Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones.

Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Research Abstract Details 

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Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Abstract Text:

Ben-Zhan Zhu,Hong-Tao Zhao,Balaraman Kalyanaraman,Jun Liu,Guo-Qiang Shan,Yu-Guo Du,Balz Frei,

The metal-independent decomposition of organic hydroperoxides and the formation of organic alkoxyl radicals in the absence or presence of halogenated quinones were studied with electron spin resonance (ESR) and the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO). We found that 2,5-dichloro-1,4-benzoquinone (DCBQ) markedly enhanced the decomposition of tert-butylhydroperoxide (t-BuOOH), leading to the formation of the DMPO adducts with t-butoxyl radicals (t-BuO* and methyl radicals *CH(3)). The formation of DMPO/t-BuO* and DMPO/*CH(3) was dose-dependent with respect to both DCBQ and t-BuOOH and was not affected by iron- or copper-specific metal chelators. Comparison of the data obtained with DCBQ and t-BuOOH with those obtained in a parallel study with ferrous iron and t-BuOOH strongly suggested that t-BuO* was produced by DCBQ and t-BuOOH through a metal-independent mechanism. Other halogenated quinones were also found to enhance the decomposition of t-BuOOH and other organic hydroperoxides such as cumene hydroperoxide, leading to the formation of the respective organic alkoxyl radicals in a metal-independent manner. Based on these data, we propose a mechanism for DCBQ-mediated t-BuOOH decomposition and formation of t-BuO*: a nucleophilic attack of t-BuOOH on DCBQ, forming a chloro-t-butylperoxyl-1,4-benzoquinone intermediate, which decomposes homolytically to produce t-BuO*. This represents a mechanism of organic alkoxyl radical formation not requiring the involvement of redox-active transition metal ions.

Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Publishing Authors By Initials

BZ Zhu,HT Zhao,B Kalyanaraman,J Liu,GQ Shan,YG Du,B Frei,

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Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Proceedings of the National Academy of Sciences of

VOLUME: 104

Page Numbers: 3698-702

Journal Abbreviation: Proc. Natl. Acad. Sci. U.S.A.

ISSN: 0027-8424

DAY: 28

MONTH: 02

YEAR: 2007

Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 7505876

Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Keywords Mesh Terms:

KEYWORDS: Spin Labels

MESH TERMS: chemistry

Chemical & Substance for Abstract: Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones. Information

Substance Name: cumene hydroperoxide

Registry Number: 80-15-9

Grant and Affiliation Information for Mechanism of metal-independent decomposition of organic hydroperoxides and formation of alkoxyl radicals by halogenated quinones.

AFFILIATION: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, People's Republic of China. bzhu@rcees.ac.cn

Country: United States

AGENCY: United States NCRR

GRANT: RR 01008

ACRONYM: RR

MEDLINETA: Proc Natl Acad Sci U S A

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