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Catalytic transformation of CO2 into chemicals in large demand such as ethanol has attracted much research attention under the background of establishing carbon-neutral societies. Supported Rh cata...

International audience; Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein–Ponndorf–Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1–10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.

The production of olefins by catalytic transformation of methanol on zeolites and zeotypes is of great interest to scientists and specialists in various fringe areas of national economy. Due to implementation of this process on industrial level, the attention gradually shifts from scientific studies devoted to the synthesis and modification of zeolites and zeotypes with different structure to investigation of pilot and industrial plants and determination of the main economic and environmental characteristics of both the existing and the future plants. In 2019, the development of 26 production sites in China with the annual output of 14 million tons of ethylene and propylene was licensed and 14 plants with the total capacity of 7.67 million tons of ethylene and propylene were launched. The created plants provide a complete cycle of coal processing, which consists of coal gasification units yielding syngas, units for the synthesis of methanol and olefins, their refinement and production of polyethylene and polypropylene. The total output of ethylene and propylene at the launched plants was more than 21 million tons. The paper presents a review of publications on the development and modification of catalysts as well as the technological, economic and environmental aspects of olefins production from methanol, which appeared in foreign journals in the recent five years.

The exceptional versatility of sulfones has been extensively exploited in organic synthesis across several decades. Since the first demonstration in 2005 that sulfones can participate in Pd-catalysed Suzuki-Miyaura type reactions, tremendous advances in catalytic desulfitative functionalizations have opened a new area of research with burgeoning activity in recent years. This emerging field is displaying sulfone derivatives as a new class of substrates enabling catalytic C-C and C-X bond construction. In this review, we will discuss new facets of sulfone reactivity toward further expanding the flexibility of C-S bonds, with an emphasis on key mechanistic features. The inherent challenges confronting the development of these strategies will be presented, along with the potential application of this chemistry for the synthesis of natural products. Taken together, this knowledge should stimulate impactful improvements on the use of sulfones in catalytic desulfitative C-C and C-X bond formation. A main goal of this article is to bring this technology to the mainstream catalysis practice and to serve as inspiration for new perspectives in catalytic transformations.

With the rapid expansion of biodiesel industry, its main by-product, crude glycerol, is anticipated to reach a global production of 6 million tons in 2025. It is actually a worrying phenomenon as glycerol could potentially emerge as an excessive product with little value. Glycerol, an alcohol and oxygenated chemical from biodiesel production, has essentially enormous potential to be converted into higher value-added chemicals. Using glycerol as a starting material for value-added chemical production will create a new demand on the glycerol market such as lactic acid, propylene glycol, alkyl lactatehydrogen, olefins and others. This paper briefly reviews the recent development on value-added chemicals derived from glycerol through catalytic conversion of refined and crude glycerol that have been proven to be promising in research stage with commercialization potential, or have been put in a corporate marketable production. Despite of the huge potential of products that can be transformed from glycerol, there are still numerous challenges to be addressed and discussed that include catalyst design and robustness; focus on crude or refined glycerol; reactor technology, reaction mechanism and thermodynamic analysis; and overall process commercial viability. The discussion will hopefully provide new insights on justified direction to focus on for glycerol transformation technology. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

5-Hydroxymethylfurfural (HMF) is a biobased platform chemical that can be valorized into a spectrum of valuable products. In this report, supported Ir, Ir–Co, Ir–Ni, and Ir–Ru catalysts were investigated for this purpose. Only hydrogenation of HMF to 2,5-bis-(hydroxymethyl)furan (BHMF) occurred over all catalysts. The effect of the second metal (Co, Ni, and Ru) on Ir/SiO2 was reflected by the kinetic constants being in the order Ir–Ni/SiO2 > Ir–Co/SiO2 > Ir–Ru/SiO2. The oxophilic nature of the secondary metal improved the catalytic performance of the bimetallic catalysts compared to the monometallic iridium catalyst (Ir/SiO2). Addition of HCOOH and H2SO4 as cocatalysts is a strategy to reach one-pot conversion of HMF to 2,5-di-methylfuran (DMF). Over-hydrogenolysis products such as 2,5-dimethyltetrahydrofuran were formed when only H2SO4 was added, giving higher activity compared to addition of HCOOH. Simultaneous presence of acids gave the highest HMF conversion, promoting esterification to 5-formyloxymethyl furfural and allowing the one-pot transformation of HMF to DMF. Thermodynamic analysis of HMF transformations revealed that both hydrogenation and dehydration steps are feasible.

