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Liquid-phase epoxidation of propylene with molecular oxygen by chloride manganese meso-tetraphenylporphyrins

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Chinese Journal of Chemical Engineering 2022年第8期35卷 61-65页

作者： Xian-Tai Zhou Ling-Ling Wang Yang Li Hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou 510275China School of Chemical Engineering Guangdong University of Petrochemical TechnologyMaoming 525000China

Propylene molecule owns two active sites,the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of selectivity.In this work,the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin(MnTPPCl)was developed.The conversion of propylene was 12.7%,and the selectivity towards PO(propylene oxide)reached up to 80.5%.The formation of PO was attributed to the mechanism via high-valent Mn species,which was confirmed by means of in situ UV–vis spectrum.

关键词： Propylene epoxidation Dioxygen Manganese porphyrins Liquid phase

Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin epoxidation

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Chinese Journal of Chemistry 2022年第1期40卷 115-122页

作者： Xiao-Hui Liu Jia-Ying Huang Lei-Ming Tao Hai-Yang Yu Xian-Tai Zhou Can Xue Qi Han Wen Zou Hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhaiGuangdong 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhouGuangdong 510275China School of Chemical Engineering Guangdong University of Petrochemical TechnologyMaomingGuangdong 525000China

The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reductant(Mukaiyama epoxidation)has been reported,however,comprehensive examination of oxygen atom transfer mechanism involving free radical and highly reactive intermediates has yet to be presented.Herein,meso-tetrakis(pentafluorophenyl)porphyrinatooxidovanadium(Ⅳ)(VOTPFPP)was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of isobutyraldehyde.In situ electron paramagnetic resonance spectroscopy(in situ EPR)showed the generation,transfer pathways and ascription of free radicals in the epoxidation.According to the spectral and computational studies,the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process.In the cyclohexene epoxidation catalyzed by VOTPFPP,the kinetic isotope effect value of 1.0 was obtained,indicating that epoxidation occurred via oxygen atom transfer mechanism.The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory(DFT)calculations.

关键词： Vanadium-oxo porphyrin epoxidation Reaction mechanisms Oxygen atom transfer Radicals

Bromine and oxygen redox species mediated highly selective electro-epoxidation of styrene

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Organic Chemistry Frontiers 2022年第2期9卷 436-444页

作者： Yuchi Zhang Asma Iqbal Jiantao Zai Shu-Yu Zhang Hongran Guo Xuejiao Liu Ibrahim ul Islam Hira Fazal Xuefeng Qian Shanghai Electrochemical Energy Devices Research Center School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong University Shanghai200240P.R.China

Olefin epoxidation is an essential transformation and arouses great interest among the scientific community for the key role of epoxide in the chemical industry.Traditional methods suffer from harmful oxidants and require harsh operating conditions and complex separation processes.Electro-epoxidation through bromine redox reactions is an eco-friendly strategy.However,the lack of efficient electrodes always limits the selectivity of epoxidation and results in massive energy consumption.Herein,we found that GF-CoS_(2)/CoS heterostructures anchored on graphite felt(GF-CoS_(2)/CoS)can efficiently facilitate the generation of bromine redox species on the anode.The synergistic cooperation between the bromine redox species and oxygen redox species(generated on a graphite rod cathode)can establish a benign electro-epoxidation system for olefin substrates in an ambient environment.Under the optimized reaction conditions,the epoxidation of styrene can achieve a yield of 97% at 30 mA cm^(-2).Importantly,the applied voltage(4-5 V)is roughly half of the Pt-based electrode system(7.8-9.3 V),hence,saving half of the energy.We demonstrated that our proposed strategy could also be applied to other olefins.Because of the simple,sustainable,and economic advantages of the epoxidation process,we believe this strategy is highly desirable for technical applications.

关键词： redox epoxidation styrene

Manganese porphyrin-mediated aerobic epoxidation of propylene with isoprene: A new strategy for simultaneously preparing propylene epoxide and isoprene monoxide

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Chinese Chemical Letters 2023年第3期34卷 236-239页

作者： Xian-Tai Zhou Hai-Yang Yu Yang Li Hai-Bo Wu Hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou 510275China Huizhou Research Institute Sun Yat-sen UniversityHuizhou 516081China Advanced Energy Science and Technology Guangdong Laboratory Huizhou 516003China

The direct epoxidation of propylene by O_(2) is a significant and challenging topic. The key factor for this homogeneous aerobic epoxidation is the activation of molecular oxygen under mild conditions. In this work,the aerobic epoxidation of propylene catalyzed by manganese porphyrins was achieved in the presence of isoprene. Isoprene contains an allyl methyl group, and the α-H can be easily removed to achieve the activation of molecular oxygen. The conversion of propylene was 38% and the selectivity toward propylene oxide(PO) was up to 87%. The role of isoprene was demonstrated, and a plausible mechanism was proposed. The protocol reported herein is expected to provide a strategy for the simultaneous preparation of propylene oxide and isoprene monoxide.

