Due to the endocrine toxicity,neurotoxic,and reproductive toxicity to organisms,the sources and risks of brominated organic pollutants have attracted widespread attention.However,knowledge gaps remain in the brominati...Due to the endocrine toxicity,neurotoxic,and reproductive toxicity to organisms,the sources and risks of brominated organic pollutants have attracted widespread attention.However,knowledge gaps remain in the bromination processes of emerging phenolic pollutants in plants,whichmay increase the potential health risk associated with food exposure.Our study discovered that light induced generation and accumulation of more toxic brominated organic compounds(Br-org)in lettuce leaves under the stress of acetaminophen(ACE)than that without light,as evidenced by an increase in C-Br bond intensity in FTIR analysis.This result can be explained by the oxidation of bromide ions(Br^(-))by reactive species(ROS and ^(3)Chl*)of chloroplast into reactive bromine species(RBS).The main mechanism is that the redox of Br^(-)reduced the oxidative damage of ACE to the structure and function of chloroplasts,providing good conditions for light energy uptake and utilization and promoting the increase of pigments and active species.Compared with the dark group exposed to 5 mg/L Br^(-),the pigment content,H_(2)O_(2) and ^(1)O_(2) level of the light group increased by 56%,84% and 69%,respectively.On the other hand,RBS attacks certain electrophilic organic compounds in leaves to generate Br^(-)org.Triple excited state of chlorophyll(^(3)Chl^(*))was the dominant species for the transformation of ACE,while RBS is a key factor in the generation of Br-org in the Br^(-)/light/chlorophyll system.A total of six transformation products were identified by HPLC-MS/MS,which were involved in three transformation pathways:methylation,hydroxyl oxidation and hydroxylation followed by bromination.This is the first report that Br^(-)could enter the chloroplast and improved chloroplast structure under ACE stress,and elucidated the bromination mechanism of organics in terrestrial plant involving of biophotochemical bromination in chloroplast besides enzyme-catalyzed bromination.This study is beneficial for risk assessment and prevention of emerging phenolic pollutants.展开更多
A series of α-bromoarylethanones were prepared in high yields by a practical and efficient method. The arylethanones were reacted with bromine to give a mixture of α- and α, α-dibromides, which were debrominated w...A series of α-bromoarylethanones were prepared in high yields by a practical and efficient method. The arylethanones were reacted with bromine to give a mixture of α- and α, α-dibromides, which were debrominated with diethylphosphite in the presence of triethylamine to give the desired α-monobromo products.展开更多
The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discu...The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discussed.展开更多
Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ...Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ET-HR was first brominated at 30 or 200℃,and then heat-treated at 350℃to enable the dehydrobromination/polycondensation reactions.GC/MS and LDI TOF/MS spectra indicated that the ET-HR was mainly composed of compounds containing 3-to 6-ring aromatic species with a considerable aliphatic chain content.Compared with thermal condensation alone,such a two-step method increased the softening point of the pitches from 152 to 264℃with a yield in the range of 62 wt.%-67 wt.%and a coking value in the range of 57 wt.%-77 wt.%,depending on the bromination temperature and the bromine content.Structural characterization of the as-prepared pitches by elemental analysis,1H NMR,FT-IR and LDI-TOF/MS showed increased aromatization and polymerization of the precursor during the dehydrobrominatio/polycondensation.All the homogeneous isotropic pitches showed an ability to transform into an anisotropic texture after coking at 800℃.展开更多
An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes（NO2,Cl,Br,H,CH3） were high selectively ...An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes（NO2,Cl,Br,H,CH3） were high selectively brominated at the benzyl position for monobromination in CH2C12 at ice water with catalyst free.This simple but effective bromination of toluene derivatives with an aqueous H2O2-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods.展开更多
Mild and efficient method for bromination of electron-rich aromatic compounds is described using polyvinylpolypyrrolidone- bromine complex （PVPP-Br2）. The reaction proceeded smoothly with phenols and N.N-alkylated a...Mild and efficient method for bromination of electron-rich aromatic compounds is described using polyvinylpolypyrrolidone- bromine complex （PVPP-Br2）. The reaction proceeded smoothly with phenols and N.N-alkylated amines to afford the correspond- ing monobrominated product in good yields at ambient temperature.展开更多
An efficient and mild protocol for bromination of aryl azides with N-bromosuccinimide（NBS） under FeCl_3 catalysis in 1,2- dichloroethane was developed.It is proved to be an efficient method for obtaining brominated ...An efficient and mild protocol for bromination of aryl azides with N-bromosuccinimide（NBS） under FeCl_3 catalysis in 1,2- dichloroethane was developed.It is proved to be an efficient method for obtaining brominated aryl azides.展开更多
Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for t...Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for the purposes of producing either CH3Br or CH3Br and CO. It was found that the catalyst having a low specific surface area （calcined at relatively high temperature） favors the selective oxidation of methane to prepare CH3Br, while the catalyst having a high specific surface area favors the deeper partial oxidation of methane, which is good for CH3Br and CO preparation, The 650 h on stream life-time test revealed that the catalytic performance of the 0.4Rh/SiO2-900-10 catalyst was excellent. Both methane conversion and CH3Br selectivity kept increasing trends during the life-time test. No matter how serious was the Rh leaching during the reaction, the 0.4Rh/SiO2-900-10 catalyst did not deactivate at all.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42377428 and 42077391)the National Key Research&Developmental Program of China(No.2022YFC3701301)+1 种基金the Shandong Provincial Natural Science Foundation,China(Nos.ZR2020ZD34 and ZR2023YQ031)the Instrument Improvement Funds of Shandong University Public Technology Platform(No.ts20230108).
