Structure of the head group,nucleophilicity, and micellar effects of functional detergents in acyl transfer reactions

The micellar effects of 1-cetyl-2-methyl-3-(2-hydroxyiminopropyl)imidazolium and 1-cetyl-3-hydroxyiminomethylpyridinium halides in acyl transfer reactions (phosphoryl, phosphonyl, and toluenesulfonyl) were investigated. Variation of the nature of the head group does not lead to change in the reactivity of the oximate group, while the nucleophilicity follows the basicity of the functional fragment. The increase of the observed reaction rates during transfer of the disintegration of the substrates from water to the micellar pseudophase is due both to concentration of the reagents and to change in the reactivity of the oximate group. The new detergent 1-cetyl-2-methyl-3-(2-hydroxyiminopropyl)imidazolium chloride is one of the most effective functional surfactants in the decomposition of organophosphorus compounds. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 2, pp. 90–97, March–April, 2008.     

Nucleophilicity of functional surface active substances in the transfer of phosphoryl groups

The reactivity of α-nucleophilic groups in functional detergents is comparable with those for analogous compounds which do not form micelles. Methods are proposed for the modification of surface active compounds to produce supernucleophilic systems for the decomposition of organophosphorus compounds. A new functional detergent — 1-cetyl-3-(2-hydroxyiminoethyl)imidazolium chloride-is the most powerful of the investigated surface active reagents capable of achieving half lives for the decomposition of 4-nitrophenyl diethyl phosphonate and 4-nitrophenyl diethyl phosphate of ≤2 and 14 s respectively. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 288–294, September–October, 2006.     

Aminolysis of 4-nitrophenyl esters of phosphorus acids in reversed micelles of 2-hydroxyethyldimethylpentadecylammonium bromide

The reactions ofn-cetyl- andn-hexylamines with 4-nitrophenyl esters of tetracoordinated phosphorus acids in chloroform in the presence of 2-hydroxyethyldimethylpentadecylammonium bromide and the influence of the latter on the acid—base equilibrium of the bromphenol blue dye (BPB) were studied by the spectrophotometric method. In the presence of reversed micelles of the cationic surfactant, the observed rate constant of aminolysis increases by more than two orders of magnitude. The catalytic efficiency of the micelles increases as the concentration of the long-chain amine decreases and on going from the latter to a short-chain amine. The acid—base equilibrium of BPB in micellar solutions is shifted due to the formation of a complex between the surfactant and the BPB dianion. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2125–2128, December, 1997.     

Functional Detergents Containing an Imidazole Ring and Typical Fragments of α-Nucleophiles Underlying Micellar Systems for Cleavage of Esters of Prosphorus Acids

1-Cetyl-3-(2-oximinopropyl)imidazolium, 1-cetyl-3-(2-oxaminoethyl-2-one)imidazolium, and 1-cetyl-3-(2-amino-2-oximinoethyl)imidazolium halides were synthesized.These compounds form in water solutions functional zwitter-ionic micelles as surfactants. The cleavage kinetics of 4-nitrophenyl diethyl phosphate, 4-nitrophenyl ethyl ethylphosphonate, and 4-nitrophenyl tosylate in micelles of the functional detergents and combined micelles of the functional detergents with cetyltrimethylammonium chloride are adequately described in a framework of a simple pseudophase distribution model, and the micellar systems of the detergents are typical -nucleophilic reagents. An equation was suggested for quantitative estimation of the micellar effect of the surfactants that took into account the change in the nucleophilic and basic characteristics of the -nucleophilic center of the detergent and also the influence of the reagents concentrating on transition of the reaction from the water into micelle phase. The maximum acceleration of the S N 2-reaction in the micelles of the functional zwitter-ionic detergents for the cleavage of 4-nitrophenyl diethyl phosphate and 4-nitrophenyl tosylate reached 3500 and 75 000 (oximate surfactant), 3300 and 66 000 (amidoximate surfactant ), and 4800 and 12200 (hydroxamate surfactant) times respectively. New functional detergents underlie unique supernucleophilic micellar system affording extremely high cleavage rates of organophosphorus substrates-ecotoxicants.     

