GREEN CHEMISTRY
·
2023
·
IF 9.8
Shihao Su,Guojun Lv,Xuyang Zou,Jiangzhang Wang,Chaoyi Zhou,Yan Chen,Jialing Shen,Yangbin Shen,Zhongmin Liu
In the cyclic alkene epoxidation reactions using molecular oxygen as oxidant, aldehyde is generally added as co-oxidant to assist transition metal catalyst to activate the oxygen molecule, oxidizing cyclic alkene and producing the corresponding epoxide; however, the added aldehyde would be converted into byproduct carboxylic acid. Herein, we report the room-temperature tandem conversion of cyclic alkenes into 1,2-diols through the application of byproduct carboxylic acid as a catalyst for epoxide hydration reaction, realizing effective utilization of the byproduct and saving energy consumption. Four kinds of nanosized MnO2 specimens, including α-, β-, δ-, and γ-MnO2, were hydrothermally synthesized and applied as heterogeneous catalysts for the room-temperature tandem conversion of cyclohexene into 1,2-cyclohexanediol using molecular oxygen as oxidant and isobutyraldehyde as co-oxidant. The characterization results demonstrated that the obtained β-MnO2 sample had the maximum Mn4+/Mn3+ ratio of 1.42 and the minimum Oads/OLatt ratio of 0.34, consistent with its least oxygen vacancies evidenced by EPR measurement. Accordingly, the β-MnO2 sample revealed the quickest alkene epoxidation reaction rate and could achieve a 99.2% cyclohexene conversion within 1 h, and meanwhile, a 73.6% 1,2-cycloheanediol yield could be attained within 24 h. A plausible mechanism for the tandem conversion of cyclohexene into 1,2-cyclohexanediol over the β-MnO2 heterogeneous catalyst was proposed and further verified by quenching experiments and DFT calculations. Furthermore, the synthesized β-MnO2 catalyst sample could be reused more than ten times, and meanwhile, the tandem conversion way could be expanded to most of the cyclic alkene substrates, which demonstrated that the β-MnO2 catalyst was an active and stable heterogeneous catalyst for tandem conversion of cyclic alkenes into 1,2-diols.
研究领域:
催化化学
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环境科学
·
材料科学
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产品关联
DOI
高影响因子
Journal of Energy Storage
·
2022
·
IF 8.907
Hongmei Qin,Man Liu,Ziwei Li,Yuheng Fu,Jinhui Song,Jian Xie,Chuanxi Xiong,Shan Wang
Cycloolefin copolymer (COC) could be a best promising commercial polymer dielectric for metallized film capacitors at elevated temperature according to the molecular structure, but the dielectric energy storage about COC remains a huge challenge due to the lack of processing strategies of its ultrathin films . Herein, we demonstrate that COC dielectric film of around 10 μm can be fabricated by solution casting followed by uniaxial stretching and steadily service at 140 °C. Excitedly, the charge-discharge efficiency ( η ) of COC film is up to 97.8 % at 600 MV/m at 25 °C, which is superior to the commercially available biaxially oriented polypropylene (BOPP). Remarkably, at 140 °C, COC film exhibits a maximum discharge energy density ( U e ) of 2.32 J/cm 3 and a η of 85.7 %, far outperforming the heat-resistant polyimide (PI) with a maximum U e of 1.00 J/cm 3 and a η of 24.1 %. Our work provides a novel strategy for the manufacture of ultrathin COC film and could promote the commercialization of high-temperature polymer capacitor films for the energy storage.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2021
·
IF 4.354
Yuanyuan Tang,Kuan Liu,Jinjin Zhang,Long Liu,Tianzeng Huang,Chunya Li,Zhi Tang,Tieqiao Chen
A palladium-catalyzed difunctionalization of bicyclic alkenes with organoammonium salts and organoboronic compounds was reported. A wide range of functionalized cyclic products, including those bearing functional groups, were produced stereoselectively in good to excellent yields. The gram-scale experiment, one-pot operation, and synthetic application of β-borylated products further demonstrated the synthetic value of this new reaction in organic synthesis.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 39
·期 6
·709-715
·
IF 3.603
Wang Zhen-Yu,Xu Guang-Qiang,Zhou Li,Lv Cheng-Dong,Yang Ru-Lin,Dong Bing-Zhe,Wang Qing-Gang
The isoselective ring-opening polymerization of racemic lactide was achieved by combining N -heterocyclic olefin (NHO) with mono(thio)ureas or bis(thio)ureas as catalytic systems. The polymerization process shows high stereoselectivity, controllability and reactivity, delivering multi-block isotactic polylactides with high chain-end fidelity and narrow molecular weight distributions. The enhancement of catalytic performance was observed in the following order: bisthiourea (DTU) < monothiourea (TU) < bisurea (DU) < urea (U). The highest P m (probability of forming a meso dyad) = 0.91 was observed at −70 °C when using NHO/U1 catalytic system and the high stereoselectivity was attributed to chain-end control mechanism.
