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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Effects of Ionic Surfactants and Cyclodextrins on Hydride-Transfer Reaction of l-Benzyl-l,4-dihydronicotinamide with Methylene Blue
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Effects of Ionic Surfactants and Cyclodextrins on Hydride-Transfer Reaction of l-Benzyl-l,4-dihydronicotinamide with Methylene Blue

机译：离子表面活性剂和环糊精对1-苄基-1,4-二氢烟酰胺与亚甲基蓝的氢化物转移反应的影响

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摘要

The kinetics of the hydride-transfer reaction between methylene blue (MB+) and l-benzyl-l,4-dihydronictinamide (BNAH) were studied in media containing cyclodextrins (beta- and gamma-CD) and surfactants (sodium dodecyl sulfate (SDS),dodecyltrimethylammonium bromide,tetradecyltrimethylammonium bromide,and hexadecyltrimethylammonium bromide).Cationic surfactants decreased the apparent first-order rate constant (k_(obsd)) above the cmc,while SDS increased k_(obsd) just above the cmc and then decreased k_(obsd) with increasing surfactant concentration.This behavior for cationic surfactants was typical of micellar effects due to a separation of the reactants by the micelles.BNAH associated with micelles,whereas MB+ ions were repelled from the cationic interface of the micelles.Binding of BNAH and MB+ to the same SDS micelle enhanced the reaction,but dilution of reagents within the micellar interface with the increase in [SDS] caused a decrease in k_(obsd).In beta-CD-cationic surfactant mixtures,the results were interpreted in terms of the model which takes into account the formation of CD-BNAH,CD-MB+,and CD-surfactant complexes and the association of BNAH with micelles.The decrease in k_(obsd) with increasing surfactant concentration observed in gamma-CD-cationic surfactant mixtures can be explained by the decrease in the concentration of free gamma-CD by the formation of 1:1 and 2:1 complexes of surfactant monomer with gamma-CD.
机译：在含有环糊精（β-和γ-CD）和表面活性剂（十二烷基硫酸钠（SDS））的介质中研究了亚甲基蓝（MB +）和1-苄基-1,4-二氢噻吩酰胺（BNAH）之间的氢化物转移反应动力学。阳离子表面活性剂可降低cmc上方的表观一级速率常数（k_（obsd）），而SDS则可将cm_（obsd）刚好高于cmc，然后降低k_（obsd）。阳离子表面活性剂的这种行为是典型的胶束效应，这是由于反应物被胶束分离所致.BNAH与胶束相关，而MB +离子则从胶束的阳离子界面被排斥.BNAH和MB +的结合相同的SDS胶束增强了反应，但随着[SDS]的增加，胶束界面内试剂的稀释导致k_（obsd）降低。在β-CD-阳离子表面活性剂混合物中res，结果以模型的形式解释，该模型考虑了CD-BNAH，CD-MB +和CD表面活性剂复合物的形成以及BNAH与胶束的缔合.k_（obsd）的降低与表面活性剂浓度的增加有关在γ-CD-阳离子表面活性剂混合物中观察到的现象可以通过表面活性剂单体与γ-CD形成1：1和2：1的络合物形成来减少游离γ-CD的浓度来解释。

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