RT info:eu-repo/semantics/article
T1 The formation of urea in space: I. Ion-molecule, neutral-neutral, and radical gas-phase reactions
A1 Siro Brigiano, Flavio
A1 Jeanvoine, Yannick
A1 Largo Cabrerizo, Antonio
A1 Spezia, Riccardo
K1 Astrochemistry
K1 Astroquímica
K1 Astrobiology methods
K1 Métodos astrobiológicos
K1 Interstellar medium
K1 Medio interestelar
AB 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.
PB EDP Sciences
SN 1432-0746
YR 2018
FD 2018
LK http://uvadoc.uva.es/handle/10324/45882
UL http://uvadoc.uva.es/handle/10324/45882
LA eng
NO Astronomy & Astrophysics, 2018, vol. 610. 15 p.
NO Producción Científica
DS UVaDOC
RD 19-abr-2024