研究领域:
高分子化学
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有机催化
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产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2023
·
IF 7.3
Bowen Xu,Mengshan Deng,Kehang Lin,Yuexia Wang,Xinqing Lu,Rui Ma,Yanghe Fu,Weidong Zhu
The Ti-MWW zeolites with a layered morphology, synthesized by a conventional method, usually show low catalytic activities in the epoxidation of bulky alkenes due to the serious steric constraint imposed by the zeolite micropores and the adverse effects from some extra-framework octahedral Ti species. In the present work, the Ti-MWW zeolite was prepared by the reaction of an ultra-thin layered borosilicate MWW-type zeolite (D-ERB-1) with tetrabutyl orthotitanate (TBOT) in a HNO 3 aqueous solution, wherein D-ERB-1 was hydrothermally synthesized by introducing an organosilane into the synthetic gel. In combination with the results from extensive characterizations for the synthesized zeolites, it is found that the currently synthesized Ti-MWW zeolite without extra-framework octahedral Ti species has thinner nanosheets that are very helpful to the epoxidation of cycloalkenes with tert-butyl hydroperoxide (TBHP), and is more active than the conventional Ti-MWW and other titanosilicate zeolites. Moreover, the developed catalyst is recyclable after the regeneration of the deactivated zeolite by washing with acetonitrile (MeCN). Therefore, the present work provides some guidance in the development of an efficient titanosilicate catalyst for the epoxidation of bulky alkenes.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2018
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IF 8.097
Yarong Zhao,Dan Zhou,Tianjun Zhang,Yun Yang,Ke Zhan,Xinchao Liu,Hui Min,Xinhuan Lu,Renfeng Nie,Qinghua Xia
This work first reports high-efficiency epoxidation of large cycloalkenes (carbon number ≥ 7) with tert-butyl hydroperoxide (TBHP) over single-/double-/multi-unit-cell nanosheet-constructed hierarchical zeolite, which is synthesized by one-step hydrothermal crystallization using piperidine as the structure-directing agent of the microporous structure. The excellent catalytic property of the material is ascribed to its unique structural characteristic. Plenty of surface titanols or silanols on the surface of MWW nanosheets are beneficial for the formation of transition-state intermediates; a large number of intercrystalline mesopores in the shell of the material not only facilitate the formation of the intermediate for TBHP but also have nearly no hindrance for the diffusion and mass transfer of bulky cycloalkene to the above intermediates; the 12-MR side cups penetrating into the crystals from the external surface are exposed as much as possible to the reaction system because of the single-/double-/multi-unit-cell MWW nanosheet, serving as the primary reaction space for the epoxidation of bulky cyclic alkene and oxidants and providing enough space for the transition state of Ti–OOtBu and bulky cycloalkane. Moreover, an efficient calcination-free catalytic reaction–regeneration method is developed to overcome the challenge for the recyclability of microporous Ti-zeolite in the catalytic epoxidation of bulky cycloalkenes.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2023
·Vol. 61
·期 24
·3329-3342
·
IF 3.4
Xuan Li,Jiabin Yao,Deqian Peng,Xian Wang,Xuelian He
