Catalysts
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2019
·Vol. 10
·期 1
·10
·
IF 3.444
Wan-Qiang Wang,Hua Cheng,Ye Yuan,Yu-Qing He,Hua-Jing Wang,Zhi-Qin Wang,Wei Sang,Cheng Chen,Francis Verpoort
The transition-metal-catalyzed alcohol dehydrogenation to carboxylic acids has been identified as an atom-economical and attractive process. Among various catalytic systems, Ru-based systems have been the most accessed and investigated ones. With our growing interest in the discovery of new Ru catalysts comprisingN-heterocyclic carbene (NHC) ligands for the dehydrogenative reactions of alcohols, we designed and prepared five NHC/Ru complexes ([Ru]-1–[Ru]-5) bearing different ancillary NHC ligands. Moreover, the effects of ancillary and additional ligands on the alcohol dehydrogenation with KOH were thoroughly explored, followed by the screening of other parameters. Accordingly, a highly active catalytic system, which is composed of[Ru]-5combined with an additional NHC precursorL5, was discovered, affording a variety of acid products in a highly efficient manner. Gratifyingly, an extremely low Ru loading (125 ppm) and the maximum TOF value until now (4800) were obtained.Keywords:ruthenium (Ru);N-heterocyclic carbenes (NHCs);carboxylic acids;ancillary ligands;additional ligands
研究领域:
化学
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催化反应
✓ 已验证
DOI
高影响因子
Advanced Industrial and Engineering Polymer Research
·
2020
·
IF 0
Lishuai Zong,Chuang Li,Yuan Zu,Jinyan Wang,Xigao Jian
Modern microelectronics devices urgently request low dielectric constant materials with commendable mechanical properties. Novel fluorinated poly(aryl ether)s (FPPEs) were prepared by traditional polycondensation of 4-(4-Hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ), Bisphenol AF (BAF) and Decafluorobiphenyl (DFB) to study bulky phthalazinone effects on mechanical and dielectric behavior of polymers. After the introduction of phthalazinone moieties, FPPEs showed excellent solubility to readily solve in many organic solvents like NMP, DMAc, CHCl 3 , and THF. Simultaneously, they exhibited relatively high glass transition temperatures ( T g s) from 180 °C to 294 °C, increasing with the content of phthalazinone groups. The FPPEs still possessed excellent thermal stability with decomposition temperature up to 514 °C and char yield at 800 °C as high as 56% under nitrogen atmosphere. FPPE films showed good mechanical strength with tensile stress higher than 68 MPa and modulus surpassing 10.8 MPa, also increasing with phthalazinone concentration. The dielectric property of FPPEs was investigated with impedance analyzer. FPPE8020 and FPPE 6040 showed dielectric constant from 3.10 to 3.30 and dielectric loss of 0.005–0.008 under a large frequency range of 0.02–60 GHz. The phthalazinone moieties mainly contributed to the decrease of dielectric constant. The results evidently suggest FPPEs as commendable candidate for those high-tech electronic applications.
研究领域:
材料科学
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高分子化学
✓ 已验证
DOI
Molecular Catalysis
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2024
·
IF 3.9
Hui Cao,Yu Liu,Yanqiu Li,Yingxiong Wang,Yan Qiao
The α-hydroxyketones and 1,2-diols are versatile building blocks for the preparation of many natural and synthetic bioactive compounds. In this study, N-heterocyclic carbon (NHC) promoted coupling of several aldehydes with formaldehyde enabled the synthesis of 1,2-diols in moderate to high yields. The highly selective conversion of several aldehydes and formaldehyde into 1,2-diols and α-hydroxyketones was achieved in a one-pot two-step process via [BHMIm][OAc] as a key intermediate. In the first step, formaldehyde was quantitatively converted to [BHMIm][OAc] through the carbene addition. In the second step, 1,2-diol was produced through the intermediate-promoted aldol reaction. The results showed that benzaldehyde was capable to react with [BHMIm][OAc] efficiently, with a 54.1% yield of 1,2-diol after the 3-hour reaction at 85 °C. Among the tested benzaldehyde derivatives, the 4-nitrobenzaldehyde showed the highest yield of 1,2-diol (73.3%) under the optimized reaction conditions. Incorporation of an electron rich group on benzaldehyde promoted carbene regeneration. With 4-methoxybenzaldehyde as the substrate, the yield of α-hydroxyketone reached a maximum of 30.6%. Additionally, dihydroxyacetone derivatives were detected in the system. In situ NMR technique confirmed that it was generated from the further reaction of the carbene/1,2-diol complex with another aldehyde. Based on the results of NMR spectroscopy and mass spectrometry, a possible reaction pathway was also proposed.
