Reactivity of Typical Solvolytic Reactions in SDS and TTABr Water-in-Oil Microemulsions

García‐Río, Luis; Leis, and J. Ramón; Reigosa, C.

doi:10.1021/jp970460n

Cited by 22 publications

(23 citation statements)

References 68 publications

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“…The model was successfully applied to reactions that are catalyzed by b-CD [5,6] and those that are not. [7] In both cases we observed a significant quantity of uncomplexed b-CD in equilibrium with the micellar system and the absence of interactions between b-CD and the micelles once these have been formed. Here we present the results of a study on the basic hydrolysis of m-nitrophenylacetate (m-NPA) in micelle ± b-CD mixed systems of dodecyltrimethylammonium bromide (LTABr), trimetyltetradecylammonium bromide (TTABr), and trimethyloctadecylammonium chloride (OTACl).…”

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confidence: 67%

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Micellization versus Cyclodextrin–Surfactant Complexation

Dorrego

García‐Río

Hervés

et al. 2000

Angew. Chem. Int. Ed.

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Complete saturation of the complexation capacity of cyclodextrins (CDs) is not required for micellization to take place. Investigation of the competition between micellization and complexation of surfactant monomers with β‐CD (shown schematically) shows the presence of a high concentration of uncomplexed β‐CD in equilibrium with the micellar system. This concentration increases with the length of the hydrocarbon chain of the surfactant.

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confidence: 67%

“…less, space group P1 Å (no. 2), a 8.9501 (7), b 12.4181 (6), c 15.7582 (10) , a 88.342(4), b 83.656 (6), g 71.097 (5)8, V 1646.8(2) 3 , Z 2, 1 1.964 g cm À3 , m(Mo Ka ) 7.13 mm À1 . A total of 10 787 reflections were measured at 150 K on a CAD4T/rotating anode diffractometer (l 0.71073 ) and averaged in a unique set of 7569 reflections (R av 0.036).…”

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confidence: 99%

Micellization versus Cyclodextrin–Surfactant Complexation

Dorrego

García‐Río

Hervés

et al. 2000

Angew. Chem. Int. Ed.

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“…As a co-surfactant, 1-hexanol stabilizes the micellar system, reduces interfacial polarity and thereby also tends to reduce the rates of solvolysis reactions taking place at the water-surfactant interface. 20 This paper describes the determination of iodine using the RMM-CL reaction of luminol in a chloroform-free micellar medium of CTAC dissolved in 1-hexanol-cyclohexane mixture. Four component systems of surfactant, co-surfactant (generally a short chain alcohol), oil and water have many important features and are the most studied microemulsion systems.…”

Section: Introductionmentioning

confidence: 99%

An Improved Method for the Flow-Injection Determination of Iodine Using the Luminol Chemiluminescence Reaction in a Reversed Micellar Medium of Cetyltrimethylammonium Chloride in 1-Hexanol-Cyclohexane

et al. 2006

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Amphiphilic molecules (surfactants) when dissolved in a bulk organic non-polar solvent form organized assemblies called reverse micelles when an appropriate concentration of surfactants, the critical micellar concentration, is reached. 1 The structure of a reverse micelle is the inverse prototype of the normal micellar structure. The polar head groups of the surfactant molecules are in contact with the tiny water pool (containing the associated counter ions) in the core of the reverse micelle while the hydrophobic chains are directed outward into the bulk organic solvent. In our previous work, chemiluminescence (CL) generation was observed upon mixing iodine with luminol dispersed in the carbonate-buffered water pool of the reversed micelle of cetyltrimethylammonium chloride (CTAC). 2 Absorption measurements demonstrated that, on mixing of the cyclohexane solution of iodine with the CTAC reversed micellar solution, iodine could be transferred instantly and completely from the organic phase into the buffered water pool of the reverse micelle.2 On the other hand, when iodine was premixed with the reversed micellar solution containing the carbonate buffer alone and then the resulting mixture was mixed with the reversed micellar solution of luminol, no CL emission was produced. 3 In the CL reaction of luminol with iodine, hypoiodous acid and the iodite ion have been proposed as oxidants in usual alkaline aqueous solutions. 4 Thus, a possible explanation would be that, on iodine uptake by the reverse micelle, these oxidizing agents may be produced initially and be present transiently at the surfactant-water pool interface, before reacting immediately with luminol anion to generate luminescence. 2,3 The chloride ion, the counter ion of CTAC, is also presumed to be available mostly at the surfactant-water pool interface, 5 and to cause its association with iodine. 6 This might facilitate the quantitative uptake of iodine by the CTAC reverse micelle. In addition, the concentration effect of iodine can be achieved by entrance of iodine into a small volume of the interfacial region in the CTAC reverse micelles, where acceleration of the luminol CL reaction seems likely due to more efficient association of luminol with the generated oxidants, resulting in the generation of more intense or higher CL signals.Several metal ions present in aqueous samples may interfere with iodine determination by using the usual aqueous phase luminol CL reaction; thus, their removal is needed by incorporating separation science techniques into the procedure. 7 When iodide is oxidized into iodine, since iodide is not CLactive, subsequent separation from the oxidant used which could interfere with the CL determination is also required. 2,3,8 One of the effective methods of preconcentration and separation of iodine from such interferents as oxidant and metallic species is its extraction with a suitable organic solvent. Yasuda Women's College, Yasuhigashi, Japan To eliminate the use of chlorinated hydrocarbons, we have improved the method for...

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“…Thus, the solvolysis of anisoyl chloride was found to always be faster in cationic microemulsions (TTABr/hexanol/ isooctane/water), TTABr being tetradecyltrimethylammonium bromide, than in the case of anionic ones (SDS/hexanol/ isooctane/water); also, the k + /k -ratio increased with decreasing water content in the microemulsion. 21 This effect can be ascribed to the release of the leaving group, Cl -, being more favorable in the presence of cationic TTABr headgroups than in that of anionic SDS headgroups. By contrast, Bunton et al 22 found the k + /k -ratio in aqueous micelles to be only 0.1.…”

Section: Discussionmentioning

confidence: 99%

AOT-Based Microemulsions Accelerate the 1,3-Cycloaddition of Benzonitrile Oxide to N-Ethylmaleimide

et al. 2006

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We studied the 1,3-dipolar cycloaddition of benzonitrile oxide to N-ethylmaleimide in AOT/isooctane/water microemulsions at 25.0 degrees C and found the reaction rate to be roughly 150 and 35 times greater than that in isooctane and pure water, respectively. The accelerating effect of the microemulsion is the combined result of an increase in the local concentrations of the reactants through incorporation into the interface and of the intrinsic rate of the process through electrostatic interactions with the headgroups in the surfactant.

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Reactivity of Typical Solvolytic Reactions in SDS and TTABr Water-in-Oil Microemulsions

Cited by 22 publications

References 68 publications

Micellization versus Cyclodextrin–Surfactant Complexation

Micellization versus Cyclodextrin–Surfactant Complexation

An Improved Method for the Flow-Injection Determination of Iodine Using the Luminol Chemiluminescence Reaction in a Reversed Micellar Medium of Cetyltrimethylammonium Chloride in 1-Hexanol-Cyclohexane

AOT-Based Microemulsions Accelerate the 1,3-Cycloaddition of Benzonitrile Oxide to N-Ethylmaleimide

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