ChemInform Abstract: INFLUENCE OF COUNTERION BINDING ON MICELLAR REACTION RATES. REACTION BETWEEN P-NITROPHENYL ACETATE AND HYDROXIDE ION IN AQUEOUS CETYLTRIMETHYLAMMONIUM BROMIDE

1979 ◽  
Vol 10 (20) ◽  
Author(s):  
M. ALMGREN ◽  
R. RYDHOLM
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Reaction Rates ◽  
Counterion Binding ◽  
Hydroxide Ion

scholarly journals Kinetics of Reduction of Colloidal MnO2 by Glyphosate in Aqueous and Micellar Media

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Uzma Aisha ◽  
Qamruzzaman ◽  
M. Z. A. Rafiquee
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Binding Constants ◽  
Reaction Rates ◽  
Lauryl Sulfate ◽  
Micellar Media ◽  
First Order Kinetics ◽  
Rate Of Reaction ◽  
Colloidal Mno2 ◽  
Kinetics Of ◽  
Kinetics Of Reduction

The kinetics of the reduction of colloidal MnO2 by glyphosate has been investigated spectrophotometrically in an aqueous and micellar (cetyltrimethylammonium bromide, sodium lauryl sulfate) media. The reaction follows first-order kinetics with respect to colloidal MnO2 in both the aqueous and micellar media. The rate of oxidation increases with increase in [glyphosate] in the lower concentration range but becomes independent at its higher concentrations. The addition of both the anionic (NaLS) and cationic (CTAB) micelles increased the rate of reduction of colloidal MnO2 by glyphosate while the nonionic TX-100 micelles did not influence the rate of reaction. In both aqueous and micellar media, the oxidation of glyphosate occurs through its adsorption over colloidal MnO2 surface. The reaction in micellar media was treated by considering the pseudophase model. The values of reaction rates and binding constants in the presence of micelles were determined.

Micellar catalysis of organic reactions. Part 33. Amide hydrolysis in neutral solution in the presence of a copper-containing micelle

1993 ◽  
Vol 71 (5) ◽  
pp. 670-673 ◽  
Author(s):  
Trevor J. Broxton ◽  
Robin A. Coa
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Cupric Chloride ◽  
Buffer Concentration ◽  
Neutral Solution ◽  
Hydroxide Ion ◽  
Amide Hydrolysis ◽  
Mechanism Of Reaction ◽  
Rate Of Reaction ◽  
Hydrolysis Of ◽  
Micelle Surface

The hydrolysis of 5-nitro-2-(trifluoroacetylamino)benzoic acid (1) has been studied at pH 7 in water and in the presence of micelles of cetyltrimethylammonium bromide (ctab) and of copper-containing micelles formed from the reaction of N,N,N′-trimethyl-N′-hexadecylethylenediamine and cupric chloride. It has been found that the hydrolysis of 1 is inhibited by micelles of ctab but strongly catalysed by the copper-containing micelle at this pH. At a higher pH where the hydroxide ion reaction becomes important the reaction is catalysed by micelles of ctab as well, but the catalysis is stronger by the copper-containing micelle. The effect of added sodium chloride on the rate of reaction is shown to be larger for reaction in the presence of ctab than for reaction in the presence of the copper micelles. Also reported are the effects of the buffer concentration on the rate of reaction at various pH for both micelles. It is concluded that the mechanism of reaction in the copper-containing micelle involves a metal-bound hydroxyl rather than a free hydroxide ion loosely associated with the cationic micelle surface. It is interesting that the catalysis of this reaction by the copper-containing micelle is large enough to allow amide hydrolysis at a reasonable rate at neutral pH at ambient temperature.

Reaction of hydroxide ion with 1,3,5-trinitrobenzene in cationic micelles: evidence of variable counterion binding to micellar head groups

1985 ◽  
Vol 63 (3) ◽  
pp. 598-601 ◽  
Author(s):  
Leong-Huat Gan
Keyword(s):  
Rate Constant ◽  
Hexadecyltrimethylammonium Bromide ◽  
Ion Distribution ◽  
Counterion Binding ◽  
Hydroxide Ion ◽  
Micellar Systems ◽  
Cationic Micelles ◽  
Head Groups ◽  
Distribution Constants ◽  
The Stability

Cationic micelles of hexadecyltrimethylammonium bromide, chloride, and hydroxide (CTABr, CTACl, and CTAOH) greatly enhance the stability of anionic σ-complex formed by hydroxide ion and 1,3,5-trinitrobenzene (TNB). The counterion binding to the micellar head groups is assumed to vary but is governed by a distribution constant. Different distribution constants are used for different types of counterion. Using this treatment, the rate constant – surfactant concentration profiles for the reactions of TNB with hydroxide ion in CTAOH, CTABr, and CTACl can all be satisfactorily accounted for, yielding consistent results in various conditions. The ion distribution constants, KOH = 55 mol−1 dm3, KBr = 1800 mol−1 dm3, and KCl = 420 mol−1 dm3 and the rate constant KM = 3600 s−1 are obtained. In view of the success of this treatment, the assumption of a constant β value associated with the pseudophase model at best could only be viewed as an approximation, valid only for micellar systems with tightly bound counterions such as those in the micelles of CTABr.

