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The application of C–H bond functionalization in the total syntheses of indole natural products

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Organic Chemistry Frontiers 2022年第4期9卷 1195-1210页

作者： Dong-Xing Tan Fu-She Han CAS Key Lab of High-Performance Synthetic Rubber and its Composite Materials Changchun Institute of Applied ChemistryChinese Academy of Sciences5625 Renmin StreetChangchunJilin 130022China

The direct functionalization of unactivated C–H bonds has been a rapidly growing field in organic chem-istry in recent years because of its indisputable advantages in bond forming reactions in terms of step and atom-... 详细信息

关键词： functionalization bonds bond

Recyclable polythioesters and polydisulfides with near-equilibrium thermodynamics and dynamic covalent bonds

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Science China Chemistry 2023年第3期66卷 725-738页

作者： Wei Xiong Hua Lu Beijing National Laboratory for Molecular Sciences Center for Soft Matter Science and EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The accumulation of discarded petroleum-based plastics causes serious environmental crises.Currently,recyclable polymers with neutrality in thermodynamics,such as polyesters,polycarbonates,and polyolefins,have been developed as promising alternatives to traditional petroleum-based polymers.However,the chemical recycle of these polymers usually requires high energy input and expensive catalysts.Dynamic covalent bonds,such as thioester and disulfide bonds,have emerged as building blocks for constructing recyclable polymers that can be rapidly degraded/recycled under mild conditions.In this review,we introduce representative studies on recyclable polythioesters and polydisulfides with respect to their synthetic strategies,thermodynamic manipulation,physicochemical properties,and preliminary applications.We also highlight the important role of kinetic factors played in the design of recyclable polymers.Finally,major challenges,perspectives,and future opportunities in the synthesis and applications of polythioesters/polydisulfides are discussed.

关键词： polythioesters polydisulfides recyclable near-equilibrium thermodynamics dynamic covalent bond

Electrocatalytic construction of the C–N bond from the derivates of CO_(2) and N_(2)

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Science China Chemistry 2022年第2期65卷 204-206页

作者： Yanmei Huang Yuting Wang Yongmeng Wu Yifu Yu Bin Zhang Institute of Molecular Plus Department of ChemistrySchool of ScienceTianjin UniversityTianjin 300072China

Electrochemical synthesis of C-N bond-containing compounds(e.g.,urea,amino acid,amide,amine,and their derivates)from CO_(2)/N_(2)and their derivates is emerging as a promising sustainable strategy[1-7].CO_(2)and its derived products,CO,HCOOH,(COOH)_(2),etc.,could serve as carbon sources(Figure 1)[8].N_(2),making up 80%of air,is an appealing nitrogen source.However,the low solubility of N2 and the high dissociation energy for the N≡N bond limit its application.

关键词： bond Figure solubility

Redox-neutral photocatalytic strategy for selective C–C bond cleavage of lignin and lignin models via PCET process

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Science Bulletin 2019年第22期64卷 1658-1666页

作者： Yinling Wang Yue Liu Jianghua He Yuetao Zhang State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University

It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and selectivity.We have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/mol.Without breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and selectivities.Preliminary studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.

关键词： C–C bond cleavage Lignin depolymerization Photocatalysis Proton-coupled electron transfer Redox-neutral

Visible light-mediated C—P bond formation reactions

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Science Bulletin 2019年第5期64卷 337-350页

作者： Bao-Gui Cai Jun Xuan Wen-Jing Xiao Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials College of Chemistry & Chemical Engineering Anhui University Key Laboratory of Pesticide & Chemical Biology Ministry of Education College of Chemistry Central China Normal University

Organophosphorus compounds have attracted continuous attention in materials science, agrochemical and pharmaceutical fields due to their unique bioactivities. Thus, the development of novel and robust manners for the construction new C—P bond has therefore gained great interests in synthetic organic chemistry. Because of their intrinsic sustainability and green chemistry character, visible light-induced photoredox catalysis has been widely applied in the construction of new chemical bonds, including the formation of C—P bond. In this review, we summarized recent achievements in C—P bond formation reactions initiated by visible light-induced photoredox catalysis, which mainly focusing on the discussion of reaction design and the mechanism.