研究领域:
有机化学
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合成化学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
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2018
·Vol. 42
·期 11
·9140-9150
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IF 3.201
Jiliang Ma,Xinwen Peng,Linxin Zhong,Runcang Sun
The application of biomass-based carbonaceous solid acids in catalysis is attracting increasing attention in the field of chemistry. In this study, a heterogeneous carbon-based solid acid biocatalyst (CXH-SO3H) with regular spherical structure was synthesized from xylan-type hemicellulose (XH) by a simple two-step method. The catalyst was successfully applied in the synthesis of O- and N-heterocycles with yields of 80–99% and 60–97%, respectively. In view of environment and economy, CXH-SO3H shows the merits of environmental friendliness, easy operation, simple work-up, excellent yields, and the avoidance of use of organic solvents and expensive catalysts. Moreover, the as-synthesized solid acid catalyst could be used for several cycles without significant loss in its catalytic activity. The results of FT-IR, XRD, and SEM showed that no distinct differences in physico-chemical structures of CXH-SO3H were observed. Thus, the eco-friendly CXH-SO3H catalyst is a promising candidate for green synthesis of O- and N-heterocycles from low-cost feed-stocks and has good prospect in partially substituting commercially available solid and liquid acid catalysts and precious metal catalysts.
研究领域:
化学
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可再生资源
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绿色化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
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2019
·
IF 3.774
Yunwu Zheng,Zhen Wang,Can Liu,Lei Tao,Yuanbo Huang,Zhifeng Zheng
By introducing exogenous nitrogen during biomass pyrolysis under nitrogen-rich conditions, high-value nitrogen-containing products, i.e., nitrogen-rich char and oil may be produced. Based on the cogeneration of high-value nitrogen products from biomass, biomass nitrogen-enriched pyrolysis was performed in a fixed bed with different sources and contents of ammonia. The yields, composition and characteristics of the products were investigated. Moreover, the formation mechanism of N-containing species was explored in depth for the pyrolysis and catalytic pyrolysis with HZSM-5 and Zn/HZSM-5 catalysts via elemental analysis, XPS, FTIR and BET. The results showed that ammonia impregnation could promote a Maillard reaction, reduce the content of small aldehydes and ketones, and produce a nitrogen-enriched bio-oil. The contents of N-containing species and phenolic substances in the pyrolysis oil of biomass impregnated with 10% urea reached 15.66% and 56.69%, respectively. Moreover, the nitrogen on the coke surface after pretreatment was mainly composed of C N, C N and N COO functional groups. The bio-char generated abundant pyridinic-N, pyrrolic-N, quaternary-N, and pyridone-N oxides. The presence of urea introduced many alkaline N-containing functional groups on the surface of the bio-char and promoted the transformation of nitrogen from amides and imides to heterocyclic nitrogen with higher thermal stability. Furthermore, Zn was an excellent catalyst for the Maillard reaction, and the Zn/HZSM-5 catalyst had a higher selectivity for aromatic hydrocarbons (96.98% for biomass and 86.48% for urea/biomass) and N-containing heterocyclic compounds, such as indoles (6.16% for biomass and 13.51% for urea/biomass). Additionally, the coke content decreased, and the catalyst deactivation decreased.
研究领域:
能源与环境科学
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化学工程
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DOI
高影响因子
ChemCatChem
·
2017
·Vol. 9
·期 13
·2565-2573
·
IF 4.803
Wei Su,Hussein A. Younus,Somboon Chaemchuen,Cheng Chen,Francis Verpoort
Graphical Tune up the backbone : The effects on water oxidation of tuning the donating ability of carbon donors by ligand substitutions in the backbones of N-heterocyclic carbenes (NHCs) in Ru–NC NHC O type complexes were investigated. In this work, the effects of substitutions in the backbone of imidazolylidene and axial ligands on the reactivity and stability of water-oxidation catalysts were investigated. Three pincer-type asymmetric imidazolium salts NC NHC O , NC NHC-4Br O , and NC NHC-B O (NHC: N-heterocyclic carbene), of which the donating ability of the corresponding imidazolylidene decreases in the same sequence, were prepared. Their application in metalation afforded the corresponding Ru complexes 1 a , 1 b , 2 , and 3 . It was found that the complexes incorporating the stronger donor displayed lower potential for each redox couple and longer lifetimes, but relatively low reaction rates. Under acidic conditions, water oxidation driven by cerium ammonium nitrate resulted in turnover numbers (TONs) of 2322, 1728, 1928, and 2208 for 1 a , 1 b , 2 , and 3 , respectively. Complex 2 exhibited a good match of reactivity and stability with a TON of 136 in a typical three-component photocatalysis. Importantly, NHCs could be another powerful tool for tuning the reactivity and stability of water-oxidation catalysts, in addition to substituted pyridines. Rational orchestration of modified NHCs and pyridines could eventually result in water-oxidation catalysts exhibiting appreciable effectiveness and considerable robustness.