Mesoporous carbonaceous materials were functionalized with iron or copper by a mechanochemical approach. The structural and textural properties of these catalysts were characterized by N2 physisorp...

This contribution highlights a number of approaches developed by coordination and organometallic chemists that go beyond mainstream inorganic reactivity. A few of these strategies have been known for decades and are fundamental tools in synthesis and catalysis, while others are more recent and still belong to a niche. Through selected examples, we show herein how transmetalation, metal exchange, metal cooperativity, and catalytic transformation of metal complexes provide unique new opportunities to expand the reactivity arsenal of inorganic systems for synthetic and technological applications L.S. acknowledges financial support from the Spanish State Research Agency for the grant PID2019-109111RB-I00 and the Spanish Multi-MetDrugs network (RED2018-102471-T) for fruitful discussions. This work was performed under the Severo Ochoa Centres of Excellence Program of the Spanish State Research Agency, Grant No. CEX2018-000867-S (DIPC).

State-of-the-art catalyst systems for hydroxy- and alkoxycarbonylations of olefins make use of palladium complexes. In this work, we report a complementary ruthenium-catalysed hydroxycarbonylation of olefins applying an inexpensive Ru-precursor (Ru3(CO)12) and PCy3 as a ligand. Crucial for the success of this transformation is the use of hexafluoroisopropanol (HFIP) as the solvent in the presence of an acid co-catalyst (PTSA). Overall, moderate to good yields are obtained using aliphatic olefins including the industrially relevant substrate di-isobutene. This atom-efficient catalytic transformation provides straightforward access to various carboxylic acids from unfunctionalized olefins.

Direct catalytic transformation of chlorosilanes into organosilicon compounds remains challenging due to difficulty in cleaving the strong Si-Cl bond(s). We herein report the palladium-catalyzed cross-coupling reaction of chlorosilanes with organoaluminum reagents. A combination of [Pd(C

Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzyl alcohols with (hetero)aryl electrophiles. The reaction proceeds with a broad substrate scope of both coupling partners. The electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles (e.g., Ar-OTf, Ar-I, Ar-Br, and inert Ar-Cl) all coupled well. Most of the functionalities, including aldehyde, ketone, amide, ester, nitrile, sulfone, furan, thiophene, benzothiophene, pyridine, quinolone, Ar-SiMe

Zeolite deactivation during the methanol transformation into hydrocarbons is a complex chemical process that includes reversible and irreversible degradation of active sites. The irreversible deactivation of the catalyst is associated with the degradation of active sites during long-term functioning of the zeolite under high-temperature exposure conditions of to water vapor as one of the main reaction products. The carbon deposits formation on the catalyst surface is the main cause of reversible deactivation. The formation of carbon can occur both in the cavities of the zeolites channels, which usually leads to a change in the selectivity of the process for light hydrocarbons, and at the junctions of the channels, which leads to pores blockage and a decrease in the activity of the catalyst. In addition, carbon deposition can occur directly on the active site of the zeolite, which also reduces the activity of the catalyst. The study of the synthesized catalytic systems deactivation rate to process time correlation was carried out in a tubular reactor installation of continuous operation, consisting of a reactor for producing dimethyl ether and a reactor for transformation of dimethyl ether into hydrocarbons. Determination of the kinetic regularities of the deactivation process of zeolite H-ZSM-5 makes it possible to adequately describe the actual course of the catalytic transformation of methanol into hydrocarbons. As a result of solving the differential equations of catalyst deactivation by numerical methods, the values of the preexponential factors and activation energies were obtained. Base on the values of the preexponential factors and activation energies, the methanol into hydrocarbons conditions range optimal for the catalytic transformation was determined, providing the minimum rate of catalyst deactivation, Ptotal = 1 Bar, W (methanol) = 2.3 kg (methanol) / (kg (cat) × h), t = 330–360 °C, which correlates with the results of the literature data on the transformation of methanol into zeolite of the H-ZSM-5 type.

Direct catalytic transformation of C–H bonds to new functionalities has provided a powerful strategy to synthesize complex molecular scaffolds in a straightforward way. Unstinting efforts of the sy...