关键词： Propylene epoxidation Dioxygen Isoprene Metalloporphyrins

epoxidation of Styrene-Isoprene-Styrene Block Copolymer and Research on Its Reaction Mechanism

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Journal of Wuhan University of Technology(Materials Science) 2010年第3期25卷 403-407页

作者：李红强曾幸荣 College of Materials Science and Engineering South China University of Technology

Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.

关键词： styrene-isoprene-styrene block copolymer epoxidation ring-open reaction mechanism

Well-dispersed Mn/g-C_(3)N_(4)as bifunctional catalysts for selective epoxidation of olefins and carbon dioxide cycloaddition

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Chinese Chemical Letters 2023年第12期34卷 150-154页

作者： Minxing Du Yuxia Sun Jiaojiao Zhao Haiyan Hu Liwei Sun Yuehui Li State Key Laboratory for Oxo Synthesis and Selective Oxidation Suzhou Research Institute of LICPCenter for Excellence in Molecular SynthesisLanzhou Institute of Chemical Physics(LICP)Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

epoxidation is an important chemical process for the production of epoxides,key building blocks in chemical industry.Despite great efforts being made to facilitate this process,it remains a significant challenge to develop cost-effective,environmental-friendly,and selective catalysts.Herein,we reported a highly dispersed Mn supported by g-C_(3)N_(4)(Mn/g-C_(3)N_(4))with Mn loading up to 2.56 wt%.The Mn/g-CN_(4)exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion(91%),high selectivity(93%)as well as outstanding recycling stability.Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer.Besides,an efficient synthesis of cyclic carbonates from styrene epoxide and CO_(2)has been achieved(88%conversion,89%selectivity)based on the polar Mn-N coordinated characteristics of Mn/g-C_(3)N_(4)catalyst.

关键词： Well-dispersed Mn catalyst Bifunctional catalyst epoxidation CO_(2) Cycloaddition

Orbital Interaction of epoxidation on the Same Curvature Bonds of Single-walled Carbon Nanotubes

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Chinese Journal of Structural Chemistry 2007年第11期26卷 1308-1314页

作者：贾桂霄李俊篯李奕陈林刚陈勇 Department of Chemistry Fuzhou University

The epoxidation of different bonds with the same bond curvature in one nanotube including armchair, zigzag and chiral tubes was studied. The calculated results showed that for the adducts with opened C-O--C configuration, the magnitude of the binding energies was related with their corresponding bonding characteristics in HOMO, and the larger binding energies were attributed to stronger orbital interaction between one O atom and the nanotube; whereas for the adducts with 3MR structures, the binding energies were related with the changes of C-C bond length and independent of the frontier orbital interaction before and after epoxidation.

关键词： carbon nanotube epoxidation bond curvature orbital interaction

Can lanthanum doping enhance catalytic performance of silver in direct propylene epoxidation over NaMoAg/SiO_2?

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Journal of Rare Earths 2019年第5期37卷 500-507页

作者： Hany M.Abdel Dayem Shar S.Al-Shihry Salah A.Hassan Chemistry Department Faculty of Science Ain Shams University Chemistry Department College of Science King Faisal University

In the attempt to reduce surface free energy of silica to improve interaction of silica with silver, silica was doped by different amounts of low surface energy lanthanum, La_2O_3, through impregnation. The doped and undoped silica were used as supports for preparation of Na/Ag/Mo/La_2O_3-SiO_2 catalysts. Catalytic performances of the catalysts were evaluated in direct epoxidation of propylene(DPO) using molecular oxygen under atmospheric pressure and without adding hydrogen. Adding 5 wt%La to the Na/Ag/Mo/SiO_2 catalyst improves both the catalysts electivity in DPO and its stability over 20h of time-on-stream.The characterization results show that La_2O_3 species interact strongly with silver particles on the silica surface which result in significant improvement in the dispersion profile of silver and marked decrease in the size of silver nanoparticles(AgNPs). The estimated mean diameter of AgNPs is ca. 4.0 nm in Na/Ag/Mo/5 wt%La_2O_3-SiO_2, which is smaller than that(53.9 nm) found in Na/Ag/SiO_2. The presence of subnanometer AgNPs on Ag/La_2O_3-SiO_2 prior addition of MoO_3 and NaCl to the sample can enhance the mutual electronic synergism between Ag, MoO_3 and Na for selective production of propylene oxide.

关键词： Direct epoxidation Propylene Gas phase Silver Subnanometer Lanthanum

Calix[6]arene-bismetalloporphyrins as Enzyme Models for P450 V. Catalytic Performance in epoxidation of Styrene

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Chinese Journal of Chemistry 2003年第6期21卷 683-686页

作者：李东红陈淑华赵华明 The Faculty of Chemistry Sichuan University Chengdu Sichuan 610064 China

In this paper the catalytic performance of thecalix[6]arene-bismetalloporphyrins in the epoxidation of styrene was studied. The influence of phasetransfer catalyst, pH value, buffer agent, substrate concentration, substituent on the benzene ringof porphyrin, and the central metal ion, etc., on the reaction rates were investigatedmeticulously. The results showed that the calix [6] arene-bismetalloporphyrins had a much highercatalytic activity than that of the corresponding metalloporphyrins.

关键词： calix arene-bismetalloporphyrins cytochrome P450 model compound styrene epoxidation