Formation of methyl ketenimine (CH3CH = C = NH) and ethylcyanide (CH3CH2C≡N) isomers through successive hydrogenations of acrylonitrile (CH2 = CH − C≡N) under interstellar conditions: The role of CH3C°H − C≡N radical in the activation of the cyano group chemistry

Krim, Lahouari; Guillemin, Jean‐Claude

doi:10.1093/mnras/stz698

Cited by 16 publications

(12 citation statements)

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“…Four are simple chains: methanimine (CH 2 NH, Godfrey et al 1973;Dickens et al 1997), ethanimine (CH 3 CHNH, Loomis et al 2013), ketenimine (CH 2 CNH, Lovas et al 2006), and 3-imino-1,2-propadienylidene (CCCNH, Kawaguchi et al 1992); but there are also the substituted C-cyanomethanimine (NCCHNH, Zaleski et al 2013;Rivilla et al 2019), and the cumulated "diimine" carbodiimide (HNCNH, McGuire et al 2012). Hypotheses on their formation in astrophysical environments point mainly to a chemical route from simple nitriles via tautomerisation (Lovas et al 2006) or by partial hydrogenation on dust grain surfaces (Theule et al 2011;Krim et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

Bizzocchi

Prudenzano

Rivilla

et al. 2020

A&A

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Context. Small imines containing up to three carbon atoms are present in the interstellar medium (ISM). As alkynyl compounds are abundant in this medium, propargylimine (2-propyn-1-imine, HC ≡C−CH =NH) thus represents a promising candidate for a new interstellar detection. Aims. The goal of the present work is to perform a comprehensive laboratory investigation of the rotational spectrum of propargylimine in its ground vibrational state in order to obtain a highly precise set of rest frequencies and to search for it in space. Methods. The rotational spectra of E and Z geometrical isomers of propargylimine have been recorded in the laboratory in the 83–500 GHz frequency interval. The measurements have been performed using a source-modulation millimetre-wave spectrometer equipped with a pyrolysis system for the production of unstable species. High-level ab initio calculations were performed to assist the analysis and to obtain reliable estimates for an extended set of spectroscopic quantities. We searched for propargylimine at 3 mm and 2 mm in the spectral survey of the quiescent giant molecular cloud G+0.693-0.027 located in the central molecular zone, close to the Galactic centre. Results. About 1000 rotational transitions have been recorded for the E- and Z-propargylimine, in the laboratory. These new data have enabled the determination of a very accurate set of spectroscopic parameters including rotational, quartic, and sextic centrifugal distortion constants. The improved spectral data allowed us to perform a successful search for this new imine in the G+0.693-0.027 molecular cloud. Eighteen lines of Z-propargylimine were detected at level >2.5σ, resulting in a column-density estimate of N = (0.24 ± 0.02) × 1014 cm−2. An upper limit was retrieved for the higher energy E isomer, which was not detected in the data. The fractional abundance (with respect to H2) derived for Z-propargylimine is 1.8 × 10−10. We discuss the possible formation routes by comparing the derived abundance with those measured in the source for possible chemical precursors.

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Section: Introductionmentioning

confidence: 99%

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

Bizzocchi

Prudenzano

Rivilla

et al. 2020

A&A

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“…For the barrier-less addition reactions on unsaturated radicals, such as H + H 2 CCCN, we consider addition on several sites due to non-localised radical character of the lonely electron (H 2 C=C • -C≡N ↔ H 2 C=C=C=N • ) with branching ratios deduced from Mulliken atomic spin density given by theoretical calculations. This leads to nitrile (R-CN) and imine (R=NH) production (Krim et al 2019), but only low alcohol production in the case of s-H reaction through H atom addition on unsaturated aldehyde radicals (Krim et al 2018).…”

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confidence: 99%

The ALMA-PILS survey: first detection of the unsaturated 3-carbon molecules Propenal (C₂H₃CHO) and Propylene (C₃H₆) towards IRAS 16293–2422 B

