Effects of Nonionic and Mixed Cationic–Nonionic Micelles on the Rate of Alkaline Hydrolysis of 4-Nitrophthalimide

Khan, M. Niyaz; Ismail, Emran

doi:10.1006/jcis.2001.7638

Cited by 11 publications

(2 citation statements)

References 22 publications

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“…But such unusual observations were not obtained in the presence of C 16 E 20 micelles under essentially similar conditions. , The observed data, obtained at R < R t , fit satisfactorily to the PM model of the micelle. Perhaps the most unusual observation, revealed by recent studies, ,, is an apparent depletion of hydroxide ions and water molecules from C 12 E 23 micellar environment where organic substrate molecules (sub = PSH, PB, phthalimide, and 4-nitrophthalimide) reside, and consequently, it causes irreversible trapping of sub molecules by micelles at R values > R t . Such irreversible micellar trapping of sub molecules is expected to increase with the increase in hydrophobicity of sub molecules.…”

Section: Introductionmentioning

confidence: 98%

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

2007

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Pseudo-first-order rate constants (k(obs)) for alkaline hydrolysis of N-benzylphthalimide (1) show a nonlinear decrease with the increase in [C(m)E(n)]T (total concentration of Brij 58, m = 16, n = 20 and Brij 56, m = 16, n = 10) at constant [CH(3)CN] and [NaOH]. These nonionic micellar effects, within the certain typical reaction conditions, have been explained in terms of the pseudophase micellar (PM) model. The values of micellar binding constants (KS) of 1 are 1.04 x 10(3) M(-1) (at 1.0 x 10(-3) M NaOH) and 1.08 x 10(3) M(-1) (at 2.0 x 10(-3) M NaOH) for C(16)E(20) as well as 600 M(-1) (at 7.6 x 10(-4) M NaOH) and 670 M(-1) (at 1.0 x 10(-3) M NaOH) for C(16)E(10) micelles. The pseudo-first-order rate constants (kM) for hydrolysis of 1 in C(16)E(20) micellar pseudophase are approximately 90-fold smaller than those (kW) in water phase. The values of kM for hydrolysis of 1 in C(16)E(10) micelles are almost zero. Kinetic coupled with UV spectral data reveals significant irreversible nonionic micellar binding of 1 molecules in the micellar environment of nearly zero hydroxide ion concentration at >or=0.14 M C(16)E(20) and 1.0 x 10(-3) M NaOH while such observations could not be detected at or=3 x 10(-3) M C(16)E(10) and 7.6 x 10(-4) M NaOH, while the rate of hydrolysis of 1 is completely ceased at >or=0.05 M C(16)E(10) and 7.6 x 10(-4) M NaOH. The rate of hydrolysis of 1 at 5.0 x 10(-2) and 8.8 x 10(-2) M C(16)E(10) and 1.0 x 10(-3) M NaOH reveals the formation of presumably phthalic anhydride, whereas such observation was not observed in the C(16)E(20) micellar system under similar experimental conditions.

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Section: Introductionmentioning

confidence: 98%

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

2007

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“…To benefit from the strong electric contribution to the catalysis phenomenon, most of the investigations have been carried out with charged surfactant solutions. , On the other hand, few studies have investigated bimolecular reactions between a neutral reagent and an ionic species in the presence of micelles of neutral amphiphiles. 7c, However, this system must be investigated with care. Indeed, if one carefully analyzes the values of the equilibrium and rate constants obtained in the case of catalysis by the cationic amphiphiles (DTABr and CTABr), for example for the addition of hydroxide ion to 1,3,5-trinitrobenzene, one notices an important acceleration of the rate of attack by OH - relative to that in water and simultaneously a strong decrease in the reverse rate of reaction corresponding to the destruction of the monoadduct.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics and Kinetics in Micellar Media. Reaction of the Hydroxide Ion with 1,3,5-Trinitrobenzene in Aqueous Solutions of a Neutral Nonionic Surfactant. Effect of the Concentration of Background Electrolyte