Effect of the alkyl chloride-to-aluminum molar ratio in the catalysts of dec-1-ene oligomerization on the product distribution and the chlorine content in the products

Dec-1-ene oligomerization in the presence of an aluminum—1-dodecyl chloride system was studied. A mixture of low-molecular-weight oligodecenes containing 25–40 wt.% dimers and 30–52 wt.% dec-1-ene trimers is formed at the molar ratios RCl/A1 = 0.5–1.5. The oligomerization was assumed to occur under the action of cationic active sites, which are formed during the reaction of 1-chlorodedecane with aluminum. At temperatures of 120–130°C and molar ratios RCl/A1 = 0.5–1.5 metallic aluminum completely dechlorinates 1-chlorododecane in a dec-1-ene medium. The character of the effect of highly dispersed Al and the RCl/A1 molar rato on the fractional composition and chlorine content in oligodecenes was revealed. The latter are formed by an aluminum—tert-butyl chloride system used in the industrial oligomerization of dec-1-ene. A mechanism of Al dissolution by alkyl chlorides with the simultaneous dechlorination of alkyl chloride and formation of cationic active sites in A1-RCl systems was proposed to explain the results obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 661–665, March, 2008.     

Studies on the interaction of bacterial capsular polysaccharide- Klebsiella K16 with cationic and mixed surfactants

The spectral studies of cationic dyes, pinacyanol chloride (PCYN) and acridine orange (AO) with capsular polysaccharide Klebsiella K16 (PK16) biopolymer in micellar media reveal many interesting phenomena. Intensity of the metachromatic band (μ) at 490 nm decreases gradually on addition of cationic single surfactant to the biopolymer PK16–dye system of P/D = 30, whereas the intensity of α and β bands reach to the value of original pure dye. As a result, the cationic surfactant destroys the metachromatic compound and forms a new complex with biopolymer PK16 by freeing the dye molecule. Enhancement of fluorescence intensity of AO-PK16 system with cationic surfactant is another evidence for the binding between the biopolymer and the surfactant. Interaction between the biopolymer and mixed surfactant has also been studied. Finally, the binding ability of cationic surfactants with or without non ionic surfactant, the idea of the critical aggregation concentration (cac) of the surfactant, mole fraction and the charge density of mixed surfactant for binding with PK16 and also the site of interaction have been pointed out.     

Novel mixed hemimicelles based on nonionic surfactant–imidazolium ionic liquid and magnetic halloysite nanotubes as efficient approach for analytical determination

Analytical and Bioanalytical Chemistry - The co-adsorption of mixed nonionic surfactant and imidazolium-based ionic liquid, Triton X100 (TX100), with 1-cetyl-3-methylimidazolium bromide (C16mimBr)...     

Optical and chromaticity parameters of transition metal complexes with 1-nitroso-2-naphthol-3,6-disulfonic acid in the presence of surfactants

Optimal conditions for the complexation of transition metal ions [Cu(II), Ni(II), Co(II, III), and Fe(II, III)] with 1-nitroso-2-naphthol-2,6-disulfonic acid have been determined by spectrophotometry in the presence of cationic (cetylpyridinium and cetyltrimethylammonium bromides) and nonionic (OP-10, neonol) surfactants. The introduction of nonionic surfactants does not influence the optical parameters of the system, while the introduction of cationic ones leads to hyperchromic and hypsochromic (for the system Fe(III)-NRS-surfactant) effects. The stoichiometric ratios determined by the method of isomolar series and treatment of the saturation curves of cationic surfactants at pH 4.0 are Me(II): R: surfactant = 1: 2: 4, Me(III): R: surfactant = 1: 3: 6. The molar absorption coefficients and chromaticity parameters of ternary complexes have been determined. A 2–5-fold increase in the molar absorption coefficients and chromaticity functions as compared to binary systems has been revealed.     

Supramolecular systems of amphiphilic derivatives of calix[4]resorcinarenes and surfactants in chloroform

