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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.

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...

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.

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.

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.

Acceleration of the catalytic transformation of molecules via heterogeneous materials occurs through design of active binding sites to optimally balance the requirements of all steps in a catalytic...

Cobalt catalysts bearing 2-imino-1,10-phenanthroline ligands are quite efficient bench-stable catalysts for the oligomerization of ethylenes. Herein, their further application was developed in the catalytic transformation of N,N-diallylanilines to pyrrolidines through a cycloisomerization process. In this protocol, chlorobenzene is a vital additive to promote reaction efficiency.

A series of metal-modified hierarchical M/H-ZSM-5 catalysts were prepared for catalytic conversion of cellulose in an aqueous medium. Characterization of the catalysts showed that the impregnation of metal into H-ZSM-5 did not change the basic framework and pore structure of H-ZSM-5, but it decreased the total acidity. Analysis of the products indicated that the catalysts significantly affected products distribution. When Co/H-ZSM-5 and Fe/H-ZSM-5 were used as the catalysts, the yields of lactic acid and cyclic ketones obviously increased. At last, a recommendable catalytic transformation pathway of cellulose over M/H-ZSM-5 was proposed on the basis of the obtained experimental results and the published literatures. In this paper, a series of metal-modified hierarchical M/H-ZSM-5 (M = Ce, Co, Ga, and Fe) catalysts were prepared and employed in catalytic conversion of cellulose in aqueous media to examined the products distribution of cellulose catalytic conversion. Based on our results and previous works, the plausible general reaction pathways of cellulose over M/H-ZSM-5 were proposed.

The first catalyst for the alkoxycarbonylation of gem-difluoroalkenes is described. This novel catalytic transformation proceeds in the presence of Pd(acac)2 /1,2-bis((di-tert-butylphosphan-yl)methyl)benzene (btbpx) (L4) and allows for an efficient and straightforward access to a range of difluoromethylated esters in high yields and regioselectivities. The synthetic utility of the protocol is showcased in the practical synthesis of a Cyclandelate analogue using this methodology as the key step.

Asymmetric hydroformylation (AHF) of alkenes is a prototypical, complicated catalytic transformation with a mechanism that comprises three concurrent, isomeric catalytic cycles. A persistent challe...

The construction of carbon–carbon bonds is a central tenet of modern synthetic chemistry. Metal-catalyzed C–H functionalization can serve as a particularly powerful tool for achieving carbon–carbon bond formation. This review summarizes the early adventures and recent advancements in catalytic transformation of unactivated C(sp3)–H bonds into C(sp3)–C(sp3) bonds. To date, three main strategies have emerged to enable this transformation, namely, metallocarbene-triggered C(sp3)–H alkylation, auxiliary-directed C(sp3)–H alkylation, and photo-induced C(sp3)–H alkylation. Compared with traditional cross-coupling reactions having both coupling partners activated with functional groups or base-promoted enolate chemistry, catalytic alkylation of unactivated C(sp3)–H bonds for C(sp3)–C(sp3) bond formation not only offers novel disconnections in retrosynthetic analysis, but also represents the future trend in green and atom-economic chemistry.

A metal free gem selective dimerization of terminal alkynes catalyzed by a pyridonate borane complex is described. Each individual step of the catalytic cycle was verified experimentally and a protocol for the catalytic reaction was developed. The mechanism of the reaction was further investigated by DFT and DLPNO-CCSD(T) computations. The catalytic transformation commences with C–H cleavage by a boroxypyridine that displays frustrated Lewis pair reactivity. The pyridone borane complex that forms upon C–H cleavage dissociates into a pyridone and an alkynylborane. An unprecedented 1,2-carboboration and a protodeborylation effected by the pyridone yield the 1,3-enyne and complete the catalytic cycle. The change in the coordination mode of the boroxypyridine upon C–H cleavage, described by the term boron-ligand cooperation, enables the dissociation of the formed pyridone borane complex and the 1,2-carboboration and is thus vital for the catalytic reaction.

