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1.
ChemSusChem ; : e202401456, 2024 Oct 08.
Article in English | MEDLINE | ID: mdl-39377744

ABSTRACT

Polyoxometalates@metal-organic frameworks (POMs@MOFs) have attracted much attention as multifunctional materials in biomass catalysis. Individual POMs and MOFs are hindered by their respective defects, such as poor stability and single catalytic active site, which make it difficult to realize large-scale applications. However, the combination of POMs and MOFs can be used to maximize the catalytic advantages of each. MOFs with high specific surface area and rich pore structure can effectively stabilize and uniformly disperse POMs, while the introduction of POMs also provides more catalytic possibilities for POMs@MOFs. Therefore, POMs@MOFs with ultra-high porosity, large specific surface area and excellent acid catalytic activity have unique catalytic advantages in the field of biomass catalytic conversion. In this work, we provide an overview of the current development of POMs@MOFs in the field of biomass catalysis. The synthesis strategies of POMs@MOFs are summarized and discussed, highlighting the in-situ synthesis methods. We focus on the nanostructure engineering of POMs@MOFs, and explore the "structure-property" relationship in depth. In addition, the representative work of POMs@MOFs in the catalysis of biomass derivatives is summarized. Filially, the prospects, and challenges for the future development of POMs@MOFs in the field of biomass catalysis are also presented.

2.
Top Curr Chem (Cham) ; 381(6): 33, 2023 Nov 03.
Article in English | MEDLINE | ID: mdl-37921912

ABSTRACT

Palladium-catalyzed allylation cyclization reaction has recently emerged as an efficient and powerful synthetic platform for the construction of diverse and valuable carbo- and heterocycles. Thus the development of new allylic motifs for achieving this type of transformations in high reactivity and selectivity is of great importance. Generally, these substrates have been utilized as 1,3-, 1,4-, 1,5-, 1,6-dipoles in many reactions, which are applied to prepare highly functionalized products with complete control of chemo-, regio-, diastereo-, and enantioselectivity. In this review, we focus our attention on the development of palladium-catalyzed [4 + n] cycloaddition of allylic motifs and describe a comprehensive and impressive advances in this area. Meanwhile, the related mechanism and the application of these annulation strategies in natural product total synthesis will be highlighted in detail.


Subject(s)
Lactones , Palladium , Cycloaddition Reaction , Catalysis , Carbonates
3.
ChemSusChem ; 16(24): e202301091, 2023 Dec 19.
Article in English | MEDLINE | ID: mdl-37656427

ABSTRACT

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

4.
ChemSusChem ; 15(17): e202201074, 2022 Sep 07.
Article in English | MEDLINE | ID: mdl-35790081

ABSTRACT

In recent years, electrocatalysis was progressively developed to facilitate the selective oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) towards the value-added chemical 2,5-furandicarboxylic acid (FDCA). Among reported electrocatalysts, alloy materials have demonstrated superior electrocatalytic properties due to their tunable electronic and geometric properties. However, a specific discussion of the potential impacts of alloy structures on the electrocatalytic HMF oxidation performance has not yet been presented in available Reviews. In this regard, this Review introduces the most recent perspectives on the alloy-driven electrocatalysis for HMF oxidation towards FDCA, including oxidation mechanism, alloy nanostructure modulation, and external conditions control. Particularly, modulation strategies for electronic and geometric structures of alloy electrocatalysts have been discussed. Challenges and suggestions are also provided for the rational design of alloy electrocatalysts. The viewpoints presented herein are anticipated to potentially contribute to a further development of alloy-driven electrocatalytic oxidation of HMF towards FDCA and to help boost a more sustainable and efficient biomass refining system.


