Chemical Science
·
2024
·Vol. 15
·期 33
·13486-13494
·
IF 7.6
Chun Tang,Meiling Su,Taige Lu,Jueting Zheng,Juejun Wang,Yu Zhou,Yu-Ling Zou,Wenqing Liu,Ruiyun Huang,Wei Xu,Lijue Chen,Yanxi Zhang,Jie Bai,Yang Yang,Jia Shi,Junyang Liu,Wenjing Hong
Nucleophilic substitution is one of the most fundamental chemical reactions, and the pursuit of high reaction rates of the reaction is one of the ultimate goals in catalytic and organic chemistry. The reaction barrier of the nucleophilic substitution originates from the highly polar nature of the transition state that can be stabilized under the electric field created by the solvent environment. However, the intensity of the induced solvent-electric field is relatively small due to the random orientation of solvent molecules, which hinders the catalytic effects and restricts the reaction rates. This work shows that oriented external electric fields applied within a confined nanogap between two nanoscopic tips could accelerate the Menshutkin reaction by more than four orders of magnitude (over 39 000 times). The theoretical calculations reveal that the electric field inside the nanogap reduces the energy barrier to increase the reaction rate. Our work suggests the great potential of electrostatic catalysis for green synthesis in the future.
研究领域:
有机化学
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催化化学
·
理论化学
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DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2022
·
IF 3.841
Yuzhen Zhao,Yang Zhao,Zemin He,Zhun Guo,Huimin Zhang,Zongcheng Miao,Haiquan Zhang
Three reaction mechanisms were reported in the replacement reaction of bay area dibromine atoms in perylene diimide derivatives in previous studies. However, the effect of the reaction solvents and intermediate compound (perylene diimide radical anion) on the reaction mechanisms and product structure had not been reported. Here, we report the role of the reaction solvents and the perylene diimide radical anion in replacement reactions of bay area dibromine atoms of perylene diimide. Two isomers in the replacement reactions of bay area dibromine atoms in perylene diimides were found when using proton solvents (such as ethanol), and presenting the about 41% 1-bromo-7- ethoxy substituted perylene diimide derivative changed into 1,6- diethoxy substutent perylene diimide derivative in double substituted reaction. In polar non-proton solvents, inorganic base (K 2 CO 3 ) can induce dibromo perylene diimide to form its radical anion. Further, the substitution reactions is a S N1 mechanism in proton solvents, and the substitution reactions is belong to a S N 2 and SRN1 mechanism in polar non-proton solvents.
研究领域:
有机化学
·
材料科学
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DOI
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Wenrui Xiang,Jingyi Chang,Ruijuan Qu,Gadah Albasher,Zunyao Wang,Dongmei Zhou,Cheng Sun
Bromophenols (BPs) are ubiquitous phenolic contaminants and typical halogenated disinfection byproducts (DBPs) that are commonly detected in aquatic environments. The transformation of 2,4-dibromophenol (2,4-DBP) during chlorination process was fully explored in this research. It was found that active chlorine can react with 2,4-DBP effectively in a wide pH range of 5.0–11.0, with an apparent second-order rate constant ( k app ) varying from 0.8 M −1 s −1 to 110.3 M −1 s −1 . The addition of 5 mM ammonium ions almost completely suppressed the reaction via competitive consumption of free chlorine. With the concentration of HA increasing from 1.0 to 10.0 mg L −1 , the inhibition on the degradation of 2,4-DBP increased from 8.7% to 63.4%. By contrast, bromide ions at a concentration of 5 mM accelerated the process by about 4 times, due to the formation of hypobromous acid. On the basis of the eleven products (with eight nominal masses) identified by LC-TOF-MS, electrophilic substitution reactions and single-electron transfer reactions were mainly involved in the chlorination process. The concentration of primary chlorine-substituted products was about 4 times that of the dimer products, demonstrating that electrophilic substitution reaction was predominant during chlorination of 2,4-DBP. Density functional theory (DFT) based calculations revealed that HOCl is the dominant active oxidizing species for elimination of 2,4-DBP and coupling reaction occurs more easily at para and ortho position of hydroxyl group in the phenolic moiety. These findings could provide some new insights into the environmental fate of bromophenols during chlorine disinfection of water and wastewaters.
