{"title":"非质子溶剂中水诱导的超氧化物离子歧化","authors":"Yong Che, Manabu Tsushima, Futoshi Matsumoto, Takeyoshi Okajima, Koichi Tokuda, Takeo Ohsaka","doi":"10.1021/jp9625523","DOIUrl":null,"url":null,"abstract":"<p >The water-induced disproportionation of the electrogenerated superoxide ion (O<sub>2</sub><sup>-</sup>) in acetonitrile, dimethylformamide, and dimethyl sulfoxide media containing various concentrations of water as a Br?nsted acid has been examined by UV?vis spectroscopy. Analysis of the kinetics as a function of O<sub>2</sub><sup>-</sup> and water concentrations and of the measurement time demonstrated that the disproportionation of O<sub>2</sub><sup>-</sup> by water in these media obeys a common mechanism:? O<sub>2</sub><sup>-</sup> + H<sub>2</sub>O ? HO<sub>2</sub><sup>?</sup> + OH<sup>-</sup> (<i>k</i><sub>1</sub>, <i>k</i><sub>-1</sub>) HO<sub>2</sub><sup>?</sup> + O<sub>2</sub><sup>-</sup> → HO<sub>2</sub><sup>-</sup> + O<sub>2</sub> (<i>k</i><sub>2</sub>) (HO<sub>2</sub><sup>?</sup>, hydroperoxyl radical; HO<sub>2</sub><sup>-</sup>, hydrogen peroxide anion). The solvent dependence of the obtained kinetic parameters of (<i>k</i><sub>1</sub>/<i>k</i><sub>-1</sub>)<i>k</i><sub>2</sub>, <i>k</i><sub>1</sub> and <i>k</i><sub>-1</sub>/<i>k</i><sub>2</sub> is discussed in terms of the solvation of O<sub>2</sub><sup>-</sup> and H<sub>2</sub>O as well as the effective acidities of H<sub>2</sub>O in different aprotic solvents. </p>","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.7810,"publicationDate":"1996-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/jp9625523","citationCount":"64","resultStr":"{\"title\":\"Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents\",\"authors\":\"Yong Che, Manabu Tsushima, Futoshi Matsumoto, Takeyoshi Okajima, Koichi Tokuda, Takeo Ohsaka\",\"doi\":\"10.1021/jp9625523\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >The water-induced disproportionation of the electrogenerated superoxide ion (O<sub>2</sub><sup>-</sup>) in acetonitrile, dimethylformamide, and dimethyl sulfoxide media containing various concentrations of water as a Br?nsted acid has been examined by UV?vis spectroscopy. Analysis of the kinetics as a function of O<sub>2</sub><sup>-</sup> and water concentrations and of the measurement time demonstrated that the disproportionation of O<sub>2</sub><sup>-</sup> by water in these media obeys a common mechanism:? O<sub>2</sub><sup>-</sup> + H<sub>2</sub>O ? HO<sub>2</sub><sup>?</sup> + OH<sup>-</sup> (<i>k</i><sub>1</sub>, <i>k</i><sub>-1</sub>) HO<sub>2</sub><sup>?</sup> + O<sub>2</sub><sup>-</sup> → HO<sub>2</sub><sup>-</sup> + O<sub>2</sub> (<i>k</i><sub>2</sub>) (HO<sub>2</sub><sup>?</sup>, hydroperoxyl radical; HO<sub>2</sub><sup>-</sup>, hydrogen peroxide anion). The solvent dependence of the obtained kinetic parameters of (<i>k</i><sub>1</sub>/<i>k</i><sub>-1</sub>)<i>k</i><sub>2</sub>, <i>k</i><sub>1</sub> and <i>k</i><sub>-1</sub>/<i>k</i><sub>2</sub> is discussed in terms of the solvation of O<sub>2</sub><sup>-</sup> and H<sub>2</sub>O as well as the effective acidities of H<sub>2</sub>O in different aprotic solvents. </p>\",\"PeriodicalId\":58,\"journal\":{\"name\":\"The Journal of Physical Chemistry \",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7810,\"publicationDate\":\"1996-12-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1021/jp9625523\",\"citationCount\":\"64\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Journal of Physical Chemistry \",\"FirstCategoryId\":\"1\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/jp9625523\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Physical Chemistry ","FirstCategoryId":"1","ListUrlMain":"https://pubs.acs.org/doi/10.1021/jp9625523","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Water-Induced Disproportionation of Superoxide Ion in Aprotic Solvents
The water-induced disproportionation of the electrogenerated superoxide ion (O2-) in acetonitrile, dimethylformamide, and dimethyl sulfoxide media containing various concentrations of water as a Br?nsted acid has been examined by UV?vis spectroscopy. Analysis of the kinetics as a function of O2- and water concentrations and of the measurement time demonstrated that the disproportionation of O2- by water in these media obeys a common mechanism:? O2- + H2O ? HO2? + OH- (k1, k-1) HO2? + O2- → HO2- + O2 (k2) (HO2?, hydroperoxyl radical; HO2-, hydrogen peroxide anion). The solvent dependence of the obtained kinetic parameters of (k1/k-1)k2, k1 and k-1/k2 is discussed in terms of the solvation of O2- and H2O as well as the effective acidities of H2O in different aprotic solvents.
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