TETRAHEDRON
·
2021
·
IF 2.457
Xiao-Long Su,Sheng-Peng Jiang,Liu Ye,Guo-Xing Xu,Ji-Jun Chen,Qiang-Shuai Gu,Zhong-Liang Li,Xin-Yuan Liu
A general copper-catalyzed C( sp 3 )−C( sp 2 ) cross-coupling of (hetero)benzyl bromides with the air- and moisture-stable aryl nucleophiles has been developed, providing a facile access to pharmaceutically useful 1,1-di(hetero)arylalkane and 1-aryl-1-heteroarylalkane scaffolds. Critical to the success is the utilization of a proline-based N,N,P-ligand to enhance the reducing capability of copper, thus easily converting benzyl bromides to the corresponding radical species via a single-electron transfer process under ambient conditions. The reaction features a broad substrate scope, covering (hetero)arylboronate esters, oxadiazoles , and benzo[ d ]oxazoles, as well as primary and secondary (hetero)benzyl bromides with excellent functional group tolerance.
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Nature Communications
·
2021
·Vol. 12
·期 1
·1-12
·
IF 14.919
Xie Chao,Lin Longfei,Huang Liang,Wang Zixin,Jiang Zhiwei,Zhang Zehui,Han Buxing
Selective cleavage of C-C bonds is very important in organic chemistry, but remains challenging because of their inert chemical nature. Herein, we report that Zn/NC-X catalysts, in which Zn 2+ coordinate with N species on microporous N-doped carbon (NC) and X denotes the pyrolysis temperature, can effectively catalyze aerobic oxidative cleavage of C(CO)-C bonds and quantitatively convert acetophenone to methyl benzoate with a yield of 99% at 100 °C. The Zn/NC-950 can be applied for a wide scope of acetophenone derivatives as well as more challenging alkyl ketones. Detail mechanistic investigations reveal that the catalytic performance of Zn/NC-950 can be attributed to the coordination between Zn 2+ and N species to change the electronic state of the metal, synergetic effect of the Zn single sites with their surrounding N atoms, as well as the microporous structure with the high surface area and structural defects of the NC.
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PubMed
高影响因子
ChemNanoMat
·
2021
·Vol. 7
·期 10
·1131-1137
·
IF 3.154
Panpan Chang,Fan Yang,Yongbing Cen,Jie Zheng,Xuguang Li,Qingruo Xie,Jinshi Dong
Graphical A hierarchical nanoporous C/C composite with high specific surface area was synthesized from sulfonated pitch and fulvic acid for high-energy-density EDLCs. It exhibits a highly continuous 3D carbonaceous network. By fully exploiting the synergistic effect between high e -conductivity and high specific surface area, it shows excellent electrochemical stability in EMIMBF 4 ionic liquid electrolyte. The maximum energy density can be as high as 55.4 Wh kg −1 , largely better than commercial activated carbon. As a new type of energy storage device, electric double layer capacitors (EDLCs) possess fast charge/discharge speed and good cycling stability. However, the low energy density and high production cost of EDLC electrodes are still big challenges. Herein, a hierarchical nanoporous C/C composite is synthesized by chemical recombination and subsequent activation strategy from low-cost carbon resources, namely renewable humic fulvic acid (FA) and industrial sulfonated pitch (SP). Profiting from the abundant polycyclic aromatic hydrocarbons in SP and plentiful oxygen-containing groups in FA, the resultant nanoporous C/C composite has both high e -conductivity and high specific surface area (SSA). Thus, this porous C/C composite can be directly fabricated as EDLC electrode without any conductive agent. By fully exploiting the synergistic effect between high e -conductivity and high SSA, it shows excellent electrochemical stability in EMIMBF 4 ionic liquid electrolyte. Furthermore, it possesses a higher specific gravimetric capacitance (117 F g −1 ) than that of pure FA-based porous carbon (92.5 F g −1 ) at a current density of 1 A g −1 . More importantly, the maximum energy density can be as high as 55.4 Wh kg −1 , largely better than commercial activated carbon.