The two-way shape memory polymers (2 W-SMPs) have garnered significant interest from researchers due to their great performance and wide range of applications. In this study, we present the synthesis and assessment of crosslinked copolymers P(CDD- co -DCPD) and P(COE- co -DCPD) using dicyclopentadiene and different comonomers via ring-opening metathesis polymerization (ROMP). The two-way shape memory behavior of these copolymers was altered by not only varying the species and incorporation level of a second comonomer, but also by adjusting the concentration of the second comonomer. The results indicated that the melting and crystalline temperature of the crosslinked copolymer decreased with increasing content of DCPD. Additionally, it was observed that the P(CDD- co -DCPD) copolymers exhibited one-way shape memory function rather than two-way shape memory performance under constant stress. With the increasing content of DCPD in the copolymers, the shape recovery ratio exhibited an upward trend and reached a maximum of 94.44%. Additionally, the shape fixation ratio of the P(CDD- co -DCPD) copolymers also surpassed 95%. In contrast, the P(COE- co -DCPD) copolymers demonstrated both one-way and two-way shape memory functions, particularly, when the molar content of DCPD was 4 mol%, the shape recovery ratio reached a maximum of 95.03% and the shape fixation ratio exceeded 90%. Graphical
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2023
·Vol. 69
·期 7
·e18085
·
IF 3.7
Wei Wang,Baian Pu,Chi Ma,Chengxiang Shi,Lun Pan,Xiangwen Zhang,Ji-Jun Zou
Cyclopropane derivates are appealing to synthesis of high-energy-density fuels because of the high strained energy of the three-numbered ring. The catalytic cyclopropanation of olefin with diazomethane is very effective to construct the carbocycle. The majority of the catalysts employed are nonrecyclable homogeneous compounds. Herein, we report cyclopropanation of polycyclic olefins catalyzed by heterogeneous Pd/C. The optimal cyclopropanation conditions were explored utilizing dicyclopentadiene as model substrate and a series of polycyclic olefins were cyclopropanated with high yield. Additionally, the catalyst has good recyclability and stability, as shown by characterizations as well as the fact that no inactivation happens after cyclopropanation. The synthesized cyclopropane derivates exhibit good fuel characteristics like high density (1.006–1.087 g/cm 3 ), high volumetric net heat of combustion (42.58–46.45 kJ/cm 3 ), good low-temperature and combustion performance. This work shows industrial potential for cyclopropanation of polycyclic olefins with diazomethane.
研究领域:
化学工程
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能源科学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2021
·
IF 4.354
Qifu Lin,Wen Yang,Yongqi Yao,Yue Li,Lin Wang,Dingqiao Yang
A novel copper-catalyzed cycloaddition of diaryl disulfides to heterobicyclic alkenes has been developed. The C—S and C—C bonds can be formed simultaneously on the C═C bond of the olefins via a single-step cycloaddition to afford a series of 2,3-dihydrobenzo[b]thiophene derivatives. This reaction exhibits excellent diastereoselectivity and relatively broad substrate scope. Various functional groups attached to the substrates are tolerated in this protocol to give the corresponding exo adducts in moderate yields.