Aggregation of amphiphilic calix[4]resorcinarenes (CRA) modified by carboxymethyl (1), 2-hydroxyethyl (2), methylamino acetal (3), and aminomethyl (4) fragments and their interaction with some synthetic (5, 6) and natural (7, 8) surfactants in the low-polarity solvent (chloroform) were studied by permittivity measurements and FT-IR spectroscopy. Compounds 1–4 and surfactants form aggregates at critical micelle concentrations (CMC) of 2.0·10⁻⁵–7.5·10⁻⁵ and 1.7·10⁻⁵–2.0·10⁻³ mol L⁻¹, respectively. The CMC values of CRA—surfactant mixed aggregates depend on the surfactant structure and the structure and concentration of CRA. Analysis of the IR spectra of solutions of a series of amphiphilic CRA (2–4, 9, 10) and their mixtures with the cationic surfactant N-cetyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bromide (5) showed that an increase in the concentration of the solutions in individual and mixed systems is accompanied by a decrease in the molar integral intensities and intensities in the maxima of the absorption bands of the O—H and C—H bonds down to the CMC point, after which these values change slightly. The discovered effect, which is differently pronounced for all systems studied, indicates that both the polar “head” groups and nonpolar fragments of CRA and surfactant are involved in the formation of supramolecules of the reverse micelle type in all cases. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 459–466, March, 2007.     

A proton NMR study on aggregation of cationic surfactants in water: effects of the structure of the headgroup

 ¹H NMR chemical shifts of solutions of the following cationic surfactants in D₂O were determined as a function of their concentrations: cetyltrimethylammonium chloride, CTACl, a 1 : 1 molar mixture of CTACl and toluene, cetylpyridinium chloride, CPyCl, cetyldimethylphenylam-monium chloride, CDPhACl, cetyldimethylbenzylammonium chloride, CDBzACl, cetyldimethyl-2-phenylethylammonium chloride, CDPhEtACl, and cetyldimethyl-3-phenylpropylammonium chloride, CDPhPrACl. Plots of observed chemical shifts versus [surfactant] are sigmoidal, and were fitted to a model based on the mass-action law. Satisfactory fitting was obtained for the discrete protons of all surfactants. From these fits, we calculated the equilibrium constant for micelle formation, K, the critical micelle concentration, CMC and the chemical shifts of the monomer, δ_mon and the micelle δ_mic. ¹H NMR-based CMC values are in excellent agreement with those which we determined by surface tension measurements of surfactant solutions in H₂O, allowing for the difference in structure between D₂O and H₂O. Values of K increase as a function of increasing the size of the hydrophilic group, but the free energy of transfer per CH₂ group of the phenylalkyl moiety from bulk water to the micellar interface is approximately constant, 1.9±0.1 kJ mol^-1. Values of (δ_mic–δ_mon) for the surfactant groups at the interface, e.g., CH₃–(CH₂)₁₅–N+(CH₃)₂ and within the micellar core, e.g., CH₃–(CH₂)₁₅–N⁺ were used to probe the (average) conformation of the phenyl group in the interfacial region. The picture that emerges is that the aromatic ring is perpendicular to the interface in CDPhACl and is more or less parallel to it in CDBzACl, CDPhEtACl, and CDPhPrACl. Received: 23 February 1996 Accepted: 29 August 1996     

Surfactant to dye binding degree method for the determination of fluvoxamine maleate and citalopram hydrobromide in pharmaceuticals

The surfactant to dye binding degree (SBDB) methodology was used to determine fluvoxamine maleate and citalopram hydrobromide. Neutral red and sodium dodecyl sulfate (SDS) were used as the dye and surfactant, respectively, to form dye-surfactant aggregates. When a cationic drug is added to dye-surfactant mixture, it interacts with the surfactant and decreases the dye-surfactant binding degree. This decrease is proportional to the drug concentration. This was measured by monitoring the absorbance changes of the dye at 532 nm. Under the optimum conditions, the calibration graphs were linear over the range of 1.2–15 μg mL⁻¹ and 1.1–15 μg mL⁻¹ for fluvoxamine maleate and citalopram hydrobromide, respectively. The detection limits (signal to noise ratio = 3) were found to be 0.37 and 0.35 μg mL⁻¹, for fluvoxamine maleate and citalopram hydrobromide, respectively.      

A new method for the synthesis of [1,4]diazepino[6,5-b]indole derivatives

Reactions of 3-[(N-aryl-N-chloroacetyl)amino]-2-formylindoles with substituted anilines gave 1,4-diaryl-2-oxo-1,2,3,6-tetrahydro[1,4]diazepino[6,5-b]indol-4-ium chlorides and those with 4-aminopyridine yielded 4-amino-1-(1-aryl-2-oxo-2,5-dihydro-1H-pyrido[3,2-b]indol-3-yl)pyridinium chlorides. Reduction of 1,2,3,6-tetrahydrodiazepinoindol-4-ium chlorides afforded the corresponding hexahydro derivatives. An alternative synthesis of 1-(4-nitrophenyl)-3-oxo-4-phenyl-1,2,3,4,5,6-hexahydro[1,4]diazepino[6,5-b]indole from 3-[N-(4-nitrophenyl)amino]-2-[(phenylimino)methyl]indole was developed. The method involves the following sequence of transformations: reduction, chloroacetylation, and intramolecular alkylation. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2193–2199, December, 2006.     