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ACS Catalysis
·
2021
·
IF 13.084
Yuebing Xu,Wenda Yu,Hao Zhang,Jian Xin,Xiaohui He,Bing Liu,Feng Jiang,Xiaohao Liu
Various Co-based SAPO-34 catalysts were prepared using different methods, including ion exchange (IE), incipient-wetness impregnation (IWI), and solid-phase grinding (SPG), to correlate the chemical states of Co species with the C–H and C–C bond scissions in ethane dehydrogenation. The IE-prepared Co/SAPO-34 led to stable, unreducible, and isolated exchanged Co sites anchored on the zeolite framework with a structure of −AlF–O–Co–O– and showed the highest selectivity to ethylene of close to 98% at 600 °C, which suggests that these Co sites favors suppressing the C–C bond scission in ethane. In comparison, the IWI- and SPG-prepared Co/SAPO-34 catalysts, especially for those with a high Co loading, inevitably give Co oxide clusters that are easily reduced into metallic Co. Together with catalytic results, characterizations, and DFT calculations, it is confirmed that the reduced Co clusters, especially for those outside SAPO-34 channels without the confinement effect, favor both C–H and C–C bond scission, boosting the conversion of ethane into CH4 or/and coke; however, the ionic-state −Co–O– species can smoothly terminate the ethane dehydrogenation for the ethylene product due to relatively high energy barriers for both C–H and C–C bond scission, avoiding a deep dehydrogenation and C–C cracking. As expected, the unreducible −Co–O– sites are very stable in the title reaction without deanchoring from the zeolite framework in a 100 h cyclic test. This study not only demonstrates the stable −Mδ+–Oδ− structure favorable for suppressing C–C bond scission but also highlights a catalyst-constructing strategy for Co-based and similar metal-based catalysts for dehydrogenation of other light alkanes.
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GREEN CHEMISTRY
·
2016
·Vol. 18
·期 22
·6029-6034
·
IF 8.506
Na Li,Wenjun Yan,Pengju Yang,Hongxia Zhang,Zhijian Wang,Jianfeng Zheng,Suping Jia,Zhenping Zhu
Theoretically, selective C–H manipulation in ethanol can result in a direct C–C coupling synthesis of 2,3-butanediol (2,3-BDO). However, this process is typically extremely difficult to achieve because of the high complexity of the involved chemical bonds. In this work, we determine that hydroxide radicals generated from the photolysis of H2O2 can selectively attack the α-hydrogen atom in ethanol aqueous solutions and crack the C–H bond to produce hydroxyethyl radicals, which subsequently undergo C–C coupling to form 2,3-BDO. This selective C–H breakage is determined by the reaction rate, which is primarily controlled by the local H2O2 concentration at a given irradiation intensity. At a moderate reaction rate of ethanol (37 mmol h−1), the 2,3-BDO selectivity reaching as high as 91% can be obtained. The introduction of a catalyst can further increase ethanol conversion and enhance the 2,3-BDO formation rate by controlling the reaction rate. This result provides an environment-friendly approach to convert bio-ethanol directly to 2,3-BDO and to manipulate a single bond selectively in complex bonding situations.
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Molecular Catalysis
·
2017
·
IF 0
Zhanao Lv,Haibin Wang,Zhuqi Chen,Shuhua Zou,Shuaishuai Zhu,Chenlin Lou,Guochuan Yin
Dioxygen activation as the solely terminal oxidant in organic synthesis and catalytic oxidation is particularly attractive from the point of economic and environmental view. In our previous study, we have displayed that the introducing of non-redox metal ions can sharply improve the olefin epoxidation catalyzed by ruthenium complex with PhI(OAc) 2 as the organic oxidation. Inspired by the successful strategy and dioxygen activation, in this study, we demonstrate an alternative protocol that adding non-redox metal ions to cis -Ru(bpy) 2 Cl 2 catalyst can remarkably improve the oxidation from Ru(II) to Ru(IV) = O with dioxygen as the oxidant and promote oxidative dehydrogenation of saturated C–C bond whereas Ru(bpy) 2 Cl 2 alone is very sluggish. Through UV–Vis, NMR, cyclic voltammogram and EPR characterization, it has been testified that oxidation from Ru(II) to Ru(IV) = O can be realized under the condition of 1 atm of dioxygen and 323 K within 25 min while extreme tough condition of 20 atm of dioxygen, 343 K and 8 h is necessary for Ru(bpy) 2 Cl 2 alone. Combined the reaction data with characterization results, an adduct of Ru(IV) = O/Sc(III) is proposed as the key active species to improve the catalytic efficiency. The activity improvement in oxidative dehydrogenation illustrated a novel strategy of that adding non-redox metal ions to sluggish catalysts can remarkably improve its efficiency for dehydrogenation of saturated C–C bond, especially through dioxygen as ultimate oxidant.
