Synthesis of urea in cometary model ices and implications for Comet 67P/Churyumov–Gerasimenko

Förstel, Marko; Maksyutenko, Pavlo; Jones, Brant M.; Sun, Bing‐Jian; Chang, Agnes H. H.; Kaiser, Ralf I.

doi:10.1039/c5cc07635h

Cited by 35 publications

(33 citation statements)

References 37 publications

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“…Thee nergies are refined by the coupled cluster [28] CCSD(T)/cc-pVDZ with B3LYP/cc-pVTZ zero-point energy corrections.B 3LYP/cc-pVTZ//CCSD(T)/ cc-pVTZ level of calculationare expected to have an accuracywithin 9kJmol À1 . [29] TheG AUSSIAN09 program [30] is used in these electronic structure calculations.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition–Dehydrocyclization: The Third Way

et al. 2019

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Polycyclic aromatic hydrocarbons (PAHs) represent the link between resonance‐stabilized free radicals and carbonaceous nanoparticles generated in incomplete combustion processes and in circumstellar envelopes of carbon rich asymptotic giant branch (AGB) stars. Although these PAHs resemble building blocks of complex carbonaceous nanostructures, their fundamental formation mechanisms have remained elusive. By exploring these reaction mechanisms of the phenyl radical with biphenyl/naphthalene theoretically and experimentally, we provide compelling evidence on a novel phenyl‐addition/dehydrocyclization (PAC) pathway leading to prototype PAHs: triphenylene and fluoranthene. PAC operates efficiently at high temperatures leading through rapid molecular mass growth processes to complex aromatic structures, which are difficult to synthesize by traditional pathways such as hydrogen‐abstraction/acetylene‐addition. The elucidation of the fundamental reactions leading to PAHs is necessary to facilitate an understanding of the origin and evolution of the molecular universe and of carbon in our galaxy.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition–Dehydrocyclization: The Third Way

et al. 2019

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“…For example, the formation of glycine (Holtom et al 2005), amino acids (Elsila et al 2007), dipeptides (Kaiser et al 2013), hydroxyacetonitrile, aminomethanol and polyoxymethylene (Danger et al 2012(Danger et al , 2014, glycolaldehyde and glyceraldehyde (de Marcellus et al 2015), or alpha-aminoethanol (Duvernay et al 2010) in ice was reported experimentally. Recently, Forstel et al (2016) have synthesized urea in cometary model ices thanks to the irradiation of inorganic ice (which contains CO and NH 3 ), proposing a mechanism in which NH 2 • is added to hydrogenated CO.…”

Section: )mentioning

confidence: 99%

The formation of urea in space

Brigiano

Jeanvoine

Largo

et al. 2018

A&A

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Context. Many organic molecules have been observed in the interstellar medium thanks to advances in radioastronomy, and very recently the presence of urea was also suggested. While those molecules were observed, it is not clear what the mechanisms responsible to their formation are. In fact, if gas-phase reactions are responsible, they should occur through barrierless mechanisms (or with very low barriers). In the past, mechanisms for the formation of different organic molecules were studied, providing only in a few cases energetic conditions favorable to a synthesis at very low temperature. A particularly intriguing class of such molecules are those containing one N–C–O peptide bond, which could be a building block for the formation of biological molecules. Urea is a particular case because two nitrogen atoms are linked to the C–O moiety. Thus, motivated also by the recent tentative observation of urea, we have considered the synthetic pathways responsible to its formation. Aims. We have studied the possibility of forming urea in the gas phase via different kinds of bi-molecular reactions: ion-molecule, neutral, and radical. In particular we have focused on the activation energy of these reactions in order to find possible reactants that could be responsible for to barrierless (or very low energy) pathways. Methods. We have used very accurate, highly correlated quantum chemistry calculations to locate and characterize the reaction pathways in terms of minima and transition states connecting reactants to products. Results. Most of the reactions considered have an activation energy that is too high; but the ion-molecule reaction between NH2OHNH2OH2+ and formamide is not too high. These reactants could be responsible not only for the formation of urea but also of isocyanic acid, which is an organic molecule also observed in the interstellar medium.

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“…The formamide molecule (HCONH 2 ) as detected in the interstellar medium (ISM; Gottlieb et al 1973;Hollis et al 2006;Halfen et al 2011;Adande et al 2013) represents the simplest molecule carrying the amide (peptide) bond (Figure 1). Very recently, Jones et al (2011) elucidated the formation mechanism of formamide in astrophysically relevant ices exposed to energetic electrons via the radical-radical recombination of formyl (HCO) with the amidogen radical (NH 2 ) inside astrophysically relevant ices at 10 K. The next homologue molecule in this series-urea (CO (NH 2 ) 2 )-was also detected in processed ices online and in situ, exploiting photoionization of the subliming molecules during the temperature programmed desorption (TPD) phase via tunable vacuum ultraviolet (VUV) light and by detecting the parent ion through a reflectron time-of-flight mass spectrometer (PI-ReTOF-MS; Förstel et al 2015a) It is also well established that amino acids (Bernstein et al 2002;Munoz Caro et al 2002;Elsila et al 2007;Chen et al 2008;Hudson et al 2008) and their formal condensation products-dipeptides-as complex as Glycylglycine (Gly-Gly) and LeucylAlanine (Leu-Ala) can be synthesized abiotically in energetically processed ices ; Figure 1). Note that formamide (HCONH 2 ) might act as a key intermediate in the synthesis of amino acids (Dederichs et al 1975;Apene & Mikstais 1978;Kostakis et al 2007).…”

Section: Introductionmentioning

confidence: 99%

On the Formation of Amide Polymers via Carbonyl–amino Group Linkages in Energetically Processed Ices of Astrophysical Relevance

Förstel

Maksyutenko

Jones

et al. 2016

ApJ

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We report on the formation of organic amide polymers via carbonyl-amino group linkages in carbon monoxide and ammonia bearing energetically processed ices of astrophysical relevance. The first group comprises molecules with one carboxyl group and an increasing number of amine moieties starting with formamide (45 u), urea (60 u), and hydrazine carboxamide (75 u). The second group consists of species with two carboxyl (58 u) and up to three amine groups (73 u, 88 u, and 103 u). The formation and polymerization of these linkages from simple inorganic molecules via formamide und urea toward amide polymers is discussed in an astrophysical and astrobiological context. Our results show that long chain molecules, which are closely related to polypeptides, easily form by energetically processing simple, inorganic ices at very low temperatures and can be released into the gas phase by sublimation of the ices in star-forming regions. Our experimental results were obtained by employing reflectron time-of-flight mass spectroscopy, coupled with soft, single photon vacuum ultraviolet photoionization; they are complemented by theoretical calculations.

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Synthesis of urea in cometary model ices and implications for Comet 67P/Churyumov–Gerasimenko

Cited by 35 publications

References 37 publications

Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition–Dehydrocyclization: The Third Way

Synthesis of Polycyclic Aromatic Hydrocarbons by Phenyl Addition–Dehydrocyclization: The Third Way

The formation of urea in space

On the Formation of Amide Polymers via Carbonyl–amino Group Linkages in Energetically Processed Ices of Astrophysical Relevance

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