The ubiquitous distribution of halogenated aromatic compounds（XAr） coupled with their carcinogenicity has raised public concerns on their potential risks to both human health and the ecosystem. Recently, advanced ox...The ubiquitous distribution of halogenated aromatic compounds（XAr） coupled with their carcinogenicity has raised public concerns on their potential risks to both human health and the ecosystem. Recently, advanced oxidation processes（AOPs） have been considered as an＂environmentally-friendly＂ technology for the remediation and destruction of such recalcitrant and highly toxic XAr. During our study on the mechanism of metal-independent production of hydroxyl radicals（UOH） by halogenated quinones and H_2O_2, we found, unexpectedly, that an unprecedented UOH-dependent two-step intrinsic chemiluminescene（CL） can be produced by H_2O_2 and tetrachloro-p-benzoquinone, the major carcinogenic metabolite of the widely used wood preservative pentachlorophenol. Further investigations showed that, in all UOH-generating systems, CL can also be produced not only by pentachlorophenol and all other halogenated phenols, but also by all XAr tested. A systematic structure–activity relationship study for all 19 chlorophenolic congeners showed that the CL increased with an increasing number of Cl-substitution in general. More importantly, a relatively good correlation was observed between the formation of quinoid/semiquinone radical intermediates and CL generation. Based on these results, we propose that UOH-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual CL production; and a rapid, sensitive,simple, and effective CL method was developed not only to detect and quantify trace amount of XAr, but also to provide useful information for predicting the toxicity or monitoring real-time degradation kinetics of XAr. These findings may have broad chemical, environmental and biological implications for future studies on halogenated aromatic persistent organic pollutants.展开更多
Although literature abounds with examples of formation of perhaloalkanes by photo-lytic or Lewis-acid induced halogen exchange reactions involving radical or carbocationintermediates,the procedures are seldom applicab...Although literature abounds with examples of formation of perhaloalkanes by photo-lytic or Lewis-acid induced halogen exchange reactions involving radical or carbocationintermediates,the procedures are seldom applicable to the preparation of perhaloalkanes ingood yields under mild conditions.Recently,we have reported the spontaneous reactionsof some perhalofluoroalkanes with various types of nucleophiles.All these reactions areinitiated by the halophilic attack of nucleophiles on C—Br or C—Cl bonds,followed byanionic chain steps involving carbanion as well as olefin intermediates.Notably,the latter areformed after the β-elimination of a good leaving group from the former.On the other hand,it is well known that halogenated carbanions can effectively make halophilic attacks on theC—X bonds of other halogenated substrates,e.g.,in the“halogen dance”of Bunnett.There-展开更多
基金supported by the Strategic Priority Research Program of CAS(No.XDB01020300)NSF China Grants(Nos.21577149,21477139,21237005 and 21321004)NIH Grants(Nos.ES11497,RR01008 and ES00210)
文摘The ubiquitous distribution of halogenated aromatic compounds（XAr） coupled with their carcinogenicity has raised public concerns on their potential risks to both human health and the ecosystem. Recently, advanced oxidation processes（AOPs） have been considered as an＂environmentally-friendly＂ technology for the remediation and destruction of such recalcitrant and highly toxic XAr. During our study on the mechanism of metal-independent production of hydroxyl radicals（UOH） by halogenated quinones and H_2O_2, we found, unexpectedly, that an unprecedented UOH-dependent two-step intrinsic chemiluminescene（CL） can be produced by H_2O_2 and tetrachloro-p-benzoquinone, the major carcinogenic metabolite of the widely used wood preservative pentachlorophenol. Further investigations showed that, in all UOH-generating systems, CL can also be produced not only by pentachlorophenol and all other halogenated phenols, but also by all XAr tested. A systematic structure–activity relationship study for all 19 chlorophenolic congeners showed that the CL increased with an increasing number of Cl-substitution in general. More importantly, a relatively good correlation was observed between the formation of quinoid/semiquinone radical intermediates and CL generation. Based on these results, we propose that UOH-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual CL production; and a rapid, sensitive,simple, and effective CL method was developed not only to detect and quantify trace amount of XAr, but also to provide useful information for predicting the toxicity or monitoring real-time degradation kinetics of XAr. These findings may have broad chemical, environmental and biological implications for future studies on halogenated aromatic persistent organic pollutants.
基金the National Natural Science Foundation of China.
文摘Although literature abounds with examples of formation of perhaloalkanes by photo-lytic or Lewis-acid induced halogen exchange reactions involving radical or carbocationintermediates,the procedures are seldom applicable to the preparation of perhaloalkanes ingood yields under mild conditions.Recently,we have reported the spontaneous reactionsof some perhalofluoroalkanes with various types of nucleophiles.All these reactions areinitiated by the halophilic attack of nucleophiles on C—Br or C—Cl bonds,followed byanionic chain steps involving carbanion as well as olefin intermediates.Notably,the latter areformed after the β-elimination of a good leaving group from the former.On the other hand,it is well known that halogenated carbanions can effectively make halophilic attacks on theC—X bonds of other halogenated substrates,e.g.,in the“halogen dance”of Bunnett.There-
