共查询到20条相似文献,搜索用时 818 毫秒
1.
R. F. Bakeeva L. A. Kudryavtseva G. Eme E. M. Kosacheva V. E. Bel'skii D. B. Kudryavtsev R. R. Shagidullin V. F. Sopin 《Russian Chemical Bulletin》1998,47(8):1454-1459
The influence of micellar (Mi) and hexagonal (E) mesophases of the cetyldimethylethylammonium bromide—NaOH—water system (I) on the rates on alkaline hydrolysis ofO-p-nitrophenyl-O,O-diethyl phosphate (2),O-p-nitrophenyl-O-ethylethyl phosphonate (3), andO,O-di(p-nitrophenyl)methyl phosphonate (4) was studied by UV spectrophotometry. The binding constants of the substrates, critical micelle concentrations, and rate
constants of reactions in the micellar phase were determined. In micellar solutions of systemI, a tenfold increase in the rates of alkaline hydrolysis of2–4 was observed. An increase in the degree of medium ordering during the formation of the E-phase results in a twofold acceleration
of alkaline hydrolysis of2 and3 and in the inhibition of this process in the case of4.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1499–1504, August, 1998. 相似文献
2.
Alexander P. Boichenko Le Thi Kim Dung Lidia P. Loginova 《Journal of solution chemistry》2011,40(6):968-979
The apparent dissociation constants of 1-propanoic, 1-butanoic, 1-pentanoic and 1-hexanoic acids were obtained for the first
time in Brij 35 micellar solutions with concentration from 0.03 to 0.20 mol⋅L−1 and sodium dodecyl sulfate (SDS) micellar solutions with concentrations from 0.01 to 0.30 mol⋅L−1. A pronounced effect of Brij 35 micelles on the acid-base properties of aliphatic acids was observed. The binding constants,
K
b, of carboxylic acids to micellar pseudophases of SDS and Brij 35 were estimated within the framework of the pseudophase model.
The dependences of Gibbs energies of transfer from water to the micellar pseudophases were constructed, and Gibbs energies
were evaluated for methylene and carboxylic group transfers into Brij 35 and SDS micelles. Comparison of the Gibbs energies
of methylene group transfer from water to Brij 35 and SDS suggests that the mechanisms of hydrocarbon group transfer into
the core of nonionic and anionic micelles involving the same monomer hydrophobic tail length are similar. 相似文献
3.
L. N. Vakhitova S. V. Zhil’tsova A. V. Skrypka N. G. Razumova N. A. Taran V. A. Savelova A. F. Popov 《Theoretical and Experimental Chemistry》2006,42(5):287-294
The kinetics and mechanism of the catalysis by ammonium hydrogen carbonate oxidation of methyl phenyl sulfide with hydrogen
peroxide has been investigated. Using the classical pseudo-phase model of micellar catalysis, the basic parameters of the
catalytic process have been determined: the binding constants of H2O2, the HCO
4
−
anion, and the substrate to the surface of the micelles, and also the second order rate constants for the oxidation of methyl
phenyl sulfide in the micellar phase.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 281–287, September–October, 2006. 相似文献
4.
Effect of dioctyl sulfide on the kinetics of oxidative dissolution of gold nanoparticles in triton N-42 reverse micelles 总被引:1,自引:0,他引:1
V. V. Tatarchuk A. I. Bulavchenko I. A. Druzhinina A. P. Sergievskaya 《Russian Journal of Inorganic Chemistry》2011,56(5):808-815
The effect of additions of hydrophobic dioctyl sulfide (L) on the kinetics of dissolution of gold nanoparticles in the interaction
with a dispersed aqueous hydrochloric solution of H2O2 in Triton N-42 reverse micelles (decane was the dispersion medium) was studied spectrophotometrically. The process consists
of a two-stage oxidation Au0 → AuCl2− → AuCl4− at the surface of gold particles; the first stage occurs in two ways: a spontaneous reaction and an autocatalytic reaction
involving AuCl4− ions. With small additions of L (c
L < c
Au), only spontaneous oxidation of Au(0) to Au(I) takes place because Au(I) is completely bound in an inert complex AuLCl. When
unbound L is exhausted, the newly formed AuLCl is accumulated in micellar shells, changes the properties of the medium inside
the micelles, and affects the rate constant of the autocatalytic reaction, which increases with increasing c
L. At high concentrations of L, the coagulation of particles occurs instead of their dissolution, because of the deterioration
of the protective properties of micellar shells as a result of the ingression and accumulation of dioctyl sulfide molecules
on account of selective adsorption on gold particles. The rate constants of all stages of dissolution and coagulation are
determined. 相似文献
5.
