The catalytic transfer hydrogenation of furfural to the fuel additives 2‐methylfuran (2‐MF) and 2‐methyltetrahydrofuran (2‐MTHF) was investigated over various bimetallic catalysts in the presence of ...the hydrogen donor 2‐propanol. Of all the as‐prepared catalysts, bimetallic Cu‐Pd catalysts showed the highest catalytic activities towards the formation of 2‐MF and 2‐MTHF with a total yield of up to 83.9 % yield at 220 °C in 4 h. By modifying the Pd ratios in the Cu‐Pd catalyst, 2‐MF or 2‐MTHF could be obtained selectively as the prevailing product. The other reaction conditions also had a great influence on the product distribution. Mechanistic studies by reaction monitoring and intermediate conversion revealed that the reaction proceeded mainly through the hydrogenation of furfural to furfuryl alcohol, which was followed by deoxygenation to 2‐MF in parallel to deoxygenation/ring hydrogenation to 2‐MTHF. Finally, the catalyst showed a high reactivity and stability in five catalyst recycling runs, which represents a significant step forward toward the catalytic transfer hydrogenation of furfural.
Identifying the intermediates: The catalytic transfer hydrogenation of biomass‐derived furfural to fuel additives 2‐methylfuran and 2‐methyltetrahydrofuran is performed over a bimetallic Cu‐Pd catalyst in the presence of 2‐propanol. The reaction proceeds via the intermediate furfuryl alcohol, which is then deoxygenated/hydrogenated to the desired products.
Cellulose is the most abundant, renewable carbohydrate resource in nature, providing human society with a broad spread of materials for production and living. Compared with the mature textile and ...paper industries, technologies for cellulose utilization to produce energy and chemicals are still under development. In particular, the depolymerization of cellulose to glucose and further transformation into various fuel compounds or chemicals has received considerable attention as a sustainable approach to address the energy crisis and environmental issues raised by massive fossil consumption. Among various cellulose derived molecule types, ester is one of the most appealing owing to its unique physicochemical properties, reactivities and functions. This review summarizes recent advances in the chemical synthesis of esters from cellulose and its derivatives. Various esters, including alkyl levulinates, γ-valerolactone, valerates, pentenoates, lactates
etc.
, have been effectively prepared from cellulose feedstock or its downstream platform compounds. The catalytic systems were highlighted with rational integration of the active sites for the tandem reactions involved in the conversions. The kinetics, process integration, selectivity control and catalysis mechanism were also discussed in detail. Finally, an outlook of the future direction, as well as the challenges, for cellulose ester production were also illustrated.
This review highlights recent advances in the conversion of cellulose and its derivatives (monosaccharides and platform molecules) into ester chemicals.
Inflammatory diseases are caused by abnormal immune responses and are characterized by an imbalance of inflammatory mediators and cells. In recent years, the anti-inflammatory activity of natural ...products has attracted wide attention. Rosmarinic acid (RosA) is a water-soluble phenolic compound that is an ester of caffeic acid and 3, 4-dihydroxyphenyl lactic acid. It is discovered in many plants, like those of the Boraginaceae and Lamiaceae families. RosA has a wide range of pharmacological effects, including anti-oxidative, anti-apoptotic, anti-tumorigenic, and anti-inflammatory effects. The anti-inflammatory effects of RosA have been revealed through
and
studies of various inflammatory diseases like arthritis, colitis, and atopic dermatitis. This article mainly describes the preclinical research of RosA on inflammatory diseases and depicts a small amount of clinical research data. The purpose of this review is to discuss the anti-inflammatory effects of RosA in inflammatory diseases and its underlying mechanism.
Legumes form symbiotic associations with either nitrogen-fixing bacteria or arbuscular mycorrhizal fungi. Formation of these two symbioses is regulated by a common set of signalling components that ...act downstream of recognition of rhizobia or mycorrhizae by host plants. Central to these pathways is the calcium and calmodulin-dependent protein kinase (CCaMK)-IPD3 complex which initiates nodule organogenesis following calcium oscillations in the host nucleus. However, downstream signalling events are not fully understood. Here we show that Medicago truncatula DELLA proteins, which are the central regulators of gibberellic acid signalling, positively regulate rhizobial symbiosis. Rhizobia colonization is impaired in della mutants and we provide evidence that DELLAs can promote CCaMK-IPD3 complex formation and increase the phosphorylation state of IPD3. DELLAs can also interact with NSP2-NSP1 and enhance the expression of Nod-factor-inducible genes in protoplasts. We show that DELLA is able to bridge a protein complex containing IPD3 and NSP2. Our results suggest a transcriptional framework for regulation of root nodule symbiosis.
Methylation of amines is increasingly being employed as a powerful structural modification tool in medicinal chemistry. However, selectively accessing the mono- or di-methylated amines with an ...integrated catalytic system remains a pivotal challenge. We here report the selective
N
-mono- and di-methylation of amines over heterogeneous bimetallic CuCo nanoparticle catalysts with tunable supports relying on a methanol-based methyl source.
