ChemInform Abstract: One‐Electron Reduction of N‐Bromosuccinimide. Rapid Expulsion of a Bromine Atom.

Lind, Johan; Shen, X.; Eriksen, Trygve E.; Merényi, Gábor; Eberson, Lennart

doi:10.1002/chin.199136110

Cited by 1 publication

(10 citation statements)

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“…In contrast to NCS •-, which has a moderate lifetime at room temperature, 55 NBS •has only been detected at 77 K by EPR spectroscopy. 30 This observation is consistent with the current results where no intermediates (other than Br 2…”

Section: Species Generated By Reduction Of N-halogenatedsupporting

confidence: 93%

“…with NBS (k 2 , 5 Â 10 8 M -1 s -1 ), with the assumption that the rate-determining step in this reaction was the reduction of NBS at Brconcentrations >1 mM. 30 With the current data, this approach yields an approximate second-order rate constant of 2 Â 10 8 M -1 s -1 for the reaction of NBS with O 2…”

Section: •-mentioning

confidence: 84%

“…In contrast to these N-chlorinated species, few data are available for N-brominated compounds with eaq , with the only reported rate constant that we are aware of being for Nbromosuccinimide with k 2 = 2.9 Â 10 10 M -1 s -1 . 30 This rate constant is 1.8 times faster than the corresponding reaction for NCS. Thus, the approximate rate constants (>10 10 M -1 s -1 ) determined here for N-bromoglutarimide, (Gly) 2 Br, and CANBr compare favorably with those expected on the basis of the corresponding N-chloro data.…”

mentioning

confidence: 82%

“…In the light of the above observations, approximate rate constants for the one-electron reduction of the N-brominated species by eaq were determined; corresponding data for N-chlorinated species have been published. 30,37,[55][56][57][58] 3.3.1. N-Bromoglutarimide.…”

Section: Rate Constants For the Reduction Of N-halogenatedmentioning

confidence: 99%

“…•-. [26][27][28] In the case of chloramines and most N-brominated species, nitrogen-and carbon-centered radicals and halide ions are generated, 12,16,25,29 but for some Nbrominated species (e.g., N-bromosuccinimide 30,31 ) heterolytic cleavage of the N-Br bond may result in the formation of imidyl anions and bromine atoms (Br • ).…”

Section: Introductionmentioning

confidence: 99%

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One-Electron Reduction of N-Chlorinated and N-Brominated Species Is a Source of Radicals and Bromine Atom Formation

Pattison

O'Reilly

Skaff

et al. 2011

Chem. Res. Toxicol.

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Hypochlorous (HOCl) and hypobromous (HOBr) acids are strong bactericidal oxidants that are generated by the human immune system but are implicated in the development of many human inflammatory diseases (e.g., atherosclerosis, asthma). These oxidants react readily with sulfur- and nitrogen-containing nucleophiles, with the latter generating N-halogenated species (e.g., chloramines/bromamines (RR'NX; X = Cl, Br)) as initial products. Redox-active metal ions and superoxide radicals (O(2)(•-)) can reduce N-halogenated species to nitrogen- and carbon-centered radicals. N-Halogenated species and O(2)(•-) are generated simultaneously at sites of inflammation, but the significance of their interactions remains unclear. In the present study, rate constants for the reduction of N-halogenated amines, amides, and imides to model potential biological substrates have been determined. Hydrated electrons reduce these species with k(2) > 10(9) M(-1) s(-1), whereas O(2)(•-) reduced only N-halogenated imides with complex kinetics indicative of chain reactions. For N-bromoimides, heterolytic cleavage of the N-Br bond yielded bromine atoms (Br(•)), whereas for other substrates, N-centered radicals and Cl(-)/Br(-) were produced. High-level quantum chemical procedures have been used to calculate gas-phase electron affinities and aqueous solution reduction potentials. The effects of substituents on the electron affinities of aminyl, amidyl, and imidyl radicals are rationalized on the basis of differential effects on the stabilities of the radicals and anions. The calculated reduction potentials are consistent with the experimental observations, with Br(•) production predicted for N-bromosuccinimide, while halide ion formation is predicted in all other cases. These data suggest that interaction of N-halogenated species with O(2)(•-) may produce deleterious N-centered radicals and Br(•).

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Section: Species Generated By Reduction Of N-halogenatedsupporting

confidence: 93%

Section: •-mentioning

confidence: 84%

mentioning

confidence: 82%