The use of small molecules with defined cavities that catalyze unique chemical transformations to emulate enzyme sites have resulted in sustainable catalytic transformation with unprecedented selectivity that proceed under ambient conditions using benign solvents and clean energy. Of these reported host molecules, Werner-type capsules have been of particular interest to researchers because of their structural modifiability and rich chemical properties arising from their uniform cavities. In this review, we focus on the catalytic properties of several important catalytic transformations that have occurred within the confined pockets of these Werner-type capsules with special attention to the aspects that are derived from the ‘confined space effect’ of these Werner-type capsules.

Described here are the ethanol heterogeneous catalytic transformations to higher value-added products such as hydrogen (H2), ethylene (C2H4), Guerbet condensation products (mostly 1-butanol), the Lebedev dehydration product 1,3-butadiene, and other relevant products, focusing on catalysts based on non-noble metals. Ethanol catalytic transformation can be a crucial technology in producing organic chemicals and building blocks since it is renewable and fits low-carbon economy requirements. Although promising, much effort is still needed to develop new catalysts, reaction methodologies, and up-scaling, which open new perspectives for intense research and development. Due to the low-cost and high-production of ethanol in Brazil, as well as the energy surplus in the sugarcane mills, research groups in this country are dedicating efforts to develop new ethanol catalytic transformations. However, there remains a need for ethanol valorization into more complex condensed products.

Funding: This work was supported by Sasol Ltd. SC is grateful for a St Leonard’s postgraduate fellowship by the University of St Andrews. A bis-ethene chromium(I) species, which is the postulated key intermediate in the widely accepted metallacyclic mechanism for ethene oligomerization, is experimentally observed. This catalytic transformation is an important commercial route to linear α-olefins (primarily, 1-hexene and 1-octene), which act as comonomers for the production of polyethene. Here, electron paramagnetic resonance studies of a catalytic system based on [Cr(CO)4(PNP)][Al(OC(CF3)3)4] [PNP = Ph2PN(iPr)PPh2] activated with Et6Al2 provide the first unequivocal evidence for a chromium(I) bis-ethene complex. The concentration of this species is enhanced under ethene and isotope labeling studies that confirm its composition as containing [Cr(C2H4)2(CO)2(PNP)]+. These observations open a new route to mechanistic studies of selective ethene oligomerization. Publisher PDF

A copper/silver co-catalyzed cross-dehydrogenative coupling reaction is developed to achieve exclusively remote C5–H coupling of 8-aminoquinoline amides with the methylenic sp3 C–H bond of 1,3-dicarbonyl compounds. This protocol provides a highly regioselective synthetic route for the functionalization of 8-aminoquinoline amides at C5 under mild conditions. Preliminary experiments reveal that radicals may be involved in this catalytic transformation.

A simple and high‐efficiency method is proposed to synthesize hierarchical ZSM‐5 zeolites with micropore and multistage mesopores by adopting water‐soluble carbon dots (CDots) with various size distributions, such as 1‐stage size distribution of CDots‐1 of around 23 nm, 2‐stage size distribution of CDots‐2 of 6 and 9 nm, 3‐stage size distribution of CDots‐3 of 5, 8, and 18 nm. The abundant OH and COOH groups on the surface of CDots provide high solubility in water. The characterization techniques confirmed that the dual‐porous h‐ZSM‐5 (MIcro–mEsopores) and multi‐porous h‐ZSM‐5 (MIcro–mEso–mEsopores), h‐ZSM‐5 (MIcro–mEso–mEso–mEsopores, M‐IEEE) catalysts are obtained. Notably, the hierarchical ZSM‐5(M‐IEEE) catalyst with micropore of 0.55 nm, two small mesopores of 4.8 and 7.4 nm, and one large mesopore of 17.5 nm show excellent catalytic performance with the highest 1,3,5‐triisopropylbenzene (TIPB) cracking conversion (97.3%) and high stability. Similarly, the h‐ZSM‐5(M‐IEEE) shows the high ethanol to olefins conversion (100%). The improved catalytic activity can be attributed to the more efficient diffusion of reactants and products in the crystals with the help of multistage mesopores, improved anti‐coking stability, combined with the effect of suitable acidity, and the increased accessibility of the acid sites.

