Chemical fixation of CO 2 with propylene oxide catalyzed by Trimethylsulfonium bromide in the presence of HBr: a computa
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Chemical fixation of CO2 with propylene oxide catalyzed by Trimethylsulfonium bromide in the presence of HBr: a computational study Jemal Mohamed Ali1,2 · Teshome Abute Lelisho1 Received: 6 August 2020 / Accepted: 1 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The chemical fixation of C O2 into value-added chemicals has recently received much attention with regard to the utilization of CO2, a gas responsible for global warming. One of the most well-known methods is the fixation of CO2 with epoxides to form cyclic carbonates. In this work, the conversion of C O2 and PO into five-membered cyclic carbonate catalyzed by (CH3)3SBr alone and ( CH3)3SBr in the presence of HBr have been studied by using DFT method at B3LYP/6-311 ++ G (d, p)//B3LYP/6-31G (d) level of theory to understand the reaction mechanism and efficiency of the catalyst. Two possible reaction mechanisms (α and β) were considered and it was found that the β pathway is more favorable over α pathway for the catalyzed route in gas phase. The ring-opening step was the rate-determining step that results from the nucleophilic attack of the bromide to the carbon atom of the epoxide. The synergetic effect of HBr is tested as HBD for the (CH3)3SBr/HBr catalyzed reaction and it gave better result and minimized the activation energy for the reaction and the rate-determining step was the ring closure with free energy of activation 5.2 kcal/mol in gas phase. Keywords DFT · CO2 · Chemical fixation · PO · (CH3)3SBr
1 Introduction The world’s population faces a major problem, the rise of global warming due to excessive greenhouse gas emissions [1]. Among the greenhouse gases, CO2 has the greatest negative impact, causing about 55% of the global warming observed thus showing the need for mitigating CO2 emission [2, 3]. This points out the need for an increasing development of innovative strategies to reduce the C O2 emission. Besides the prevention of CO2 emissions, which is the most Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00214-020-02673-1) contains supplementary material, which is available to authorized users. * Jemal Mohamed Ali [email protected] 1
Department of Chemistry, Collage of Natural and Computational Science, Hawassa University, Hawassa, Ethiopia
Department of Chemistry, Collage of Natural and Computational Science, Werabe University, Werabe, Ethiopia
2
reasonable long-term approach, the use of CO2 as an alternative feedstock for the chemical industry received more attention and it is hot topic in both academia and industry [4]. Currently, the product of cyclic carbonates via cycloaddition of CO2 into epoxides has attracted considerable interest since the reaction is 100% atom-economical and avoids using toxic reagents [5]. It is predicted that the current carbon-based raw materials from fossil fuels will be depleted in the decades to come thus, renewable resources should be utilized for a sustainable society [6]. To
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