Frontier Orbital Control for the Hydroxyl Radical Attack on Aromatics

Tezuka, Takahiro; Ichikawa, Kazuhiko; Marusawa, Hiroshi; Narita, Nozomu

doi:10.1246/cl.1983.1013

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…The OH radical has long been known to be a moderate electrophile, and studies of reactions similar to this involving addition of hydroxyl radicals onto substituted aromatic benzene rings have shown clear electrophilic tendencies in the radical 30. 31 It has been shown that the electron density of the HOMO orbital correlates with the site of hydroxyl radical attack on an aromatic ring 32. Therefore, we have also considered the HOMO and LUMO orbitals, as the present radical reactions with the aromatic rings of the nucleobases are expected to behave in a similar fashion.…”

Section: Resultsmentioning

confidence: 99%

“…[30,31] It has been shown that the electron density of the HOMO orbital correlates with the site of hydroxyl radicala ttack on an aromatic ring. [32] Therefore, we have also considered the HOMO and LUMO orbitals, as the present radicalr eactions with the aromatic rings of the nucleobases are expectedt o behavei nasimilarf ashion. We believe that the HOMO orbital of the molecules influence the ease with which an RC is created through interactions of the electrophilicO Hr adical with the most electron-rich part of the HOMO orbitali nt he creation of RCs for both abstractionsa nd additions.…”

Section: Energetics Of the Purine Nucleobasesmentioning

confidence: 99%

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Insight into the Mechanism of the Initial Reaction of an OH Radical with DNA/RNA Nucleobases: A Computational Investigation of Radiation Damage

Milhøj

Sauer

2015

Chemistry A European J

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Earlier theoretical investigations of the mechanism of radiation damage to DNA/RNA nucleobases have claimed OH radical addition as the dominating pathway based solely on energetics. In this study we supplement calculations of energies with the kinetics of all possible reactions with the OH radical through hydrogen abstraction and OH radical addition onto carbon sites, using DFT at the ωB97X-D/6-311++G(2df,2pd) level with the Eckart tunneling correction. The overall rate constants for the reaction with adenine, guanine, thymine, and uracil are found to be 2.17×10(-12) , 5.64×10(-11) , 2.01×10(-11) , and 5.03×10(-12) cm(3) molecules(-1) s(-1) , respectively, which agree exceptionally well with experimental values. We conclude that abstraction of the amine group hydrogen atoms competes with addition onto C8 as the most important reaction pathway for the purine nucleobases, while for the pyrimidine nucleobases addition onto C5 and C6 competes with the abstraction of H1 . Thymine shows favourability against abstraction of methyl hydrogens as the dominating pathway based on rate constants. These mechanistic conclusions are partly explained by an analysis of the electrostatic potential together with HOMO and LUMO orbitals of the nucleobases.

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Section: Resultsmentioning

confidence: 99%

Section: Energetics Of the Purine Nucleobasesmentioning

confidence: 99%

Insight into the Mechanism of the Initial Reaction of an OH Radical with DNA/RNA Nucleobases: A Computational Investigation of Radiation Damage

Milhøj

Sauer

2015

Chemistry A European J

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On the mechanism of catalytic hydroxylation of aromatic hydrocarbons by hydrogen peroxide

Караханов

Narin

Дедов

1991

Applied Organom Chemis

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Oxygen‐atom transfer chemistry of α‐AZO hydroperoxides: Effect of competitive intramolecular hydrogen bonding and α‐methyl substitution

Baumstark

Vásquez

1988

J of Physical Organic Chem

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1‐(Phenylazo)‐1‐(2‐pyridyl)ethyl hydroperoxide, 1, 1‐(phenylazo)‐1‐(2‐furyl)ethyl hydroperoxide, 2, phenylazo(2‐furyl)methyl hydroperoxide, 3, 1‐(phenylazo)‐1‐(4‐anisyl)ethyl hydroperoxide, 4, were synthesized in moderate yield by autoxidation of the phenylhydrazones in benzene. The ionic oxidation of benzyl methyl sulfide in benzene by 1‐4 yielded the sulfoxide and the metastable α‐azo hydroxides in essentially quantitative yield. The reaction was of the first order in α‐azo hydroperoxide and sulfide, respectively. The relative reactivity series found was: 1(1.0) <4(1.4) < phenylazo(4‐anisyl)methyl hydroperoxide 5 (2·9) <2 (3·8) < 3 (9·6). α‐Methyl substitution was found to slow the rate of oxygen‐atom trasfer by a factor of 2 to 2.5. The low relative reactivity of 1 was opposite that expected based on electronic effects. Competitive intramolecular hydrogen bonding of the hydroperoxy proton to the pyridyl nitrogen in 1 accounted for the observed result.

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Frontier Orbital Control for the Hydroxyl Radical Attack on Aromatics

Abstract: The ortho:meta:para isomer ratio and p/m value observed in the aromatic hydroxylation with hydroxyl radical in anhydrous organic media are correlated with the electron density of HOMO of aromatics.

Cited by 8 publications

References 9 publications

Insight into the Mechanism of the Initial Reaction of an OH Radical with DNA/RNA Nucleobases: A Computational Investigation of Radiation Damage

Insight into the Mechanism of the Initial Reaction of an OH Radical with DNA/RNA Nucleobases: A Computational Investigation of Radiation Damage

On the mechanism of catalytic hydroxylation of aromatic hydrocarbons by hydrogen peroxide

Oxygen‐atom transfer chemistry of α‐AZO hydroperoxides: Effect of competitive intramolecular hydrogen bonding and α‐methyl substitution

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