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Journal of the American Chemical Society
·
2024
·
IF 14.4
Ernest Pahuyo Delmo,Yian Wang,Yihua Song,Shangqian Zhu,Haichuan Zhang,Hongming Xu,Tiehuai Li,Juhee Jang,Yongjun Kwon,Yinuo Wang,Minhua Shao
The reaction mechanism of CO2 electroreduction on oxide-derived copper has not yet been unraveled even though high C2+ Faradaic efficiencies are commonly observed on these surfaces. In this study, we aim to explore the effects of copper anodization on the adsorption of various CO2RR intermediates using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS) on metallic and mildly anodized copper thin films. The in situ SEIRAS results show that the preoxidation process can significantly improve the overall CO2 reduction activity by (1) enhancing CO2 activation, (2) increasing CO uptake, and (3) promoting C–C coupling. First, the strong *COO– redshift indicates that the preoxidation process significantly enhances the first elementary step of CO2 adsorption and activation. The rapid uptake of adsorbed *COatop also illustrates how a high *CO coverage can be achieved in oxide-derived copper electrocatalysts. Finally, for the first time, we observed the formation of the *COCHO dimer on the anodized copper thin film. Using DFT calculations, we show how the presence of subsurface oxygen within the Cu lattice can improve the thermodynamics of C2 product formation via the coupling of adsorbed *CO and *CHO intermediates. This study advances our understanding of the role of surface and subsurface conditions in improving the catalytic reaction kinetics and product selectivity of CO2 reduction.
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PubMed
高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2024
·Vol. 137
·期 4
·1911-1925
·
IF 1.7
Song Linyan,Nie Genkuo,Chen Xiulei,Wang Hongyu,Liu Shiwei,Yu Hailong,Liu Xuguang,Yang Guihua,Yu Shitao
The multifunctional groups of 5-hydroxymethylfurfural (5-HMF) make it could extend carbon chain by different C–C coupling reactions and extensively applied in the bio-jet fuel synthesis. Herein, one-pot reaction of lignocellulose derived chemicals with 5-HMF was studied by experimental and density functional theory (DFT) methods. The kinetic models of products were established and the apparent activation energies of the products by C–C coupling reaction of phenol, anisole, guaiacol, cyclohexanone and acetone with 5-HMF on Hβ were 95.3 kJ/mol, 104.8 kJ/mol, 90.4 kJ/mol, 90.0 kJ/mol and 112.2 kJ/mol, indicating these reactions centering on 5-HMF competitive intensively. Then the effects of the catalysis were analyzed by applying commercial catalysis to the mixed coupling reaction of 5-HMF. It was found that Brønsted acid is more favorable to alkylation reaction, and Lewis acid is more beneficial to aldol condensation reaction. By Fukui function, due to the nucleophilic index of cyclohexanone (2.74 eV) is higher than that (2.48 eV) of acetone, and the Mulliken electronegativity (3.43 eV) is weaker than that (3.55 eV) of acetone, cyclohexanone is more conducive than acetone to the aldol condensation reaction. This work provides data reference for product regulation in the bio-jet fuel synthesis.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Wei Wei,Zhenyao Li,Jitao Shang,Chenxi Xia,Xuli Hu,Yangshun Hu,Junchen Xu,Yan Zhao,Mingyue Ding
The selective electrochemical reduction of CO to valuable multi-carbon (C 2 + ) products is a key strategy for mitigating global warming and addressing the energy crisis. Nevertheless, the activity and selectivity of CO-to-C 2+ products conversion remain low due to the lack of effective catalysts. In this study, bimetallic CuPd was grown in situ on Cu nanoparticles via a seed-mediated approach, constructing a stable CuPd/Cu interface for the CO reduction reaction (CORR). The CuPd alloy promotes CO adsorption and hydrogenation, resulting in abundant and stable *COH intermediates over catalytic sites. Consequently, a stable asymmetric coupling is established at the CuPd/Cu interface, lowering the reaction energy barrier and facilitating C-C coupling. A high acetate selectivity of 49 % was achieved at –1.0 V versus the reversible hydrogen electrode (RHE) with a current density of 349 mA/cm². This study highlights the critical role of constructing CuPd/Cu asymmetric sites for C–C coupling, paving the way for designing highly selective catalysts that enhance C 2+ product formation and acetate production.
