Isonitroso Hydrogen (Hydroxy Nitrene, HON)

Maier, Günther; Reisenauer, Hans Peter; Marco, Michael De

doi:10.1002/(sici)1521-3773(19990115)38:1/2<108::aid-anie108>3.0.co;2-u

Cited by 48 publications

(51 citation statements)

References 3 publications

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“…Chromium(VI) oxidizing reagents have been widely used in organic chemistry. Industrial demands have led many workers to search for more ideal oxidants with a number of specifications including: lower cost, higher yields, better selectivity, milder neutral conditions, easier preparations, higher solubility and shorter reaction times [1][2][3]. In recent years, significant improvements were achieved by the use of new oxidizing agents such as: pyridinium dichromate (PDC) [4], pyridinium fluorochromate (PFC) [5], tripropylammonium fluorochromate (TriPAFC) [6], chromium trioxide-3,5-dimethylpyrazole complex (CrO 3 3,5-DMP), [7], tributylammonium chlorochromate (Tri-BACC) [8], 3,5-dimethylpyrazolium fluorochromate (DmpzHFC), [9], quinolinium fluorochromate (QFC) [10], 2,2¢-bipyridinium chlorochromate (BiPCC) [11].…”

Section: Introductionmentioning

confidence: 99%

Some aspects of tetramethylammonium fluorochromate (VI) oxidations and identification of the reduced chromium species

Ghammamy

Baghy

2007

Transition Met Chem

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The reduction product of tetramethylammonium fluorochromate, TMAFC, isolated after oxidation, has been identified from the results of chemical analyses, chemical determination of the oxidation state of chromium, magnetic susceptibility, cyclic voltametry, n.m.r. and i.r. spectral studies as (CH 3 ) 4 N[CrO 2 F], chromium(IV) species. The facile oxidation of triphenylphosphine to triphenylphosphine oxide by TMAFC in acetonitrile provides a clear-cut example of an oxygen transfer reaction.

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Section: Introductionmentioning

confidence: 99%

Some aspects of tetramethylammonium fluorochromate (VI) oxidations and identification of the reduced chromium species

Ghammamy

Baghy

2007

Transition Met Chem

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“…There is continued interest in the development of new chromium(VI) reagents for the effective and selective oxidation of organic substrates, in particular alcohols, under mild conditions. In recent years, significant improvements were achieved by the use of new oxidizing agents by Bhandari et al [1], Meenahshisundaram and Soctaungam [2], such as pyridinium chlorochromate, Corey and Boger [3], Maier et al [4], pyridinium dichromate, Corey and Schmidt [5], pyridinium fluorochromate, Bhattacharjee et al [6] and 2,2¢-bipyridinium chlorochromate, Luzzio and Bobb [7]. Tetramethylammonium fluorochromate (TMAFC) was synthesized in the belief that this reagent could be used for the oxidation of organic substrates.…”

Section: Introductionmentioning

confidence: 99%

X-ray Structural Analysis of Tetramethylammonium Fluorochromate(VI). A Link between Reactivity and the Extent of Symmetry

Ghammamy

Dastpeyman

Sadjadi

2006

Transition Met Chem

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The crystal and molecular structure of tetramethylammonium fluorochromate(VI), (CH 3 ) 4 N[CrO 3 F] has been determined at 130(2) K by X-ray diffraction. X-ray data clearly demonstrate inequality between the CrÀO and the CrÀF bonds that is responsible for the higher reactivity of this compound over similar oxidizing agents in terms of the amount of oxidant and solvent required, short reaction times and high yields. The reason for this inequality is due to the CHÁ Á ÁF hydrogen bond that forms between the methyl hydrogen of the cation and the fluoride atom of the anion. The IR spectrum and hydrogen bonding of this compound is similar to the tetramethylammonium perchlorate salt and shows the existence of hydrogen bonding.

