Robby Vroemans

AA, my my: The production of adipic acid (AA) by a two-step pathway is studied. Ru/Al₂O₃ catalyst is used to obtain THFDCA and HAA (see graphic) by hydrogenation of furandicarboxylic acid. The ionic liquid [MIM(CH₂)₄SO₃H]I serves as both a reaction medium for conveying hydrogen and a highly catalytic system for furan ring-opening toward AA with 99 % yield.

Abstract

Efficient catalytic ring-opening coupled with hydrogenation is a promising but challenging reaction for producing adipic acid (AA) from 2,5-furan dicarboxylic acid (FDCA). In this study, AA synthesis is carried out in two steps from FDCA via tetrahydrofuran-2,5-dicarboxylic acid (THFDCA) over a recyclable Ru/Al₂O₃ and an ionic liquid, [MIM(CH₂)₄SO₃H]I (MIM=methylimidazolium) to deliver 99 % overall yield of AA. Ru/Al₂O₃ is found to be an efficient catalyst for hydrogenation and hydrogenolysis of FDCA to deliver THFDCA and 2-hydroxyadipic acid (HAA), respectively, where ruthenium is more economically viable than well-known palladium or rhodium hydrogenation catalysts. H₂ chemisorption shows that the alumina phase strongly affects the interaction between Ru nanoparticles (NPs) and supports, resulting in materials with high dispersion and small size of Ru NPs, which in turn are responsible for the high conversion of FDCA. An ionic liquid system, [MIM(CH₂)₄SO₃H]I is applied to the hydrogenolysis of THFDCA for AA production. The [MIM(CH₂)₄SO₃H]I exhibits superior activity, enables simple product isolation with high purity, and reduces the severe corrosion problems caused by the conventional hydroiodic acid catalytic system.

Publication date: Available online 15 March 2022

Source: Chem

Author(s): Emilia Paone, Francesco Mauriello

Single atom catalysts (SACs) have the potential to revolutionize the field of heterogeneous catalysis. The use of a single atomic layer of the active catalyst phase brings a huge saving in catalyst cost. Additionally, activity and selectivity are significantly improved with down-sizing the catalytic particles to an atomic level. With a single atomic layer of the active catalytic phase, coordination of the single atoms and their interactions with supports can be tuned in a way to improve catalytic performance. Thus, coordination and support-SACs interactions are the focus of this review.

Abstract

Catalyst utilization is a key economic factor in heterogeneous catalysis, particularly, when noble metals are used as the active phase. A huge saving on catalyst cost can be achieved with developing a single atomic layer of the active catalyst on a given cheap support. Besides the economic benefit, single atom catalysts (SACs) have also shown superior activity and selectivity relative to catalytic particles or nanoparticles; yet they are prone to aggregation and deactivation. The development of effective, stable, and commercially viable SACs is still a huge challenge. One of the remaining key obstacles is the ability to easily and effectively tune SACs-support interactions and coordination in a way that enables the production of robust, stable, and versatile SACs. Accordingly, the coordination and interactions between metallic supports and SACs and their impacts on SACs stability and activity are reviewed in this article.

Nature, Published online: 09 March 2022; doi:10.1038/d41586-022-00645-y

Boosted: Pt/MnO₂/CNT catalysts were utilized to chemoselective oxidation of glycerol, in which MnO₂ not only boosted the catalytic activity but also accelerated the activation of the formyl C−H bond in GLYAD to form GLYA.

Abstract

The metal oxide promoters remarkably enhance the catalytic activity of supported Pt catalysts in the glycerol oxidation toward glyceric acid, whereas the primary factor that metal oxide promotes the reaction, as well as the kinetics relevant step remain indistinct. Herein, manganese dioxide (MnO₂) is chosen as a model to uncover the role of promoter in the glycerol oxidation over Pt-based catalyst in alkali-free solution. The results prove that the superior catalytic performance is mainly attributed to the increased synergistic interaction between Pt particles and the metal oxides to boost the activation of oxygen (not glycerol), while the increased dispersion shows slight effect. Furthermore, the detailed kinetic studies reveal that MnO₂ is prone to accelerate the awkward step of glyceraldehyde to glyceric acid, and the lattice oxygen of MnO₂ also involves in this particular step.

Sugar: To enable the hydrogenolysis of sugars and sugar alcohols to glycols, we have synthesized different N- and O-doped carbon materials as catalyst supports for Ru. All N-doped catalysts yield a high glycol selectivity of up to 80 % for different substrates. XPS analysis confirms different ligand effects for O and N, altering the activity and selectivity of the resulting catalyst.

