EUROPEAN POLYMER JOURNAL
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2023
·
IF 6
Xiongfei Zhang,Chuang Ma,Peiyu Liu,Dan Huang,Pengyun Li
Because of its high crosslinking density, compact structure and stable performance, epoxy resin is difficult to be degraded, which leads to serious environmental pollution problems. In this work, using dipropylene glycol dimethyl ether as swelling agent and nitric acid as oxidant, the degradation of amine cured epoxy resin was studied. Results are as follows: The degradation rate obtained by swelling agent assisted oxidation degradation method is much higher than that obtained by oxidation degradation method only. And the degradation rate of the epoxy resin even reached 100 % at 100 °C only in an hour under the condition of swelling agent assisted nitric acid. FT-IR and GC–MS showed that the degradation was mainly caused by that the C N bond in the molecular chain was gradually weakened and fractured finally. The molecular weight of the degradation product was relatively dispersive, which was composed of low molecular polymer and small fragments, and the molecular weight of low molecular polymer was about 2167. And the degradation products primarily contain 4-isopropylphenol and (allyloxy)benzene rings. This work provides a new way to solve the problem about the degradation, recycling and pollution of epoxy resin.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
JACS Au
·
2024
·
IF 8.5
Xixi Liu,Liang Huang,Yurong He,Peng Zhou,Xuedan Song,Zehui Zhang
It remains challenging to construct C═N bonds due to their facile hydrogenation. Herein, a single Co atom catalyst was discovered to be active for the selective construction of C═N bonds toward the synthesis of imines and N-heterocycles via reductive coupling of nitroarenes with various alcohols, including inert aliphatic ones. DFT calculations and experimental data revealed that the transfer hydrogenation proceeded via the intramolecular hydride transfer and the transfer of H from the α-Csp3-H bond to the nitro group was the rate-determining step. The single Co atoms served as a bridge to transfer the electrons from the catalyst to the adsorbed alcohol molecules, resulting in the activation of the α-Csp3-H bond. Unlike metal nanoparticles, the C═N bonds in imine products can be reserved due to the large steric hindrance from substituents on C and N. DFT calculation also confirmed that transfer hydrogenation of the C═N bonds in imines is thermodynamically unfavored with a much higher energy barrier compared with the transfer hydrogenation of the –NO2 group (1.47 vs 1.15 eV).
研究领域:
化学
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催化反应
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理论计算
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
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2022
·
IF 4.198
Menghan Cui,Rong Wang,Qing Yang,Chunxiang Kuang
Herein, we report the copper-catalyzed one-pot Sandmeyer-type reaction of aromatic amines with triazoles to afford N-aryl-1,2,3-triazoles. Diazonium salts, formed from aromatic amines and tert-butyl nitrite in the presence of fluoroboric acid, reacted with triazoles in a copper-catalyzed Sandmeyer-type reaction. The reaction proceeded under mild conditions to afford N-aryltriazoles in moderate to good yields. This method is amenable to a wide range of aromatic amines and triazoles and shows diverse functional group tolerance. Inhibition of the reaction upon the addition of free radical scavengers suggested a radical pathway, in which the aryl radical, copper, and triazole formed a complex that underwent reductive elimination to give aryltriazole compounds; this is consistent with the mechanism underlying the Sandmeyer reaction. Thus, we demonstrate a new effective strategy for the construction of C–N bonds via Sandmeyer-type reactions and a valuable alternative approach for the synthesis of aryltriazole derivatives.
研究领域:
有机化学
·
合成化学
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DOI
PubMed
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Xiaohui Leng,Xin Zhou,Lu Ma,Yonghua Du,Ouwen Peng,Zhongxin Chen,Jinhui Pan,Ming-Yu Qi,Jian-Hui Zheng,Yi-Jun Xu,Kian Ping Loh
Visible light induced oxidative C–C and C–N coupling provides a milder alternative to the current synthetic strategies. However, the photochemical C–C coupling of benzylamine and chromoselective C–C/C–N conversion are not widely reported. Herein, we demonstrate that the introduction of indium vacancies in ZnIn2S4 improves the catalytic activity for C–C coupling of benzylamine and imparts a strong chromoselectivity for C–C or C–N coupled products. A high C–C selectivity of ∼80% is achieved with a benzylamine conversion of ∼80%. Mechanistic studies unveil the switchable reaction routes between kinetically favored C–C coupling and thermodynamically favored C–N coupling under specific illumination conditions.