R. F. Bakeeva L. A. Kudryameva V. E. Bel'skii S. B. Fedorov B. E. Ivanov 《Russian Chemical Bulletin》1996,45(8):1900-1903
The effect ofn-decylammonium chloride/n-decylamine mixed micelles on the rate of hydrolysis of aryl esters of acids of four-coordinate phosphorus was studied spectrophotometrically. The shape of the concentration curves is characteristic of the micellar catalysis reactions. The binding constants of the substrate, critical micelle concentrations, and the rate constants in the micellar phase were determined. A specific effect of the structure of substrates on these parameters was shown.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2003–2006, August, 1996. 相似文献
6.
Quenching kinetics of the 4,4′-dimethylbenzophenone triplet state with para-substituted phenol derivatives RC6H4OH (R = H, F, Cl, Br, I) was studied by nanosecond laser photolysis in aqueous micellar solutions of sodium dodecyl sulfate.
The kinetic data were processed in the framework of a model with the Poisson distribution of phenols between micelles. The
partition constants of RC6H4OH between the aqueous and micellar phases and the rate constants of their escape from a micelle and quenching of the 4,4′-dimethylbenzophenone
triplet state with phenols in micelles were obtained. The quenching proceeds with high rate constants through hydrogen atom
transfer to form the ketyl and phenoxyl radicals (no radicals are formed in the case of 4-iodophenol), which then recombine
in a micelle or escape into the outer aqueous volume. The application of an external magnetic field retards radical pair recombination
in a micelle and increases the fraction of radicals escaped into the aqueous phase. The quantum yield of radical pairs decreases
2.5-fold, and the rate of their recombination in micelles increases 2.5-fold on going from 4-chloro- to 4-bromophenol. This
is caused by the acceleration of triplet radical pair recombination in the solvent cage.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1391–1396, June, 2005. 相似文献
7.
A. I. Kazakov Yu. I. Rubtsov L. P. Andrienko G. B. Manelis 《Russian Chemical Bulletin》1997,46(10):1694-1699
The rates of heat release in the nitrogen dioxide—n-decane system at a molar ratio of nitrogen oxides ton-decane (β) from 2.4·10−3 to 3.1 and gaseous volumes per mole ofn-decane (V(g)) equal to 0.05–4.5 were studied in the 55.2–92.8 °C temperature range. The initial rate of the process is determined by
the interaction of NO2 withn-decane. The equilibrium constants of dissociation of N2O4 inn-decane and Henry's constants of NO2 and N2O4 in ann-decane solution were determined by complex analysis of the thermodynamic equilibrium in the NO2—n-decane system and dependences of the initial rates onV(g) and β. The experimentally observed self-acceleration of the process in the region of high β and lowT values was suggested to be due to the reaction of N2O4 with intermediate oxidation products. The rate constants of the reaction of NO2 withn-decane were compared with analogous values determined in its mixtures with HNO3 solutions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1789–1794, October, 1997. 相似文献
8.
L. Ya. Zakharova F. G. Valeeva A. R. Ibragimova L. A. Kudryavtseva Yu. F. Zuev L. V. Avvakumova V. I. Kovalenko A. I. Konovalov 《Russian Chemical Bulletin》2007,56(1):62-69
The kinetics of alkaline hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate in a sodium bis(2-ethylhexyl)sulfosuccinate—n-nonane—polyethylene glycol—water reverse micellar system was studied in a wide range of concentrations of the surfactant
and water. The sign of the catalytic effect of micelles is inverted in the presence of the polymer. A sharp change in the
apparent rate constant of hydrolysis of the phosphonate was found in a region of the temperature percolation threshold.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 60–67, January, 2007. 相似文献
9.
A. B. Mirgorodskaya L. A. Kudryavtseva L. Ya. Zakharova V. E. Bel'skii 《Russian Chemical Bulletin》1998,47(7):1296-1301
The effects of cetylpyridinium bromide (CPB) on the acid-base equilibria of primary aliphatic amines and on the kinetics of
reactions of the amines withp-nitrophenyl acetate (PNPA) andp-nitrophenyl caprylate (PNPC) were studied by potentiometric titration and UV spectroscopy. The values of apparent pK
a of the amines in the micellar phase, binding constants of their neutral forms, and the surface potentials of micelles were
determined. Cetylpyridinium bromide accelerates the aminolysis of PNPA by factors of 3 to 8 by forming mixed micellar aggregates
with the amines. The shift of pK
a values of the amines in micellar solutions is not the only factor that enhances their reactivity. The substrate specificity
was found: in contrast to the reaction with PNPA, CPB accelerates (by factors of 15 to 65) or retards (by factors of 4 to
6) the aminolysis of PNPA depending on the hydrophobicity of the nucleophilic reagent. The binding constants of substrates,
the rate constants in the micellar phase, and the critical concentrations of micellization were determined from the data obtained.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1333–1338, July, 1998. 相似文献
10.
