Synthesis cyclic carbonates with BmimCl-based ternary deep eutectic solvents system

CO2 Valorization in Deep Eutectic Solvents

The deep eutectic solvent (DES) has emerged in recent years as a valuable medium for converting CO2 into valuable chemicals because of its easy availability, stability, and safety, and its capability to dissolve carbon dioxide. CO2 valorization in DES has evolved rapidly over the past 20 years. As well as being used as solvents for acid/base-promoted CO2 conversion for the production of cyclic carbonates and carbamates, DESs can be used as reaction media for electrochemical CO2 reduction for formic acid and CO. Among these products, cyclic carbonates can be used as solvents and electrolytes, carbamate derivatives include the core structure of many herbicides and pesticides, and formic acid and carbon monoxide, the C1 electrochemical products, are essential raw materials in the chemical industries. An overview of the application of DESs for CO2 valorization in recent years is presented in this review, followed by a compilation and comparison of product types and reaction mechanisms within the different types of DESs, and an outlook on how CO2 valorization will be developed in the future.

Aerobic Oxidation of 5-Hydroxymethylfurfural via Hydrogen Bonds Reconstruction with Ternary Deep Eutectic Solvents

Hydrogen bonding effect exists widely in various chemical and biochemical systems, primarily stabilizing the molecular structure as a positive factor. However, the presence of intermolecular hydrogen bonds among biomass molecules results in a formidable challenge for the efficient utilization of biomass resources. Here in, a novel strategy of "hydrogen bonds reconstruction" was developed by a series of ternary deep eutectic solvent (DESs) as molecular scissors, which disrupting the initial intermolecular hydrogen bonds and reconstructing the new ones to increase the reactivity of the biomass-based compound. The DESs played a crucial role in enhancing the reactivity of 5-hydroxymethylfurfural (HMF) and promoting its oxidation through reconstructing the hydrogen bonds interactions. Furthermore, DESs was also found to activate the Anderson-type catalyst Na5IMo6O24 (IMo6) through an electron-transfer mechanism, which facilitated the generation of oxygen vacancies and significantly enhances its ability to activate molecular oxygen. With this novel catalytic system, oxidation of HMF exhibited remarkable efficiency as HMF was almost entirely converted into FFCA with an impressive yield of 98 % under the optimized conditions. This finding offers novel insights into the utilization of biomass resources and endows the solvent with new functions in the chemical reaction.

Deep Eutectic Solvents as Catalysts for Cyclic Carbonates Synthesis from CO2 and Epoxides

In recent years, the chemical industry has put emphasis on designing or modifying chemical processes that would increasingly meet the requirements of the adopted proecological sustainable development strategy and the principles of green chemistry. The development of cyclic carbonate synthesis from CO₂ and epoxides undoubtedly follows this trend. First, it represents a significant improvement over the older glycol phosgenation method. Second, it uses renewable and naturally abundant carbon dioxide as a raw material. Third, the process is most often solvent-free. However, due to the low reactivity of carbon dioxide, the process of synthesising cyclic carbonates requires the use of a catalyst. The efforts of researchers are mainly focused on the search for new, effective catalysts that will enable this reaction to be carried out under mild conditions with high efficiency and selectivity. Recently, deep eutectic solvents (DES) have become the subject of interest as potential effective, cheap, and biodegradable catalysts for this process. The work presents an up-to-date overview of the method of cyclic carbonate synthesis from CO₂ and epoxides with the use of DES as catalysts.

Efficient imidazolium ionic liquid as a tri-functional robust catalyst for chemical fixation of CO2 into cyclic carbonates