研究领域:
环境科学
·
化学
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DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2022
·Vol. 41
·期 3
·307-313
·
IF 5.56
Run-Ze Yuan,Peng-Fei Cui,Yue-Jian Lin,Guo-Xin Jin
Comprehensive Summary Herein, we describe the synthesis of a carborane-supported octanuclear palladacycle complex, Pd 8 ( o -C 2 B 10 H 10 CS 2 CH 3 ) 4 Cl 4 (CH 3 CN) 4 (complex 1 ), with B(3)–H activations on o -carborane ligand. The substitution reaction of 1 has been explored, and three of its substituted complexes Pd 8 ( o -C 2 B 10 H 10 CS 2 CH 3 ) 4 Cl 4 (L) 4 (L = t BuNC, 2 ; L = C 5 H 5 N, 3 ; L = C 4 H 8 S, 4 ) have been synthesized. The m - and p -carborane disubstituted ligands m - and p -C 2 B 10 H 10 (CS 2 CH 3 ) 2 (ligands 5 and 6 ) as well as their B—H activated carborane complexes [ m -C 2 B 10 H 9 (CS 2 CH 3 ) 2 PdCl] ( 7 ) and [ p -C 2 B 10 H 8 (CS 2 CH 3 ) 2 ][PdCl( t BuNC)] 2 ( 8 ) have also been synthesized by the similar method. All of these complexes have been characterized, including X-ray single crystal diffraction, NMR spectroscopy, IR spectroscopy and elemental analysis methods.
研究领域:
无机化学
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材料科学
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DOI
高影响因子
MACROMOLECULAR RESEARCH
·
2012
·Vol. 21
·期 6
·681-686
·
IF 1.153
Xu Yewei,Tang Jie,Chang Guanjun,Zhu Fanghua,Luo Xuan,Zhang Lin
Poly( N -arylenebenzimidazole ketone ketone)s (PNABIKKs) consisting of m - and p -phenylene linkages have been synthesized by nucleophilic aromatic substitution from bis(benzimidazolyl) derivatives containing sulfonyl, carbonyl, and ether groups with activated aromatic difluorides in sulfolane at 210 °C in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier tramsfom infrared (FTIR), proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, and elemental analysis, and the results were largely consistent with the proposed structure. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) measurements demonstrated that polymers had high glass transition temperatures ( T
g
>220 °C) and good thermal stability with high decomposition temperatures ( T
D
>480 °C). These novel polymers also showed good solubility.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2025
·
IF 1.9
Jiadi Zhou,Shangkun Bai,Weilong Zhang,Bingbing Chen,Yuyu Yang,Qilin Xu,Zhiqun Yu
Monosubstituted symmetrical dialkoxysilanes, intermediates in the production of numerous well-known materials, present challenges for selective monosubstitution due to the presence of two alkoxy groups in similar chemical environments. Notably, kinetic studies on this phenomenon have not been documented. In addressing this knowledge gap, we developed a continuous flow system to the reaction kinetics between diethoxydimethylsilane and vinyl magnesium chloride, enhancing our understanding of these reactions. We initially analyzed the reaction order, pre -exponential factors, and activation energies systematically. The kinetic investigation revealed that the partial reaction order for diethoxydimethylsilane was first-order, the partial reaction order for vinyl magnesium chloride was also first-order, and the overall reaction order was second-order. The activation energy of the main reaction was 39.21 kJ/mol, and the activation energy of the side reaction was 59.72 kJ/mol. Therefore, precise control of the reaction conditions is essential for improving the yield. This kinetic investigation identified a potential reaction mechanism, which was later confirmed through a series of experiments. These experiments accurately determined the applicable concentration and temperature ranges for our kinetic model. Further, simulations of the model assessed the influences of reaction temperature and molar ratios on the monosubstitution selectivity, aiming to achieve controlled reaction outcomes. This study provides new insights into the reaction kinetics of Grignard reagents with symmetrical dialkoxysilanes and offers valuable guidance for optimizing reaction conditions in industrial applications. This study demonstrates selective monosubstitution of symmetrical dialkoxysilanes in a laminar flow reactor. Compared to traditional batch processes, the laminar flow reactor achieved milder conditions and higher selectivity, reaching 99.5% selectivity and 97.9% yield through kinetic studies and model simulations.