MoVOx-type catalysts are very active and very selective in the commercially important oxidation of acrolein to acrylic acid. To contribute to unravelling the thus far poorly understood mechanism, we carried out hybrid DFT calculations on embedded cluster models, focusing on the so-called pentameric unit as active site. In the absence of water, we calculated a large energy span, 169 kJ mol–1, for this transformation. After addressing the hydrolysis of the surface, we examined four scenarios of the acrolein conversion to explore the effect of water. The most favorable variant has a notably lower energy span, 146 kJ mol–1, in line with experimental observations that indicate a strong acceleration of the catalytic transformation in the presence of water.

Fe-catalyzed direct transformation of nitro compounds to aldehyde under batch/continuous flow module is reported. This catalytic transformation is highly selective for syntheses of various aldehyde...

The synthesis of aromatic ketones by chromium-catalyzed Kumada arylation of secondary amides with organomagnesium reagents is described. This reaction was enabled by using low-cost chromium(III) salt as a precatalyst, combined with trimethylsilyl chloride as an additive, and presents a rare example of catalytic transformation of secondary amides to ketones at room temperature. It was shown that catalytically active low-valent chromium species might be responsible for the amide–ketone exchange by mechanism involving the activation of benzimidate intermediate.

Amides are generally considered as a low-reactive chemical entity among the carbonyl group, and therefore fewer opportunities to be involved in catalytic transformations as substrates. The origin of the stable nature of amides is resonance stabilization in the planar structure, which has drawn considerable attention from organic and physical chemists, leading to the discovery of distorted amides that exhibit a substantially reactive nature. Recent focus in this field is on the catalytic transformation of designed amides with moderate distortion or reduced resonance stabilization. This digest reviews the brief history of the quest for highly distorted amides and introduces a collection of recent studies on catalytic transformations of designed amides.

The direct transformation of lignocellulosic biomass into valuable chemicals and fuels, which is recognized as a promising strategy for easing the present situation of energy depletion, has brought...

[Fe4N(CO)12]− is a first-row transition element electrocatalyst that selectively produces C–H bonds to give formate from CO2 in water at −1.2 V vs SCE. We present a thermochemical analysis which probes the possibility that [H-Fe4N(CO)12]2– ((H-1)2–) is an intermediate in this process: we show that (H-1)2– is accessible at −1.2 V vs SCE, but if it were formed, we predict that it would generate H2. [Fe4N(CO)12]3– and (H-1)2– were interrogated spectroscopically, and the product of CO loss, [Fe4N(CO)9(μ-CO)2]3–, was synthesized and characterized. Ultimately, we demonstrate that (H-1)2– is an unlikely participant in the catalytic transformation of CO2 to formate.

A catalytic transformation of allylic hydroperoxides into α,β-unsaturated carbonyl compounds using IBX as a dehydration catalyst is described. The combination of a singlet oxygen ene reaction and the IBX-catalyzed dehydration provides α,β-unsaturated carbonyl compounds from alkenes via oxygenative allylic transposition with H2O as the only byproduct.

A novel catalytic behavior of simple rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Yb(4), Y(5)) in the intermolecular addition of alcohols to carbodiimides was disclosed. A series of isoureas were obtained in good to excellent yields via the addition reaction in the presence of the optimal lanthanum amide La[N(SiMe3)2]3. Kinetic studies were also conducted and a possible mechanism of catalytic transformation was suggested.

A ligand-free bimetal-catalyzed aminosulfonylation of aryl iodides is successfully developed. The protocol provids a straightforward approach to access a broad range of structral intriguing sulfonamides in one-pot manner at low catalyst loading from the sulfur dioxide surrogate DABSO and O-benzoyl hydroxylamines under mild conditions. Even without additional ligands, the protocol reveals broad substrate scope for both partners and tolerates all kinds of functional groups. Furthermore, the plausible intermediate sulfinate is critical for this ligand-free catalytic transformation.

Amide, as a ubiquitous functional group, is essential in various aspects of chemistry and biology. Although the history of studying amide is rich and fruitful, the synthetic application of amide is very limited due to the inertness of amide C–N bond. Recently, significant advances have been achieved towards the nickel-mediated C–N activation of amides. This approach allows a facile generation of acyl-nickel intermediates, and a number of unique transformations have been designed and realized based on the amide C–N bond activation. Focused on the catalytic transformation, this review summarizes and categorizes the recent advances on the synthetic applications of Ni-mediated C–N bond activation of amides.