نتایج جستجو برای: brønsted acid

تعداد نتایج: 747867  

Journal: :Chinese Journal of Organic Chemistry 2020

Journal: :Supramolecular Chemistry 2021

Four new quinoxaline-spanned cavitands having a diester hydrogen phosphate group were successfully synthesised. These phosphorous derivatives applied in Brønsted acid-assisted catalytic conjugate addition reactions. The results ranked with the control of diphenyl as well among those four cavitands. structure–activity relationship revealed that catalyst centre surrounded by two trans-positioned ...

In this protocol, 3-(2-carboxybenzoyl)-1-methyl-1H-imidazol-3-ium chloride [Cbmim]Cl and sulfonic acid functionalized pyridinium chloride [pyridine-SO3H]Cl as a new, reusable, and green Brønsted acidic ionic liquid (BAIL) catalyst were synthesized and successfully used for the one-pot ring opening of epoxide with sodium azide (NaN3) in water at room temperature. Epoxides under ring-opening easi...

Journal: :Carbohydrate research 2013
Luis Miguel Azofra Ibon Alkorta José Elguero

The acid catalysis of the mutarotation mechanism in the two aldotetroses, d-erythrose and d-threose, has been studied at B3LYP/6-311++G(d,p) computational level in gas phase and in solution employing the PCM-water model. The open-chain, the furanose and the connecting TS structures have been characterized. To study the enhancing effect of acid groups on the electrophilicity of the carbonyl carb...

2017
Qixuan Lin Huiling Li Xiaohui Wang Longfei Jian Junli Ren Chuanfu Liu Runcang Sun

A sulphated tin ion-exchanged montmorillonite (SO4/Sn-MMT) was successfully prepared by the ion exchange method of montmorillonite (MMT) with SnCl4, followed by the sulphation. This catalysis was applied as a solid acid catalyst for the heterogeneous catalytic transformations of xylose and xylan into furfural in the bio-based 2-methyltetrahydrofuran/H2O biphasic system. These prepared catalysts...

Journal: :RNA 2006
Anne T Perrotta Timothy S Wadkins Michael D Been

In the ribozyme from the hepatitis delta virus (HDV) genomic strand RNA, a cytosine side chain is proposed to facilitate proton transfer in the transition state of the reaction and, thus, act as a general acid-base catalyst. Mutation of this active-site cytosine (C75) reduced RNA cleavage rates by as much as one million-fold, but addition of exogenous cytosine and certain nucleobase or imidazol...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید