Electrolyte effects on the cationic micelle catalyzed decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion

We investigated the viscoelasticity of aqueous threadlike micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), and additives, sodium p-toluenesulfonate (NapTS) and sodium salicylate (NaSal). The dependence of the rheological longest relaxation time (τ m ) on a molar ratio of pTS − relative to that of Sal − in the interior of threadlike micelles was mainly discussed. The value of τ m was dependent on the ratio and also on the total concentration (C * S ) of free pTS − and Sal − anions in the bulk aqueous phase at C * S < 30 mmol kg −1 . On the other hand, the value of τ m in the solutions with the molar ratio in the micellar interior higher than 0.5 exhibited the same C * S dependence at C * S > 50 mmol kg −1 as observed in a threadlike micellar system formed by CTAB and NaSal. These imply that the entanglement relaxation mechanism in the threadlike micellar system is influenced by both the microstructure of the threadlike micelles and the C *

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“…Chemical shift values (δ) for ring protons of pTS − or Sal − are sensitive to chemical microenvironment or polarity around them (3,5,9 …”

Section: H Nmr Measurementsmentioning

confidence: 99%

Viscoelastic Behavior of Surfactant Threadlike Micellar Solutions: Effect of Additives 3

Imai

Shikata

2001

Journal of Colloid and Interface Science

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“…The study is also important from the viewpoint that various suitable surfactants (e.g., Gemini surfactants [31,32] or mixed surfactants [33]) could be tried to study the ninhydrin reaction for enhanced sensitivity. Finally, we can conclude that the interaction of Gly-Gly with ninhydrin in micellar media could successfully be treated using the pseudo-phase and Piszkiewicz models.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and mechanism of interaction of dipeptide (glycyl–glycine) with ninhydrin in aqueous micellar media

Akram¹,

Zaidi²,

Kabir-ud-Din³

2006

Int J of Chemical Kinetics

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The rates of reaction between ninhydrin and dipeptide glycyl-glycine (Gly-Gly) have been determined by studying the reaction spectrophotometrically at 70 • C and pH 5.0 in aqueous and in aqueous cationic micelles of cetyltrimethylammonium bromide (CTAB). The reaction follows first-and fractional-order kinetics, respectively, in [Gly-Gly] and [ninhydrin]. The observed rate constant is affected by [CTAB] changes and the maximum rate enhancement is ca. three-fold. As the k ψ − [CTAB] profile shape is characteristic of bimolecular reactions catalyzed by micelles, the catalysis is explained in terms of the pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton and Romsted). The presence of inorganic salts (NaCl, NaBr, Na 2 SO 4 ) does not reveal any regular effect but the data with organic salts (NaBenz, NaSal) show an increase in the rate followed by a decrease. The kinetic data have been used to calculate the micellar binding constants K S for Gly-Gly and K N for ninhydrin and the respective values are 317 and 69 mol −1 dm 3 .

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“…The present studies are important from the viewpoint that various suitable surfactants (e.g., gemini surfactants (17,33) or mixed surfactants (34) could be tried to study the ninhydrin reaction for enhanced sensitivity.…”

Section: (I) Effect Of Inorganic Saltsmentioning

confidence: 99%

“…It is well known that the addition of a salt decreases the electrostatic interactions between monomers in the micelle and also affects the partitioning of organic compounds between micelles and bulk solvent (15). Micellar catalysis can be enhanced by adding some salts indicating that the rate enhancement is sensitive to changes in micellar morphology and charge density (16,17).…”

Section: Introductionmentioning

confidence: 99%

Effect of Cationic Micelles on the Kinetics of Interaction of Ninhydrin withl-Leucine andl-Phenylalanine

Kabir-ud-Din

Salem

Kumar

et al. 1999

Journal of Colloid and Interface Science

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Electrolyte effects on the cationic micelle catalyzed decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion

Cited by 187 publications

References 7 publications

Viscoelastic Behavior of Surfactant Threadlike Micellar Solutions: Effect of Additives 3

Viscoelastic Behavior of Surfactant Threadlike Micellar Solutions: Effect of Additives 3

Kinetics and mechanism of interaction of dipeptide (glycyl–glycine) with ninhydrin in aqueous micellar media

Effect of Cationic Micelles on the Kinetics of Interaction of Ninhydrin withl-Leucine andl-Phenylalanine

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