Barsukova Tatiana, Sato Takeyuki, Takumi Haruki, Niwayama Satomi
Graduate School of Engineering, Muroran Institute of Technology 27-1, Mizumoto-cho Muroran Hokkaido Japan
RSC Adv. 2022 Sep 12;12(39):25669-25674. doi: 10.1039/d2ra04419f. eCollection 2022 Sep 5.
Monoalkyl oxalates are among the most important building blocks being applied to the synthesis of a variety of significant classes of compounds or applied to various cutting-edge reactions. However, their commercial availability is limited. Their synthetic methods are also limited because of the difficulty to synthesize them, and those hitherto reported are carried out in organic solvents often with the use of toxic reagents with mostly low to modest yields. Here we have developed practical synthesis of monoalkyl oxalates in aqueous media by applying the highly efficient selective monohydrolysis reactions of symmetric diesters which we reported previously. The best conditions apply an aqueous NaOH solution with relatively nontoxic THF or acetonitrile as a co-solvent at around 0-5 °C. The procedures are simple and environmentally friendly without requiring toxic or expensive reagents, yet yielding the corresponding half-esters in high yields with high purities. All the half-esters prepared here are stable over a long period of time. Therefore, our studies are expected to offer practical green methods for the synthesis of monoalkyl oxalates.
草酸单烷基酯是应用于合成各类重要化合物或各种前沿反应的最重要的基础原料之一。然而，它们的商业可得性有限。由于合成困难，其合成方法也有限，而且迄今为止报道的合成方法是在有机溶剂中进行的，通常使用有毒试剂，产率大多较低至中等。在此，我们通过应用我们之前报道的对称二酯的高效选择性单水解反应，开发了在水介质中实用的草酸单烷基酯合成方法。最佳条件是使用NaOH水溶液，并以相对无毒的四氢呋喃（THF）或乙腈作为共溶剂，温度约为0 - 5°C。该方法操作简单且环保，无需使用有毒或昂贵的试剂，却能以高收率和高纯度得到相应的半酯。在此制备的所有半酯在很长一段时间内都是稳定的。因此，我们的研究有望为草酸单烷基酯的合成提供实用的绿色方法。
