The Structure of Fulminic Acid, HCNO

Beck, Wolfgang; Feldl, Klaus

doi:10.1002/anie.196607221

Cited by 47 publications

(11 citation statements)

References 4 publications

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“…[8b] The C=N further Beckmann-type reactions with ketone substrates. Our DFT-computed mechanism is consistent the recently determined activation (enthalpy) barrier of 23.3 � 1.5 kcal/mol in aqueous HCl solution [8b] but involving energetically more favorable cationic instead of neutral intermediates proposed previously [7][8] [9] Further electrophilic activation with Tf 2 O at the O-site (via TS6) followed by nucleophilic HCOOH addition at the C-site (via TS7) is À 12.5 kcal/mol exergonic over a sizeable barrier of 24.5 kcal/ mol to form HCOOCH=NHOTf + . For comparison, the competing protic activation of HCNO with HOTf at the O-site followed by a nucleophilic TfO À addition at the C-site (via TS8) ethanol solution.…”

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confidence: 90%

Mechanistic Insights for Nitromethane Activation into Reactive Nitrogenating Reagents

Zhu

Grimme

2021

ChemCatChem

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Recently, it was found that nitromethane (CH 3 NO 2 ) can be activated into a useful nitrogenating reagent for the synthesis of amide and nitrile compounds. In this work, the mechanisms of CH 3 NO 2 activation are explored in detail by extensive DFT calculations. In aqueous triflic acid (HOTf) solution, the formal 1,3-H-shift of CH 3 NO 2 into transient CH 2 =NO 2 H is identified as the rate-limiting step over a barrier of 29.6 kcal/mol, followed by multistep acid hydrolysis to cleave the C=N bond to form NH 3 OH + (and HCOOH) as final product. In contrast, in nonaqueous acetic acid (AcOH) solution with electrophilic Tf 2 O and nucleophilic HCOOH additives, the C=N bond is cleaved by sequential steps of H 2 O elimination, electrophilic Tf 2 O activation, nucleophilic HCOOH addition and acetate/TfO À exchange, affording AcONH 3 + as more reactive nitrogenating reagent for Beckmann-type reactions.

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confidence: 90%

Mechanistic Insights for Nitromethane Activation into Reactive Nitrogenating Reagents

Zhu

Grimme

2021

ChemCatChem

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“…40 The large difference between the C-H bond lengths observed experimentally in HCN (1.063 Á41) and HCNO (1.027 Á38) is also not reproduced by the calculations. The very short C-H internuclear distance in HCNO has recently been interpreted as the projection of a C-H bond length of 1.061 Á upon the heavy-atom Formonitrile Oxide (3). This molecule is computed to be 80 kcal mol-1 (6-31G*/4-31G) less stable than the most stable isomer isocyanic acid (1).…”

Section: Discussionmentioning

confidence: 99%

“…The Formonitrile Oxide-Isocyanic Acid Rearrangement. The interconversion of formonitrile oxide (3) and isocyanic acid (1) may, in principle, take the five different routes shown in Figure 3. In pathway A, the oxygen atom moves first, followed by the migration of the hydrogen atom.…”

Section: Discussionmentioning

confidence: 99%

A theoretical study of the CHNO isomers

Poppinger¹,

Radom²,

Pople³

1977

J. Am. Chem. Soc.

136

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A detailed exploration of the singlet potential surface for the system CHNO has been carried out with the aid of ab initio molecular orbital theory with minimal, split-valence, and split-valence + polarization basis sets. Direct search procedures are used to locate minima and transition states within the surface. The most stable isomer of CHNO is predicted to be isocyanic acid (HNCO) followed by cyanic acid (HOCN), formonitrile oxide (HCNO), and carboxime (HONC). Each of these isomers is predicted to be quite stable with respect to intramolecular rearrangement. HCNO is found to have a linear equilibrium geometry while HNCO, HOCN, and HONC are each predicted to have trans bent structures. It is shown that singlet formyl nitrene and the cyclic isomers of CHNO are unlikely to be observable species. The rearrangement of HCNO to HNCO proceeds via structures resembling oxazirine and formylnitrene; however, neither of these species is predicted to be an intermediate on the reaction path.One of the simplest typical "organic" molecules-containing the typical "organic" elements carbon, hydrogen, nitrogen, and oxygen-is the molecule with the empirical formula CHNO. Although reasonable valence structures may be drawn for at least seven CHNO isomers (Table I), relatively little is known experimentally about these compounds. Only two isomers, HNCO2 and HCNO,3 have been isolated in pure form and subjected to detailed spectroscopic examination. The substituted isomers RNCO,4 RCNO,5 and ROCN4 are more common, and substituted formylnitrenes RC(0)N have fre-

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“…Liebig already recognized the close similar between metal fulminates and metal cyanides [5,21]. In analogy, the correct structure for fulminic acid is H-CϵN-O [2d, 22,23] and not CϵN-OH. Furthermore, the fulminate ligand forms transition metal complexes that are very similar to those of cyanide [5,24].…”

Section: Introductionmentioning

confidence: 99%