Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392, Giessen, Germany.
Department of Chemistry, W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI, 96822, USA.
Angew Chem Int Ed Engl. 2019 Apr 16;58(17):5663-5667. doi: 10.1002/anie.201901059. Epub 2019 Mar 26.
With nearly 200 molecules detected in interstellar and circumstellar environments, the identification of the biologically relevant α-keto carboxylic acid, glyoxylic acid (HCOCOOH), is still elusive. Herein, the formation of glyoxylic acid via cosmic-ray driven, non-equilibrium chemistry in polar interstellar ices of carbon monoxide (CO) and water (H O) at 5 K via barrierless recombination of formyl (HCO) and hydroxycarbonyl radicals (HOCO) is reported. In temperature-programmed desorption experiments, the subliming neutral molecules were selectively photoionized and identified based on the ionization energy and distinct mass-to-charge ratios in combination with isotopically labeled experiments exploiting reflectron time-of-flight mass spectrometry. These studies unravel a key reaction path to glyoxylic acid, an organic molecule formed in interstellar ices before subliming in star-forming regions like SgrB2(N), thus providing a critical entry point to prebiotic organic synthesis.
在星际和星周环境中检测到近 200 种分子，但生物相关的α-酮羧酸，即乙醛酸（HCOCOOH）的鉴定仍然难以捉摸。本文报道了在 5 K 时通过一氧化碳（CO）和水（H2O）的极地星际冰中，宇宙射线驱动的非平衡化学反应，通过无势垒的甲酰基（HCO）和羟羰基自由基（HOCO）的复合，形成乙醛酸。在程序升温脱附实验中，升华的中性分子被选择性光解，并根据电离能和独特的质荷比，结合利用反射飞行时间质谱的同位素标记实验进行识别。这些研究揭示了乙醛酸的关键反应途径，乙醛酸是一种在星际冰中形成的有机分子，然后在像 SgrB2(N) 这样的恒星形成区域升华，从而为前生物有机合成提供了一个关键的切入点。
