The Deprotonation of Benzyl Alcohol Radical Cations: A Mechanistic Dichotomy in the Gas Phase as in Solution

Baciocchi, Enrico; Bietti, Massimo; Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta

doi:10.1002/1521-3765(20020118)8:2<532::aid-chem532>3.0.co;2-t

Cited by 13 publications

(3 citation statements)

References 32 publications

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“…This deprotonation mechanism is pH dependent favouring C-H bond cleavage at acidic conditions. [47][48][49][50][51] The calculations here are performed in vacuum and are therefore not directly affected by the solvent. However, the solvent effects need to be considered.…”

Section: ) Formation Of N-(2¢-deoxyguanosin-8-yl)-3-aminobenzanthrone...mentioning

confidence: 99%

Theoretical investigations on the formation of nitrobenzanthrone-DNA Adducts

2011

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3-Nitrobenzanthrone (3-NBA) is a potent mutagen and suspected human carcinogen identified in diesel exhaust. The thermochemical formation cascades were calculated for six 3-NBA-derived DNA adducts employing its arylnitrenium ion as precursor using density functional theory (DFT). Clear exothermic pathways were found for four adducts, i.e., 2-(2'-deoxyadenosin-N(6)-yl)-3-aminobenzanthrone, 2-(2'-deoxyguanosin-N(2)-yl)-3-aminobenzanthrone, N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone and 2-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone. All four have been observed to be formed in cell-free experimental systems. The formation of N-(2'-deoxyadenosin-8-yl)-3-aminobenzanthrone is predicted to be not thermochemically viable explaining its absence in either in vitro or in vivo model systems. However, 2-(2'-deoxyadenosin-8-yl)-3-aminobenzanthrone, can be formed, albeit not as a major product, and is a viable candidate for an unknown adenine adduct observed experimentally. 2-nitrobenzanthrone (2-NBA), an isomer of 3-NBA, was also included in the calculations; it has a higher abundance in ambient air than 3-NBA, but a much lower genotoxic potency. Similar thermochemical profiles were obtained for the calculated 2-NBA-derived DNA adducts. This leads to the conclusion that enzymatic activation as well as the stability of its arylnitrenium ion are important determinants of 2-NBA genotoxicity.

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Section: ) Formation Of N-(2¢-deoxyguanosin-8-yl)-3-aminobenzanthrone...mentioning

confidence: 99%

Theoretical investigations on the formation of nitrobenzanthrone-DNA Adducts

2011

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“…This was shown by a FT-ICR study of the gas-phase deprotonation of the radical cations derived from benzyl alcohol and some derivatives by a variety of bases of different strength. 33 It was observed that with the relatively weak base cyclopropylmethylketone, C 6 D 5 CD 2 OH Áþ undergoes predominantly deprotonation from the benzylic C-D bond, displaying carbon acidity, whereas with the stronger base 1,3-propanediamine deprotonation from the O-H group (oxygen acidity) is the major pathway. Moreover, experiments carried out on 4-MeOC 6 H 4 CD 2 OH Áþ showed that this radical cation exhibits exclusive or predominant carbon acidity depending on base strength, clearly indicating that by increasing radical cation stability oxygen acidity decreases more than carbon acidity, as observed in solution.…”

Section: Fragmentations Involving O-h Bond Cleavage (A) 1-arylalkanolmentioning

confidence: 99%

Fragmentation reactions of radical cations

Baciocchi¹,

Bietti

Lanzalunga³

2006

J of Physical Organic Chem

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This paper summarizes most of the recent work by our group on the kinetic aspects of a variety of fragmentation reactions of radical cations involving the cleavage of C-H, O-H, C-C, and C-S bonds. In particular, the problems that have been addressed concern: (a) the carbon acidity/oxygen acidity dichotomy in the fragmentation of aryl- and thioarylalkanol radical cations; (b) the decarboxylation of aryl and thioarylacetic acid radical cations; (c) the structural factors influencing the rate of C-S bond cleavage in the radical cations of phenyl alkyl sulfides. The results presented and discussed have allowed us to recognize the important role played by the electron reorganization energy, associated with the intramolecular electron transfer from the scissile bond to the SOMO, with respect to the dynamics and mechanism of the fragmentation process in the radical cation. Copyright (c) 2006 John Wiley & Sons, Ltd

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“…Lastly, Baciocchi and co-workers have used bracketing experiments to determine the acidities of ionized benzyl alcohols, 104 i.e. the proton affinities of the corresponding radicals.…”

Section: Bde(r-h)mentioning

confidence: 99%

12 Organic gas-phase ion chemistry

Munsch

Wenthold

2003

Annu. Rep. Prog. Chem., Sect. B

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Gas-phase ion chemistry is a useful approach for the investigation of physical organic chemistry and the study of reactivity, structure, and thermochemical properties of ionic and neutral organic substrates. This review summarizes the physical organic chemistry studies utilizing gas-phase ion chemistry reported in the past year. Among the more significant advances reported in the past year included a report of the reactivity of p-benzyne by Kenttämaa and co-workers, 1 a comparison of the S N 2 reaction in the gas-phase and in solution by Brauman and co-workers, 2 and a full characterization of the structure and energetics of cyanocarbene. 3,4 Information learned from these gas-phase ion studies includes: 1) p-benzyne undergoes radical reactions but also reacts as a weak electrophile; 2) unlike what is found in solution, steric bulk does not significantly affect the barriers for S N 2 reactions of halogenated nitriles; and 3) HCCN is a "floppy" molecule with a triplet ground state and a singlet excited state that is ca. 50 kJ mol Ϫ1 higher in energy.Papers included in this review were selected by considering contributions to the standard organic, physical, and mass spectrometry journals. The selected articles are those that address the issue of reactivity and structure of organic molecules. Our emphasis in this work is on the chemistry that is observed, and information regarding the instrumental technique is only provided in situations where it is critical for understanding the results. The majority of the studies were carried out by using Fourier transform-ion cyclotron resonance (FT-ICR), quadrupole ion trap, or flowing afterglow techniques. We have generally not included papers regarding ionization fragmentation patterns, unless the work was part of broader studies. Studies of organometallic ions were generally not included if the chemistry was dominated by the metal center. Moreover, computational studies were also not included unless they provided significant insight into specific experimental results.It was with some trepidation that we restrict the number of biological studies included in this paper. Recent advances in mass spectrometric capabilities have led to numerous fundamental studies of the properties of biologically relevant molecules. In this work, we generally have only included the studies of the simplest biological molecules, amino acids, nucleic acids, and monosaccharides. It is clear that many more future mass spectrometric studies will likely involve biological substrates. As such, it is anticipated that future versions of this report may need to be expanded to include more biologically relevant material.The articles summarized in this review are organized into broad classifications: 420

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The Deprotonation of Benzyl Alcohol Radical Cations: A Mechanistic Dichotomy in the Gas Phase as in Solution

Cited by 13 publications

References 32 publications

Theoretical investigations on the formation of nitrobenzanthrone-DNA Adducts

Theoretical investigations on the formation of nitrobenzanthrone-DNA Adducts

Fragmentation reactions of radical cations

12 Organic gas-phase ion chemistry

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