Formation of the prebiotic molecule NH<sub>2</sub>CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations

Song, Lei; Kästner, Johannes

doi:10.1039/c6cp05727f

Cited by 81 publications

(89 citation statements)

References 79 publications

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“…Because acetamide, CH 3 CONH 2 , is predominantly formed as a result of H-abstraction from formamide, followed by methylgroup addition, its overabundance is related to that of NH 2 CHO. The majority of the latter molecule is formed via the reaction NH 2 + H 2 CO → NH 2 CHO + H, which we include on the grains as well as in the gas phase, assuming the activation energy barrier determined by Barone et al (2015) of 26.9 K. However, Song & Kästner (2016) find a substantially higher barrier that would render the reaction rate negligible (as determined for a gas-phase interaction). In order to test this possibility, we remove the NH 2 +H 2 CO mechanism both in the gas phase and on grains.…”

Section: Model Resultsmentioning

confidence: 99%

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Беллоче

Meshcheryakov

Garrod

et al. 2017

A&A

156

261

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Context. N-methylformamide, CH 3 NHCHO, may be an important molecule for interstellar pre-biotic chemistry because it contains a peptide bond, which in terrestrial chemistry is responsible for linking amino acids in proteins. The rotational spectrum of the most stable trans conformer of N-methylformamide is complicated by strong torsion-rotation interaction due to the low barrier of the methyl torsion. For this reason, the theoretical description of the rotational spectrum of the trans conformer has up to now not been accurate enough to provide a firm basis for its interstellar detection. Aims. In this context, as a prerequisite for a successful interstellar detection, our goal is to improve the characterization of the rotational spectrum of N-methylformamide. Methods. We use two absorption spectrometers in Kharkiv and Lille to measure the rotational spectra over the frequency range 45-630 GHz. The analysis is carried out using the Rho-axis method and the RAM36 code. We search for N-methylformamide toward the hot molecular core Sagittarius (Sgr) B2(N2) using a spectral line survey carried out with the Atacama Large Millimeter/submillimeter Array (ALMA). The astronomical spectra are analyzed under the assumption of local thermodynamic equilibrium. The astronomical results are put into a broader astrochemical context with the help of a gas-grain chemical kinetics model. Results. The new laboratory data set for the trans conformer of N-methylformamide consists of 9469 distinct line frequencies with J ≤ 62, including the first assignment of the rotational spectra of the first and second excited torsional states. All these lines are fitted within experimental accuracy for the first time. Based on the reliable frequency predictions obtained in this study, we report the tentative detection of N-methylformamide towards Sgr B2(N2). We find N-methylformamide to be more than one order of magnitude less abundant than formamide (NH 2 CHO), a factor of two less abundant than the unsaturated molecule methyl isocyanate (CH 3 NCO), but only slightly less abundant than acetamide (CH 3 CONH 2 ). We also report the tentative detection of the 15 N isotopologue of formamide ( 15 NH 2 CHO) toward Sgr B2(N2). The chemical models indicate that the efficient formation of HNCO via NH + CO on grains is a necessary step in the achievement of the observed gas-phase abundance of CH 3 NCO. Production of CH 3 NHCHO may plausibly occur on grains either through the direct addition of functional-group radicals or through the hydrogenation of CH 3 NCO. Conclusions. Provided the detection of N-methylformamide is confirmed, the only slight underabundance of this molecule compared to its more stable structural isomer acetamide and the sensitivity of the model abundances to the chemical kinetics parameters suggest that the formation of these two molecules is controlled by kinetics rather than thermal equilibrium.

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Section: Model Resultsmentioning

confidence: 99%

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Беллоче

Meshcheryakov

Garrod

et al. 2017

A&A

156

261

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“…Hence, the gaseous CH 3 CHO abundance evolution is rather independent on the formation route (surface chemistry or gas-phase chemistry). We finally checked the possibility that the gas-phase reaction NH 2 + H 2 CO is not efficient (Song & Kästner 2016). In this case, no model can reproduce the observations (both the abundance and the evolution).…”