Gall¹,

Loppinet-Serani²,

Letellier³

2003

J. Phys. Chem. B

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The use of a neutral surfactant (Brij 35) allows us to investigate its influence upon the kinetics of the reaction between a neutral substrate and a charged reactant. The thermodynamic description of a micellar system can be obtained by introducing a variable of area in the expression of the internal energy. Thus, the content of micellar solutions is separated into two components: a volume content associated with dimension 3, and an area content associated with dimension 2. The volume is an extensive parameter and a homogeneous function of degree unity of its content, but the area is not necessarily an extensive function and does not vary linearly with content. In this way, we can describe the evolution of the behavior of micellar solutions when the concentration of surfactant increases. We introduce the notion of “micellar catalysis” in terms of an increase of the exchange rate at equilibrium, m v 0, for the studied reaction. The formal separation of the content of the solution into two components with different dimensions leads us to suppose a difference in reactivity. The exchange rate associated with the content of dimension 2 equals 40 times the one associated with the content of dimension 3.

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Study of the reaction methyl 4‐nitrobenzene‐sulfonate + Cl⁻ in mixed hexadecyltrimethyl‐ammonium chloride‐triton X‐100 micellar solutions

Fernández

Rodrı́guez

Graciani

et al. 2002

Int J of Chemical Kinetics

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The reaction methyl 4-nitrobenzenesulfonate + Cl − was studied in hexadecyltrimethylammonium chloride (CTAC) in the absence and presence of 0.1 M NaCl, as well as in mixed CTAC/Triton X-100 (polyoxyethylene(9.5)octylphenyl ether) aqueous micellar solutions with CTAC molar fractions of 0.9, 0.8, 0.7, and 0.6. Conductivity measurements were used to obtain critical micellar concentrations and micellar ionization degrees of the various micellar reaction media. From these data, thermodynamic information on the cationic/nonionic mixed micellar solutions was obtained. Micellar effects on the observed rate constant were explained by pseudophase kinetic models. The estimated second-order rate constants in the micellar pseudophase of the different micellar reaction media showed that pure CTAC and mixed CTAC/Triton X-100 micelles, at the high cationic surfactant molar fractions studied, provide reaction sites of similar characteristics at the interfacial region. This was in agreement with previous structural studies carried out on mixed CTAC/Triton X-100 micellar solutions. C 2002

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Effects of Nonionic and Mixed Cationic–Nonionic Micelles on the Rate of Alkaline Hydrolysis of 4-Nitrophthalimide

Cited by 11 publications

References 22 publications

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

Thermodynamics and Kinetics in Micellar Media. Reaction of the Hydroxide Ion with 1,3,5-Trinitrobenzene in Aqueous Solutions of a Neutral Nonionic Surfactant. Effect of the Concentration of Background Electrolyte

Study of the reaction methyl 4‐nitrobenzene‐sulfonate + Cl⁻ in mixed hexadecyltrimethyl‐ammonium chloride‐triton X‐100 micellar solutions

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Effects of Nonionic and Mixed Cationic–Nonionic Micelles on the Rate of Alkaline Hydrolysis of 4-Nitrophthalimide

Cited by 11 publications

References 22 publications

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

Kinetic Coupled with UV Spectral Evidence for Near-Irreversible Nonionic Micellar Binding of N-Benzylphthalimide under the Typical Reaction Conditions: An Observation Against a Major Assumption of the Pseudophase Micellar Model

Thermodynamics and Kinetics in Micellar Media. Reaction of the Hydroxide Ion with 1,3,5-Trinitrobenzene in Aqueous Solutions of a Neutral Nonionic Surfactant. Effect of the Concentration of Background Electrolyte

Study of the reaction methyl 4‐nitrobenzene‐sulfonate + Cl− in mixed hexadecyltrimethyl‐ammonium chloride‐triton X‐100 micellar solutions

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Study of the reaction methyl 4‐nitrobenzene‐sulfonate + Cl⁻ in mixed hexadecyltrimethyl‐ammonium chloride‐triton X‐100 micellar solutions