研究领域:
化学工程
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材料科学
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DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2017
·Vol. 40
·期 9
·1993-2001
·
IF 2.557
Tianfu Wei,Gongke Li,Zhuomin Zhang
Semicarbazide, a toxic food contaminant, widely exists in food products and it originates from the thermal degradation of a food additive of azodicarbonamide or a metabolite of nitrofurazone abused in meat specimens. Many previous methods for semicarbazide determination usually required expensive instruments, difficult-to-prepare monoclonal antibodies, and a long operation time. In this study, a high-performance liquid chromatography method was developed for the rapid determination of trace semicarbazide coupling with a nucleophilic substitution reaction firstly using 4-nitrobenzoyl chloride as derivatization reagent. The derivatization reaction was mild at room temperature for 1 min in neutral solution. Then, semicarbazide derivative was separated and quantified by high-performance liquid chromatography with ultraviolet detection under optimal separation conditions at λ max = 261 nm. The proposed method offered the detection limit of 1.8 μg/L and was successfully applied for the rapid determination of trace semicarbazide in flour products. Semicarbazide in positive real samples could be actually found and quantified in the range of 0.47−7.53 mg/kg. The recoveries were 76.6−119% with relative standard deviations of 0.5–9.1% ( n = 3). This developed method was rapid, reliable, and convenient for the determination of trace semicarbazide in food.
研究领域:
分析化学
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食品安全
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产品关联
DOI
PubMed
高影响因子
DALTON TRANSACTIONS
·
2014
·Vol. 43
·期 26
·9968-9975
·
IF 4.097
Xiujuan Jiang,Li Long,Hailong Wang,Limei Chen,Xiaoming Liu
The CO-releasing behaviours of nine diiron carbonyl complexes (1–9) were examined via the substitution reaction of cysteamine (CysA), of which complex 4 was reported recently. These complexes fall into three categories, the diiron core bridged by two thiolates, a dithiolate and 1,8-naphthalene dithiolate. Our results reveal that the CO-releasing rates of these complexes are highly dependent on their structures. Complexes (2–4) bearing two monothiolates as their bridging linkage (“open” form) are more vulnerable to decomposition upon nucleophilic substitution reactions compared with complexes (6–9) that possess a dithiolate as their bridging linkage. When the bridging linkage lacks an electron-donating group (complex 1), the metal centre is less negatively charged as revealed by DFT calculation, and thus it exhibits fast substitution reaction with CysA to release CO. A linkage with conjugating nature (5) shows a similar effect because electron density on the metal centre decreases due to electron-density diverting from the metal centre into the naphthalene moiety. Kinetic analysis suggests that CO-releasing at the first stage of these complexes is a first-order reaction.