文摘Due to the endocrine toxicity,neurotoxic,and reproductive toxicity to organisms,the sources and risks of brominated organic pollutants have attracted widespread attention.However,knowledge gaps remain in the bromination processes of emerging phenolic pollutants in plants,whichmay increase the potential health risk associated with food exposure.Our study discovered that light induced generation and accumulation of more toxic brominated organic compounds(Br-org)in lettuce leaves under the stress of acetaminophen(ACE)than that without light,as evidenced by an increase in C-Br bond intensity in FTIR analysis.This result can be explained by the oxidation of bromide ions(Br^(-))by reactive species(ROS and ^(3)Chl*)of chloroplast into reactive bromine species(RBS).The main mechanism is that the redox of Br^(-)reduced the oxidative damage of ACE to the structure and function of chloroplasts,providing good conditions for light energy uptake and utilization and promoting the increase of pigments and active species.Compared with the dark group exposed to 5 mg/L Br^(-),the pigment content,H_(2)O_(2) and ^(1)O_(2) level of the light group increased by 56%,84% and 69%,respectively.On the other hand,RBS attacks certain electrophilic organic compounds in leaves to generate Br^(-)org.Triple excited state of chlorophyll(^(3)Chl^(*))was the dominant species for the transformation of ACE,while RBS is a key factor in the generation of Br-org in the Br^(-)/light/chlorophyll system.A total of six transformation products were identified by HPLC-MS/MS,which were involved in three transformation pathways:methylation,hydroxyl oxidation and hydroxylation followed by bromination.This is the first report that Br^(-)could enter the chloroplast and improved chloroplast structure under ACE stress,and elucidated the bromination mechanism of organics in terrestrial plant involving of biophotochemical bromination in chloroplast besides enzyme-catalyzed bromination.This study is beneficial for risk assessment and prevention of emerging phenolic pollutants.
文摘A series of α-bromoarylethanones were prepared in high yields by a practical and efficient method. The arylethanones were reacted with bromine to give a mixture of α- and α, α-dibromides, which were debrominated with diethylphosphite in the presence of triethylamine to give the desired α-monobromo products.
文摘The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under different reaction conditions. The mechanism was also discussed.
基金We thank the National Natural Science Foundation of China(No.30070888)the Chengdu Diao Pharmaceutical Company for support of this work.
文摘Treatment of lappaconitine 1 with NaIO_4 and Br_2-HOAc at room temperature for 7 h afforded smoothly the bromine-containing derivative 4 in 71% yield.
文摘Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar(ET-HR)by a two-step method of bromination and subsequent dehydrobromination/polycondensation.The ET-HR was first brominated at 30 or 200℃,and then heat-treated at 350℃to enable the dehydrobromination/polycondensation reactions.GC/MS and LDI TOF/MS spectra indicated that the ET-HR was mainly composed of compounds containing 3-to 6-ring aromatic species with a considerable aliphatic chain content.Compared with thermal condensation alone,such a two-step method increased the softening point of the pitches from 152 to 264℃with a yield in the range of 62 wt.%-67 wt.%and a coking value in the range of 57 wt.%-77 wt.%,depending on the bromination temperature and the bromine content.Structural characterization of the as-prepared pitches by elemental analysis,1H NMR,FT-IR and LDI-TOF/MS showed increased aromatization and polymerization of the precursor during the dehydrobrominatio/polycondensation.All the homogeneous isotropic pitches showed an ability to transform into an anisotropic texture after coking at 800℃.
基金This project was supported by the National Natural Science Foundation of Zhejiang Province(No.Y407306)the National Natural Science Foundation of China(No.20876148)
文摘An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes（NO2,Cl,Br,H,CH3） were high selectively brominated at the benzyl position for monobromination in CH2C12 at ice water with catalyst free.This simple but effective bromination of toluene derivatives with an aqueous H2O2-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods.
基金the Research Council of Islamic Azad University-Ayatollah Amoli Branch for financial support of this work
文摘Mild and efficient method for bromination of electron-rich aromatic compounds is described using polyvinylpolypyrrolidone- bromine complex （PVPP-Br2）. The reaction proceeded smoothly with phenols and N.N-alkylated amines to afford the correspond- ing monobrominated product in good yields at ambient temperature.
基金supported by National Natural Science Foundation of China(No30873153)the Key Projects of Shanghai in Biomedical(No08431902700)the Scientific Research Foundation of State Education Ministry for the Returned Overseas Chinese Scholars
文摘An efficient and mild protocol for bromination of aryl azides with N-bromosuccinimide（NBS） under FeCl_3 catalysis in 1,2- dichloroethane was developed.It is proved to be an efficient method for obtaining brominated aryl azides.
基金supported by the Chinese Ministry of Education Project No.107132the Chinese Ministry of Science and Technology Project No.2005CB221406, 2006BAE02B05
文摘Rh/SiO2 was prepared for the oxidative bromination of methane. The catalyst was prepared by calcination at different temperatures and for different times to obtain catalysts with different specific surface areas for the purposes of producing either CH3Br or CH3Br and CO. It was found that the catalyst having a low specific surface area （calcined at relatively high temperature） favors the selective oxidation of methane to prepare CH3Br, while the catalyst having a high specific surface area favors the deeper partial oxidation of methane, which is good for CH3Br and CO preparation, The 650 h on stream life-time test revealed that the catalytic performance of the 0.4Rh/SiO2-900-10 catalyst was excellent. Both methane conversion and CH3Br selectivity kept increasing trends during the life-time test. No matter how serious was the Rh leaching during the reaction, the 0.4Rh/SiO2-900-10 catalyst did not deactivate at all.
