A deep eutectic solvent (DES), composed of choline chloride and urea, demonstrated exceptional solubility properties, allowing the dissolution of 0.8 wt % of zinc oxide. This liquid system was used as both solvent and catalyst (DES 300 mol %; ZnO 7.8 mol %) for the transesterification of dimethyl terephthalate (DMTP) with various alcohols (1-butanol, 2-butanol, 2-ethylhexanol, 1-hexanol, and 1-octanol). For example, the use of 1-butanol caused full conversion of DMTP after 24 h at 120 °C. The synergistic effect of the DES and ZnO was demonstrated via a comparison with the catalytic efficiency of the components used separately. The advantage of the catalytic system is the lack of miscibility of the product with DES–ZnO, resulting in the formation of a biphasic system during the reaction, the shifting of the reaction equilibrium being the main driving force for this process. DES–ZnO was used in six consecutive reaction cycles without any significant drop in efficiency.

中文翻译：

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低共熔溶剂与氧化锌在对苯二甲酸二甲酯酯交换合成对苯二甲酸烷基酯中的协同作用

由氯化胆碱和尿素组成的低共熔溶剂 (DES) 表现出优异的溶解性能，可溶解 0.8 wt% 的氧化锌。该液体体系用作对苯二甲酸二甲酯 (DMTP) 与各种醇（1-丁醇、2-丁醇、2-乙基己醇、1-己醇、和 1-辛醇）。例如，使用 1-丁醇在 120 °C 下 24 小时后导致 DMTP 完全转化。通过与单独使用的组分的催化效率比较，证明了 DES 和 ZnO 的协同效应。该催化体系的优点是产物与DES-ZnO不互溶，导致反应过程中形成双相体系，反应平衡的移动是该过程的主要驱动力。 DES-ZnO 在连续六个反应循环中使用，效率没有任何显着下降。