Micellar and liquid-crystalline properties of bicyclic fragment-containing cationic surfactant

NMR spectroscopy is employed to study the aggregation of a cationic surfactant, 4-aza-1-cetyl-1-azoniabicyclo[2.2.2]octane bromide, in aqueous solutions. Self-diffusion coefficients are determined for micelles and monomers and the hydrodynamic radius and aggregation number are calculated for micelles. Polarization microscopy data demonstrate that the examined compound is an amphotropic substance. It is found that the lyotropic liquid-crystalline system is characterized by a wider temperature range of mesophase existence as compared to the thermotropic system.     

Effect of substituents in the propynyl fragment and at the nitrogen atom on the intramolecular cyclization of (3-aryl-2-propynyl)-(4-hydroxy- 2-butynyl)ammonium chlorides and also on the recyclization of the products formed

Cyclization of dialkyl(4-hydroxy-2-butynyl)[3-(α-naphthyl)-2-propynyl]ammonium chlorides using aqueous KOH solution occurs under more rigorous conditions (1:1 ratio of salt to base) than in the case of their 3-phenyl(p-chlorophenyl, alkenyl)-substituted analogs (5:1 ratio of salt to KOH). Similarly, more rigorous conditions are also needed for the cyclization of (4-hydroxy-2-butynyl)-(3-phenyl-2-propynyl)piperazinium- and dicyclohexylammonium chlorides. In addition to the cyclization products - corresponding dialkyl(7-hydroxymethyl)naphtho[1,2-f]isoindolinium or dialkyl-(4-hydroxy-methyl)benzo[f]isoindolinium chlorides, the products of recyclization of these – dialkyl-amino-phenanthro[1,2-c]furan or dialkylaminonaphtho[1,2-c]furan are also formed. The indicated derivatives become the main products of conversion of the starting salts by a change of salt to KOH ratio, 1:2, and with an increase in the time of the reaction. The results obtained can be explained by steric effect and also the lower thermal stability of the obtained naphtho[1,2-f]isoindolinium salt system compared to the analogous benzo[f]isoindolinium systems.     

Size-controlled synthesis of CuO–ZrO<Subscript>2</Subscript> nanoparticles prepared through reverse micelle method

In this research, CuO–ZrO₂ nanoparticles are synthesized using microreactors made of surfactant/water/cyclohexane microemulsions. The effect of different microemulsion variables on the particle size and its distribution, such as water-to-surfactant molar ratio (W ₀) and different surfactants are discussed. Three different surfactant types including cationic (CTAB), anionic (AOT), and nonionic (Brij56) are used. Also a different amount of water to surfactant in nano composite synthesis is used. The powders were characterized by DTA/TG, XRD, SEM, EDS, TEM and BET techniques and their physical properties are compared. The results show a decrease of particles size in presence of cationic surfactant. Narrow particles size distribution of the resultant CuO–ZrO₂ nanocomposite in presence of cationic surfactant, anionic and nonionic surfactant is compared. Also for AOT surfactant, by raising water to surfactant molar ratio the particles size is increased and the optimum ratio is H₂O: Surfactant = 0.32:0.055, respectively.     

