Electron spin resonance study of benzoyl .sigma. radicals in solution

Krusic, Paul J.; Rettig, T. A.

doi:10.1021/ja00706a061

Cited by 71 publications

(24 citation statements)

References 2 publications

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“…82 Therefore, we used a low concentra- tion of benzaldehyde in ethyl acetate to minimize such side reactions. Photolysis of 3a and 4a in ethyl acetate generate the benzoyl radical 4b, and the resulting SS-ESR spectrum is shown in Figure 4a.…”

Section: Steady-state Esr Experimentsmentioning

confidence: 99%

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

2001

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Addition of two radicals (diphenyl phosphinoyl and 2-hydroxy-2-propyl) to the bifunctional alkene, vinyl acrylate, was studied by both time-resolved (TR) and steady-state (SS) ESR and laser flash photolysis (LFP). The adduct radicals are predominately a result of tail addition (addition to the unsubstituted carbon atom) of the acrylate double bond. Chemical structures of the adducts were established by comparison of the observed ESR spectra with those of adducts of the same reactive radicals to structurally related alkenes, tert-butyl acrylate and vinyl pivalate, which have only one type of double bond. Adducts of bulky phosphinoyl radicals to the acrylates demonstrate hindered rotation and a cis-trans isomerization at room temperature. The structure of the adduct radicals and the reactivity of the two radicals are discussed. Absolute rate constants for the addition of the phosphinoyl radical to the alkenes were measured by LFP in ethyl acetate at 296 K. A rate constant of k add ) (33 ( 1) × 10 6 M -1 s -1 was found for vinyl acrylate. The latter value is ∼1.5 times higher than that for tert-butyl acrylate (k add ) (22 ( 1) × 10 6 M -1 s -1 ) and ∼17 times higher than that for vinyl pivalate (k add ) (2.0 ( 0.1) × 10 6 M -1 s -1 ). These rate constants are consistent with conclusions derived from the ESR data. The results provide some insights into free radical polymerization of vinyl acrylate and vinyl ethers.

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Section: Steady-state Esr Experimentsmentioning

confidence: 99%

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

2001

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“…The benzoyl radical 1 is highly reactive, and to characterize this radical spectroscopically either low temperature spectroscopy or time resolved spectroscopy (laser flash photolysis LFP) is necessary. Radical 1 was generated in the solid state at 77 K and characterized by EPR spectroscopy 11,12. The EPR spectrum could also be obtained by time resolved EPR spectroscopy in solution 5.…”

Section: Introductionmentioning

confidence: 99%

Matrix Isolation and IR Characterization of the Benzoyl and Benzoylperoxy Radicals

Mardyukov

Sander

2010

Eur J Org Chem

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“…Formyl hydrogen atoms are sensitive to abstraction, yielding acyl radicals 19), which may undergo further reactions, for instance decarbonylation to an alkyl radical. This reaction sequence seemed also to be appropriate to produce 7-norbornadienyl radical 15 from norbornadiene-7-carbaldehyde (18).…”

Section: 17mentioning

confidence: 99%

ChemInform Abstract: SIGMATROPIC AND ELECTROCYCLIC REACTIONS OF BICYCLO(3.2.0)HEPTADIENYL RADICALS, 3‐QUADRICYCLANYL RADICALS, AND 7‐NORBORNADIENYL RADICAL

Sustmann¹,

Brandes²,

Lange³

et al. 1985

Chemischer Informationsdienst

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The rearrangement of matrix-isolated organic radicals with bicyclo[3.2.0]heptadienyl structure (2, 5, lla,b), 3-quadricyclanyl structure (16,26,27), and of 7-norbornadienyl radical 15 is studied. Final rearrangement products are radicals with tropylium structure. 16, 26, and 27 isomerize to radicals with bicyclo[3.2.0]heptadienyl skeleton before electrocyclic ring opening to tropylium radicals takes place. 7-Norbornadienyl radical 15 is the least stable radical on the C,-hypersurface. Free radical rearrangements of bicyclic model systems under conditions of long life time have been the subject of several electron spin resonance investigations and a part of the work presented here has been published in preliminary form'-3). The purpose of studying rearrangements of matrix isolated free radicals is to demonstrate that sofar unknown radical reactions can take place with activation energies similar to reactions of comparable ionic species. Eventually this may lead to the application of such reactions in the synthesis of complex organic molecules.In solution bicyclo[3.2.0]hepta-2,6-diene (1) is converted by hydrogen abstraction of an allylic hydrogen atom with photolytically generated tert-butoxy radicals to bicyclo[3.2.0]heptadienyl radical (2). Its ESR spectrum can be interpreted in terms of four different coupling constants. Due to the molecular symmetry hy-0 VCH Verlagsgesellschaft mbH, D

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Electron spin resonance study of benzoyl .sigma. radicals in solution

Cited by 71 publications

References 2 publications

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

Electron Spin Resonance and Laser Flash Photolysis Study of Radical Addition to Vinyl Acrylate and Related Alkenes

Matrix Isolation and IR Characterization of the Benzoyl and Benzoylperoxy Radicals

ChemInform Abstract: SIGMATROPIC AND ELECTROCYCLIC REACTIONS OF BICYCLO(3.2.0)HEPTADIENYL RADICALS, 3‐QUADRICYCLANYL RADICALS, AND 7‐NORBORNADIENYL RADICAL

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