Formation Of The Glycine Isomer Glycolamide (NH2C(O)CH2OH) On The Surfaces Of Interstellar Ice Grains: Insights From Atomistic Simulations

Syn-glycolamide, a glycine isomer, has recently been detected in the G+0.693-0.027 molecular cloud. Investigations on its formation in the interstellar medium could offer insights into synthetic routes leading to glycine in prebiotic environments.

Quantum chemical simulations on glycolamide (NH₂C(O)CH₂OH) formation on interstellar ice mantles, mimicked by a water ice cluster model, are presented. Glycolamide synthesis has been here modeled considering a stepwise process: the coupling between formaldehyde (H₂CO) and the radical of formamide (NH₂CO∙) occurs first, forming the glycolamide precursor NH₂C(O)CH₂O∙, which is then hydrogenated to give anti-glycolamide.

We hypothesize that anti-to-syn interconversion will occur in conjunction with glycolamide desorption from the ice surface. The reaction barrier for NH₂C(O)CH₂O∙ formation varies from 9 to 26 kJ mol−1, depending on surface binding sites. Kinetic studies indicate that this reaction step is feasible in environments with a T>35 K, until desorption of the reactants. The hydrogenation step leading to anti-glycolamide presents almost no energy barrier due to the easy H atom diffusion towards the NH₂C(O)CH₂O∙ intermediate.

However, it competes with the extraction of an H atom from the formyl group of NH₂C(O)CH₂O∙, which leads to formyl formamide, NH₂C(O)CHO, and H₂. Nonetheless, according to our results, anti-glycolamide formation is predicted to be the most favored reactive channel.

Jessica Perrero, Silvia Alessandrini, Hexu Ye, Cristina Puzzarini, Albert Rimola

Comments: 16 pages, 12 figures, accepted for publication in Astronomy & Astrophysics
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2504.17372 [astro-ph.GA] (or arXiv:2504.17372v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2504.17372
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Submission history
From: Jessica Perrero
[v1] Thu, 24 Apr 2025 08:44:07 UTC (22,265 KB)
https://arxiv.org/abs/2504.17372
Astrobiology, Astrochemistry,