研究领域:
化学
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催化化学
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配位化学
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DOI
高影响因子
Catalysis Science & Technology
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2019
·Vol. 9
·期 20
·5651-5659
·
IF 5.726
Hossain M. Shahadat,Hussein A. Younus,Nazir Ahmad,Md. Abdur Rahaman,Zafar A. K. Khattak,Serge Zhuiykov,Francis Verpoort
Water-soluble homogeneous nickel catalysts have been rarely investigated for catalytic water oxidation as compared to their heterogeneous counterparts. Herein, we report homogenous electrochemical water oxidation by a nickel(II) complex, ([NiL](PF6)2 (L = bis(2-pyridyl-methylimidazolylidene)methane), based on a macrocyclic N-heterocyclic carbene/pyridine hybrid ligand under neutral and alkaline conditions. The catalyst displayed the stable catalytic current of 0.65 mA cm−2 at the overpotential of 0.80 V (∼0.55 V at GCE for CV) with a ∼93% Faradaic efficiency at pH 9.0 for oxygen evolution in long-term bulk electrolysis. The CV, UV-vis, ESI-MS, SEM, and EDX results demonstrated that the catalyst was impressively stable even after long-term controlled potential electrolysis (CPE) (11 h) and homogeneous in nature. The synthesis of this catalyst is straightforward, and its complex is air and moisture stable. To the best of our knowledge, this is the first study on the investigation of a Ni–NHC complex for water oxidation under aqueous conditions (acetate/phosphate). According to the literature, the role of the phosphate ion in homogenous nickel-catalysed water oxidation was found to vary from catalyst poisoning to activation. Interestingly, the catalytic activity of our catalyst in phosphate buffer was significantly higher than that with acetate ions at the same pH value; this might indicate the key role of phosphate ions as proton acceptors, which boosted the catalyst activity via enhanced PCET during catalysis.
研究领域:
无机化学
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电化学
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催化化学
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配位化学
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能源化学
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DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2022
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IF 6.437
Bingbing Luo,Kai Wu,Jiajun Yu,Siyu Wang,Yihan Wang,Chenyang Chu,Huiyan Zhang
Catalytic pyrolysis of biomass for efficient N-heterocycles production is highly promising but extremely challenging. Herein, catalytic co-pyrolysis of glycerol and cellulose under ammonia atmosphere was proposed to enhance the N-heterocycles yield. First, a solvolysis effect of glycerol, which could improve the thermal depolymerization of cellulose, was observed in thermogravimetric analysis (TGA). After that, the major influential factors, including Si/Al ratio, reaction temperature, and glycerol-to-cellulose (Gly:Cel) ratio, were investigated systematically. The N-heterocycles yield, as well as the comprehensive synergies of feedstocks, reached their maximum value under the conditions of Si/Al = 85, 550 ℃, and Gly:Cel = 5:1. The best synergistic extents for pyrroles , pyridines, and indoles were 105.3%, 71.3%, and 38.8%, respectively. The mechanism insight showed that, the thermal decomposition of cellulose was promoted while the coking of oxygenated molecules was suppressed during the catalytic co-pyrolysis process. Consequently, more oxygenated molecules were generated and retained for further catalytic conversion into imine intermediates and N-heterocycles.
研究领域:
能源与燃料化学
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生物质转化
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Yue Sun,Yingpeng Gu,Jinpeng Yang
N-heterocyclic compounds (NHCs) in industrial wastewater, such as pyridine, have potential toxicity to organisms and are difficult to biodegrade, causing great harm to the environment and human health. In this work, four sulfonic acid-functionalized resins (30-R, 40-R, 60-R and 70-R) with different sulfonation degree were prepared on the basis of the conventional hypercrosslinked resin by controlling the reaction temperature with concentrated sulfuric acid. The batch experiments showed that the adsorption capacities of pyridine on the sulfonic resins are pH-dependent, and the optimum pH increases with the increase of sulfonation degree. The adsorption of pyridine on the resin was monolayer, and the maximum adsorption capacity fitted by Langmuir model was positively correlated with sulfonation degree. The fitting results of Weber-Morris model showed that high sulfonation degree meant high intraparticle diffusion rate. The driving forces of adsorption included electrostatic attraction, π-π conjugation and hydrophobic interaction. Although the electrostatic attraction, which played the most important role, significantly improved the adsorption capacity of the sulfonic resin, it weakened the effect of the other two. This phenomenon was caused by the introduction of sulfonic groups significantly promoted the adsorption performance of the resin for single-ring NHCs, but that for fused-ring NHCs with π-electron-rich regions and strong hydrophobicity was unremarkable, or even decreased. Under the synergism of the three driving forces, sulfonic acid-functionalized hypercrosslinked resin exhibited superior adsorption performance for NHCs with easy protonation, high π-electron cloud density and strong hydrophobicity.