K. Fukada M. Kawasaki T. Seimiya Y. Abe M. Fujiwara K. Ohbu 《Colloid and polymer science》2000,278(6):576-580
The apparent molar volume and the apparent molar adiabatic compressibility of the sugar-based surfactants methyl 6-O-octanoyl-α-d-glucopyranoside (α-MOnG), methyl 6-O-octanoyl-β-d-glucopyranoside (β-MOnG), and octyl β-d-glucoside were measured over a wide concentration range. Also, the aggregation number of their micelles was determined from
the Debye plot using static light scattering data. It was found that the micellar aggregation number for α-MOnG is 179 at
35 °C, which is 1.5 times larger than that for β-MOnG, suggesting that the anomerism of the head group influences the packing
of the monomers during micelle formation.
Received: 30 September 1999 Accepted: 15 December 1999 相似文献
11.
Kinetics of the decay of the transient radicals formed from 2,2,4,6-tetramethyl-1,2-dihydroquinoline (TMQ) in aqueous and
micellar solutions of sodium dodecyl sulfate were studied by flash photolysis as a function of pH. In aqueous and micellar
solutions of TMQ the mechanism of the decay of the transient species and the reaction products are different from those in
homogeneous organic solutions. The decay of the transient radicals follows first-order kinetics in the entire range of pH
under consideration in both aqueous and micellar solutions. In aqueous solutions at pH 9–12, the decay rate constant decreases
from 25.3 to 3.7 s−1. In micellar solutions at different pH, different types of micellar catalysis were observed. At pH 1, the rate constant in
a micellar solution is slightly lower than that in an aqueous solution. At pH 3–11, the decay rate constant increases (positive
micellar catalysis). The apparent rate constant depends linearly on the concentration of TMQ in micelles. The rate constant
for the reaction of the transient radical cation with TMQ was determined (200 L mol−1 s−1). At pH>13, the decay rate constant in micelar solutions is lower than that in aqueous solutions (negative micellar catalysis).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 703–708, April, 1997. 相似文献
12.
Valeeva F. G. Zakharov A. V. Voronin M. A. Zakharova L. Ya. Kudryavtseva L. A. Isaikina O. G. Kalinin A. A. Mamedov V. A. 《Russian Chemical Bulletin》2004,53(7):1563-1571
The data are presented on the synthesis of podands with terminal quinoxaline fragments of rings and their influence on both the micellization properties of cetyltrimethylammonium bromide in a water—DMF solution and kinetics of basic hydrolysis of O-p-nitrophenyl O-ethyl chloromethylphosphonate and O-p-nitrophenyl O-hexyl chloromethylphosphonate in the absence and presence of surfactants. The mechanism of the podand effect on the reaction rate depends on the structures of phosphonate and podand. 1,8-Bis(3-ethyl-1,2-dihydro-2-oxoquinoxalin-1-yl)-3,6-dioxaoctane inhibits the basic hydrolysis of the substrates to 3—4 times. In a micellar solution of the surfactant, an approximately 20-fold acceleration of the reaction rate constant is observed. The observed rate constant decreases when podand is added to a micellar solution. The catalytic effect of the polycomponent system is due to concentrating of the reactants. The micellar microenvironment can exert both positive and negative effects on the reactivity of phosphonates. 相似文献
13.
The oxidative degradation of d-xylose by cerium(IV) has been found to be slow in acidic aqueous solution with the evidence of autocatalysis. The reaction is accelerated in the cetyltrimethylammonium bromide (CTAB) micellar medium but sodium dodecyl sulfate (an anionic surfactant) has no effect. The pseudo first-order rate constants have been determined at different [reductant], [oxidant], [H2SO4], temperature, and [CTAB]. The reaction rate increased with increasing [d-xylose] and decreased with increase in [H2SO4]. The CTAB-micelle-catalyzed kinetic results can be interpreted by the pseudophase model. The kinetic parameters such as association constant (K
s), micellar medium rate constant (k
m), and activation parameters (E
a, ΔH
# and ΔS
#) are evaluated and the reaction mechanism is proposed. The reaction rate is inhibited by electrolytes and the results provide an evidence for the exclusion of the reactive species from the reaction site. 相似文献
14.
