Accelerated non-enzymatic and metal-free “reaction and extraction” of sugar esters at the interface of two immiscible liquid microdroplets is demonstrated. The bimolecular reaction occurs by collision of microdroplets originating from two home-built electrospray sonic ion sources, carrying sugar molecules in water and long-chain fatty acids in toluene, respectively. Our method shows that the rate of reaction is enhanced ∼10⁷ times in comparison to the bulk, initiated by ultrasonic activation. Such a high rate of reaction in the microdroplets can be attributed to factors such as surface activity, concentration enhancement, partial solvation, and temperature-assisted dehydration of the species occurring in microdroplets. We provide evidence for an interfacial nucleophilic addition–elimination reaction mechanism. This method of synthesis is extended to 18 similar reactions. Microdroplet synthesis offers a sustainable method for biphasic reactions, eliminating the need for phase transfer reagents and activating agents such as acids/bases, metals, or enzymes.

中文翻译：

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微滴碰撞过程中加速的非酶脂肪酸酯化：一种提高可持续性的方法

展示了在两个不混溶的液体微滴的界面处加速的糖酯的非酶促和无金属“反应和提取”。双分子反应通过源自两个自制电喷雾声波离子源的微滴碰撞发生，分别在水中携带糖分子和在甲苯中携带长链脂肪酸。我们的方法表明反应速率提高了~ ^{10 7}与体积相比的倍数，由超声波激活引发。微滴中如此高的反应速率可归因​​于诸如表面活性、浓度增强、部分溶剂化和微滴中发生的物质的温度辅助脱水等因素。我们为界面亲核加成-消除反应机制提供了证据。这种合成方法扩展到 18 个类似的反应。微滴合成为双相反应提供了一种可持续的方法，无需相转移试剂和活化剂，如酸/碱、金属或酶。