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在298.15 K和101.325 kPa条件下,根据密度泛函理论,使用Gaussian03程序,在B3LYP/6-31G水平上,以实验上所检测到的白术内酯Ⅰ、表白术内酯Ⅰ、白术内酯Ⅱ、白术内酯Ⅲ和双白术内酯为设计反应路径的出发点,详细研究苍术酮氧化反应的机理。在拟定反应机理的基础上,获得了14个稳定构型和13个过渡态,优化构型表明五元环为白术的官能团,五元环经历了开环,闭环的过程——从平面结构到扭曲再到平面结构,证明苍术酮在氧化过程中有2条反应通道:通道1生成白术内酯Ⅰ,通道2生成表白术内酯Ⅰ。并计算了各反应路径的热力学和动力学参数,结果说明苍术酮与水的加成反应,是整个反应过程的速度控制步骤,活化能分别为223.25 kJ/mol和216.75 kJ/mol,且前者为吸热过程,后者为放热过程。计算结果确认了实验上已检测的物质,并从理论上预测了可能存在的氧化物质。苍术酮的氧化机理对研究白术的炮制及提纯具有重要意义。
Under the conditions of 298.15 K and 101.325 kPa, according to the density functional theory, the Gaussian03 program was used to detect atractyloside Ⅰ, atractylenolide Ⅱ , Atractylenolide Ⅲ and diacetyl lactone are the starting points for designing the reaction pathway, and the mechanism of atractylenol oxidation is studied in detail. Based on the proposed reaction mechanism, 14 stable configurations and 13 transition states were obtained. The optimized configuration indicated that the five-membered ring was a functional group of Atractylodes and the five-membered ring underwent open-loop and closed-loop processes - from planar structure to Twisted to planar structure, that athere ketone in the oxidation process has two reaction channels: channel 1 to generate atractylodes lactone Ⅰ, channel 2 to form albino lactone Ⅰ. The thermodynamic and kinetic parameters of each reaction path were calculated. The result shows that the addition reaction of atractyloside with water is the speed control step of the whole reaction process, the activation energies are 223.25 kJ / mol and 216.75 kJ / mol respectively, and the former is Endothermic process, which is the exothermic process. The calculation confirms the experimentally detected substances and predicts theoretically the possible oxidation substances. It is of great significance to study the oxidation mechanism of atractyloside on the processing and purification of Atractylodes.