The Gas-Phase Formation of Methyl Formate in Hot Molecular Cores
The Gas-Phase Formation of Methyl Formate in Hot Molecular Cores
复制标题
甲酸甲酯在热分子核中的气相形成
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
T. D. Fridgen
中科院分区：
文献类型：
--
作者：
A. Horn;H. Møllendal;O. Sekiguchi;E. Uggerud;H. Roberts;E. Herbst;A. Viggiano;T. D. Fridgen
甲酸甲酯，HCOOCH3，是一种著名的星际分子，在热分子核心的光谱中突出。目前关于它形成的观点是，它发生在前体甲醇的气相中，甲醇是在前一个较冷的时代在颗粒地幔表面合成的，在高质量恒星形成过程中，随着温度的上升而蒸发。认为形成甲酸甲酯的具体反应顺序，即质子化甲醇与甲醛的离子-分子反应，然后质子化离子[HCO(H)OCH3]+的解离复合，尚未在实验室中详细研究。本文介绍了[CH3OH2]+与H_2CO离子-分子反应的量子化学研究结果和对该体系的新的实验工作。此外，我们报告了导致甲酸甲酯离子前体的各种其他可能的气相反应的理论和实验研究。所研究的导致甲酸甲酯的化学过程包含在热核的化学模型中。我们的结果表明，这些气相过程都没有产生足够的甲酸甲酯来解释其观察到的丰度。
Methyl formate, HCOOCH3, is a well-known interstellar molecule prominent in the spectra of hot molecular cores. The current view of its formation is that it occurs in the gas phase from precursor methanol, which is synthesized on the surfaces of grain mantles during a previous colder era and evaporates while temperatures increase during the process of high-mass star formation. The specific reaction sequence thought to form methyl formate, the ion-molecule reaction between protonated methanol and formaldehyde followed by dissociative recombination of the protonated ion [HCO(H)OCH3]+, has not been studied in detail in the laboratory. We present here the results of both a quantum chemical study of the ion-molecule reaction between [CH3OH2]+ and H2CO as well as new experimental work on the system. In addition, we report theoretical and experimental studies for a variety of other possible gas-phase reactions leading to ion precursors of methyl formate. The studied chemical processes leading to methyl formate are included in a chemical model of hot cores. Our results show that none of these gas-phase processes produces enough methyl formate to explain its observed abundance.