The The mechanism of reaction between 3-hydroxy-3-methyl-2-butanone and malononitrile for the synthesis of 2-dicyanomethylene-4, 5, 5-trimethyl-2,5-dihydrofuran-3-carbonitrile catalyzed by lithium ethoxide was investigated by density functional theory (DFT). The geometries and the frequencies of reactants, intermediates, transition states and products were calculated at the B3LYP/6-31G(d) level. The vibration analysis and the IRC analysis verified the authenticity of transition states. The reaction processes were confirmed by the changes of charge density at the bond-forming critical point. The results indicated that lithium ethoxide is an effective catalyst in the synthesis of 2-dicyanomethylene-4, 5, 5-trimethyl-2, 5-dihydrofuran-3-carbonitrile from malononi-trile and 3-hydroxy-3-methyl-2-butanone. The activation energy of the reaction with lithium ethoxide was 115.86 kJ·mol⁻¹ less than the uncatalyzed reaction. The mechanism of the lithium ethoxide catalyzed reaction differed from the mechanism of the uncatalyzed reaction.

中文翻译：

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乙醇锂催化3-羟基-3-甲基-2-丁酮与丙二腈反应机理的理论研究

研究了3-羟基-3-甲基-2-丁酮与丙二腈反应在乙醇酸锂催化下合成2-二氰基亚甲基-4、5、5-三甲基-2,5-二氢呋喃-3-甲腈的反应机理。通过密度泛函理论（DFT）。在B3LYP / 6-31G（d）水平上计算了反应物，中间体，过渡态和产物的几何形状和频率。振动分析和IRC分析验证了过渡态的真实性。通过在形成键的临界点的电荷密度的变化来确认反应过程。结果表明，乙醇酸锂是由丙二腈和3-羟基-3-甲基-2-二甲基合成2-二氰基亚甲基-4、5、5-三甲基-2、5-二氢呋喃-3-甲腈的有效催化剂。丁酮。^-1小于未催化的反应。乙醇锂的催化反应机理与未催化的反应机理不同。