Basic hydrolysis of some alkyl and phenyl N-Aryl-N-methylcarbamates

1983 ◽  
Vol 36 (11) ◽  
pp. 2203 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Rate Constants ◽  
Cetyltrimethylammonium Bromide ◽  
Ester Hydrolysis ◽  
Micellar Catalysis ◽  
Bond Breaking ◽  
Methyl Ethyl ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Rate constants for the basic hydrolysis of methyl, ethyl and phenyl N-aryl-N-methylcarbamates in the presence and absence of micelles of cetyltrimethylammonium bromide are reported. Hammett plots for the methyl and ethyl carbamates were curved, and this is explained by consideration of the competition between C-N and C-OR bond breaking for decomposition of the tetrahedral intermediate. In one case (p-nitro-substituted), rate-determining formation of the tetrahedral intermediate is suggested, whereas for other compounds rate-determining C-N bond breaking or C-OR bond breaking is proposed. Micellar catalysis for each of the reactions is reported, and large catalysis (× 50) was observed for compounds where C-N bond breaking was kinetically significant. This is compared with results in the literature for amide and ester hydrolysis. Whereas, for ester hydrolysis, loss of alkoxide ion from the tetrahedral intermediate is favoured over loss of hydroxide ion, in carbamate hydrolysis, loss of hydroxide ion is favoured. A possible reason for this reversal of nucleofugicity of OH- and OR- is proposed.

scholarly journals Quantitative analysis of micellar effect on the reaction rate of alkaline fading of phenolphthalein

2018 ◽  
Keyword(s):  
Quantitative Analysis ◽  
Ion Exchange ◽  
Kinetic Data ◽  
Cetyltrimethylammonium Bromide ◽  
Reaction Rate ◽  
Hydroxide Ion ◽  
Micellar Systems ◽  
Brij 35 ◽  
Quantitative Treatment ◽  
Micellar Effect

Quantitative treatment of the kinetic data of the reaction between phenolphthalein dianion and hydroxide ion in aqueous solutions containing variable concentration of various surfactants is presented. Following surfactants are used: Brij-35 (nonionic), sodium n-dodecyl sulfate (anionic), cetyltrimethylammonium bromide (cationic) and 3-(dimethyl-n-dodecylammonio)-propansulfonate (zwitterionic). The quantitative treatment is carried out basing of Piszkiewicz’s, Berezin’s, and Pseudophase Ion-Exchange (PIE) models. It is revealed that the Berezin’s model is a more applicable one for describing the effect of nonionic, anionic, and zwitterionic micellar systems. The values of the corresponding kinetic parameters are discussed. The effect of cetyltrimethylammonium hydroxide on the reaction is also examined and quantitatively described by the PIE model. The research of systems based on a cationic surfactant shows previously unknown effect called by us as “diverting influence”.

SEM analysis of the change in the reaction rates with deposit structures in the copper-iron cementation system

1978 ◽  
Vol 36 (1) ◽  
pp. 456-457
Author(s):  
V. Annamalai ◽  
L.E. Murr
Keyword(s):  
Structural Characteristics ◽  
Secondary Electron Emission ◽  
Copper Deposit ◽  
Reaction Rates ◽  
Sem Analysis ◽  
Experimental Conditions ◽  
Major Drawback ◽  
Emission Mode ◽  
Scrap Iron ◽  
Image Position

Economical recovery of copper metal from leach liquors has been carried out by the simple process of cementing copper onto a suitable substrate metal, such as scrap-iron, since the 16th century. The process has, however, a major drawback of consuming more iron than stoichiometrically needed by the reaction.Therefore, many research groups started looking into the process more closely. Though it is accepted that the structural characteristics of the resultant copper deposit cause changes in reaction rates for various experimental conditions, not many systems have been systematically investigated. This paper examines the deposit structures and the kinetic data, and explains the correlations between them.A simple cementation cell along with rotating discs of pure iron (99.9%) were employed in this study to obtain the kinetic results The resultant copper deposits were studied in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25kV in the secondary electron emission mode.

Sign in / Sign up

Export Citation Format

Share Document