A computational study on the chemical fixation of carbon dioxide with epoxide catalyzed by LiBr salt.
A computational study on the chemical fixation of carbon dioxide with epoxide catalyzed by LiBr salt.
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DOI：
10.1021/jp104184v
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发表时间：
2011-03
期刊：
影响因子：
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通讯作者：
Ying Ren;Caihong Guo;Jian-Feng Jia;Hai-Shun Wu
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文献类型：
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作者：
Ying Ren;Caihong Guo;Jian-Feng Jia;Hai-Shun Wu
在B3 LYP密度泛函水平上，对LiBr盐催化下二氧化碳与2，3-环氧丙基苯基醚的化学固定反应进行了研究，得到了一个五元环状碳酸酯4-（苯氧基甲基）-1，3-二氧戊环-2-酮.溶剂效应已通过PCM模型进行了研究。所有可能的途径进行检查，并证明其相应的能量。我们的结果表明，整个反应包括三个主要步骤：环氧化物开环、二氧化碳插入和环状碳酸酯闭环，其中没有一个包含显着大的屏障。根据计算的活化自由能，在N-甲基吡咯烷酮（NMP）溶剂中，反应的速率控制步骤可以是环氧化物的开环或环状碳酸酯的闭环，反应条件的变化对反应速率的影响很大。计算表明，在气相中，路径2比路径1更有利，而在NMP溶剂中，两者都可能存在。整个反应是放热的。此外，还得到了气相和NMP溶剂中所有反应路径沿着最小能量路径的自由能分布，并进行了比较。结果表明，NMP溶剂不改变反应势能面的一般趋势。
The chemical fixation of carbon dioxide with 2,3-epoxypropyl phenyl ether catalyzed by LiBr salt to produce a five-membered cyclic carbonate, 4-(phenoxymethyl)-1,3-dioxolan-2-one, has been extensively investigated at the B3LYP density functional level of theory. The solvent effects have been studied by means of a PCM model. All possible pathways are examined, and their corresponding energetics are demonstrated. Our results reveal that the overall reaction comprises three main steps: epoxide ring-opening, carbon dioxide insertion, and ring-closure of cyclic carbonate, none of which contains significantly large barriers. On the basis of the computed free energies of activation, the rate-determining step can be the ring-opening of epoxide or the ring-closure of cyclic carbonate with variation in the reaction conditions in N-methylpyrrolidinone (NMP) solvent. Our calculations indicate that path 2 is more favorable than path 1 in the gas phase, while both of them exist possibly in NMP solvent. The overall reaction is exothermic. Furthermore, the free energy profiles of all reaction pathways along the minima energy path in the gas phase and in NMP solvent were obtained and compared. It is shown that NMP solvent does not change the general trends for the reaction potential energy surfaces.