Free-radical reductions of arenediazonium ions in aqueous solution. Part III. Kinetics of reactions of toluene-p-diazonium ions with ethanol, propan-2-ol, and acetaldehyde

Packer, John E.; Richardson, Russell K.

doi:10.1039/p29750000751

Cited by 20 publications

(5 citation statements)

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“…Regardless, the KIEs observed at both sites clearly imply that direct strand breaks involve abstraction of the C2‘ hydrogen from the dA bound to the 5‘-phosphate of BrdU. Furthermore, the magnitudes of the observed KIEs are similar to those measured for σ radicals reacting with organic substrates, strongly supporting proposals that direct strand scission results from abstraction of the C2‘ hydrogen by 1 . 1a, …”

Section: Resultssupporting

confidence: 61%

A Novel Mechanism for the Formation of Direct Strand Breaks upon Anaerobic Photolysis of Duplex DNA Containing 5-Bromodeoxyuridine

and

Greenberg

1996

J. Am. Chem. Soc.

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The mechanism of UV-induced cleavage of duplex DNA containing 5-bromodeoxyuridine under anaerobic conditions was investigated via product analysis and kinetic isotope effect measurements using gel electrophoresis. KIEs strongly suggest that strand breaks result from abstraction of the C2‘ hydrogen atom from the 5‘-adjacent nucleotide by deoxyuridin-5-yl (1). It is proposed that under anaerobic conditions the C2‘ radical is subsequently oxidized by the cation radical of adenine. The resulting carbocation undergoes 1,2-hydride migrations from C1‘ and C3‘ competitively, giving rise to cleavage products containing 3‘-phosphate and the novel, labile 3‘-ketone (4). The identity of the latter product is supported by electrospray mass spectrometric analysis of the crude photolysate. The results also suggest that the formation of alkaline labile lesions proceed via hydrogen atom abstraction from the C2‘ position by 1.

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Section: Resultssupporting

confidence: 61%

A Novel Mechanism for the Formation of Direct Strand Breaks upon Anaerobic Photolysis of Duplex DNA Containing 5-Bromodeoxyuridine

and

Greenberg

1996

J. Am. Chem. Soc.

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“…No differences were observed in the spectra recorded after the first, second, or even tenth pulse. However, it should be mentioned that chain processes involving alcohols and diazonium salts are well-known, 33,34 and indeed their presence was also observable herein for X ) F at large salt concentrations. We did not pursue this point further.…”

Section: Resultsmentioning

confidence: 54%

Reduction of Substituted Benzenediazonium Salts by Solvated Electrons in Aqueous Neutral Solution Studied by Pulse Radiolysis

Daasbjerg

Sehested

2002

J. Phys. Chem. A

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A pulse radiolysis study of six parasubstituted benzenediazonium salts, X−C6H4N2 + [X = COOC2H5, F, H, CH3, OCH3, and N(CH3)2], has been carried out in neutral aqueous solutions, where the principal reductant is the solvated electron. In the first step, the solvated electron reduces the diazonium salts to the corresponding diazenyl radicals, X−C6H4N2 • , in a diffusion-controlled process. On a short time scale, X−C6H4N2 • is either involved in an equilibrium reaction with the parent diazonium salt (K > 100 M-1) in which a (X−C6H4)2N4 • + adduct is formed or decays to the aryl radical, X−C6H4 • , through the expulsion of dinitrogen. Simulation of this kinetic scheme allows us to make a rough determination of the rate constants involved. The rate constants for the formation of the adducts are in the range (0.7−1.9) × 107 M-1 s-1, whereas the fragmentation rate constants are in the range (0.4−4.0) × 105 s-1. The aryl radicals subsequently attack the diazonium salts mainly at the terminal nitrogen atom with rate constants of (0.13−5.9) × 107 M-1 s-1, thereby forming the radical cations of the corresponding azobenzenes, (X−C6H4)2N2 • +, or eventually the corresponding OH adducts, (X−C6H4)2N2OH • , upon further reaction with water. These intermediates were identified in pulse radiolysis by generating the very same species through an alternative pathway involving oxidation of the parent azobenzenes. The reaction between the aryl radical and the salt exhibits a clear substituent effect in the sense that the reactivity increases as the electron-donating power of the substituent is enhanced. This is attributed to the stabilizing effect exerted by electron-donating groups on radical cations. Thus, the radical cations can be detected only for the methoxy and dimethylamino groups, whereas for the other substituents the transformation of (X−C6H4)2N2 • + to (X−C6H4)2N2OH • takes place instantaneously.

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“…At a potential lower than -1.4 V, the reduction of Arl begins to contribute as well. Under photosimulation, di-tert-butyl nitroxide donates electrons to a diphenyliodonium ion201 (eq 76).…”

Section: Arlmentioning

confidence: 99%

Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

Galli¹

1988

Chem. Rev.

731

490

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Contents I. Introduction 765 II. Evolution of the Mechanistic View of the 766 Diazonium Group Replacement III. Homolytic Dediazoniation Reactions: A 769 General Description A. How the Homolytic Dediazoniation Takes 769 Place 1. Reduction at the Electrode 769 2. Radiolytic Approach 770 3. Photoinduced Electron Transfer 770 4. Reduction by Metal Cations 771 5. Anion-Induced Dediazoniation 772 6. Solvent-Induced Dediazoniation 775 7. Summary 776 B. Product Patterns of the Aryl Radical 777 1. Hydrogen Atom Abstraction 777 (Hydro-dediazoniation) 2. Reaction with X' (Halo-dediazoniation) 777 3. Other Sandmeyer-like Reactions 779 4. Addition to Olefins 779 5. Arylation of Aromatic Compounds 781 6. Conclusions 782 IV. Related Reactions 782 A. Intermediacy of the Aryl Radical 782 1. Reactions of Diaryliodonium Ions 783 2. SRN1 Reactions 784 B. Interchange of Product Patterns 786 V. Unrelated Reactions 788 VI. Acknowledgment 789 VII. References 789

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Free-radical reductions of arenediazonium ions in aqueous solution. Part III. Kinetics of reactions of toluene-p-diazonium ions with ethanol, propan-2-ol, and acetaldehyde

Cited by 20 publications

References 0 publications

A Novel Mechanism for the Formation of Direct Strand Breaks upon Anaerobic Photolysis of Duplex DNA Containing 5-Bromodeoxyuridine

A Novel Mechanism for the Formation of Direct Strand Breaks upon Anaerobic Photolysis of Duplex DNA Containing 5-Bromodeoxyuridine

Reduction of Substituted Benzenediazonium Salts by Solvated Electrons in Aqueous Neutral Solution Studied by Pulse Radiolysis

Radical reactions of arenediazonium ions: An easy entry into the chemistry of the aryl radical

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