物理化学学报 >> 2008, Vol. 24 >> Issue (12): 2214-2220.doi: 10.3866/PKU.WHXB20081212

研究论文 上一篇    下一篇

丁香油-β-环糊精包合物中残存态环糊精的热分解动力学

徐鹏, 宋乐新   

  1. 中国科学技术大学化学系, 合肥 230026
  • 收稿日期:2008-08-04 修回日期:2008-09-22 发布日期:2008-12-04
  • 通讯作者: 宋乐新 E-mail:solexin@ustc.edu.cn

Thermal Decomposition Kinetics of Survived β-Cyclodextrin from an Inclusion Complex of β-Cyclodextrin with Clove Oil

XU Peng, SONG Le-Xin   

  1. Department of Chemistry, University of Science and Technology of China, Hefei 230026, P. R. China
  • Received:2008-08-04 Revised:2008-09-22 Published:2008-12-04
  • Contact: SONG Le-Xin E-mail:solexin@ustc.edu.cn

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摘要： 采用双外推法确定了丁香油-β-环糊精(CD)包合物中残存态β-CD最可能的热分解机制. 基于Flynn-Wall-Ozawa方法对残存态β-CD热分解反应过程的计算结果发现, 活化能(Ea)变化曲线可划分为三个阶段. 第一和第三阶段的曲线轮廓近似平行, 并且都被推定为按照Avrami-Erofe’ev A1.5模型发生热分解反应. 但是在曲线的第二阶段, 出现了一个Ea值近似相等的平台. 为此, 采用确定反应级数的方法考察了该阶段的热分解过程. 研究表明, 反应级数随着温度升高呈现规律性的降低, 表明在这个阶段残存态β-CD分解反应的复杂性. 最后, 比较了游离态β-CD和残存态β-CD在分解过程中红外光谱的变化情况. 结果显示, 它们在1000 cm-1以下的谱图轮廓存在明显差异, 这与计算给出的二者具有不同Ea值的结果是一致的.

关键词: 环糊精, 包合物, 双外推法, 热分解动力学

Abstract: A double extrapolation method was employed to determine the most probable mechanism for the thermal decomposition reaction of the survived β-cyclodextrin (β-CD) from the inclusion complex of β-CD with clove oil. The activation energy (Ea) curve calculated by Flynn-Wall-Ozawa method was clearly divided into three stages for the thermal decomposition process of the survived β-CD. The nearly parallel linear relationship between first and last stages was assessed as an Avrami-Erofe’ev A1.5 model. Furthermore, the platform in the second stage of the decomposition of the survived β-CD in which each point has approximately equivalent Ea was carefully investigated using the reaction order (n) method. A regular decline in n as the temperature increased implied a complicated decomposition reaction mechanism for the survived β-CD in this stage. Infrared spectroscopic profiles from the thermal decomposition of free β-CD and survived β-CD were also compared. The changes in IR spectra below 1000 cm-1 between free β-CD and survived β-CD in the decomposition process were quite different which agreed with the calculated Ea values.

Key words: β-Cyclodextrin, Inclusion complex, Double extrapolation, Thermal decomposition kinetics