Owing to their extra-large pores compared to traditional aluminosilicate zeolites, silicogermanates could be attractive for the catalytic transformation of bulky molecules, provided the frameworks can be modified to incorporate acid sites and can be stabilized to survive calcination. Post-synthetic isomorphic substitution of Ge by Si and Al would present a route to achieve this goal. This report describes the transformation and characterization of the non-stable IM-12 silicogermanate into a new stable IZM-7 aluminosilicogermanate by partially substituting Ge by Si in gaseous form to stabilize the material, followed by an aqueous alumination step. IZM-7-based catalyst presents promising performance in the hydroconversion of n-decane compared to conventional zeolites, opening perspectives for the catalytic use of stable derivatives of silicogermanate zeolites. Owing to their extra-large pores compared to traditional aluminosilicate zeolites, silicogermanates could be attractive for the catalytic transformation of bulky molecules, provided the frameworks can be modified to incorporate acid sites and can be stabilized to survive calcination. Post-synthetic isomorphic substitution of Ge by Si and Al would present a route to achieve this goal. This report describes the transformation and characterization of the non-stable IM-12 silicogermanate into a new stable IZM-7 aluminosilicogermanate by partially substituting Ge by Si in gaseous form to stabilize the material, followed by an aqueous alumination step. IZM-7-based catalyst presents promising performance in the hydroconversion of n-decane compared to conventional zeolites, opening perspectives for the catalytic use of stable derivatives of silicogermanate zeolites. ispartof: Journal Of Catalysis vol:405 pages:601-605 status: published

Catalytic transformation of renewable fatty acids into value-added fatty alcohols without the use of gaseous hydrogen is a versatile technique for the utilization of waste cooking oil, where Cu-bas...

Lignin is one of the most important biomacromolecules in the plant biomass and the largest renewable source of aromatic building blocks in nature. Selectively producing value-added chemicals from the catalytic transformation of renewable lignin is of strategic significance and meet sustainability targets owing to the excessive consumption of non-renewable petroleum resource, but remains a long-term challenge owing to the complexity of lignin structure. This Minireview provides a summary and perspective of the extensive research that provides insight into selectively catalytic transformations of lignin and its derived monomers via directed scissor of chemical linkages (C-O and C-C bonds) with product-oriented targets. Furthermore, some challenges and opportunities of lignin catalytic transformation are provided based on existing problems in this field for readers to discuss future research directions.

The adsorption of toluene and 1,3,5-trimethylbenzene and the catalytic transformation of 1,3,5-trimethylbenzene are applied as probing approaches to characterize the pore system of hierarchical EU-1 zeolites prepared using organofunctionalized fumed silica as the silicon source. The adsorption and diffusion of toluene and 1,3,5-trimethylbenzene are significantly improved in the hierarchical EU-1 zeolites compared with the conventional microporous EU-1 zeolite. The adsorption kinetics of toluene and 1,3,5-trimethylbenzene suggested that introducing mesopores significantly increases the rate of adsorption and improved the diffusion of large molecules. In the catalytic transformation of 1,3,5-trimethylbenzene, the conversion of 1,3,5-trimethylbenzene on the hierarchical EU-1 zeolites is doubled compared with the conventional microporous EU-1 zeolite, due to the improved diffusion of bulky molecules and enhanced accessibility of active sites in the hierarchical EU-1 structure. Although isomerization is the main reaction, differences are observed in the product ratios of isomerization to disproportionation between the hierarchical EU-1 zeolites and the microporous counterpart with different times on stream. The transformation of 1,3,5-trimethylbenzene over the hierarchical EU-1 zeolites has a higher isomerization to disproportionation ratio than that over the microporous EU-1 zeolite; this is due to the increased mesoporosity.

The universally depleting reserves of traditional hydrocarbons require the development of a technology for producing synthetic hydrocarbons from renewable sources or human waste. Currently, among the possible methods for producing synthetic hydrocarbons, it is necessary to note the Fischer–Tropsch method and the method of methanol / dimethyl ether catalytic transformation. Moreover, the production of synthetic hydrocarbons from synthesis gas — the Fischer–Tropsch method, is suitable for the production of linear hydrocarbons. The hydrocarbons synthesis using methanol / dimethyl ether is suitable for the production of olefins, branched paraffins, aromatic and polyaromatic hydrocarbons. Depending on the synthesis conditions, it is possible to preferentially obtain a certain type of hydrocarbon, which significantly increases the value of this process. In this article modification of zeolite type H-ZSM-5 with zinc is studied in order to increase the yield of liquid hydrocarbons. Zeolite in acid form was treated with zinс acetate solutions of different concentrations, followed by calcination of the samples. The efficiency of the catalysts was studied in a flow tube reactor set-up, and the surface acidity of the samples was also determined. An increase in the zinc content in zeolite contributed to a decrease in the acidity of the samples and modification of their active centers. However, at high zinc content, a separate oxide phase forms, which contributes to a slight increase in acidity. Modification of zeolite with zinc leads to a decrease in the rate of transformation of dimethyl ether and the rate of liquid hydrocarbons formation. However, a general decrease in acidity and modification of zeolite with zinc contributes to a significant decrease in the amount of heavy aromatic compounds formed, with an increase in the amount of gaseous and liquid hydrocarbons being formed.