N
-methylamines were selectively produced on Cu-Co/MgAl-LDO under a hydrogen atmosphere, while
N
,
N
-dimethylamines could be easily accessed on Cu-Co/Al
2
O
3
under a nitrogen atmosphere. A panel of structurally and functionally diverse amines, including primary/secondary aromatic amines and aliphatic amines, were efficiently methylated in excellent yields. Alternative substrate nitroarenes and aliphatic alcohols could be transformed in a predictable manner. Further characterization of the catalysts and a mechanistic study revealed that the metal-support interaction and acid-base properties originated from the support of the two catalysts, resulting in their selective methylation performances. Further fabrication of methylated pharmaceuticals or candidates highlighted the broad applicability of the selective
N
-mono- and
N
,
N
-dimethylation strategy with which the properties of drugs can be significantly changed.
Heterogeneous non-noble bimetallic CuCo nanoparticle catalysts for selective
N
-monomethylation and
N
,
N
-dimethylation reactions under base-free conditions, offering >50 examples from aromatic/aliphatic amines, nitrocompounds and different alcohols.
A general protocol for site-preferential mono-C–H arylation of tertiary phosphine ligands catalyzed by a ruthenium(II) complex was devised. This protocol gives access to a series of modified ...Buchwald–biaryl monophosphines on a gram scale in moderate to excellent yields. A catalytic cycle is proposed derived from knowledge of the intermediates observed by ESI-MS. Importantly, these monoarylated products could be further transformed into dibenzophosphole derivatives.
Active control of graphene plasmon-induced transparency (GPIT) metamaterial structures, composed of periodically patterned monopolar graphene and dipolar graphene, are presented and investigated. ...Numerical results reveal that the resonant frequency of GPIT structures can be dynamically tuned by varying the Fermi level of the T-shape graphene strip through controlling the voltage of the electrostatic gating. Coupled Lorentz oscillator model is applied to explore the physical mechanism of the frequency tunable GPIT. Furthermore, the group index of terahertz light can be controlled to exceed 350 in the THz region. It is also found that the interaction strength between the dipolar graphene and the monopolar graphene can be tuned by changing the distance between the radiative mode and the dark mode as well as the degree of the symmetry breaking. These tunable features of the GPIT devices are significant and may offer new opportunity to design active devices in the THz region, such as ultrasensitive sensors, slow light devices, and spectral filters.
Ru(II)-catalyzed direct alkylation of tertiary phosphines via hydroarylation of activated olefins promoted by mono-N-protected amino acid (MPAA) was achieved. This protocol provides a ...straightforward access to a large library of Buchwald-type bulky alkylated monophosphines from commercially available biaryl phosphine. Moreover, two ruthenacycle intermediates of tertiary phosphines via C–H bond cleavage were isolated to illustrate the mechanism of P(III)-directed C–H activation.
An efficient and robust bimetallic catalyst has been developed for the transfer hydrogenation of biomass derived ethyl levulinate to γ-valerolactone with 2-butanol as the hydrogen donor. Several ...bimetallic catalysts were prepared and characterized by Brunauer–Emmett–Teller, transmission electron microscopy, X-ray power diffraction and X-ray photoelectron spectrometry. They exhibited different catalytic activities in the catalytic transfer hydrogenation (CTH) reaction. Results showed that 10Cu-5Ni/Al2O3 had the highest activity, providing a 97% yield of GVL product in 12 h at 150 °C. The reaction temperature, reaction time and catalyst loading were also investigated and found to affect the product yield. The catalyst was also successfully applied to the CTH of various levulinate esters with different secondary alcohols. Comparing experiments between Cu–Ni and Cu catalysts and the poisoning experiments revealed that the introduction of Ni to Cu remarkably enhanced the catalyst’s activity and stability, showing an outstanding recycling ability in the 10 runs recycling experiments without notable loss in the activity.
The seasonal human coronaviruses (HCoVs) have zoonotic origins, repeated infections, and global transmission. The objectives of this study are to elaborate the epidemiological and evolutionary ...characteristics of HCoVs from patients with acute respiratory illness. We conducted a multicenter surveillance at 36 sentinel hospitals of Beijing Metropolis, China, during 2016–2019. Patients with influenza‐like illness (ILI) and severe acute respiratory infection (SARI) were included, and submitted respiratory samples for screening HCoVs by multiplex real‐time reverse transcription‐polymerase chain reaction assays. All the positive samples were used for metatranscriptomic sequencing to get whole genomes of HCoVs for genetical and evolutionary analyses. Totally, 321 of 15 677 patients with ILI or SARI were found to be positive for HCoVs, with an infection rate of 2.0% (95% confidence interval, 1.8%–2.3%). HCoV‐229E, HCoV‐NL63, HCoV‐OC43, and HCoV‐HKU1 infections accounted for 18.7%, 38.3%, 40.5%, and 2.5%, respectively. In comparison to ILI cases, SARI cases were significantly older, more likely caused by HCoV‐229E and HCoV‐OC43, and more often co‐infected with other respiratory pathogens. A total of 179 full genome sequences of HCoVs were obtained from 321 positive patients. The phylogenetical analyses revealed that HCoV‐229E, HCoV‐NL63 and HCoV‐OC43 continuously yielded novel lineages, respectively. The nonsynonymous to synonymous ratio of all key genes in each HCoV was less than one, indicating that all four HCoVs were under negative selection pressure. Multiple substitution modes were observed in spike glycoprotein among the four HCoVs. Our findings highlight the importance of enhancing surveillance on HCoVs, and imply that more variants might occur in the future.
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