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Surfaces and Interfaces
·
2024
·
IF 5.7
Zhixiu Yang,Xiaoxuan Guo,Yong Chen,Lijing Gao,Ruiping Wei,Guomin Xiao
Modulating the surface microenvironment is crucial in strengthening C C coupling, leading to increasing selectivity in the production of multi-carbon (C 2+ ) products during CO 2 electroreduction. Herein, we have concentrated on investigating how to control the effect of surface distribution of active components of a series of Ag-decorated CuO , denoted as xAg/yCuO. These catalysts with similar chemical elements and morphology are designed, but they exhibit different selectivity in the CO 2 electroreduction process. As a result, the Ag particles in 3Ag/CuO aggregates, while the Ag in 2Ag/2CuO and Ag/3CuO is uniformly distributed on the flower-like CuO nanosphere . Besides, 3Ag/CuO has the highest Faraday efficiency (FE) of CO with a value of 30.9 % at 0.8 V vs. RHE, demonstrating rich-Ag catalysts are beneficial to produce CO. 2Ag/2CuO shows excellent FE C2H4 of 51.4 % at -1.2 V vs. RHE due to the highly dispersed distribution of Ag on the flower-like CuO and higher vacancy O. Ag/3CuO exhibits higher FE H2 compared to other catalysts across a wide potential range, and its minimal impedance is attributed to its exceptional performance in the hydrogen evolution reaction . The proposed reaction pathway for the most effective catalysts 2Ag/2CuO, as determined by in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), involves the following steps: CO 2 →*CO 2 − → *COOH → *CO→ *CHO→ *OCHCHO→ *OCHCH 2 → C 2 H 4 . These findings demonstrate that controlling the surface structure can influence the local environment to enhance the efficiency of CO 2 electroreduction.
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Journal of Materials Research and Technology-JMR&T
·
2025
·
IF 6.6
Yuanming Zhou,Mingyang Li,Shuxin Li,Shuangxing Zhu,Ruizhi Liu,Maozhong Yi,Ke Peng
The oxide layer that forms on the surface of C/C composites matrix-modified with multiphase ultra-high temperature ceramics is generally loose and poorly bonded, limiting its effectiveness in enhancing the ablation resistance of C/C composites. In this study, C/C composites were matrix-modified using solid solution ceramic TaZr 2 C 3 -SiC and multiphase ceramic TaC-2ZrC-SiC, both with the same Zr/Ta ratio. The C/C-TaZr 2 C 3 -SiC and comparative sample C/C-TaC-2ZrC-SiC composites were prepared through a high-solid-loading slurry impregnation method combined with a precursor infiltration and pyrolysis process. The flexural properties were evaluated, and ablation tests were conducted under an oxyacetylene flame. Compared to C/C-TaC-2ZrC-SiC, the C/C-TaZr 2 C 3 -SiC sample exhibited superior flexural properties and ablation resistance. The flexural strength, elastic modulus, and fracture toughness improved by 10.80%, 29.75%, and 37.67%, respectively. The mass and linear ablation rates were reduced by up to 85.49% and 77.26%, respectively. The superior ablation resistance of C/C-TaZr 2 C 3 -SiC was attributed to the formation of the anti-ablation microstructure composed of the Ta-rich oxide binder phase and Zr-rich oxide skeleton phase in the Ta-Zr-O oxide layer. The microstructure enhanced the viscosity of the oxides and strengthened their interfacial bonding, effectively suppressing the splashing and consumption of surface oxides under high heat flux while preventing their accumulation in the brim ablation region. The oxide layer was more compact and tightly bonded to the composite surface, providing the composites with significantly improved ablation protection. These findings provide a novel and effective approach for further improving the ablation resistance of C/C composites.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Huimin Li,Zhe Sun,Chenlong Dong,Xueli Zhang,Chengkun Lei,Baobao Jin,Qianqian Shen,Husheng Jia,Jinbo Xue
Photocatalytic non-oxidative coupling of methane is an attractive strategy for CH 4 to C 2 conversion, how to facilitate the photogenerated charge separation and accelerate the C–C coupling to promote the reaction kinetics remains a great challenge. Herein, a symbiotic r-Fe 2 O 3 /NiO heterostructure with robust interfaces is constructed in situ. The coherent interface not only provides unique Ni–O–Fe asymmetric sites, but also achieves the separation and transport of photogenerated charge. The unbalanced charge density distribution of two adjacent methyl or methylene at the Ni–O–Fe asymmetric site alleviates the dipole repulsion of the C–C coupling, and promotes C–C coupling to form C 2 hydrocarbons. Under visible light irradiation, the optimal r-Fe 2 O 3 /NiO performs a brilliant C 2 activity up to 71.00 μmol g −1 h −1 , and the C 2 H 4 yield can reach a high value of 40.46 μmol g −1 h −1 and the selectivity of 56.98 %. This work provides new insights into the coupling of C–C to generate C 2 hydrocarbons.
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