Thermal formation of hydroxynitriles, precursors of hydroxyacids in astrophysical ice analogs: Acetone ((CH3)2CO) and hydrogen cyanide (HCN) reactivity

Q2 Physics and Astronomy

Molecular Astrophysics Pub Date : 2015-11-01 DOI:10.1016/j.molap.2015.10.001

Aurélien Fresneau , Grégoire Danger , Albert Rimola , Fabrice Duvernay , Patrice Theulé , Thierry Chiavassa

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引用次数: 2

Abstract

Reactivity in astrophysical environments is still poorly understood. In this contribution, we investigate the thermal reactivity of interstellar ice analogs containing acetone ((CH₃)₂CO), ammonia (NH₃), hydrogen cyanide (HCN) and water (H₂O) by means of infrared spectroscopy and mass spectrometry techniques, complemented by quantum chemical calculations. We show that no reaction occurs in H₂O:HCN:(CH₃)₂CO ices. Nevertheless, HCN does indeed react with acetone once activated by NH₃ into CN⁻ to form 2-hydroxy-2-methylpropanenitrile (HOC(CH₃)₂CN), with a calculated activation energy associated with the rate determining step of about 51 kJ mol⁻¹. This reaction inhibits the formation of 2-aminopropan-2-ol (HOC(CH₃)₂NH₂) from acetone and NH₃, even in the presence of water, which is the first step of the Strecker synthesis to form 2-aminoisobutyric acid (NH₂C(CH₃)₂COOH). However, HOC(CH₃)₂CN formation could be part of an alternative chemical pathway leading to 2-hydroxy-2-methyl-propanoic acid (HOC(CH₃)₂COOH), which could explain the presence of hydroxy acids in some meteorites.

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天体物理冰类似物中羟基酸前体羟基腈的热形成:丙酮((CH3)2CO)和氰化氢(HCN)的反应性

天体物理环境中的反应性仍然知之甚少。在这篇贡献中，我们利用红外光谱和质谱技术，辅以量子化学计算，研究了含有丙酮(CH3)2CO)、氨(NH3)、氰化氢(HCN)和水(H2O)的星际冰类似物的热反应性。结果表明，在H2O:HCN:(CH3)2CO溶液中不发生反应。然而，一旦被NH3激活，HCN确实会与丙酮反应成CN -，形成2-羟基-2-甲基丙烷腈(HOC(CH3)2CN)，计算出的活化能与速率决定步长有关，约为51 kJ mol - 1。该反应抑制了丙酮和NH3生成2-氨基丙烯-2-醇(HOC(CH3)2NH2)，即使在有水存在的情况下也是如此，这是Strecker合成生成2-氨基异丁酸(NH2C(CH3)2COOH)的第一步。然而，HOC(CH3)2CN的形成可能是导致2-羟基-2-甲基丙烷酸(HOC(CH3)2COOH)的另一种化学途径的一部分，这可以解释某些陨石中羟基酸的存在。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Molecular Astrophysics ASTRONOMY & ASTROPHYSICS-

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期刊介绍： Molecular Astrophysics is a peer-reviewed journal containing full research articles, selected review articles, and thematic issues. Molecular Astrophysics is a new journal where researchers working in planetary and exoplanetary science, astrochemistry, astrobiology, spectroscopy, physical chemistry and chemical physics can meet and exchange their ideas. Understanding the origin and evolution of interstellar and circumstellar molecules is key to understanding the Universe around us and our place in it and has become a fundamental goal of modern astrophysics. Molecular Astrophysics aims to provide a platform for scientists studying the chemical processes that form and dissociate molecules, and control chemical abundances in the universe, particularly in Solar System objects including planets, moons, and comets, in the atmospheres of exoplanets, as well as in regions of star and planet formation in the interstellar medium of galaxies. Observational studies of the molecular universe are driven by a range of new space missions and large-scale scale observatories opening up. With the Spitzer Space Telescope, the Herschel Space Observatory, the Atacama Large Millimeter/submillimeter Array (ALMA), NASA''s Kepler mission, the Rosetta mission, and more major future facilities such as NASA''s James Webb Space Telescope and various missions to Mars, the journal taps into the expected new insights and the need to bring the various communities together on one platform. The journal aims to cover observational, laboratory as well as computational results in the galactic, extragalactic and intergalactic areas of our universe.