研究领域:
化学
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医学
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材料科学
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产品关联
DOI
PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Wei Li,Mao Shen,Yun-Jie Yu,Yu-Xiang Chen,Lei Chen,Shi-Bin Ren,De-Man Han
Oil-spill accidents have caused great loss of valuable natural resources to marine ecosystems. Thus, it is highly desirable to develop an efficient and environment-friendly approach for oil/water separation. Herein, we report a bottom-up strategy for the synthesis of superhydrophobic covalent organic frameworks (COFs) and show an in situ growth approach for the fabrication of COF-functionalized foam. 2,5-dihydroxyterephthalaldehyde (Da) is first modified with octyl to form superhydrophobic monomer Da-octyl via nucleophilic substitution reaction . Da-octyl was then condensed with 1,3,5-(1,3,5-Triazine-2,4,6-triyl)trianiline (Tz) to synthesis a superhydrophobic COF TzDa-octyl. TzDa-octyl can be used in complex environment due to the high thermal and chemical stability. Besides, TzDa-octyl can be in situ growth on the melamine foam for oil/water separation. The prepared foam exhibits high adsorption capacity and good reusability for oil/water separation. This work not only offers a strategy for the construction of functional COFs, but also opens an avenue for the growth of COFs on different substrates for oil/water separation.
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
Journal of Water Process Engineering
·
2021
·
IF 5.485
Zhe Wang,Kaiyuan Ma,Yufeng Zhang,Xinbo Zhang,Huu Hao Ngo,Jianqiang Meng,Lingzhong Du
Removing micro-pollutants is an important global challenge for the development of good adsorbents and environmental engineering issues. In this work, the structure of hierarchically and interconnected porous polymer has been fabricated by a high internal phase emulsion (HIPE) with water-in-oil and used for removing boron from water. This porous polymer was synthesized via monomer radical polymerization and utilized the active sites of monomer –Cl. In this way the vicinal hydroxyl group of N-Methyl- d -glucamine (NMG) was successfully introduced and grafted into HIPE by nucleophilic substitution reaction under the catalysis of triethylamine. The maximum boron uptake capacity was 2.54 mmol/g at a boron concentration of 100 mg/L, and reached adsorption equilibrium after about 2 h. Compared to traditional adsorption membrane materials, the HIPE porous polymer had better mechanical strength and able to resist acid and alkaline in the long-term. Meanwhile the regeneration efficiency of the HIPE30 %-g-PNMG porous polymer remained at 100 % after being used for 10 cycles.
研究领域:
环境工程
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Jiangtao Liu,Guofei Chen,Junchao Guo,Nafeesa Mushtaq,Xingzhong Fang
A series of cardo poly(ether ketone imide)s (PEKI-C) containing large-volume bulky phthalide groups were prepared by aromatic nucleophilic substitution reaction of commercially available phenolphthalein and 4,4′-bis(4-fluorophthalimido)diphenyl ether/4,4′-difluorobenzophenone. The glass transition temperatures ( T g s) increased from 221 to 278 °C with increasing the content of 4,4′-bis(4-fluorophthalimido)diphenyl ether moiety in the copolymerization . The 5% weight loss temperatures ( T 5% ) of PEKI-C ( a–e ) reached up to 472–495 °C in nitrogen and 466–481 °C in air. Flexible films, which could be easily cast from the polymer solutions , exhibited good mechanical properties with tensile strengths of 73–124 MPa, elongations at break of 9.7–12.8%, and tensile moduli of 2.2–2.8 GPa. Their films with cut-off wavelengths from 336 to 368 nm were transparent and essentially colorless. It is noted that the T g , T 5% , tensile strengths, elongations at break, and tensile moduli of PEKI-C ( a–e ) increased with increasing the content of 4,4′-bis(4-fluorophthalimido)diphenyl ether in the copolymerization.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
TETRAHEDRON
·
2015
·
IF 2.641
Xingzhu Xu,Haibo Wu,Zhengyi Li,Xiaoqiang Sun,Zhiming Wang
The development of bimetallic iron oxide-silver magnetic nanoparticles (Fe 2 O 3 –Ag MNPs) catalytic system provides an efficient heterogeneous synthetic pathway to allylic amines and 1,2-dihydroquinolines involving the direct inter/intramolecular nucleophilic substitution of π-activated alcohols with electron-deficient amines. The major advantages of the present method are wide substrate scope, simple product separation, low catalyst loading, and magnetically recyclable catalyst.
研究领域:
化学
·
材料科学
·
有机合成
✓ 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）