Kinetic investigation of the base hydrolysis of the chloropentaamminecobalt(III) ion in micellar sodium dodecyl sulfate solution

Calvaruso, Giuseppe; Cavasino, F. Paolo; Dio, Emanuele Di

doi:10.1016/s0020-1693(00)81326-2

Cited by 11 publications

(6 citation statements)

References 27 publications

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“…This reaction scheme considers that the hydrophilic hydroxide anions are conÐned to the outer aqueous compartment, while, in accordance with the pseudophase ion-exchange (PPIE) model,5,12 there is competition between the dipositive cobalt(III) complex ions and sodium cations for the association with the negatively charged exterior vesicular surface. Therefore, in the most general case, two reaction paths involving the hydroxide ion in the aqueous phase and the cobalt complex solubilized in both the aqueous region and the vesicular surface may contribute to the progress of the hydrolysis reaction (1).…”

Section: Resultsmentioning

confidence: 99%

“…In previous studies we have investigated the kinetics of the alkaline hydrolysis of the cationic chloropentaamminecobalt(III) complex [reaction (1)] in aqueous solutions of anionic SDS (sodium dodecyl sulfate) micelles in the absence1 and in the presence of some alkyl-substituted ureas2 and in aqueous mixed micellar solutions3 of SDS and the nonionic surfactant over the whole…”

Section: Introductionmentioning

confidence: 99%

“…H] SDS mole fraction range. The choice of reaction (1) in these studies was dictated, apart from the simplicity of the wellknown rate law1h5 followed under the experimental conditions used, by the fact that only the dipositive cobalt(III) complex cation is bound to the micellar SDS surface by electrostatic interactions, the extent of complex binding depending on the micelle surface charge density (the hydrophilic and negatively charged hydroxide ions are conÐned to the intermicellar aqueous region). The binding constants of the complex under di †erent experimental conditions have been easily estimated from the kinetic data obtained.…”

Section: Introductionmentioning

confidence: 99%

“…The binding constants of the complex under di †erent experimental conditions have been easily estimated from the kinetic data obtained. The selected reaction (1) has been shown to be a useful model system for the study of the role of the electrostatic interactions involved in the association of the cobalt(III) complex with anionic micellar aggregates and of the e †ect of additives on the charge density at the negatively charged micellar surface.…”

Section: Introductionmentioning

confidence: 99%

“…OH2`] Cl~ (1) In the present work we have extended the kinetic investigation of reaction (1) to aqueous solutions containing anionic vesicular aggregates of the double-chain surfactant sodium dihexadecylphosphate (DHP). Aqueous DHP vesicles6,7 are well characterized systems and have been mainly utilized as media in catalysis and photochemical energy conversion and storage.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of the chloropentaamminecobalt(III) cation with dihexadecylphosphate vesicles in the absence and the presence of poly(propylene glycol). A kinetic study

Cavasino¹,

Stefano²,

Sbriziolo³

et al. 1999

Phys. Chem. Chem. Phys.

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The electrostatic interaction between the cationic chloropentaamminecobalt(III) complex and the exterior anionic surface of sodium dihexadecylphosphate (DHP) vesicles in the absence and the presence of varying amounts of the polymer PPG-425 [poly(propylene glycol) with has been studied at 25.0 ¡C by M w\ 425] examining the vesicular retarding e †ects on the kinetics of the alkaline hydrolysis of the cobalt(III) complex. The kinetic data indicate that two reaction paths contribute to the overall hydrolysis rate. In the absence of polymer the interactions involving the cobalt complex, as deduced from the estimated binding constant (K A), are markedly larger than those found previously with anionic micelles of sodium dodecyl sulfate (SDS). Moreover, the rate constant for the pathway involving the hydroxide ion in the outer aqueous vesicular (k v A) compartment and the complex solubilized in the exterior vesicle surface is smaller than the corresponding rate constant obtained with SDS micelles. These results suggest the existence of greater charge density at the DHP vesicular surface. In the presence of polymer both and parameters remain substantially unchanged up to K A k v A the polymer content of 0.30%, but the binding constant undergoes a decrease and the rate constant an k v A increase at higher polymer concentration. These Ðndings are primarily attributed to the decrease in the charge density of the external vesicular surface induced by the polymer penetration.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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