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
Petroleum Science
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2023
·
IF 5.6
Fan Ding,Xin Jin,Tao Shen,Shan-Shan Mao,Qing Zhao,Mang-Lai Gao
Wettability is an important surface property that deserves to further explore the factors on its alteration. Series of bis -N-heterocyclic quaternary ammonium salts with different spacer length and N-heterocyclic headgroups (morpholinium (BMMB, BMMD and BMMH), piperidinium (BPMH) and piperazinium (BMPMH)) have been synthesized and employed for altering the wettability of vermiculite and its derivates (Vts) treated by Li + -saturated heating method. The results of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM) and N 2 adsorption/desorption isotherms indicate that all of the bis -N-heterocyclic quaternary ammonium salts have been successfully inserted into the vermiculite layers, leading to the organic monolayer. The results of capillary rise tests combined with Lipophilic to Hydrophilic Ratio ( LHR ) values unveil the wettability alteration of the organo-Vts. As the layer charge decreases, the hydrophilicity of the organo-Vts gradually increases, which is probably caused by the decline in binding sites. As the result of the change in spacer length of modifier, the wetting properties of morpholinium-based organo-Vts change in order of BMMD-Vts > BMMH-Vts > BMMB-Vts, and difference in N-heterocyclic headgroups leads to the sequence of wettability: BMPMH-Vts > BPMH-Vts > BMMH-Vts. Layer charge of Vt, spacer length and the type of the N-heterocyclic headgroup of modifier have the synergistic effect on the regulation of the wettability.
研究领域:
材料科学
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表面化学
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DOI
高影响因子
DALTON TRANSACTIONS
·
2017
·Vol. 47
·期 1
·180-189
·
IF 4.029
Dandan Yang,Jie Dong,Baiquan Wang
A series of new pincer-type tridentate o-aryloxide-N-heterocyclic carbene nickel complexes Ni1–Ni3 were synthesized, and the molecular structure of Ni3 was confirmed by X-ray crystallography. In comparison with the above tridentate complexes, the bidentate bis(aryloxide-NHC) nickel complex Ni4 was also synthesized. On activation with either Et2AlCl or Me2AlCl, all nickel complexes showed low activity toward norbornene (NB) homopolymerization. Surprisingly, Ni1–Ni3 catalysts exhibited moderate to high activity toward the homopolymerization (up to 3.21 × 106 g PNB (mol of Ni)−1 h−1) and copolymerization of norbornene with 1-octene (up to 1.39 × 105 g polymer (mol of Ni)−1 h−1) with B(C6F5)3 as the cocatalyst even at 100 °C, showing that tridentate nickel catalysts have high thermal stability. Notably, the tridentate Ni1–Ni3 complexes showed better activities than the corresponding bidentate bis(aryloxide-NHC) nickel complex Ni4. The obtained poly(NB-co-1-octene)s were confirmed to be vinyl-addition copolymers, which exhibited high 1-octene insertion ratio (9%–17%), good thermal stability (Td > 400 °C), high molecular weight (up to 105), and narrow molecular weight distribution (PDI ≤ 1.91).
研究领域:
高分子化学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Weiyou Zhou,Qianyun Tao,Fu'an Sun,Xinbai Cao,Junfeng Qian,Jie Xu,Mingyang He,Qun Chen,Jianliang Xiao
NiMn layered hydroxide compounds have been found to be efficient catalysts for the oxidative dehydrogenation of N-heterocycles by molecular oxygen under mild conditions. Various tetrahydroquinoline derivatives and some other N-heterocycles have been found to be tolerated by the catalytic system. A synergistic effect between Ni and Mn has been observed in the reaction. A kinetic study concluded that the dehydrogenation of 1,2,3,4-tetrahydroquinoline is a first-order reaction, and an apparent activation energy of 113 kJ/mol has been obtained. A probable reaction mechanism comprising an imine intermediate has been proposed according to the obtained results and XPS analysis. The key catalytic site for the dehydrogenation is thought to be Mn 3+ , which could be stabilized by Ni 2+ in the hydrotalcite structure.
研究领域:
催化化学
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材料科学
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有机化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）