p' -DPA 和p,p' -DPA 形成的活化能高于其相应的逆反应，但动力学分析表明，空间效应控制着反应产物。我们的研究结果证明了一种简单的温度控制策略来实现p,p':o,p'DPA 摩尔比为 28.3，转化率为 87%，对总 DPA 的选择性为 98%。这项工作为从生物质中生产p,p' -DPA提供了一条潜在的生产途径。