Direct Comparison of Solution and Gas-Phase Reactions of the Three Distonic Isomers of the Pyridine Radical Cation with Methanol

Widjaja, Fanny; Jin, Zhicheng; Nash, John J.; Kenttämaa, Hilkka I.

doi:10.1021/ja207899j

Cited by 16 publications

(20 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another reaction seen with t-butyl isocyanide is the addition of +26 Da corresponding to the abstraction of a cyano group by the radical cation. This abstraction is the second major product during reaction with the 2-mercaptopyridyl radical ion (10), and a less significant product in reaction with the 2-mercaptopyrimidyl radical cation (9). This reaction has been seen before when t-butyl isocyanide was used in IMR reactions of carbon-centered radicals [65,67,68].…”

Section: (9)mentioning

confidence: 70%

“…These products are depicted in Eq. (10). (10) The radical cations 7-10 favored the +75 Da addition over the +1 Da.…”

Section: Reactions With 1-propanethiolmentioning

confidence: 99%

“…However, exciting findings have been reported in many other areas of gas-phase free radical chemistry, including contributions of Bierbaum's group to understanding of interstellar processes [4][5][6][7], as well as works of Kenttämaa and co-workers on chemistry of various phenyl radicals [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The formation of resonance-stabilized sulfur-based radical cations and their gas-phase reactivity

Lesslie

Meyer

Osburn

et al. 2015

International Journal of Mass Spectrometry

View full text Add to dashboard Cite

Section: (9)mentioning

confidence: 70%

“…These products are depicted in Eq. (10). (10) The radical cations 7-10 favored the +75 Da addition over the +1 Da.…”

Section: Reactions With 1-propanethiolmentioning

confidence: 99%

See 1 more Smart Citation

The formation of resonance-stabilized sulfur-based radical cations and their gas-phase reactivity

Lesslie

Meyer

Osburn

et al. 2015

International Journal of Mass Spectrometry

View full text Add to dashboard Cite

“…Indeed, the atomic charges of 2-, 3-, and 4-pyridyl radical site (+0.015, −0.268, and −0.007, respectively) have been calculated at the BPW91/cc-pVDZ// BPW91/cc-pVDZ. 11 In this paper, it is revealed that 2-pyridyl radical with a partial positive charge behaves like an electrophilic radical, but 3-and 4-pyridyl radical behave like a nucleophilic radical. And, the relative energies of 2-, 3-, and 4-pyridyl radical (0, 26, and 21 kJ/mol, respectively) have been calculated by G3B3…”