研究领域:
有机化学
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合成化学
✓ 已验证
DOI
PubMed
高影响因子
Materials
·
2025
·Vol. 18
·期 17
·4033
·
IF 3.2
Mengjia Feng,Zhiguo Jia,Yancheng Liu,Yandong Liu,Jia Shi,Chaoyue Zhao,Tianqi Sun,Hongbo Liu,Yunqi Xing
Self-healing is imperative for the restoration of the insulation state of metallized film capacitors following breakdown during operation, thereby ensuring the safe and reliable functioning of the capacitors. Temperature is an important factor affecting the self-healing behavior of film capacitor dielectrics, but the mechanism is currently unclear. To investigate the effects of temperature and dielectric matrix on self-healing behavior, polyetherimide (PEI), cycloolefin copolymer (COC), and biaxially oriented polypropylene (BOPP) were selected as research subjects. A systematic study was conducted to examine the self-healing performance at 80, 120, and 150 °C, as well as the effect of self-healing on insulation and energy storage performance. The results showed that as the temperature increased, the capacitance of PEI decreased by 11.90%, 23.00%, and 37.88%, respectively. COC decreased by 11.76%, 7.63%, and 12.18%, respectively, while BOPP decreased by 8.75% and 9.67%, respectively. The accumulation of breakdown holes formed by self-healing decreases, the area of evaporated electrodes decreases, and the boundaries between the evaporated electrode areas formed by self-healing and the surrounding electrodes become more distinct. Furthermore, COC exhibits high dielectric strength, low dielectric loss, and self-healing properties comparable to BOPP at 150 °C, suggesting significant application potential. This research work is of great reference value for establishing the theoretical relationship between the chemical composition of dielectrics and their self-healing ability, and is of great significance for ensuring the safe and reliable operation of capacitors.
研究领域:
电气工程
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材料科学
·
高分子科学
·
电介质与电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
IF 3.764
Yaxing Li,Rui Zhang,Xianghai Meng,Ping Ouyang,Haiyan Liu,Chunming Xu,Zhichang Liu
Acid-soluble oil (ASO) was produced during isobutane alkylation catalyzed by chloroaluminate ionic liquids (CAILs). However, the ASO composition characterizations and deactivated CAIL regeneration pathway were not clarified. In this work, a series of characterizations (elemental analysis and infrared, ultraviolet, and mass spectroscopy) were performed to reveal the ASO composition. The result showed that ASO contained numerous conjugated cycloolefins with various alkyl substituents and a few O1–O5 compounds. The activity index (AI) value of fresh CAILs was 1.74 and decreased to 1.18 with the addition of 9.09 wt % ASO because the [Al2Cl7]− anion in CAILs was complexed by C═C and C═O bonds in ASO. The hydrogenation regeneration of deactivated CAILs on the Pd/C catalyst was studied. The AI value of regenerated CAILs increased to 1.45 because unsaturated bonds in ASO were hydrogenated to saturation. Recovery of unsaturated hydrocarbons followed the order benzene > 1-methylcyclopentene > pentamethylcyclopentadiene. This work demonstrated that low ASO recovery was attributed to the partial occupation of the π-electron of unsaturated bonds by the [Al2Cl7]− anion.
研究领域:
化学工程
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催化
·
石油化学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 12
·1806-1815
·
IF 5.582
Li Zhou,Zhenyu Wang,Guangqiang Xu,Chengdong Lv,Qinggang Wang
A highly efficient and controllable ring-opening polymerization of lactones (δ-valerolactone, ε-caprolactone and rac-lactide) has been achieved by using N-heterocyclic olefin (NHO) and thiourea/urea (TU/U) catalytic systems. This catalytic system showed high ring-opening activity and stereoselectivity, delivering biodegradable polyesters with high chain-end fidelity, controlled molecular weights and narrow molar mass dispersities. A detailed investigation of the structure–activity relationship was performed by exploring five NHOs and fourteen TUs/Us. For a fixed NHO, when the acidity of TUs/Us decreases, the polymerization mechanism changes from the (thio)urea anion to the neutral cooperative activation mode, and the catalytic activity first increases and then decreases, displaying a highly effective interval. For a given TU or U, as the basicity of NHOs increases, the catalytic performance improves correspondingly. Besides, highly isoselective ROP of rac-LA (Pm = 0.93) at −78 °C has been also achieved, highlighting the versatility of the NHO/TU(U) system. These findings enrich the type of TU/U and base organocatalyst.
研究领域:
材料科学
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高分子化学
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有机催化
✓ 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）