Properties of complexes and particles of gelatin with ionic surfactants

 The properties of soluble gelatinionic surfactant complexes and insoluble particles were evaluated. It was found that colloidal particles of gelatin A – cationic surfactant (dodecyltrimethyl-ammonium bromide, DTAB, and cetyltrimethylammonium bromide, CTAB) were formed. Binding isotherms showed that these particles are obtained above the CMC of each surfactant, while cooperative binding takes place. Surface tension measurements conducted for both gelatin/DTAB and gelatin/anionic surfactant, SDS (sodium dodecyl sulfate) showed a break in the curve describing surface tension vs number of bound surfactant molecules, (ν) at concentrations below the CMC of each surfactant alone. This break, which is attributed to CMC 1, is observed at the same number of bound surfactant mol ecules ν∼2 for both gelatin/surfactant couples. Contact angle measurements showed that the maximal hydro-phobicity of the gelatin-surfactant particles is obtained at the same concentration range in which the precipitation occurs. It was also found that the hydrophobicity of gelatin-SDS particles, is higher than that of the gelatin-cationic surfactants, due to a different composition of the resulting particles. The zeta potential of the particles indicated charge neutralization and even charge reversal for gelatin-CTAB at high surfactant concentration. Received: 4 April 1997 Accepted: 15 December 1997     

Self-assembled monolayer gold electrode for surfactant analysis

A gold electrode coated with a self-assembled monolayer of octane-thiol (SAM/Au) has been used as an amperometric detector for the determination of surfactants. This detector operated in the presence of a high percentage of organic solvent and was adapted to an HPLC System. At the SAM/Au, the electrochemical response of an electroactive tracer (potassium ferricyanide) was completely inhibited, but, in the presence of a cationic surfactant, the electrochemical reduction was progressively restored. In flow injection analysis, using the SAM/Au in an amperometric flow-through detector polarised at 0.0 V vs Ag/AgCl, a linear response (i=f{[surfactant]}) was observed for cationic surfactants e.g. cetylpyridinium chloride in the concentration range 2 × 10⁻⁶–1 × 10⁻³ M. The electrochemical data along with the determination of the ion pair stoichiometry between the redox tracer and the surfactant suggest an electrochemical response related to ion pair formation and governed by electron transfer by tunneling effect. Received: 28 January 1997 / Accepted: 7 March 1997     

Acylation of 2-azahetarylacetonitriles with (acetylthio)acetyl and α-(acetylthio)-propionyl chlorides. Production of 5-amino-4-hetarylthiophen-3(2H)-ones

3-Cyano-3-hetaryl-2-oxopropyl-and 3-cyano-3-hetaryl-1-methyl-2-oxopropyl ethanethioates were obtained by the acylation of 2-azahetarylacetonitriles with (acetylthio)acetyl and α-(acetylthio)propionyl chlorides respectively. They are deacetylated by the action of amines and undergo cyclization with the formation of 5-amino-4-hetarylthiophen-2(2H)-ones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1314–1319, September, 2006.     

Chemistry of hetero analogs of isoflavones 25. Synthesis of 2-alkyl-3-(2-benzimidazolyl)-chromones

2-Alkyl-3-(1-methyl-2-benzimidazolyl)-7-acyloxychromones were synthesized by the reaction of substituted or unsubstituted 2-(2,4-dihydroxyphenacyl)-1-methylbenzimidazoles with the acid chlorides and anhydrides of carboxylic acids. The products were converted into 2-alkyl-7-hydroxychromones as a result of acid hydrolysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 26–30, January, 2008.     

Competitive Self and Induced Aggregation of Calix[4]arene Ethers and Their Interaction with Pinacyanol Chloride and Methylene Blue in Nonaqueous Media

Long chain calix[4]arene ethers have been examined for aggregation in nonaqueous solvents by using UV-vis molecular absorbance spectroscopy. It has been observed that tetraalkylated (alkyl = hexadecyl and octadecyl, respectively) calix[4]arene ethers tend to aggregate in chloroform and tetrahydrofuran, possibly via π–π stacking interactions of the phenyl moieties, and the aggregation process appears to be facilitated by the alkyl chains. The analogous dialkylated compounds do not show any self-aggregation, plausibly due to strong hydrogen bonding between the –OH and the –O– of calix aryl ether which seems to disrupt the aggregation process. Addition of the anionic surfactant sodium dodecylsulfate (SDS) appears to hinder the aggregation process in nonpolar chloroform but the same surfactant facilitates aggregation in the polar tetrahydrofuran. The cationic surfactant (cetyltrimethyl ammonium bromide) and the nonionic surfactant (Brij-35) have no effect on this aggregation process. Unexpectedly, SDS induces aggregation of dialkylated calix[4]arene ethers in chloroform. It has been observed that the aggregated form of the tetraalkylated calix[4]arene ethers tend to increase the dimerization efficiency of cationic dyes (pinacyanol chloride and methylene blue) in chloroform.