关键词： C-P bond formation Organophosphorus compounds Photoredox catalysis Visible light

Experimental Study on the Degradation of bonding Behavior between Reinforcing Bars and Concrete after Corrosion and Fatigue Damage

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Structural Durability & Health Monitoring 2022年第3期16卷 195-212页

作者： Shiqin He Jiaxing Zhao Chunyue Wang Hui Wang School of Civil Engineering North China University of TechnologyBeijing100144China

In marine environments,the durability of reinforced concrete structures such as bridges,which suffer from the coupled effects of corrosion and fatigue damage,is significantly reduced.Fatigue loading can result in severe dete-rioration of the bonds between reinforcing steel bars and the surrounding concrete,particularly when reinforcing bars are corroded.Uniaxial tension testing was conducted under static loading and fatigue loading conditions to investigate the bonding characteristics between corroded reinforcing bars and concrete.An electrolyte corrosion technique was used to accelerate steel corrosion.The results show that the bond strength was reduced under fati-gue loading,although the concrete did not crack.Therefore,fatigue loading has negative effects on the bond strength between corroded steel bars and concrete.The effects of corrosion cracking on bond strength become more pronounced after corrosion cracking appears along the main reinforcing bars.When the average width of cracking along main reinforcing bars exceeds 3 mm,the bonding properties deteriorate rapidly based on the effects of corrosion cracking,whereas fatigue loading exhibits no additional effects on bond strength.

关键词： Reinforced concrete fatigue loading electrolyte corrosion bond uniaxial tension

Removal of polycyclic aromatic hydrocarbons from different soil fractions by persulfate oxidation

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Journal of Environmental Sciences 2019年第4期31卷 239-246页

作者： Xiaoyong Liao Qiongzhi Liu You Li Xuegang Gong Hongying Cao Key Laboratory of Land Surface Pattern and Simulation Beijing Key Laboratory of Environmental Damage Assessment and RemediationInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of Science University of Chinese Academy of Sciences

Removal of polycyclic aromatic hydrocarbons(PAHs) from different soil fractions of contaminated soil was investigated by using activated persulfate oxidation remediation in our research. The results showed that the light fraction, which accounted for only 10% of the soil, contained 30% of the PAHs at a concentration of 4352 mg/kg. The heavy fraction contained more high-molecular-weight PAHs, and the total PAH concentration was 625 mg/kg. After being oxidized, the removal rate of PAHs was 39% in the light fraction and nearly 90% in the heavy fraction. Among the different fractions of the heavy fraction,humic acid contained the highest concentration of PAHs, and consequently, the highest removal efficiency of PAHs was also in humic acid. Compared with the light fraction, the heavy fraction has more aromatic compounds and those compounds were broken down during the oxidation process, which may be the removal mechanism involved in the oxidation of high-ring PAHs. Similarly, the enhancement of C= C bonds after oxidation can also explain the poor removal of high-ring PAHs in the light fraction. These results imply that different fractions of soil vary in composition and structure, leading to differences in the distribution and oxidation efficiencies of PAHs.

关键词： Soil fraction Persulfate oxidation PAHs Organic matter bond

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2675-2686页

作者： Qian Liu Xianglan Zhang Wei Li School of Chemical and Environmental Engineering China University of Mining and TechnologyBeijing 100083China School of Chemical Engineering Beijing Institute of Petro-Chemical TechnologyBeijing 102600China

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

关键词： Extraction M-cresol Ionic liquids Separation COSMO-RS Hydrogen bond

Synthesis and Properties of Reversible Disulfide bond-based Self-healing Polyurethane with Triple Shape Memory Properties

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Chinese Journal of Polymer Science 2019年第11期37卷 1119-1129页

作者： Han Jia Kun Chang Shu-Ying Gu Department of Polymeric Materials School of Materials Science and Engineering Tongji University Shanghai 201804 China Key Laboratory of Advanced Civil Engineering Materials Ministry of Education Tongji University Shanghai 201804 China

A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone)(PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG), and 4,4,-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (^1H-NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal properties, selfhealing properties, triple-shape memory effect, and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments, and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 50℃(with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. As-prepared polyurethane is expected to have potential applications in multi-shape coatings, films, and step-by-step deploying structures.

关键词： Self-healing Reversible disulfide bond Triple shape memory Polyurethane