Manigand

Coutens

Loison

et al. 2021

A&A

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Context. Complex organic molecules with three carbon atoms are found in the earliest stages of star formation. In particular, propenal (C 2 H 3 CHO) is a species of interest due to its implication in the formation of more complex species and even biotic molecules. Aims. This study aims to search for the presence of C 2 H 3 CHO and other three-carbon species such as propylene (C 3 H 6) in the hot corino region of the low-mass protostellar binary IRAS 16293-2422 to understand their formation pathways. Methods. We use ALMA observations in Band 6 and 7 from various surveys to search for the presence of C 3 H 6 and C 2 H 3 CHO towards the protostar IRAS 16293-2422 B (IRAS 16293B). The identification of the species and the estimates of the column densities and excitation temperatures are carried out by modeling the observed spectrum under the assumption of local thermodynamical equilibrium. Results. We report the detection of both C 3 H 6 and C 2 H 3 CHO towards IRAS 16293B, however, no unblended lines were found towards the other component of the binary system, IRAS 16293A. We derive column density upper limits for C 3 H 8 , HCCCHO, n-C 3 H 7 OH, i-C 3 H 7 OH, C 3 O, and cis-HC(O)CHO towards IRAS 16293B. We then use a three-phase chemical model to simulate the formation of these species in a typical prestellar environment followed by its hydrodynamical collapse until the birth of the central protostar. Different formation paths, such as successive hydrogenation and radical-radical additions on grain surfaces, are tested and compared to the observational results in a number of different simulations, to assess which are the dominant formation mechanisms in the most embedded region of the protostar. Conclusions. The simulations reproduce the abundances within one order of magnitude from those observed towards IRAS 16293B, with the best agreement found for a rate of 10 −12 cm 3 s −1 for the gas-phase reaction C 3 + O → C 2 + CO. Successive hydrogenations of C 3 , HC(O)CHO, and CH 3 OCHO on grain surfaces are a major and crucial formation route of complex organics molecules, whereas both successive hydrogenation pathways and radical-radical addition reactions contribute to the formation of C 2 H 5 CHO.

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“…This pathway arises because the radical character of HOCHNC is not confined to the central C atom but is divided between both C atoms. The realization that this alternate formation pathway might be present was suggested by similar behavior observed in an analogous system in a prior study involving vinyl cyanide (Krim et al 2019). (ii) We also investigated if there is sufficient reaction energy to eject HOCH2CN from the surface.…”

Section: + + Hcn Reactions On Icementioning

confidence: 65%

Formation of the Alma Molecule Hoch2cn and Related Species From the Reaction of C+ With HCN and HNC in Icy Grain Mantles

Woon

2019

Proceedings of the 74th International Symposium on Molecular Spectroscopy

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Formation of methyl ketenimine (CH3CH = C = NH) and ethylcyanide (CH3CH2C≡N) isomers through successive hydrogenations of acrylonitrile (CH2 = CH − C≡N) under interstellar conditions: The role of CH3C°H − C≡N radical in the activation of the cyano group chemistry

Cited by 16 publications

References 47 publications

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

The ALMA-PILS survey: first detection of the unsaturated 3-carbon molecules Propenal (C₂H₃CHO) and Propylene (C₃H₆) towards IRAS 16293–2422 B

Formation of the Alma Molecule Hoch2cn and Related Species From the Reaction of C+ With HCN and HNC in Icy Grain Mantles

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Formation of methyl ketenimine (CH3CH = C = NH) and ethylcyanide (CH3CH2C≡N) isomers through successive hydrogenations of acrylonitrile (CH2 = CH − C≡N) under interstellar conditions: The role of CH3C°H − C≡N radical in the activation of the cyano group chemistry

Cited by 16 publications

References 47 publications

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM

The ALMA-PILS survey: first detection of the unsaturated 3-carbon molecules Propenal (C2H3CHO) and Propylene (C3H6) towards IRAS 16293–2422 B

Formation of the Alma Molecule Hoch2cn and Related Species From the Reaction of C+ With HCN and HNC in Icy Grain Mantles

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The ALMA-PILS survey: first detection of the unsaturated 3-carbon molecules Propenal (C₂H₃CHO) and Propylene (C₃H₆) towards IRAS 16293–2422 B