| 任宏江.化学通报,2015,78(9):815-819. |
| 黄嘌呤异构体质子转移异构化反应机理的理论研究 |
| Theoretical investigation on the proton transfer isomerization of Xanthine |
| 投稿时间：2015-02-09 修订日期：2015-03-18 |
| DOI： |
| 中文关键词: 黄嘌呤 密度泛函 质子转移 活化能 速率常数 |
| 英文关键词:Xanthine, DFT, proton transfer, activation energy, rate constant |
| 基金项目: |
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| 中文摘要: |
| 采用量子化学密度泛函理论B3LYP/6-31G(d,p)和M06-2X/6-311+ G(d,p)方法对黄嘌呤两种酮式稳定异构体X(1,3,7)与X(1,3,9)间质子转移引起的互变异构反应机理进行了计算研究,获得了异构化反应过程的反应焓﹑活化能﹑活化吉布斯自由能和质子转移反应的速率常数等参数。水相计算采用极化连续模型(PCM)。结果表明, 由于氢原子转移的顺序不同,分子内由X(1,3,7)通过质子转移向X(1,3,9)异构化共可能有16条反应路径,涉及11个中间体和20个过渡态。其主反应通道速控步骤活化吉布斯自由能为183.10kJ/mol, 速率常数为5.17×10-20 s-1,其余各通道速控步骤活化吉布斯自由能均较高,整体水溶剂效应不利于发生质子转移。 |
| 英文摘要: |
| The reaction mechanism between X(1,3,7) and X(1,3,9) tautomers of Xanthine resulted from proton transfer has been investigated using both B3LYP/6-31G(d,p) and M06-2X/6-311 G(d,p) methods. The reaction enthalpies, activation energies, activation free energies and rate constants of the tautomerization reactions were obtained. The PCM model was used for the aqueous calculation. The results showed that 16 reaction pathways from X(1,3,7) to X(1,3,9) via intramolecular proton transfer were found including the 11 tautomers and 20 transition states. The activation Gibbs free energy needed in the main pathway is 183.10 kJ/mol, the rate constant is 5.17×10-20s-1. The solvent effect does not bring out the benefits. |
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