mentioning

confidence: 94%

Photoreaction of 3-Allyloxy-2-pentamethyldisilanylpyridine

Kim¹,

Park

2014

Bulletin of the Korean Chemical Society

View full text Add to dashboard Cite

It is well established that the photoreactions of phenyldisilanes proceed through four pathways 1 : 1) formation of a silaethene, 2 Si=C, 2) formation of a silatriene via 1,3-trimethylsilyl radical migration, 3 3) elimination of a silylene, 4 and 4) nucleophilic cleavage of a Si-Si bond in the photoexcited state 5,6 since the first report on the photolysis of phenylpentamethyldisilane and (p-tolyl)pentamethyldisilane by Ishikawa et al. 7 in 1975. However, relatively little is known about the photoreactions of ortho-substituted phenylpentamethyldisilanes.Recently, we have found that the photoreactions of various ortho-substituted phenylpentamethyldisilanes 8 afforded the novel intramolecular photoproducts via silatriene intermediates.As part of our ongoing investigations for the organic synthesis of silicon-having heterocyclic compounds, 9 we were, now, interested in the pyridine ring instead of the phenyl ring as an aromatic ring. And, we would like to report detailed photochemical investigations of 3-allyloxy-2-pentamethyldisilanylpyridine 2, aza analogue of (2-allyloxyphenyl)-pentamethyldisilane, 10 since novel photoproducts from the photoreaction of 2 via new intermediates are expected. The starting 3-allyloxy-2-pentamethyldisilanylpyridine 2 was prepared by the reaction of pentamethyldisilanyl chloride with 3-allyloxy-2-pyridyl magnesium bromide in tetrahydrofuran as shown in Scheme 1. In this reaction, a compound 3 formed from the allyl group cleavage of 2 was also obtained.Irradiation of 2 in deaerated benzene with 300nm UV light afforded a novel photoproduct 4 (9%yield) in addition to 5 (15%yield) along with several decomposition products of unknown structure as shown in Scheme 1, when 92% of 2 was photolyzed. Indeed, the atomic charges of 2-, 3-, and 4-pyridyl radical site (+0.015, −0.268, and −0.007, respectively) have been calculated at the BPW91/cc-pVDZ// BPW91/cc-pVDZ. 11 In this paper, it is revealed that 2-pyridyl radical with a partial positive charge behaves like an electrophilic radical, but 3-and 4-pyridyl radical behave like a nucleophilic radical. And, the relative energies of 2-, 3-, and 4-pyridyl radical (0, 26, and 21 kJ/mol, respectively) have been calculated by G3B3 12. Therefore, it is revealed that 2-pyridyl radical is more stable than the 4-isomer, which is in turn more stable than 3-isomer in this paper. These above results suggested that the photoproduct 4 is formed from the reaction of electrophilic silylene and 2 mol of nucleophilic, unstable 3-pyridyl radical 9, formed via 1,4-radical shift from the electrophilic, stable 2-pyridyl radical 8 (Scheme 2). In this case, it is thought that the reaction of nucleophilic 4-pyridyl radical and electrophilic silylene was not occurred because of the steric hindrance of the allyoxy group. The formation of 5 is explained by the allyl group cleavage from the radical intermediates, 8 or 9 as shown in Scheme 2.The structure of the photoproduct 4 was determined by various physical methods. The 1 H NMR spectrum of the photoproduct 4 shows the ch...

show abstract

“…Recent studies have shown that charged radicals behave similarly in the gas phase and in solution [10].…”

Section: Introductionmentioning

confidence: 99%

Gas-phase Reactivity of meta-Benzyne Analogs Toward Small Oligonucleotides of Differing Lengths

Widjaja

Max

Jin

et al. 2017

J. Am. Soc. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

Abstract. The gas-phase reactivity of two aromatic carbon-centered σ,σ-biradicals (meta-benzyne analogs) and a related monoradical towards small oligonucleotides of differing lengths was investigated in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer coupled with laser-induced acoustic desorption (LIAD). The mono-and biradicals were positively charged to allow for manipulation in the mass spectrometer. The oligonucleotides were evaporated into the gas phase as intact neutral molecules by using LIAD. One of the biradicals was found to be unreactive. The reactive biradical reacts with dinucleoside phosphates and trinucleoside diphosphates mainly by addition to a nucleobase moiety followed by cleavage of the glycosidic bond, leading to a nucleobase radical (e.g., base-H) abstraction. In some instances, after the initial cleavage, the unquenched radical site of the biradical abstracts a hydrogen atom from the neutral fragment, which results in a net nucleobase abstraction. In sharp contrast, the related monoradical mainly undergoes facile hydrogen atom abstraction from the sugar moiety. As the size of the oligonucleotides increases, the rate of hydrogen atom abstraction from the sugar moiety by the monoradical was found to increase due to the presence of more hydrogen atom donor sites, and it is the only reaction observed for tetranucleoside triphosphates. Hence, the monoradical only attacks sugar moieties in these substrates. The biradical also shows significant attack at the sugar moiety for tetranucleoside triphosphates. This drastic change in reactivity indicates that the size of the oligonucleotides plays a key role in the outcome of these reactions. This finding is attributed to more compact conformations in the gas phase for the tetranucleoside triphosphates than for the smaller oligonucleotides, which result from stronger stabilizing interactions between the nucleobases.

show abstract

Direct Comparison of Solution and Gas-Phase Reactions of the Three Distonic Isomers of the Pyridine Radical Cation with Methanol

Cited by 16 publications

References 47 publications

The formation of resonance-stabilized sulfur-based radical cations and their gas-phase reactivity

The formation of resonance-stabilized sulfur-based radical cations and their gas-phase reactivity

Photoreaction of 3-Allyloxy-2-pentamethyldisilanylpyridine

Gas-phase Reactivity of meta-Benzyne Analogs Toward Small Oligonucleotides of Differing Lengths

Contact Info

Product

Resources

About