Efficient aerobic epoxidation of olefins accelerated by a bifunctional Co 2 Al layered double hydroxide
- PDF / 1,210,222 Bytes
- 14 Pages / 439.37 x 666.142 pts Page_size
- 58 Downloads / 187 Views
Efficient aerobic epoxidation of olefins accelerated by a bifunctional Co2Al layered double hydroxide Xuan Dai1 · Jiayin Huang1 · Shuangling Tang1 · Xuegen Zheng2 · Ou Jiang2 · Xinhua Peng1 Received: 5 August 2020 / Accepted: 4 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Co2Al layered double hydroxide (Co2Al–LDH) could efficiently catalyze the aerobic epoxidation of olefin in the presence of isobutaldehyde (IBA). Various alkenes could transformed to its corresponding epoxide under the catalytic system and the catalyst showed exceptional reusability under the selected reaction conditions. The relationship between catalytic performance and C o2Al–LDH has been studied in the present research. The surface basicity of hydrotalcite was found to be beneficial to the reaction. Based on the controlled results and kinetic study, it was found that basicity not only accelerate the reaction rate, but also benefit the selectivity of epoxide. A possible mechanism of the reaction was proposed based on the controlled results and analysis, which was assumed that the epoxides were generated through two paths involving acylperoxy radical and peroxyacid. Graphic abstract
Keywords Co2Al layered double hydroxide · Epoxidation · Bifunctional catalysis · Basicity · Apparent activation energy Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1114 4-020-01867-9) contains supplementary material, which is available to authorized users. * Shuangling Tang [email protected] Extended author information available on the last page of the article
13
Vol.:(0123456789)
Reaction Kinetics, Mechanisms and Catalysis
Introduction The epoxidation reactions play an important role in the chemical industry, because the epoxides are useful intermediates that can be involved in production of raw materials for pharmaceuticals, surfactants, perfumes and epoxy resins [1–4]. Traditionally, the epoxidation of olefins is generally carried out with peroxyacids, which is expensive and generates large amounts of wastewater. Developing catalytic protocol for epoxidation using molecular oxygen as an ideal oxidant is highly desirable [5]. Although homogeneous transition-metal complexes are widely used in the aerobic epoxidation of olefins with the co-reactant aldehyde, they suffer from high cost and difficulty in recovery [6]. Various heterogeneous catalysts including GFC-[Mn(L)(OH)] [5], Co-CPF-2 [6], SBA15-[Mn (TPyP)TA] [7], Mn-Porphyrin/GO [8], CoFe2O4@SiO2@ CPMS@Mn (III) salen complex [9] and GO*-[Mn (TPyP)OAc]+ Cl− [10] have been reported for the efficient selective epoxidation of alkenes in the presence of IBA (iso-butylaldehyde). The basicity of the catalyst from the introduced 3-aminopropyl was reported to be conductive to increase the initial reaction rate and accelerated the cleavage of O–O bond to give the high oxo intermediates, which can react with the olefins to generate epoxides [11, 12]. Layered double hydroxides (LDHs) are well-known basic materials, which catalyze various re
Data Loading...
