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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Reaction of Aqueous 2-(N-Methylamino)ethanol Solutions with Carbon Dioxide. Chemical Species and Their Conformations Studied by Vibrational Spectroscopy and ab Initio Theories
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Reaction of Aqueous 2-(N-Methylamino)ethanol Solutions with Carbon Dioxide. Chemical Species and Their Conformations Studied by Vibrational Spectroscopy and ab Initio Theories

机译：2-（N-甲基氨基）乙醇水溶液与二氧化碳的反应。化学物种及其形态的振动光谱和从头算理论研究

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摘要

The reaction systems of aqueous 2-(N-methylamino) ethanol (MAE) solutions with dissolved CO_2 (CO_2-MAE-H_2O system) and of liquid MAE with dissolved CO_2 (CO_2-MAE system) have been studied by vibrational spectroscopy and ab initio theories. The chemical species, molecular conformations and intramolecular and intermolecular hydrogen bonding in these systems have been elucidated. The species produced in the CO_2-MAE-H_2O system are the carbamate anion (MAECO_2~-), the protonated cation (MAEH~+), hydrogencarbonate ion (HCO_3~-), and carbonate ion (COO_3~(2-)), while the species produced in the CO_2-MAE system are MAECO_2~- and MAEH~+. In the CO_2-MAE-H_2O system, MAE (secondary amine) reacts with CO_2 to form MAECO_2~- and MAEH~+, and MAECO_2~- subsequently reacts with H_2O and CO_2 to form MAEH~+ and HCO_3~-. This reaction mechanism is contrasted with the mechanism for 2-(N,N-dimethylamino) ethanol (DMAE, tertiary amine), which reacts with CO_2 and H_2O to form directly DMAEH~+ and HCO_3~-. In the liquid state and in aqueous solution, MAECO_2~- molecules assume predominantly the S~-G~-g~+ conformation with the formation of strong intramolecular 1,6-OH…O~- hydrogen bonding, and MAEH~+ molecules assume predominantly the TG~+- t conformation with the formation of strong intramolecular 1,4-NH~+…O hydrogen bonding. MAE molecules in the condensed phases, on the other hand, assume several conformations such as TG~-x (x = t, g~-, and g~+), TG~+g~-, and G~-G~-g~+ as the result of the competition of intermolecular interactions such as OH…O or OH…N hydrogen bonding and intramolecular interactions such as the 1,4-OH…N hydrogen bonding. The interconversion, depending on pH or addition/removal of CO_2, of strong ionic hydrogen bonding such as NH~+…O, NH~+…O~-, and OH…O~- and nonionic hydrogen bonding such as OH…N and OH…O is clearly one of the important structural features in the CO_2-amine-H_2O system and probably in biomolecular systems, where intramolecular and/or intermolecular interactions between nitrogen abd oxygen atoms are involved.
机译：通过振动光谱和从头算研究了2-（N-甲基氨基）乙醇（MAE）水溶液与溶解CO_2的反应体系（CO_2-MAE-H_2O体系）和液态MAE与溶解CO_2的反应体系（CO_2-MAE体系）理论。这些系统中的化学种类，分子构象以及分子内和分子间氢键已经阐明。在CO_2-MAE-H_2O系统中产生的物质是氨基甲酸酯阴离子（MAECO_2〜-），质子化阳离子（MAEH〜+），碳酸氢根离子（HCO_3〜-）和碳酸根离子（COO_3〜（2-）），而CO_2-MAE系统产生的物种是MAECO_2〜-和MAEH〜+。在CO_2-MAE-H_2O系统中，MAE（仲胺）与CO_2反应形成MAECO_2〜-和MAEH〜+，然后MAECO_2〜-与H_2O和CO_2反应形成MAEH〜+和HCO_3〜-。该反应机理与2-（N，N-二甲基氨基）乙醇（DMAE，叔胺）的机理相反，后者与CO_2和H_2O反应直接形成DMAEH〜+和HCO_3-。在液态和水溶液中，MAECO_2〜-分子主要呈现S〜-G〜-g〜+构象，并形成强分子内1,6-OH…O〜-氢键，而MAEH〜+分子则具有主要是TG〜+ -t构象，形成强分子内1,4-NH〜+ ... O氢键。另一方面，缩合相中的MAE分子具有几种构型，例如TG〜-x（x = t，g〜-和g〜+），TG〜+ g〜-和G〜-G〜- g〜+是分子间相互作用（例如OH…O或OH…N氢键）和分子内相互作用（例如1,4-OH…N氢键）竞争的结果。根据pH值或CO_2的添加/去除，相互转换的是强离子氢键（例如NH〜+…O，NH〜+ ... O〜-和OH…O〜-）和非离子氢键（例如OH ... N和OH…O显然是CO_2-胺-H_2O系统以及生物分子系统中重要的结构特征之一，其中涉及氮和氧原子之间的分子内和/或分子间相互作用。

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