A DFT study on the reaction mechanism for dimethyl carbonate synthesis from methyl carbamate and methanol
A DFT study on the reaction mechanism for dimethyl carbonate synthesis from methyl carbamate and methanol
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DOI：
10.1016/j.molcata.2011.09.006
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发表时间：
2011-12-01
影响因子：
--
通讯作者：
Sun, Yuhan
中科院分区：
文献类型：
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作者：
Gao, Yangyan;Peng, Weicai;Sun, Yuhan
利用密度泛函理论，研究了在有和没有催化剂的情况下由氨基甲酸甲酯(MC)和甲醇(CH(3)OH)合成碳酸二甲酯(DMC)的反应机理。为了研究溶剂效应，使用类导体溶剂模型 (COSMO) 在 CH(3)OH 溶剂中模拟反应。在我们的计算中，未催化的 MC 甲醇分解反应在动力学和热力学上都是不利的。然而，它显然是由酸和碱催化剂催化的。通过轨道能量计算，MC甲醇解反应被认为是电荷控制反应。因此，静电势拟合电荷作为反应指示剂用于推断催化剂 Zn(NH(3))(2)(NCO)(2) 引发后物质的活性。并证实其在反应性预测方面是成功的。提出了涉及所选活性物质的催化循环。通过计算活化能，催化活性物质被认为是Zn(NH(3))(2)(NCO)(NHCOOCH(3))，它源自Zn(NH(3))(2)(NCO)(2)与CH(3)OH的反应。有利于催化活性物种与CH(3)OH合成DMC，有效降低反应活化能。 (C) 2011 Elsevier B.V. 保留所有权利。
Using density functional theory, the reaction mechanism for dimethyl carbonate (DMC) synthesis from methyl carbamate (MC) and methanol (CH(3)OH) with and without catalysts is investigated. And to investigate solvent effects, the reactions are simulated in CH(3)OH solvent by using the conductor like solvent model (COSMO). In our calculation, the uncatalyzed MC methanolysis reaction is kinetically and thermodynamically unfavorable. However, it is obviously catalyzed by acid and base catalysts. By orbital energy calculation, MC methanolysis reaction is considered as the charge-controlled reaction. Thus, electrostatic potential fitted charges as reaction indicator is used to infer the activity of species after catalyst Zn(NH(3))(2)(NCO)(2) initiation. And it is confirmed to be successful in reactivity prediction. The catalytic cycles involved the selected active species are proposed. By calculating activation energies, the catalytically active species is considered to be Zn(NH(3))(2)(NCO)(NHCOOCH(3)), which derives from the reaction of Zn(NH(3))(2)(NCO)(2) with CH(3)OH. The DMC synthesis from the catalytically active species and CH(3)OH is favored, of which the reaction activation energy is effectively decreased. (C) 2011 Elsevier B.V. All rights reserved.