On the Production of Polyols and Hydroxycarboxylic Acids in Interstellar Analogous Ices of Methanol

Abstract

This laboratory work studied the production of complex organic molecules (COMs) in pure methanol (CH3OH) ices exposed to ionizing radiation in the form of energetic electrons. The chemical evolution of the ices during the electron irradiation at 10 K and subsequent warm-up phase to 300 K was monitored online and in situ via Fourier Transform Infrared (FTIR) spectrometry. Polyols and hydroxycarboxylic acids related absorptions were observed in the infrared spectra of the irradiated ices and residues at room temperature. The residues were analyzed via two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS). Four polyols and five hydroxycarboxylic acids were detected. All of these compounds except 1,3-propanediol and 1,3-butanediol have been identified in the Murchison and Bell meteorites. The most abundant species, ethylene glycol, has also been found in the ISM.Our findings suggest that other polyols and acids may also be present in methanol-rich starforming regions. The non-detection of higher order sugars, as those found in the ultraviolet (UV) photon processed 13 C-methanol ( 13 CH3OH):water (H2O):ammonia (NH3) and 13 C-methanol ( 13 CH3OH):water (H2O) ice mixtures, indicates that the type of radiation source or more likely the prevalent NH3 and/or H2O molecules in the ISM are critical to the abiotic formation of the bio-essential sugars. Experiments are currently being designed to elucidate the roles of each component.

Chiroptical activity of hydroxycarboxylic acids: implications for the origin of biological homochirality

“…Formation of hydroxycarboxylic acids has been confirmed in several experiments simulating the production of organic species under astrophysical conditions, i.e. interstellar/cometary ice analogues at temperatures < 80K exposed to UV photons/energetic particles 12,53,54 . Interestingly, Tachibana et al 55 showed that UV-irradiated interstellar ice analogues composed of water, methanol and ammonia, as well as of pure water show liquid-like behavior over 65-150 and 50-140 K temperature ranges, respectively, which may enhance the formation of complex organic species.…”

Detection of glyceraldehyde and glycerol in VUV processed interstellar ice analogues containing formaldehyde: a general formation route for sugars and polyols

“…They were also detected in our Solar System, in the 67P comet (Goesmann et al 2015;Meringer et al 2018). It is thought that GA and EG are perfect precursors for the formation of glyceraldehyde (GCA) -the first sugar -and its saturated polyol derivative, glycerol (GCO) (Zhu et al 2020;Kaiser et al 2015;Fedoseev et al 2017). Although they have not yet been observed in the ISM, clues of their presence have been found in meteorites.…”

“…They have been unambiguously identified in a large variety of objects and environments: in dark clouds and pre-stellar cores (Marcelino et al 2007;Öberg et al 2010;Bacmann et al 2012;Cernicharo et al 2012;Vastel et al 2014;Jiménez-Serra et al 2016), in photon-dominated regions (Guzmán et al 2014), in hot cores and giant molecular clouds (Hollis et al 2000;Martín-Pintado et al 2001;Requena-Torres et al 2008;Belloche et al 2013), in low and high mass protostar environments (Blake et al 1987;Caselli & Ceccarelli 2012;Neill et al 2014;Tercero et al 2015;Coutens et al 2015;Taquet et al 2015;Jørgensen et al 2016;Rivilla et al 2016), as well as in molecular outflows (Arce et al 2008;Codella Figure 1. GCA and GCO formation pathways adapted from (Fedoseev et al 2017) (formation of GCA and GCO from GA hydrogenation) and (Kaiser et al 2015) and (Zhu et al 2020) (formation of GCO from EG and energetic electrons).…”

“…COM formation such as glycolaldehyde, sugars and polyols under astrophysical conditions (Zhu et al 2020;Kaiser et al 2015;Fedoseev et al 2017).…”

“…Polyols such as EG and GCO can also be formed from pure methanol ices exposed to ionizing radiation (Kaiser et al 2015;Zhu et al 2020). COMs including polyols were analysed by PI-ReToF (Kaiser et al 2015) and by two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC X GC-TOFMS, Zhu et al (2020)). The authors of these studies proposed a formation mechanism based on H-atom abstraction and radical-radical recombination (Fig.…”