With fossil energy resources increasingly drying up and gradually causing serious environmental impacts, pursuing a tandem and green synthetic route for a complex and high-value-added compound by using low-cost raw materials has attracted considerable attention. In this regard, the selective and efficient conversion of light olefins with CO2 into high-value-added organic cyclic carbonates (OCCs) is of great significance owing to their high atom economy and absence of the isolation of intermediates. To fulfill this expectation, a multifunctional catalytic system with controllable spatial arrangement of varied catalytic sites and stable texture, in particular, within a single catalyst, is generally needed. Here, by using a stepwise electrostatic interaction strategy, imidazolium-based ILs and Au nanoparticles (NPs) were stepwise immobilized into a sulfonic group grafted MOF to construct a multifunctional single catalyst with a highly ordered arrangement of catalytic sites. The Au NPs and imidazolium cation are separately responsible for the selective epoxidation and cycloaddition reaction. The mesoporous cage within the MOF enriches the substrate molecules and provides a confined catalytic room for the tandem catalysis. More importantly, the highly ordered arrangement of the varied active sites and strong electrostatic attraction interaction result in the intimate contact and effective mass transfer between the catalytic sites, which allow for the highly efficient (>74% yield) and stable (repeatedly usage for at least 8 times) catalytic transformation. The stepwise electrostatic interaction strategy herein provides an absolutely new approach in fabricating the controllable multifunctional catalysts, especially for tandem catalysis.

A practical method for the synthesis of 2H-imidazoles via a [2+3] annulation of N-H imines with vinyl azides using a copper catalyst is developed. In this conversion, environmentally friendly oxygen is used as the sole oxidant and N2 and H2O are the only by-products. The catalytic transformation, operating under mild conditions, is operationally simple and is considered as a readily available catalytic system having good substrate and functional compatibility with high atom-efficiency without the need for additional ligands or additives.

Efficient construction of medium-sized lactones has attracted considerable interest over several decades, but remains a formidable challenge in synthetic chemistry. Here, we describe an unprecedented palladium-catalysed regioselective [5 + n] cyclisation (n = 5, 6, and 7) between vinylethylene carbonates and various anhydrides. Catalytic transformation occurs under mild, room-temperature conditions and offers an exceptional substrate scope. A broad spectrum of medium-sized bislactones with skeletal diversity can be obtained easily.

Ethyl levulinate (EL) was produced via one-pot conversion of biomass-based carbohydrates under a reusable biphasic system over a solid acid catalyst. In situ EL synthesis and extraction occurred during the reaction, resulting from the addition of a small amount of inorganic NaCl salt. The possible behavior of EL formation was described in detail. No serious reduction in the turnover rate of sucrose conversion was found during the recycling process.

Utilization of CO2 for the synthesis of fine chemicals and pharmaceuticals has attracted tremendous attention. In fact, reductive transformation of CO2 is also an interesting approach in this direction. Obviously, using hydrogen as a reducing agent is the most promising pathway for this reductive transformation. However, alternative to hydrogen, hydrosilanes have been also in the forefront due to their ready availability, nontoxic nature and easy handling procedure. Based on all this information, this work summarizes the recent applications of hydrosilylation of CO2 using different catalysts such as metal catalysts, organocatalysts, and heterogeneous catalysts.

Water-dispersed gold nanoparticles decorated with an amphiphilic cyclotetrasiloxane scaffold hold promise for the catalytic transformation of diorganosilanes to tetraorganodisiloxane-1,3-diols, (RR1SiOH)2O [R = Me or Ph R1 = Ph, cyclo-Hex] via en route formation of a Pickering emulsion. The recognition ability of these compounds toward Cl− ions reveals 2 : 1 receptor-anion complexation.

