Kinetics of molecular encapsulation of 1-methylcyclopropene into α-cyclodextrin
Kinetics of molecular encapsulation of 1-methylcyclopropene into α-cyclodextrin
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DOI：
10.1021/jf072357t
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发表时间：
2007-12-26
影响因子：
6.1
通讯作者：
Furuta, Takeshi
中科院分区：
文献类型：
--
作者：
Neoh, Tze Loon;Yamauchi, Kousuke;Furuta, Takeshi
1-甲基环丙烯（1-MCP），一种乙烯抑制调节剂，以与α-环糊精（α-CD）的包合络合物的形式市售。在这项研究中，气态1-MCP到水α-CD的分子封装在一个封闭的，搅拌的容器与平坦的气液界面进行了研究。通过α-CD对气态1-MCP的分子包封是同时进行的两步反应，其涉及气态1-MCP的水溶解和通过α-CD对溶解的分子的包封。根据1-MCP在容器顶空的消耗速率，分析了分子包封的动力学和机理。包封率可以用气体吸收理论定量解释，1-MCP和α-CD之间的伪一级反应。包封反应的表观活化能为负值（-24.4kJ/mol），表明1-MCP在水溶液中的溶解是放热的。包封温度为15 ℃时，1-MCP的产率最高，包合物的包合率最高。X射线衍射图的变化表明，α-环糊精的晶格结构在加入1-MCP后发生了变化。
1-Methylcyclopropene (1-MCP), an ethylene inhibiting regulator, is commercially available in the form of an inclusion complex with alpha-cyclodextrin (alpha-CD). In this study, molecular encapsulation of gaseous 1-MCP into aqueous alpha-CD was investigated in a closed, agitated vessel with a flat gas-liquid interface. Molecular encapsulation of gaseous 1-MCP by alpha-CD is a simultaneous two-step reaction which involves the aqueous dissolution of gaseous 1-MCP and the encapsulation of the dissolved molecules by alpha-CD. The kinetics and mechanism of molecular encapsulation were analyzed based on the depletion rate of 1-MCP in the headspace of the vessel. The encapsulation rates could be explained quantitatively by the gas absorption theory with a pseudo-first-order reaction between 1-MCP and alpha-CD. The negative value of the calculated apparent activation energy of encapsulation (-24.4 kJ/mol) implied the significant effect of exothermic aqueous dissolution of 1-MCP. An encapsulation temperature of 15 degrees C was optimal; at this temperature, the highest 1-MCP yield and best inclusion ratio of inclusion complex were obtained. Changes in the X-ray diffraction pattern suggested that the crystal lattice structure of alpha-CD was altered upon inclusion of 1-MCP.