Das Kamal, Majumdar Swapan
Department of Chemistry, Tripura University Suryamaninagar 799 022 India
RSC Adv. 2022 Aug 3;12(33):21493-21502. doi: 10.1039/d2ra03855b. eCollection 2022 Jul 21.
A highly efficient trans-esterification of β-keto methyl/ethyl esters with primary, secondary, allylic, benzylic and chiral alcohols has been carried out in excellent yields under solvent-free conditions using silica supported boric acid as a heterogeneous catalyst. The surface morphology of the silica-boric acid catalyst (fresh and recycled) has been characterized by SEM and EDX techniques. This sustainable protocol resulted in a remarkable enhancement in the synthetic efficiency (87-95% yield) with high purity and eliminating the use of an environmentally toxic solvent. The work up procedure is very simple and the catalyst has been successfully recovered and recycled. The present methodology is also applicable for trans-esterification with chiral alcohols on a multi-gram scale without compromising the yield. Noteworthy features of this protocol are simple operational procedure, minimizing production of chemical waste, mild reaction conditions, easy preparation of the catalyst and its recyclability up to five cycles without any appreciable loss of catalytic activity.
在无溶剂条件下，以二氧化硅负载硼酸作为多相催化剂，实现了β-酮基甲酯/乙酯与伯醇、仲醇、烯丙醇、苄醇和手性醇的高效酯交换反应，产率优异。通过扫描电子显微镜（SEM）和能谱仪（EDX）技术对二氧化硅-硼酸催化剂（新鲜的和循环使用的）的表面形态进行了表征。这种可持续的方法显著提高了合成效率（产率87-95%），产物纯度高，且避免了使用对环境有毒的溶剂。后处理过程非常简单，催化剂已成功回收并循环使用。本方法也适用于多克规模的手性醇酯交换反应，且不影响产率。该方法的显著特点包括操作步骤简单、化学废物产生量最小化、反应条件温和、催化剂制备容易以及可循环使用多达五个循环而催化活性无明显损失。
