Unsaturated Dinitriles Formation Routes in Extraterrestrial Environments: A Combined Experimental and Theoretical Investigation of the Reaction between Cyano Radicals and Cyanoethene (C<sub>2</sub>H<sub>3</sub>CN)

Marchione, Demian; Mancini, Luca; Liang, Pengxiao; Vanuzzo, Gianmarco; Pirani, Fernando; Skouteris, Dimitrios; Rosi, Marzio; Casavecchia, Piergiorgio; Balucani, Nadia

doi:10.1021/acs.jpca.2c01802

Cited by 13 publications

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“…For this reason, we have started a systematic investigation of the reactions involving vinyl cyanide and common atomic/diatomic radicals. The results concerning the reaction CN + CH 2 CHCN have just been published 63 while other studies are still under way.…”

Section: Introductionmentioning

confidence: 99%

“…In general, we can say that very little is known on the reactions of vinyl cyanide with atomic and radical species. , The global rate coefficient is known for a few cases (H, Cl, CN, and OH , ) while the product branching fractions (BFs) are mostly undetermined. For this reason, we have started a systematic investigation of the reactions involving vinyl cyanide and common atomic/diatomic radicals.…”

Section: Introductionmentioning

confidence: 99%

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The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

et al. 2022

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The reaction of electronically excited nitrogen atoms, N( 2 D), with vinyl cyanide, CH 2 CHCN, has been investigated under single-collision conditions by the crossed molecular beam (CMB) scattering method with mass spectrometric detection and time-of-flight (TOF) analysis at the collision energy, E c , of 31.4 kJ/mol. Synergistic electronic structure calculations of the doublet potential energy surface (PES) have been performed to assist in the interpretation of the experimental results and characterize the overall reaction micromechanism. Statistical (Rice–Ramsperger–Kassel–Marcus, RRKM) calculations of product branching fractions (BFs) on the theoretical PES have been carried out at different values of temperature, including the one corresponding to the temperature (175 K) of Titan’s stratosphere and at a total energy corresponding to the E c of the CMB experiment. According to our theoretical calculations, the reaction is found to proceed via barrierless addition of N( 2 D) to the carbon–carbon double bond of CH 2 =CH–CN, followed by the formation of cyclic and linear intermediates that can undergo H, CN, and HCN elimination. In competition, the N( 2 D) addition to the CN group is also possible via a submerged barrier, leading ultimately to N 2 + C 3 H 3 formation, the most exothermic of all possible channels. Product angular and TOF distributions have been recorded for the H-displacement channels leading to the formation of a variety of possible C 3 H 2 N 2 isomeric products. Experimentally, no evidence of CN, HCN, and N 2 forming channels was observed. These findings were corroborated by the theory, which predicts a variety of competing product channels, following N( 2 D) addition to the double bond, with the main ones, at E c = 31.4 kJ/mol, being six isomeric H forming channels: c -CH(N)CHCN + H (BF = 35.0%), c -CHNCHCN + H (BF = 28.1%), CH 2 NCCN + H (BF = 26.3%), c -CH 2 (N)CCN(cyano-azirine) + H (BF = 7.4%), trans -HNCCHCN + H (BF = 1.6%), and cis -HNCCHCN + H (BF = 1.3%), while C–C bond breaking channels leading to c -CH 2 (N)CH(2H-azirine) + CN and c -CH 2 (N)C + HCN are predicted to be negligible (0.02% and 0.2%, respectively). The highly exothermic N 2 + CH 2 CCH (propargyl) channel is also predicted to be negligible because of the very high isomerization barrier from the initial addition intermedia...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

et al. 2022

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“…(2021) and Marchione et al (2022). This treatment of the entrance channel leads to some variation in the rate coefficient values with respect to those reported in Skouteris et al (2018).…”

Section: Methodsmentioning

confidence: 96%

Quantum Chemical Computations of Gas-phase Glycolaldehyde Deuteration and Constraints on Its Formation Route