Section: Chemical Modellingmentioning

confidence: 99%

“…Focussing on formamide, the gas-phase theory proposes that it is synthesised by the reaction of formaldehyde (H 2 CO) and amidogen (NH 2 ), as suggested by Barone et al (2015) and Vazart et al (2016). Various mechanisms have been advanced for the formation of formamide on the grain surfaces including the combination of amidogen and formyl radical (HCO; Garrod et al 2008;Jones et al 2011); the hydrogenation of isocyanic acid (HNCO; Mendoza et al 2014), the latter being most likely an inefficient reaction (Noble et al 2015;Song et al 2016); and particle/UV photon irradiation of ice mixtures (e.g. Kaňuchová et al 2016;Fedoseev et al 2016).…”

Section: Or On Interstellar Dust Grainsmentioning

confidence: 99%

Seeds of Life in Space (SOLIS)

Codella

Ceccarelli

Caselli

et al. 2017

A&A

110

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Context. Modern versions of the Miller-Urey experiment claim that formamide (NH 2 CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming solar-type stars and in external galaxies. Aims. How NH 2 CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods. We used the NOrthern Extended Millimeter Array (NOEMA) interferometer to image NH 2 CHO towards the L1157-B1 blue-shifted shock, a well-known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results. We report the first spatially resolved image (size ∼9 , ∼2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM 5 km s −1 . A column density of N NH 2 CHO = 8 × 10 12 cm −1 and an abundance, with respect to H-nuclei, of 4 × 10 −9 are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by a gas-phase chemical process and not on grain surfaces as previously suggested. Conclusions. The Seeds of Life in Space (SOLIS) interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas phase around Sun-like protostars.

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“…Because of the important role played by tunnelling, a strong kinetic isotopic effect is expected when comparing the rate coefficient of H + HNCO → H 2 NCO to that of D + HNCO → NHDCO both in the gas phase and on the amorphous solid water surface. This effect was quantified by Song and Kastner:132 in the gas phase, the reaction involving H is faster than that involving D by a factor of 231, which is slightly reduced to 146 in the case of the ice-assisted reaction. This aspect is extremely important because it might affect the degree of deuteration of formamide with respect to HNCO.…”

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confidence: 99%

Interstellar Formamide (NH₂CHO), a Key Prebiotic Precursor

López-Sepulcre

Balucani²,

Ceccarelli³

et al. 2019

ACS Earth Space Chem.

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Formamide (NH 2 CHO) has been identified as a potential precursor of a wide variety of organic compounds essential to life, and many biochemical studies propose it likely played a crucial role in the context of the origin of life on our planet. The detection of formamide in comets, which are believed to have -at least partially-inherited their current chemical composition during the birth of the Solar System, raises the question whether a non-negligible amount of formamide may have been exogenously delivered onto a very young Earth about four billion years ago. A crucial part of the effort to 1 arXiv:1909.11770v1 [astro-ph.SR] 25 Sep 2019 answer this question involves searching for formamide in regions where stars and planets are forming today in our Galaxy, as this can shed light on its formation, survival, and chemical re-processing along the different evolutionary phases leading to a star and planetary system like our own.The present review primarily addresses the chemistry of formamide in the interstellar medium, from the point of view of (i) astronomical observations, (ii) experiments, and (iii) theoretical calculations. While focusing on just one molecule, this review also more generally reflects the importance of joining efforts across multiple scientific disciplines in order to make progress in the highly interdisciplinary science of astrochemistry.

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Formation of the prebiotic molecule NH₂CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations

Abstract: Investigating how formamide forms in the interstellar medium is a hot topic in astrochemistry, which can contribute to our understanding of the origin of life on Earth.

Cited by 81 publications

References 79 publications

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Seeds of Life in Space (SOLIS)

Interstellar Formamide (NH₂CHO), a Key Prebiotic Precursor

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Formation of the prebiotic molecule NH2CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations

Abstract: Investigating how formamide forms in the interstellar medium is a hot topic in astrochemistry, which can contribute to our understanding of the origin of life on Earth.

Cited by 81 publications

References 79 publications

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Rotational spectroscopy, tentative interstellar detection, and chemical modeling of N-methylformamide

Seeds of Life in Space (SOLIS)

Interstellar Formamide (NH2CHO), a Key Prebiotic Precursor

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Product

Resources

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Formation of the prebiotic molecule NH₂CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations

Interstellar Formamide (NH₂CHO), a Key Prebiotic Precursor