Subject(s)
Alloys , Furaldehyde , Biomass , Dicarboxylic Acids/chemistry , Furaldehyde/analogs & derivatives , Furaldehyde/chemistry , Furans/chemistry
5.
Food Chem ; 378: 131994, 2022 Jun 01.
Article in English | MEDLINE | ID: mdl-35030461

ABSTRACT

Repeated freeze-thaw is one of the main reasons for quality deterioration of frozen meat products. The study focused on the changes of endogenous fluorescence, secondary structure, microstructure, and water retention and distribution in marinated and unmarinated Enshi black pork after 10 freeze-thaw cycles. The results revealed that marinated treatment significantly reduced the thaw and centrifugal loss (P < 0.05), and increased endogenous fluorescence intensity of samples. During the entire freeze-thaw process, free water was undetectable in marinated group. After the first 4 cycles, α-helix percentage in marinated group was higher than that in control group. Scanning electron microscopy results suggested that there was no obvious increase in muscle fiber gap until 8 cycles in marinated group. Conclusively, moderate marination could slow down the deterioration of myofibrillar protein and pork quality, but it would be better to limit freeze-thaw cycles within 4 to maintain the quality of marinated Enshi black pork.


Subject(s)
Meat Products , Pork Meat , Red Meat , Animals , Freezing , Meat Products/analysis , Proteins , Swine
6.
Chemosphere ; 286(Pt 3): 131862, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34403899

ABSTRACT

The ubiquitous presence of inorganic and organic phosphorus in wastewater and natural water bodies has deteriorated the water environment qualities and exerted significant influences on ecosystems. In this study, an effective polypyrrole modified red mud adsorbent (PRM) was optimized for the adsorptive removal of inorganic and organic phosphorus from aqueous solutions. The addition of ferric chloride and pyrrole was optimized for complete oxidation and modification of polypyrrole onto red mud. Kinetic studies illustrated that the adsorption progress was accomplished by physical and chemical adsorption. The experimental data of the optimized PRM were described well by Langmuir isotherm, and the equilibrium adsorption capacity was 32.9 and 54.7 mg/g for inorganic and organic phosphorus, respectively. The PRM showed commendable adsorption performance despite the pH conditions ranging from 3 to 11. From the effect of ion strength and X-ray photoelectron spectroscopy (XPS) tests, we found that ligand exchange is the main mechanism of orthophosphate adsorption onto PRM, while electrostatic attraction played an important role in organic phosphorus adsorption. The adsorption performance from column studies showed that the velocity of flow influenced the breakthrough time of the column but the initial concentration had minor impacts. This study would extend the potential application of polypyrrole modified red mud, acting as an efficient adsorbent for inorganic and organic phosphorus adsorption in water treatment.


Subject(s)
Water Pollutants, Chemical , Water Purification , Adsorption , Ecosystem , Hydrogen-Ion Concentration , Kinetics , Phosphorus , Polymers , Pyrroles , Water Pollutants, Chemical/analysis
7.
Molecules ; 24(3)2019 Feb 04.
Article in English | MEDLINE | ID: mdl-30720731

ABSTRACT

Stainless steel wire mesh supported molecularly imprinted composite membranes for selective separation of Ebracteolata Compound B (ECB) were prepared based on surface polymerization using ECB separated from Euphorbia fischeriana as a template, acrylamide as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, azodiisobutyronitrile as an initiator, and stainless steel wire mesh as support. Structure and purity of ECB were characterized by nuclear magenetic resonance (¹H-NMR, 13C-NMR) and ultra high performance liquid chromatography (UHPLC). The molecularly imprinted composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The membrane adsorbed on the ECB reached equilibrium about 30 min later, with a maximum adsorption amount of 3.39 µmol/cm². Adsorption behavior between ECB and the molecularly imprinted composite membranes followed pseudo-second-order kinetics equation and Freundlich isotherm model. The molecularly imprinted composite membranes that could selectively identify and transport ECB in similar structures have a permeation rate of 38.71% to ECB. The ECB content in the permeation solution derived from the extract of Euphorbia fischeriana through the imprinted membrane was 87%. Overall, the obtained results demonstrated that an efficient approach with the molecularly imprinted composite membranes for selective separation of ECB from Euphorbia fischeriana.


Subject(s)
Acetophenones/chemistry , Acetophenones/isolation & purification , Euphorbia/chemistry , Membranes, Artificial , Molecular Imprinting/methods , Stainless Steel , Adsorption , Permeability , Polymerization , Polymers/chemistry , Spectroscopy, Fourier Transform Infrared , Stainless Steel/chemistry , Temperature
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