研究领域:
化学
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材料科学
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光催化
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产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
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2023
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IF 3.8
Peng Xiong,Tong-Wei Zhang,Shi-Ming Li,Mei-Yu Xu,Guang-Ming -Liang,Liu-Cheng Gui,Xiu-Jian Wang
Two tetranuclear copper cages with tubular type, [Cu 4 (BMBA) 4 ((CH 3 ) 2 N) 2 (H 2 O) 2 ] ( 1 ) and [Cu 4 (BMBA) 4 (Bipy)(H 2 O) 2 ] ( 2 ), were successfully constructed by the reaction of Cu(NO 3 ) 2 with dicarboxylic acid 4,4′-[( ethylazanediyl ) bis ( methylene )]-bis[(1,1′-biphenyl)-2-carboxylic acid] (H 2 BMBA) under solvothermal conditions. The complexes 1 and 2 exhibit a similar cage structure, formed by four ligands connecting two binuclear copper paddle-wheel secondary building units (SBUs). Interestingly, the complex 2 was obtained by appropriately binding of 4, 4′-bipyridine (Bipy) molecule on the axial positions of two Cu paddle-wheels inside the cage. For this reason, the complex 2 exhibits excellent stability in some common organic solvents at room temperature and aqueous solutions with a pH of 2 to 12. Upon thermal activation of complex 2 , the coordinated water molecules can be removed, and its exposed metal active-sites show Lewis acid character, which can be used an efficient heterogeneous catalysis of Knoevenagel condensation (C C) and Clauson-Kaas (C N) reactions.
研究领域:
化学
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材料科学
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催化反应
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 31
·10970-10976
·
IF 4.174
Xianqiang Huang,Yuquan Qi,Yuxiao Gu,Shuwen Gong,Guodong Shen,Qiang Li,Jikun Li
A synthetic pathway for the directed preparation of three novel polyoxovanadate-based copper frameworks (POVCFs), i.e., [Cu0.5(1-ipIM)2]2[V4O11] (POVCF 1), [Cu(1-ipIM)2](VO3)2 (POVCF 2) and [Cu(1-pIM)4](HpIM)4[V10O28] (POVCF 3) (1-ipIM = 1-isopropylimidazole; 1-pIM = 1-propylimidazole) using bifunctional imidazole molecules as organic ligands and base has been developed. Systematic studies revealed that the variable base enviroment in the reaction is the key step in the preparation of 1D to 3D supermolecular networks of POVCFs 1–3. Single crystal X-ray diffraction analyses demonstrated that the Cu2+ atoms of POVCFs 1–2 were coordinated with four imidazole derivative molecules and two different polyoxovanadate {[V4O11]2− and [V10O28]6−} clusters, respectively, exhibiting a [CuN4O2] binding set and a distorted octahedral geometry. Specifically, POVCF 1 exhibited adjacent [V4O11]2− that dangle up and down arranged in a parallel 2D network and further coordinated with [Cu(1-ipIM)4]2+ to form a 3D supramolecular structure. However, POVCF 3 presented one tetrahedral coordinated vanadium atom and one four-coordinated copper atom and they further gave rise to a 1D network by the Cu–O and V–O bonds. More importantly, these POVCFs were further studied in the construction of C–N bond reactions of primary amines under mild conditions, and it was found that POVCF 1 displayed efficient heterogeneous catalytic activities in the Chan–Lam reaction (yields up to 89%).
研究领域:
材料科学
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化学
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产品关联
DOI
PubMed
高影响因子
SYNTHESIS-STUTTGART
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2019
·Vol. 51
·期 23
·4425-4433
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IF 2.867
Yong Jian,Ming Chen,Chao Yang,Wujiong Xia
A small molecule, namely nitroacenaphthene, is reported for the first time as a recyclable visible-light photocatalyst for the construction of the C=N bond from sulfonyl azides and amines. This scalable, site-selective protocol provides a convenient way to access various sulfonyl amidines under mild conditions. Two reaction pathways are proposed, according to different transformation patterns.
研究领域:
有机化学
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光催化
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DOI
高影响因子
MACROMOLECULES
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2023
·
IF 5.5
Jirong Wang,Chi Zhang,Yong Zhang,Gong Chen,Rinaldo Poli,Xiaolin Xie,Zhigang Xue
Assembling polymer electrolytes (PEs) with lithium metal anodes is a promising strategy to address safety and specific capacity concerns. Molecular design on conductive polymer matrices avoids inherent high crystallinity, poor ion transport, and combustion drawbacks by adjusting the chain structure and functional groups. However, conventional structural modulation methods are difficult to conduct via in situ polymerization and cell assembly, thus hampering the further performance enhancement of PEs in lithium batteries. Herein, we report a simple aza-Michael addition method induced by lithium salts for designing and fabricating high-performance PEs. This method fulfills the in situ structure modulation of polyether-based PEs without any introduction of non-electrolytic components. The obtained polyether electrolytes exhibit a more amorphous cross-linked structure, leading to a favorable medium for ion migration and excellent flexibility. In addition, the introduction of C–N bonds imparts excellent non-flammability to the material as well as the ability to interact with sulfolane. Hence, the in situ-constructed gel polymer electrolyte (GPE) is characterized by a high ionic conductivity (1.76 × 10–4 S cm–1 at 30 °C) and excellent interface stability with the electrodes. The assembled Li/LiFePO4 (LFP) battery based on this newly designed GPE exhibits a high initial specific discharge capacity and a good rate performance (112.7 mAh g–1 at 5 C). Long-term stability was also demonstrated, with a capacity retention of 86.8% after 500 cycles at 0.5 C.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2025
·
IF 6.7
Huazangnaowu Bai,Ruiqi Qiao,Fang Xiao,Jiawen Li,Baiyi Zu,Zhenzhen Cai
Due to the severe interference from analogues such as hydrochloric acid, it is of great significance to establish a highly reliable technique to enhance the discrimination ability toward diethyl chlorophosphate (DCP). Here, based on the electrophilicity of DCP, a series of zero-background fluorescence Schiff base materials with different densities of C═N bonds as recognition sites were designed and synthesized by modulating the chain length. It is found that the increase of the C═N bond density and the specific surface area could improve the collision efficiency with DCP, thereby improving the response speed. When the density of C═N bonds is 3.86 × 1021/cm3 and the specific surface area is 128.5 m2/g, DFDBA-POP demonstrated a more superior sensing performance toward the target analyte, including the ability to detect gaseous DCP, a rapid response (1 s), and superior selectivity even in the presence of 15 kinds of interferents including the very similar hydrochloric acid. Moreover, the practicality of DFDBA-POP was further verified by a DFDBA-POP solid-state sensor, which is capable of specifically identifying gaseous DCP. The present nonfluorescent Schiff base materials design and modulation strategy would open up a new gate for the rational design of high-performance fluorescent materials to detect and discriminate trace hazardous substances with similar structures and properties.