Herein, we present a highly efficient and convenient approach for carbon dioxide (CO2) capture and catalytic transformation under mild conditions using N,N′-bis(imidazolyl)guanidines (BIGs, organoguanidine-based strong superbases) as the organocatalyst, even from simulated flue gas (10% CO2/90% N2, v/v) or directly from dry air (∼400 ppm CO2). The zwitterionic BIG–CO2 adducts were successfully isolated and characterized. X-ray single crystal analysis revealed the bent geometry of the binding CO2 in the BIG–CO2 adduct with an O–C–O angle of 129.7° and increased C–O bond distances (1.253 and 1.237 A) in comparison with free CO2. Notably, the resulting BIG–CO2 adducts were found to be capable of catalyzing the novel cycloaddition of various propiolamidines with simulated flue gas to generate functionalized (4E,5Z)-4-imino-5-benzylideneoxazolidine-2-ones in good yields and excellent selectivity.

Benzaldehyde and benzoic acid are high-value aromatic chemicals and important intermediates in chemical industry, and the catalytic conversion of biomass-based sources to these aromatic chemicals is of great significance in both academic and industrial fields. This work demonstrated that bio-oil was directionally converted into benzaldehyde and benzoic acid by three-step process under atmospheric pressure and moderate temperatures. The process included the catalytic cracking of biooil into aromatics over 1% Ga/HZSM-5 catalyst, followed by the dealkylation of heavier alkylaromatics to toluene over Re/HY catalyst and the liquid-phase oxidation of toluene-rich aromatics to the targeted chemicals over CoCl2/NHPI (CoCl2/N-Hydroxyphthalimide) catalyst. The production of benzaldehyde and benzoic acid from the bio-oil-derived aromatics, with the overall selectivity of 86.8%, was achieved using CoCl2/NHPI catalyst at 100 °C. Furthermore, adding a small amount of methanol into the feed would efficiently suppress the coke formation, and thus, enhance the yield of aromatics. Potentially, the novel synthesis route offers a green way for the production of higher value-added aromatic chemicals using renewable and environmentally friendly biomass-based sources.

γ-Butenolides are fundamental frameworks found in many naturally occurring compounds, and they exhibit tremendous biological activities. γ-Butenolides also have proven their potential as useful synthetic intermediates in the total synthesis of natural compounds. Over the years, many γ-butenolide natural products have been isolated, having exocyclic γ-δ unsaturation in their structure. These natural products are collectively referred to as γ-alkylidenebutenolides. Considering the different biological profiles and wide-ranging structural diversity of the optically active γ-butenolide, the development of synthetic strategies for assembling such challenging scaffolds has attracted significant attention from synthetic chemists in recent times. In this report, a brief discussion will be provided to address isolation, biogenesis, and current state-of-the-art synthetic protocols for such molecules. This report aims to focus on synthetic strategies for γ-butenolides from 2010–2020 with a particular emphasis on γ-alkylidenebutenolides and related molecules. Metal-mediated catalytic transformation and organocatalysis are the two main reaction types that have been widely used to access such molecules. Mechanistic considerations, enantioselective synthesis, and practical applications of the reported procedures are also taken into consideration.

This investigation reports the in situ growth of silver nanoparticles onto covalently bonded graphene oxide-chitosan, which serve as supported nanocatalysts for the NaBH4 reduction of 2,4-dinitrophenol in aqueous systems. Fumaryl chloride reacted with chitosan in an acidic environment to yield a tailored polymeric material. The latter was, in turn, treated with the pre-synthesised graphene oxide sheets under acidic conditions to generate the GO-functionalised membrane (GO-FL-CS). The adsorption of Ag+ from aqueous media by GO-FL-CS yielded a set of membranes that were decorated with silver nanoparticles (Ag NPs@GO-FL-CS) without any reducing agent. Various analytical tools were used to characterise these composites, including Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray analysis, inductively coupled plasma-mass spectrometry, and transmission electron microscopy. The silver-loaded materials were further used for the remediation of 2,4-dinitrophenol from aqueous solutions under batch operation. The BET analysis revealed that the functionalisation of GO with chitosan and Ag NPs (average size 20–60 nm) resulted in a three-fold increased surface area. The optimised catalyst (Ag mass loading 16.95%) displayed remarkable activity with an apparent pseudo-first-order rate constant of 13.5 × 10−3 min−1. The cyclic voltammetry experiment was conducted to determine the nitro-conversion pathway. The reusability/stability test showed no significant reduction efficiency of this metal-laden composite over six cycles. Findings from the study revealed that Ag NPs@GO-FL-CS could be employed as a low-cost and recyclable catalyst to convert toxic nitroaromatics in wastewater.