The recent increase in CO₂ levels has had an extensive impact on the environment; hence an effective catalyst for chemical CO₂ fixation into value-added products is demanded. This work demonstrates a simple approach towards the chemical fixation of CO₂ to cyclic carbonates without solvent, metal and additives using one-pot synthesized tri-functional-imidazolium bromide ionic liquid. Herein, synthesized tri-functional-imidazolium-based ionic liquids, namely 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide ([VIMEtOH][Br] (24 and 72 h)), 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium hydroxyl ([VIMEtOH][OH]) and poly 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide (poly [VIMEtOH][Br]), were used for the comprehensive investigation of chemical fixation of CO₂ into cyclic carbonates and their physiochemical properties. In case of [VIMEtOH][Br] ionic liquid, it displayed time-dependent synthesis dissolution in the reaction system. This study found that [VIMEtOH][Br]-72 ionic liquid is not dissolved in the reaction system. The effect on the catalytic efficiency of the presence of functional groups in ionic liquids such as N-vinyl (-CC-N), acidic proton of imidazolium (-C (2)-H) and hydroxyl (-OH) along with bromide anion and the reaction conditions are systematically investigated. For CO₂ fixation, 99.6% conversion of propylene oxide with an excellent selectivity of propylene carbonate (≥99%) over [VIMEtOH][Br]-72 catalyst (at 120 °C, 2 MPa, 2 h) was observed without co-catalyst, metal and solvent. Also, it demonstrated an excellent wide substrates scope of epoxide and all reactions were performed on gram-scalable, which are potential prospects for industrial use.

Utilization of CO2-Available Organocatalysts for Reactions with Industrially Important Epoxides

Recent knowledge in chemistry has enabled the material utilization of greenhouse gas (CO2) for the production of organic carbonates using mild reaction conditions. Organic carbonates, especially cyclic carbonates, are applicable as green solvents, electrolytes in batteries, feedstock for fine chemicals and monomers for polycarbonate production. This review summarizes new developments in the ring opening of epoxides with subsequent CO2-based formation of cyclic carbonates. The review highlights recent and major developments for sustainable CO2 conversion from 2000 to the end of 2021 abstracted by Web of Science. The syntheses of epoxides, especially from bio-based raw materials, will be summarized, such as the types of raw material (vegetable oils or their esters) and the reaction conditions. The aim of this review is also to summarize and to compare the types of homogeneous non-metallic catalysts. The three reaction mechanisms for cyclic carbonate formation are presented, namely activation of the epoxide ring, CO2 activation and dual activation. Usually most effective catalysts described in the literature consist of powerful sources of nucleophile such as onium salt, of hydrogen bond donors and of tertiary amines used to combine epoxide activation for facile epoxide ring opening and CO2 activation for the subsequent smooth addition reaction and ring closure. The most active catalytic systems are capable of activating even internal epoxides such as epoxidized unsaturated fatty acid derivatives for the cycloaddition of CO2 under relatively mild conditions. In case of terminal epoxides such as epichlorohydrin, the effective utilization of diluted sources of CO2 such as flue gas is possible using the most active organocatalysts even at ambient pressure.

Deep eutectic solvents as non-traditionally multifunctional media for the desulfurization process of fuel oil

Deep eutectic solvents (DESs) have been intensively pursued in the field of separation processes, catalytic reactions, polymers, nanomaterial science, and sensing technologies due to their unique features such as the low cost of components, ease of preparation, tunable physicochemical properties, negligible vapor pressure, non-toxicity, renewability, and biodegradability in the recent decade. Considering these appealing merits, DESs are widely used as extraction agents, solvents and/or catalysts in the desulfurization process since 2013. This review is focused on summarizing the physicochemical properties of DESs (i.e., freezing point, density, viscosity, ionic conductivity, acidity, hydrophilicity/hydrophobicity, polarity, surface tension, and diffusion) to some extent, and their significant advances in applications related to desulfurization processes such as extraction desulfurization, extraction-oxidation desulfurization, and biomimetic desulfurization. In particular, we systematically compile very recent works concerning the selective aerobic oxidation desulfurization (AODS) under extremely mild conditions (60 °C and ambient pressure) via a biomimetic approach coupling DESs with polyoxometallates (POMs). In this system, DESs act as multifunctional roles such as extraction agents, solvents, and catalysts, while POMs serve as electron transfer mediators. This strategy is inspirational since biomimetic or bioinspired catalysis is the "Holy Grail" of oxidation catalysis, which overcomes the difficulty of O2 activation via introducing electron transfer mediators into this system. It not only can be used for AODS, but also paves a novel way for oxidation catalysis, such as the selective oxyfunctionalization of hydrocarbon. Eventually, the conclusion, current challenges, and future opportunities are discussed. The aim is to provide necessary guidance for precisely designing tailor-made DESs, and to inspire chemists to use DESs as a powerful platform in the field of catalysis science.