研究领域:
材料科学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2024
·
IF 6.7
Yilin Wei,Zhiwei Sun,Qingqing Li,Dan Wu,Jianshe Wang,Yuexing Zhang,Chunbao Charles Xu,Renfeng Nie
Cost-effective and environmentally friendly production of biomass-derived amines under mild conditions is highly desirable but challenging. Herein, bifunctional Co@CoO x catalysts comprised of Co and CoO x were prepared by controllable precipitation-reduction and adopted for furfural (FAL) reductive amination with N 2 H 4 . The structure of Co species can be regulated gradually via tuning reduction temperature, resulting in a significant influence on reductive amination. The optimal CoO x -250 can achieve 96.4 % furfurylamine (FFA) yield at 60 °C, and even 95.8 % at 30 °C. The control experiments and DFT calculations suggest that the metal Co is responsible for H 2 dissociation and C N reduction, while the oxygen-vacant CoO x favors the hydrogen spillover and the C N bond activation, thus resulting in a collaborative effort for FAL reductive amination. The catalyst is stable and versatile for various aldehydes/ketones with amine yields around 95–99 %, showing great potential for industrial application.
研究领域:
催化化学
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生物质转化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Surfaces and Interfaces
·
2023
·
IF 6.2
Jie Jiang,Yuqiang Ding
As a widely used semiconductor photocatalyst , TiO 2 has been explored in organic compounds hydrogenation. In this study, the hydrogenation of C=N bonds on the surface of TiO 2 was accomplished for the first time utilizing Cu 2 O/TiO 2 type-II (p-n) heterojunction . The probe reactions, hydrogenation of N -benzylphenylamine with benzyl alcohol, and N -methylation of amines with methanol exhibited that the hydrogenation of C=N bonds on TiO 2 surface can be achieved through borrowing hydrogen reaction (BH, alcohols as hydrogen source). Additionally, the BH reaction rate could be improved by adding external H + to the reaction system. The catalytic activity of Cu 2 O/TiO 2 was discovered to remain at an efficient level even after six reaction cycles.
研究领域:
化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2023
·Vol. 17
·期 12
·1986-2000
·
IF 4.5
Xue Yi-Fan,Feng Jie,Song Yun-Cai,Li Wen-Ying
Breakage of the C–N bond is a structure sensitive process, and the catalyst size significantly affects its activity. On the active metal nanoparticle scale, the role of catalyst size in C–N bond cleavage has not been clearly elucidated. So, Ru catalysts with variable nanoparticle sizes were obtained by modulating the reduction temperature, and the catalytic activity was evaluated using 1,2,3,4-tetrahydroquinoline and o -propylaniline with different C–N bond hybridization patterns as reactants. Results showed a 13 times higher reaction rate for sp 3 -hybridized C–N bond cleavage than sp 2 -hybridized C–N bond cleavage, while the reaction rate tended to increase first and then decrease as the catalyst nanoparticle size increased. Different concentrations of terrace, step, and corner sites were found in different sizes of Ru nanoparticles. The relationship between catalytic site variation and C–N bond cleavage activity was further investigated by calculating the turnover frequency values for each site. This analysis indicates that the variation of different sites on the catalyst is the intrinsic factor of the size dependence of C–N bond cleavage activity, and the step atoms are the active sites for the C–N bond cleavage. When Ru nanoparticles are smaller than 1.9 nm, they have a strong adsorption effect on the reactants, which will affect the catalytic performance of the Ru catalyst. Furthermore, these findings were also confirmed on other metallic Pd/Pt catalysts. The role of step sites in C–N bond cleavage was proposed using the density function theory calculations. The reactants have stronger adsorption energies on the step atoms, and step atoms have d-band center nearer to the Fermi level. In this case, the interaction with the reactant is stronger, which is beneficial for activating the C–N bond of the reactant.
研究领域:
催化化学
·
材料科学
·
理论化学
✓ 已验证
DOI
高影响因子
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