Identification of Elusive Keto and Enol Intermediates in the Photolysis of 1,3,5-Trinitro-1,3,5-Triazinane

Singh, Santosh Kumar; Vuppuluri, Vasant; Sun, Bing‐Jian; Chang, Bo-Yu; Eckhardt, André K.; Son, Steven F.; Chang, Agnes H. H.; Kaiser, Ralf I.

doi:10.1021/acs.jpclett.1c01610

Cited by 4 publications

(2 citation statements)

References 55 publications

(97 reference statements)

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“…Here, the products formed in the irradiated ices along with the reactants were sublimed by increasing the temperature of the sample to 320 K at a rate of 1 K min −1 (temperature program desorption; TPD). The subliming neutral molecules were ionized exploiting isomer-selective vacuum ultraviolet (VUV) photoionization (PI) (Supplementary Table 3) [26][27][28][29][30] . The ions formed were then mass resolved in a reflectron time-of-flight mass spectrometer (PI-ReTOF-MS).…”

Section: Resultsmentioning

confidence: 99%

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

et al. 2022

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The Strecker Synthesis of (a)chiral α-amino acids from simple organic compounds, such as ammonia (NH3), aldehydes (RCHO), and hydrogen cyanide (HCN) has been recognized as a viable route to amino acids on primordial earth. However, preparation and isolation of the simplest hemiaminal intermediate – the aminomethanol (NH2CH2OH)– formed in the Strecker Synthesis to even the simplest amino acid glycine (H2NCH2COOH) has been elusive. Here, we report the identification of aminomethanol prepared in low-temperature methylamine (CH3NH2) – oxygen (O2) ices upon exposure to energetic electrons. Isomer-selective photoionization time-of-flight mass spectrometry (PI-ReTOF-MS) facilitated the gas phase detection of aminomethanol during the temperature program desorption (TPD) phase of the reaction products. The preparation and observation of the key transient aminomethanol changes our perception of the synthetic pathways to amino acids and the unexpected kinetic stability in extreme environments.

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Section: Resultsmentioning

confidence: 99%

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

et al. 2022

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“…VUV photoionization mass spectrometry has attracted increasing interest due to its simplicity and low fragmentation of organic compounds. − Solvent doping could remarkably enhance the ionization efficiency. , Shu et al − observed that a high concentration of CH 2 Cl 2 could efficiently protonate polar molecules such as oxygenated organics. Studying the photoionization process of CH 2 Cl 2 at different pressures and concentrations will greatly help researchers to know the initial product ions and understand the enhancement mechanism.…”

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confidence: 99%

Ionization of Dichloromethane by a Vacuum Ultraviolet Krypton Lamp: Competition Between Photoinduced Ion-Pair and Photodissociation-Assisted Photoionization

Jiang

Lee

et al. 2023

J. Phys. Chem. Lett.

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The photodissociation and photoionization behaviors of haloalkanes in the VUV regime are important to fully understand the mechanism of ozone depletion in the stratosphere. The ionization of dichloromethane (CH2Cl2) under the irradiation of 10.0 and 10.6 eV light was investigated. CH2Cl+ was observed at 10 Pa, while both CH2Cl+ and CHCl2 + were observed at higher pressure. The production efficiency of CH2Cl+ decreased with the increasing number density of CH2Cl2, while that of CHCl2 + increased. A kinetic model was successfully derived to quantitatively describe the variation trends of CH2Cl+ and CHCl2 +, in which the competition between photoinduced ion-pair and photodissociation-assisted photoionization (PD-PI) were included. The ion-pair channel was quenched efficiently at higher pressure or concentration, which reduced its contribution. Our study proposed new insights into the complicated photoexcitation behaviors of CH2Cl2 in the VUV regime and revealed the important role of photodissociation in photoionization at low photon flux.

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Autocatalytic Mechanism Induced by NO₂^– Ion with Effect of Proton-Coupled Electron Transfer in Early Pyrolysis of Azacyclo-Nitramine Compounds RDX: a New Path of Denitration Reaction

Zhang,

Yang,

Liu

et al. 2024

J. Phys. Chem. C

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We show an autocatalytic mechanism involving a novel denitration reaction pathway derived from the pyrolysis of a typical azacyclo-nitramine compound, 1,3,5-trinitro-1,3,5-triazine RDX. In the current mechanism understanding, the denitration reaction of azacyclo-nitramine compounds can almost only occur through N–N bond homolysis and the HONO elimination reaction. Our first-principles molecular dynamics study identified an autocatalytic denitration reaction pathway induced by the NO2 – ion with the effect of proton-coupled electron transfer (PCET). That is, C3H x N x O y transfers a proton from −CH2– groups to the NO2 – ion; synchronously, electrons are transferred from the N-heterocycle of C3H x N x O y to the −NO2 group and results in the formation of HONO and a new NO2 – ion (C3H x N x O y + NO2 – → C3H x–1N x–1O y–2 + NO2 – + HONO). It is also found that the autocatalytic denitration reaction caused by PCET has characteristics of both a low energy barrier and high energy release. For the NO2 radical, it also has an autocatalytic effect to promote dehydrogenation and denitration of C3H x N x O y , but dehydrogenation and denitration induced by a NO2 radical are two asynchronous processes. Compared with the NO2 – ion with NO2 radicals, the denitration reaction induced by the NO2 – ion with the effect of PCET is more favorable kinetically. This work theoretically confirmed the hypothesis that azacyclo-nitramine compounds have autocatalytic effects. In general, the mechanism of the autocatalytic reaction induced by the NO2 – ion with the effect of PCET at the early stage of RDX pyrolysis is revealed for the first time. It is of great significance to the application of PCET in the NO2 – ionic fluid catalyzed molecular denitration reaction and promotes an understanding of the chemical kinetics of the C–H–N–O system under extreme conditions.

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Identification of Elusive Keto and Enol Intermediates in the Photolysis of 1,3,5-Trinitro-1,3,5-Triazinane

Cited by 4 publications

References 55 publications

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

Ionization of Dichloromethane by a Vacuum Ultraviolet Krypton Lamp: Competition Between Photoinduced Ion-Pair and Photodissociation-Assisted Photoionization

Autocatalytic Mechanism Induced by NO₂^– Ion with Effect of Proton-Coupled Electron Transfer in Early Pyrolysis of Azacyclo-Nitramine Compounds RDX: a New Path of Denitration Reaction

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Identification of Elusive Keto and Enol Intermediates in the Photolysis of 1,3,5-Trinitro-1,3,5-Triazinane

Cited by 4 publications

References 55 publications

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

Experimental identification of aminomethanol (NH2CH2OH)—the key intermediate in the Strecker Synthesis

Ionization of Dichloromethane by a Vacuum Ultraviolet Krypton Lamp: Competition Between Photoinduced Ion-Pair and Photodissociation-Assisted Photoionization

Autocatalytic Mechanism Induced by NO2– Ion with Effect of Proton-Coupled Electron Transfer in Early Pyrolysis of Azacyclo-Nitramine Compounds RDX: a New Path of Denitration Reaction

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Autocatalytic Mechanism Induced by NO₂^– Ion with Effect of Proton-Coupled Electron Transfer in Early Pyrolysis of Azacyclo-Nitramine Compounds RDX: a New Path of Denitration Reaction