Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, Ciudad de México, 04510, Mexico.
Org Biomol Chem. 2021 Aug 21;19(31):6776-6780. doi: 10.1039/d1ob01026c. Epub 2021 Jul 23.
This contribution explores the bifunctional catalytic activity of water clusters ((HO) with n = 1-5) in organic chemistry similar to that observed in the formation of HSO in acid rain (Chem. Commun., 53, 3516, (2017)). We considered for this purpose the Hydrolysis of Epoxides (HE), in particular, that of oxirane and its methyl derivatives. Surrounding water molecules with H-bond cooperative effects decrease the activation energy of the rate-limiting step of HE in condensed phase, especially when they lead to an anti-periplanar attack on the alkoxide leaving group. Furthermore, the water molecules have a bifunctional catalytic role in HE by (i) increasing the nucleophilic and electrophilic character of the attacking oxygen atom and the leaving group of the reaction, respectively, and (ii) placing the reactants in a suitable disposition for the substitution to occur. Overall, this investigation provides relevant insights into the collective action of water molecules on organic reactions in neutral, basic and acid media.
本文探讨了水团簇((HO)，n=1-5)在有机化学中的双功能催化活性，类似于在酸雨形成过程中观察到的 HSO 的形成(Chem. Commun.，53，3516，(2017))。为此，我们考虑了环氧化物的水解(HE)，特别是环氧乙烷及其甲基衍生物的水解。通过氢键协同效应将水分子包围起来，可以降低凝聚相中 HE 限速步骤的活化能，特别是当它们导致反式平面进攻离去基时。此外，水分子在 HE 中具有双功能催化作用，一方面通过增加进攻氧原子和反应离去基团的亲核性和电性，另一方面通过将反应物置于合适的位置以进行取代反应。总的来说，这项研究为在中性、碱性和酸性介质中水分子对有机反应的集体作用提供了重要的见解。
