Consequently, H 2CO is recognized as one of the most abundant OPMs known in space ( Mangum et al. Since then, it has been detected through absorption and emission bands as continually being present in vast and varied astrophysical objects, such as molecular clouds, envelopes of low- and high-mass protostars, commentary media, and asteroids (see the main detection of formaldehyde and references therein in Appendix A). (1969) from 15 radio sources with galactic and extragalactic origins, becoming the first organic polyatomic molecule (OPM) identified in the ISM. The presence of H 2CO in the ISM was first reported in 1969 by Snyder et al. The origin of formaldehyde itself is less clear. These findings highlight the possible relevance of formaldehyde in the interstellar medium (ISM) and its reactions in current prebiotic chemical evolution models. 2016) as well, and this might further result in formaldehyde oligomerization ( Furukawa et al. Recently, the formation of sugar mixtures compatible with formose reactions has been observed after ultraviolet irradiation of interstellar ices ( Meinert et al. The formose and Strecker reactions highlight the relevance of formaldehyde as a key precursor in prebiotic chemical evolution ( Menor-Salván 2018), but its role during bio-genesis on Earth is still a subject of much debate ( Cleaves II 2008). 2014) could explain the presence of amino acids in meteorites and model prebiotic reactions including the classic Miller-Urey experiment ( Miller 1953 Oró et al. The Strecker-type syntheses and the related Bucherer-Bergs synthesis from alpha-aminonitriles ( Ruiz-Mirazo et al. Additionally, the syntheses of glycine (C 2H 5NO 2) and glycolic acid (C 2H 4O 3) by Strecker synthesis require H 2CO, as well as hydrogen cyanide (HCN), ammonia (NH 3), or other amines and aldehydes for the formation of amino acids ( Choughuley et al. Key words: astrobiology / astrochemistry / ISM: molecules / molecular processesĪfter the early discovery of sugar formation by base-catalyzed aldol condensations of formaldehyde (H 2CO) in the presence of calcium ( Butlerow 1861), collectively known as formose reactions ( Loew 1889), H 2CO has been considered as a plausible primordial source of sugars on prebiotic Earth ( Delidovich et al. Reactions based on more complex reagents yield less effective thermodynamics in the gas-phase H 2CO molecular formation. Quantum chemical calculations suggest that the principal carbonaceous precursors of H 2CO in cold regions for the gas-phase are CH 2(a 1A 1), and ⋅CH 2(X 3B 1) combined with ⋅O 2( 3Σ g) and ⋅CH 3( 2A ”) + ⋅O( 3P) / O( 1D). The most probable reactions that produce H 2CO in cold astrophysical regions are: 1CH 2 + ⋅ 3O 2 → 1H 2CO + O⋅( 3P) in DMCs, ⋅ 3CH 2 + ⋅ 3O 2 → 1H 2CO + ⋅O( 3P) in DCDMCs, and ⋅CH 3 + ⋅O( 3P) → 1H 2CO + ⋅H in region III, ⋅CH 3 +⋅O( 1D) → 1H 2CO + ⋅H in region II, and 1CH 2 + ⋅ 3O 2 → 1H 2CO + ⋅O( 3P) in region I belonging to CELMPs.Ĭonclusions. A literature review on detected abundances of reactants helped us to propose the most favorable formation routes. Molecular thermodynamics and related partition functions were obtained by applying the Maxwell-Boltzmann quantum statistics theory from energies computed at CCSD(T)-F12/cc-pVTZ-F12 with corrections for zero-point energy. The potential energy surfaces, thermodynamic functions, and single-point energies for transition states were calculated at the CCSD(T)-F12/cc-pVTZ-F12 and MP2/aug-cc-pVDZ levels of theory and basis sets. We computationally determine the most favored gas-phase molecular formation mechanisms at local thermodynamic equilibrium conditions that can produce the detected amounts of H 2CO in diffuse molecular clouds (DMCs), in dark, cold, and dense molecular clouds (DCDMCs), and in three regions of circumstellar envelopes of low-mass protostars (CELMPs). However, gas-phase molecular formation mechanisms in cold regions of the ISM are poorly understood.Īims. The cold conditions of the interstellar medium (ISM) allow H 2CO to be reactive, playing a significant role as a chemical intermediate in formation pathways leading to interstellar complex organic molecules. Fortenberry 4ĭepartamentos de Física & Matemáticas y de Ingeniería Automática, Universidad de Alcalá,ĭepartamento de Biología de Sistemas, Instituto de Investigación Química “Andrés del Rio” (IQAR), Universidad de Alcalá,Į-mail: Center for Chemical Evolution, Georgia Institute of Technology,ĭepartment of Chemistry & Biochemistry, University of Mississippi,Į-mail: Formaldehyde is a potential biogenic precursor involved in prebiotic chemical evolution. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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