Reductive debromination of anhydro-6-(R)-hydroxycthyl-6-(R) 7 by zinc in ammonium acetate gave 9 in 81% yield with high stcreosclectivity of 6-(α):6-(β)= 13: 1
Polybrominated diphenyl ethers(PBDEs)are a kind of serious pollutants in the ocean.Biodegradation is considered as an economical and safe way for PBDEs removal and reductive debromination dominates the initial pathway...Polybrominated diphenyl ethers(PBDEs)are a kind of serious pollutants in the ocean.Biodegradation is considered as an economical and safe way for PBDEs removal and reductive debromination dominates the initial pathway of anaerobic degradation.On the basis of experimental study,Octa-BDE 197,Hepta-BDE 183,Hexa-BDE 153,Penta-BDE 99 and Tetra-BDE 47 were selected as the initial degradation objects,and their debromination degradation were studied using density functional theory.The structures were optimized by Gaussian 09 program.Furthermore,the molecular orbitals and charge distribution were analyzed.All C-Br bond dissociation energies at different positions including ortho,meta and para bromine atoms were calculated and the sequence of debromination was obtained.There is a close relationship between molecular structure,charge,molecular orbital and C-Br bond.All PBDEs exhibited similar debromination pathways with preferential removal of meta and para bromines.展开更多
A new technique of zero-valent zinc coupled with ascorbic acid(ZVZ/AA)was developed and applied to debrominate the 2,2,,4,4,-Tetrabromodiphenyl ether(BDE-47),which achieved high conversion and rapid debromination of B...A new technique of zero-valent zinc coupled with ascorbic acid(ZVZ/AA)was developed and applied to debrominate the 2,2,,4,4,-Tetrabromodiphenyl ether(BDE-47),which achieved high conversion and rapid debromination of BDE-47 to less-or non-toxic forms.The reaction conditions were optimized by the addition of 100 mg/L Z V Z particles and 3 mmol/L A A at original solution p H=4.00 using the solvent of methanol/H2O(v:v=4:6),which could convert approximately 94%of 5 mg/L BDE-47 into lower-brominated diphenyl ethers within a 90 min at the ZVZ/AA system.The high debromination of BDE-47 was mainly attributed to the effect of A A that inhibits the formation of Zn(Ⅱ)(hydr)oxide passivation layers and promotes the corrosion of ZVZ,which leads to increase the reactivity of ZVZ.Additionally,ion chromatography and gas chromatography mass spectrometry analyses revealed that bromine ion and lower-debromination diphenyl ethers formed during the reduction of BDE-47.Furthermore,based on the generation of the intermediates products,and its concentration changes over time,it was proposed that the dominant pathway for conversion of BDE-47 was sequential debromination and the final products were diphenyl ethers.These results suggested that the ZVZ/AA system has the potential for highly efficient debromination of BDE-47 from wastewater.展开更多
文摘Reductive debromination of anhydro-6-(R)-hydroxycthyl-6-(R) 7 by zinc in ammonium acetate gave 9 in 81% yield with high stcreosclectivity of 6-(α):6-(β)= 13: 1
基金the National Natural Science Foundation of China(Nos.41406090,42176045)the Science Foundation of Qingdao Agricultural University(No.631302)+1 种基金the Fujian Key Laboratory of Functional Marine Sensing Materials,Minjiang University(No.MJUKF-FMSM202102)the Natural Science Foundation of Shandong Province(Nos.ZR2019 MB020,ZR2020MB119)。
文摘Polybrominated diphenyl ethers(PBDEs)are a kind of serious pollutants in the ocean.Biodegradation is considered as an economical and safe way for PBDEs removal and reductive debromination dominates the initial pathway of anaerobic degradation.On the basis of experimental study,Octa-BDE 197,Hepta-BDE 183,Hexa-BDE 153,Penta-BDE 99 and Tetra-BDE 47 were selected as the initial degradation objects,and their debromination degradation were studied using density functional theory.The structures were optimized by Gaussian 09 program.Furthermore,the molecular orbitals and charge distribution were analyzed.All C-Br bond dissociation energies at different positions including ortho,meta and para bromine atoms were calculated and the sequence of debromination was obtained.There is a close relationship between molecular structure,charge,molecular orbital and C-Br bond.All PBDEs exhibited similar debromination pathways with preferential removal of meta and para bromines.
基金The authors thank the Major Science and Technology Program for Water Pollution Control and Treatment,National Water Grant(No.2017ZX07202002)the Key-Area Research and Development Program of Guangdong Provice(No.2019B110205003)the National Natural Science Foundation of China(Grant No.51979141).
文摘A new technique of zero-valent zinc coupled with ascorbic acid(ZVZ/AA)was developed and applied to debrominate the 2,2,,4,4,-Tetrabromodiphenyl ether(BDE-47),which achieved high conversion and rapid debromination of BDE-47 to less-or non-toxic forms.The reaction conditions were optimized by the addition of 100 mg/L Z V Z particles and 3 mmol/L A A at original solution p H=4.00 using the solvent of methanol/H2O(v:v=4:6),which could convert approximately 94%of 5 mg/L BDE-47 into lower-brominated diphenyl ethers within a 90 min at the ZVZ/AA system.The high debromination of BDE-47 was mainly attributed to the effect of A A that inhibits the formation of Zn(Ⅱ)(hydr)oxide passivation layers and promotes the corrosion of ZVZ,which leads to increase the reactivity of ZVZ.Additionally,ion chromatography and gas chromatography mass spectrometry analyses revealed that bromine ion and lower-debromination diphenyl ethers formed during the reduction of BDE-47.Furthermore,based on the generation of the intermediates products,and its concentration changes over time,it was proposed that the dominant pathway for conversion of BDE-47 was sequential debromination and the final products were diphenyl ethers.These results suggested that the ZVZ/AA system has the potential for highly efficient debromination of BDE-47 from wastewater.