Vazart

Ceccarelli

Balucani

et al. 2022

ApJ

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Despite the detection of numerous interstellar complex organic molecules (iCOMs) for decades, it is still a matter of debate whether they are synthesized in the gas phase or on the icy surface of interstellar grains. In the past, molecular deuteration has been used to constrain the formation paths of small and abundant hydrogenated interstellar species. More recently, the deuteration degree of formamide, one of the most interesting iCOMs, has also been explained with the hypothesis that it is formed by the gas-phase reaction NH2 + H2CO. In this paper, we aim at using molecular deuteration to constrain the formation of another iCOM, glycolaldehyde, which is an important prebiotic species. More specifically, we have performed dedicated electronic structure and kinetic calculations to establish the glycolaldehyde deuteration degree in relation to that of ethanol, which is its possible parent species according to the suggestion of Skouteris et al. We found that the abundance ratio of the species containing one D atom over the all-protium counterpart depends on the produced D isotopomer and varies from 0.9 to 0.5. These theoretical predictions compare extremely well with the monodeuterated isotopomers of glycolaldehyde and that of ethanol measured toward the solar-like protostar IRAS 16293–2422, supporting the hypothesis that glycolaldehyde could be produced in the gas phase for this source. In addition, the present work confirms that the deuterium fractionation of iCOMs cannot be simply anticipated based on the deuterium fractionation of the parent species but necessitates a specific study, as already shown for the case of formamide.

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“…Between the 2018 census (McGuire, 2018) and the 2021 census (McGuire, 2022) of extraterrestrial molecules a total of 37 molecules have been detected. This corresponds to a rate of detections of 12.33 molecules/year (see Figure 1 of McGuire (2022)), surpassing older rates by a factor between two and three. It is thus fair to highlight that we are amidst an astrochemical revolution in term of detections, with experiments and simulations needing to keep up the pace.…”

Section: Introductionmentioning

confidence: 86%

The reactivity of pyridine in cold interstellar environments: The reaction of pyridine with the CN radical

Heitkämper

Suchaneck

Concepción

et al. 2022

Front. Astron. Space Sci.

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The recent detection of cyclic species in cold interstellar environments is an exciting discovery with yet many unknowns to be solved. Among them, the presence of aromatic heterocycles in space would act as an indirect evidence of the presence of precursors of nucleotides. The seeming absence of these species in the observations poses a fascinating conundrum that can be tackled with computational insights. Whilst many arguments can be given to explain the absence of heterocycles in space, one of the possible scenarios involves fast chemical conversion and formation of new species to be detected. We have tested this hypothesis for the reaction of pyridine with the CN radical to find possible scenarios in which the detectability of pyridine, as an archetypical heterocycle, could be enhanced or diminished via chemical conversions. Using a combination of ab-initio characterization of the reactive potential energy surface and kinetic and chemical simulations, we have established that pyridine does react very fast with CN radicals, estimating that the studied reactions is between 2.5–4.5 times faster in pyridine than in benzene, with a total loss rate constant of 1.33 × 10–9 cm3s−1 at 30 K, with an almost null temperature dependence in the (30–150) K range. Addition reactions forming 1,2,3-cyanopyridine are favored over abstraction reactions or the formation of isocyanides. Besides, for 1 and 2-cyanopyridine there is an increase in the total dipole moment with respect to pyridine, which can help in their detection. However, the reaction is not site specific, and equal amounts of 1,2,3-cyanopyridine are formed during the reaction, diluting the abundance of all the individual pyridine derivatives.

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Unsaturated Dinitriles Formation Routes in Extraterrestrial Environments: A Combined Experimental and Theoretical Investigation of the Reaction between Cyano Radicals and Cyanoethene (C₂H₃CN)

Cited by 13 publications

References 94 publications

The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

Quantum Chemical Computations of Gas-phase Glycolaldehyde Deuteration and Constraints on Its Formation Route

The reactivity of pyridine in cold interstellar environments: The reaction of pyridine with the CN radical

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Unsaturated Dinitriles Formation Routes in Extraterrestrial Environments: A Combined Experimental and Theoretical Investigation of the Reaction between Cyano Radicals and Cyanoethene (C2H3CN)

Cited by 13 publications

References 94 publications

The N(2D) + CH2CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

The N(2D) + CH2CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

Quantum Chemical Computations of Gas-phase Glycolaldehyde Deuteration and Constraints on Its Formation Route

The reactivity of pyridine in cold interstellar environments: The reaction of pyridine with the CN radical

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Product

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Unsaturated Dinitriles Formation Routes in Extraterrestrial Environments: A Combined Experimental and Theoretical Investigation of the Reaction between Cyano Radicals and Cyanoethene (C₂H₃CN)

The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan

The N(²D) + CH₂CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan