Thermolysis of α-hydroperoxyalkyl diazenes. Spin trapping of radical intermediates and spin trapping kinetics

Mathew, Lukose; Osei-Twum, Emmanuel Y.; Warkentin, John

doi:10.1139/v91-206

Cited by 8 publications

(3 citation statements)

References 18 publications

(24 reference statements)

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“…while k R is given [76] by eqn (78) log (k R / s -1 ) = 10·7 -32·6/2·3 RT (78) where R is in kJ mol -1 . This gives k R(298 K) = 1 ϫ 10 5 s -1 .…”

Section: ·1·1·2 Competition Methodsmentioning

confidence: 99%

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Kinetic Aspects of Spin Trapping

Kemp

1999

prog. rct. kin. mech.

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288 1. 3·2·4 Rate constants of dimerization 330 3·2·5 Induced decomposition of spin adducts 334 3·3 Rates of isomerization reactions from spin trapping 336 3·4 Rates of radical abstraction reactions 341 3·5 Rates of radical addition reactions 345 3·6 Rates of polymerisation processes 345 3·7 Rates of reactions of excited states 349 3·7·1 Rates of abstraction reactions by excited states 349 3·7·2 Interactions of excited states with spin adducts 350 3·8 Reaction rates of transient radicals with stable aminoxyls 350 3·9 Radical traps as mediators in electron-transfer reactions 352 4. ACKNOWLEDGEMENTS 353 REFERENCES 353ABSTRACT Kinetics are described of the spin-trapping process itself, based on indirect methods such as radical clocks and other competition methods, and also direct methods based on flash photolysis and pulse radiolysis. The stability of spin traps and their dimerization are discussed, as is the stability of spin adducts, once formed. Caution is given over the utilisation of spin traps in photo -and redox systems where the spin trap can undergo excitation and/or dissociation to lead to radicals which undergo trapping processes to give potentially misleading spectral data. The use of well-authenticated spin trapping kinetic data to examine rates of ringopening and -closing and isomerization reactions is covered. The role of spin trapping as a probe of biochemical processes is also included, with particular reference to the trapping of hydroxyl and superoxide radicals. GLOSSARYBPG alkyl tert-butyl peroxyglyoxalates DMPO 5,5-dimethyl-1-pyrroline-N-oxide DMSO dimethyl sulfoxide epr electron paramagnetic resonance HFCC hyperfine coupling constant MBN methylene-N-tert-butylnitrone MNP 2-methyl-2-nitrosopropane NB nitrosobenzene ND nitrosodurene NM nitromethane PBN phenyl tert-butyl nitrone PMNB pentamethylnitrosobenzene SOD superoxide dismutase TBNtri-tert-butylnitrosobenzene TEMPO 2,2,6,6-tetramethylpiperidine N-oxyl 1.

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“…while k R is given [76] by eqn (78) log (k R / s -1 ) = 10·7 -32·6/2·3 RT (78) where R is in kJ mol -1 . This gives k R(298 K) = 1 ϫ 10 5 s -1 .…”

Section: ·1·1·2 Competition Methodsmentioning

confidence: 99%

“…The ring opening of cyclopropylmethyl radicals to 3-butenyl radicals was used [78] to estimate the rate constant of trapping by the pyrazole (XX).…”

Section: ·1·1·2 Competition Methodsmentioning

confidence: 99%

Kinetic Aspects of Spin Trapping

Kemp

1999

prog. rct. kin. mech.

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“…The spin-trapping technique (1)(2)(3)(4) involves an addition reaction of such a radical to an efficient scavenger (spin trap) to afford a long-lived radical (spin adduct). Nitroso compounds, R NO, are important spin traps because they are readly available and because they react rapidly and irreversibly with many radicals, accordingly to equation 1:…”

Section: Introductionmentioning

confidence: 99%