In this work, the optimum process conditions and kinetics of the green synthesis of isobutyl cinnamate using deep eutectic solvents (DESs) as catalysts were investigated. Isobutyl cinnamate is a spice with low toxicity and is widely used in the food industry. However, there is a lack of reports on its green synthesis. Three DESs were prepared by adjusting the mixing ratio of choline chloride (ChCl) and p-toluenesulfonic acid (PTSA). Response surface methodology with Box-Behnken design (RSM-BBD) was used to optimize the process parameters of the esterification of cinnamic acid with isobutanol. The effects of catalyst loading, stirring speed, cinnamic acid/isobutanol molar ratio, and temperature on the conversion of cinnamic acid over time were evaluated. Using ChCl-PTSA as a catalyst, the kinetics data and chemical equilibrium constants of the esterification were determined at a temperature range of 353.15–383.15 K. The pseudo-homogeneous (PH) model based on activity was then adopted to describe the kinetics of the reaction, and the relative deviations between the experimental values and the calculated ones by PH model are less than 5.5%. Thermodynamic data (Δ_rH⁰, Δ_rS⁰, Δ_rG⁰) for the esterification reaction was calculated as well. In addition, the results of six consecutive cycles of the catalyst showed that ChCl-PTSA has good stability and recyclability.

中文翻译：

---

基于DESs催化剂的肉桂酸异丁酯合成：优化和动力学

在这项工作中，研究了使用低共熔溶剂（DES）作为催化剂绿色合成肉桂酸异丁酯的最佳工艺条件和动力学。肉桂酸异丁酯是一种低毒香料，广泛应用于食品工业。但目前缺乏对其绿色合成的报道。通过调整氯化胆碱（ChCl）和对甲苯磺酸（PTSA）的混合比例制备了三种DES。采用 Box-Behnken 设计响应面法 (RSM-BBD) 优化肉桂酸与异丁醇酯化的工艺参数。评价了催化剂负载量、搅拌速度、肉桂酸/异丁醇摩尔比和温度对肉桂酸随时间的转化率的影响。以 ChCl-PTSA 作为催化剂，在 353.15-383.15 K 的温度范围内测定了酯化反应的动力学数据和化学平衡常数。然后采用基于活性的伪均相（PH）模型来描述酯化反应的动力学。反应良好，实验值与PH模型计算值的相对偏差小于5.5%。还计算了酯化反应的热力学数据(Δr _H 0 ^、 Δr _S 0 ^、 Δr _G 0 ⁾ 。此外，催化剂连续6次循环的结果表明ChCl-PTSA具有良好的稳定性和可回收性。