Abstract

Glycols are accessible via metal-catalyzed hydrogenolysis of sugar alcohols such as xylitol obtained from hemicellulose. Ru-based catalysts are highly active but also catalyze side-reactions such as decarbonylation and deoxygenation. To achieve high selectivity, these reactions need to be suppressed. In our study, we introduce heteroatom doped carbon materials as catalyst supports providing high selectivity. Heteroatom doping with nitrogen and oxygen was achieved by treating activated carbon with HNO₃, NH₃ and H₂ or carbonization of organic precursors. For all N-doped materials a high glycol selectivity of 80 % for sorbitol and xylitol and 44 % for xylose and glucose was reached. XPS analysis confirms the presence of different nitrogen species at the carbon surface and varying ligand effects for oxygen and nitrogen. Oxygen has an electron withdrawing effect on ruthenium and leads to a decreased activity. Nitrogen has weaker electron withdrawing properties, resulting in an enhanced selectivity.

The incorporation of cerium oxides over boron nitride enables atomic metal dispersion of Ni which simultaneously promoted the activity and coke resistance of dry reforming of methane.

Abstract

Dry reforming of methane (DRM) is a very promising protocol to mitigate the greenhouse gases by making use of CO₂ and CH₄ to produce valuable syngas. Ni-based catalysts exhibit high activity and low cost for DRM, but suffer from inferior stability because of serious carbon deposition. Herein, we proposed atomically dispersed Ni supported by ceria-upgraded boron nitride whose specific activity exceeds that of boron nitride-supported Ni by 3 times. The results of temperature-programmed surface reaction show ceria enhanced the adsorption of CO₂ and its surface-active oxygen species would contribute to the activation of CH₄. Moreover, Ni exhibited a strong metal-support interaction which suppressed the metal sintering during the DRM reaction while the incorporation of BN could suppress carbon deposition. The incorporation of active metal oxides into inert support provides a route to adjust the interaction between metal and support, and to achieve a synergistic improvement in catalytic performance.

Abstract

The C−F bond is the strongest single bond and it is one of the most challenging tasks to achieve the C−F bond functionalization. Here, we describe the first nickel-catalyzed selective defluorinative carboxylation of aryl C−F bonds with CO₂. Various methyl carboxylates including partially fluorinated carboxylation compounds were obtained. Mechanistic studies reveal that the azanickelacycles might be vital intermediates in this transformation. This novel and straightforward carboxylation strategy will extend the scope of C−F bond functionalization and enhance the understanding of the reactivity of very stable bonds.

Nature Chemistry, Published online: 07 March 2022; doi:10.1038/s41557-022-00901-8

A highly versatile synthetic route to symmetric and asymmetric αβ-fused BODIPY molecules possessing a butterfly shape is described. These dyes exhibit very attractive optical properties such as panchromatic absorption and effective emission in the NIR region.

Abstract

Here, we report the synthesis and properties of heterosubtituted αβ-fused BODIPY fluorophores. The compounds were obtained in good yields by sequential and selective Stille cross-coupling reactions from 2,3,5,6-tetrahalo-BODIPY, allowing the introduction of different substituents at the 3,5 and 2,6 positions of the BODIPY ring. The final fused compounds were synthesized using oxidative cyclisation with ferrous chloride. The fully fused compounds show a strong bathochromically shifted emission along with a hyperchromic shift of the absorption maxima. The fluorescence quantum yields remain relatively large for compounds emitting in this wavelength range. Computational studies have been carried out to fully understand the photophysical behaviour of these dyes.

Beilstein J. Org. Chem. 2022, 18, 240–242. doi:10.3762/bjoc.18.28

Nature Chemistry, Published online: 28 February 2022; doi:10.1038/s41557-022-00904-5

Abstract

Phenol derivatives are widespread as important building blocks in various pharmaceuticals, agrochemicals and materials. Modern economy requires development of “green” methodologies that improve the efficiency of their use and reduction of waste. One such method is the C−H/C−H cross-coupling, also known as the cross-dehydrogenative coupling reaction. In this review article, we have summarised the C−H/C−H cross-coupling reactions of phenols with five- and six-membered heterocyclic compounds, systemised methods of activation of phenol or coupling partner. We discuss these advances with the goal of motivating increased interest to develop novel methodologies in this field of organic chemistry.