Kallol K. Ghosh Sancheeta Kolay Sunita Bal Manmohan L. Satnami Pierluigi Quagliotto P. R. Dafonte 《Colloid and polymer science》2008,286(3):293-303
The kinetics of the hydrolysis of p-nitrophenyl acetate (PNPA) and p-nitrophenyl diphenyl phosphate (PNPDPP) by hydroxamate ions mediated by gemini surfactants with quaternary ammonium bromide
(16-n-16,2Br−, n = 3, 4, 6, 12) and pyridinium chloride (12py-n-py12,2Cl−, n = 3, 4) head group have been investigated at 27 °C. The gemini surfactant with the pyridinium head group, 12-py-4-py12,2Cl− (tetramethylene-1,4 bis dodecylpyridinium chloride) shows a large rate acceleration effect than that with an ammonium head group, 16-12-16,2Br−, relative to those in water. The apparent pK
a of the hydroxamic acids have been determined in the presence of gemini surfactants. Catalytic system N-phenylbenzohydroxamate/12py-4-py12,2Cl− demonstrated over ~1,590-fold and ~255-fold rate enhancement in the hydrolysis of PNPA and PNPDPP, respectively, for the
identical reaction performed in buffer aqueous media at 27 °C. The second order rate constant and binding constants for reactions
were determined employing pseudophase model for micellar catalysis. 相似文献
15.
R. A. Shagidullina L. A. Kudryavtseva L. Ya. Zakharova B. E. Ivanov 《Russian Chemical Bulletin》1993,42(12):1977-1981
The reaction of (o-aminomethyl)phenols with ethylp-nitrophenyl chloromethylphosphonate in aqueous micellar solutions of cation-active surfactants has been studied. The effect of the structure of the surfactant and the nucleophile, pH of the medium, and temperature on the reaction rate in the micellar phase has been investigated. The rate constants in micelles are much higher than those in water.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2065–2068, December, 1993. 相似文献
16.
N. A. Burmistrova S. P. Mushtakova S. N. Shtykov V. N. Rodnikova L. F. Kozhina 《Russian Chemical Bulletin》2000,49(8):1380-1382
The influence of aqueous solutions of surfactants on the redox and acid—base properties of diphenylamine redox reagents was
studied by potentiometric titration and UV spectroscopy. The formal redox potentials, the pK
a values of the reagents in aqueous solutions and in the presence of surfactants, and the constants of binding of the reagents
by micellar solutions of surfactants were estimated.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1386–1388, August. 2000. 相似文献
17.
This paper describes the use of an aluminum electrode plated by metallic palladium and modified by Prussian blue (PB/Pd-Al)
in the electrocatalytic reduction of hydrogen peroxide (H2O2). The effect of pH on the electroreduction of H2O2 on the modified electrode is investigated and a simple irreversible reduction pathway is suggested. The electroreduction
kinetics including transfer coefficient α, potential-dependent charge transfer rate constants k
f, and diffusion coefficient D are estimated by means of forced hydrodynamic voltammetry using a rotating disk PB/Pd-Al electrode. The mean values obtained
for kinetics are 0.38, 10−2 cm−1, and 7.6 × 10−6 cm2 s−1, respectively. The long-term stability of the modifying layers on the Al substrate was studied. 相似文献
18.
Shagidullina R. A. Zakharova L. Ya. Valeeva F. G. Kudryavtseva L. A. 《Russian Chemical Bulletin》2001,50(7):1181-1185
The micellar effect of cationic surfactants in alkaline hydrolysis of O-alkyl-O-aryl-chloromethyl phosphonates involves a positive contribution of concentrating the reagents and a negative effect of the micellar environment due to a loss in the activation entropy. The reactivity of substrates in micelles depends on both electronic and hydrophobic characteristics of substituents in the aryl group. 相似文献
19.
A. B. Mirgorodskaya N. S. Erzikova L. A. Kudryavtseva A. I. Konovalov 《Russian Chemical Bulletin》2006,55(10):1788-1793
The pK
a values and constants of tautomeric equilibrium of several o-aminomethylphenols with different hydrophilic-lipophilic ability were measured in aqueous micellar solutions and in direct
microemulsions based on cetyltrimethylammonium bromide. The kinetics of hydrolysis of p-nitrophenyl acetate at different pH and concentrations of aminomethylphenol and surfactant was studied.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1724–1729, October, 2006 相似文献
20.
R. N. Zaripov R. L. Safiullin E. I. Yaubasarova A. A. Mukhametzyanova V. D. Komissarov 《Russian Chemical Bulletin》1997,46(5):895-897
The kinetics of the decomposition of acetylcyclohexylsulfonyl peroxide (ACSP) in CCl4, benzene, toluene, ethylbenzene, cumene, acetonitrile, ethanol, and 2-propanol in an atmosphere of O2 were studied at 40–70 °C. The rate constants (k
0) and activation parameters of the monomolecular decomposition of ACSP were determined. A linear dependence between logA
0 and activation energyE
0 (compensation effect) was established. The dependence ofk
0 on the nature of a solvent is described by the four-parameter Koppel-Palm equation.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 935–937, May 1997. 相似文献