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“…Spectroscopic and theoretical studies (27)(28)(29)(30)(31) and our own calculations place the energy of this triplet ground-state species at 20-23 kcal͞mol above the HNO singlet ground state. Therefore, HON is unlikely to be a participant in the physiological chemistry of HNO.…”

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On the acidity and reactivity of HNO in aqueous solution and biological systems

Bartberger

Fukuto

Houk

2001

Proc. Natl. Acad. Sci. U.S.A.

163

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The gas phase and aqueous thermochemistry and reactivity of nitroxyl (nitrosyl hydride, HNO) were elucidated with multiconfigurational self-consistent field and hybrid density functional theory calculations and continuum solvation methods. The pK a of HNO is predicted to be 7.2 ؎ 1.0, considerably different from the value of 4.7 reported from pulse radiolysis experiments. The ground-state triplet nature of NO ؊ affects the rates of acid-base chemistry of the HNO͞NO ؊ couple. HNO is highly reactive toward dimerization and addition of soft nucleophiles but is predicted to undergo negligible hydration (Keq ‫؍‬ 6.9 ؋ 10 ؊5 ). HNO is predicted to exist as a discrete species in solution and is a viable participant in the chemical biology of nitric oxide and derivatives.T he discoveries of nitric oxide (NO) biosynthesis in mammalian cells and the diverse biological activity associated with NO and NO-derived species (1) have brought intense interest in the physiological chemistry of nitrogen oxides. The chemistry of NO and its biologically accessible oxidized congeners nitrogen dioxide (NO 2 ), nitrite (NO 2 Ϫ ), peroxynitrite (ONOO Ϫ ), dinitrogen trioxide (N 2 O 3 ), and nitrate (NO 3 Ϫ ) is fairly well established (2). By contrast, the reduced congeners such as nitroxyl (HNO) and its conjugate base (NO Ϫ ) are less well understood, and consequently their role in biology is not clear. The importance of HNO or NO Ϫ in biology has often been neglected or dismissed, in part because NO metabolism is thought to be primarily oxidative in nature (3), and because HNO is thought to be only metastable (3), a strong acid (4), and to dimerize readily (5). NO Ϫ is known to react rapidly and irreversibly with NO (6), making the examination of NO Ϫ in the presence of NO difficult. Additionally, HNO might be expected to be electrophilic, and hydration under physiological conditions would serve to attenuate its aqueous reactivity.Nitroxyl (HNO), or its conjugate base, NO Ϫ , is known to be formed under physiological conditions; for example, oxidation of N-hydroxy-L-arginine (an intermediate in NO biosynthesis) (7), reaction of S-nitrosothiols with thiols (8, 9), nitric oxide synthase (10-12), and even direct reduction of NO by mitochondrial cytochrome c (13), may all generate HNO. Nitroxyl has been generated via the interaction of NO with manganese superoxide dismutase (14) and with ubiquinol (15). HNO has biological activity; it can act as a potent cytotoxic agent that causes double-stranded breaks in DNA, depletion of cellular glutathione (16), as well as elicitation of smooth muscle relaxation (17). HNO has been found to be a potent inhibitor of thiol-containing enzymes (18,19) and attenuates the activity of the NMDA receptor via thiol modification, thus providing neuroprotection (20).Much of the fundamental biological chemistry associated with HNO is unknown, aside from the rate constant for dimerization is a typical nucleophile, yet several studies find that HNO generated at physiological pH reacts readily as an electrophile, par...

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Isonitroso Hydrogen (Hydroxy Nitrene, HON)

Cited by 48 publications

References 3 publications

Some aspects of tetramethylammonium fluorochromate (VI) oxidations and identification of the reduced chromium species

Some aspects of tetramethylammonium fluorochromate (VI) oxidations and identification of the reduced chromium species

X-ray Structural Analysis of Tetramethylammonium Fluorochromate(VI). A Link between Reactivity and the Extent of Symmetry

On the acidity and reactivity of HNO in aqueous solution and biological systems

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