Hydrolysis of phosphorus acid esters in the sodium bis(2-ethylhexyl)sulfosuccinate—<Emphasis Type="Italic">n</Emphasis>-nonane—polyethylene glycol—water supramolecular system before and after the percolation threshold

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.     

Kinetics of alkaline hydrolysis of ethylp-nitrophenyl ethylphosphonate in the reverse micellar system: sodium dodecyl sulfate-hexanol-water

The kinetics of alkaline hydrolysis of ethylp-nitrophenyl ethylphosphonate in the reverse micellar system sodium dodecyl sulfate—hexanol—water was studied. At high pH and low water content, the process occurs at the surface layer and can satisfactorily be described by the pseudo-phase model equation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp 262–266, February, 2000.     

Probing the Interaction Between a Surfactant–Cobalt(III) Complex and Bovine Serum Albumin

The mechanism of binding of the surfactant–cobalt(III) complex, cis-[Co(phen)₂(C₁₄H₂₉NH₂)Cl](ClO₄)₂⋅3H₂O (phen = 1,10-phenanthroline, C₁₄H₂₉NH₂ = tetradecylamine) with bovine serum albumin (BSA) was investigated by UV–vis absorption, circular dichroism (CD) and fluorescence spectroscopic techniques. The results of fluorescence titration revealed that the surfactant–cobalt(III) complex quenched the intrinsic fluorescence of BSA through a combination of static and dynamic quenching. The apparent binding constant (K _a) and number of binding sites (n) were calculated below and above the critical micelle concentration (CMC). The thermodynamic parameters determined by the van’t Hoff analysis of the constants (ΔH ^∘=14.87 kJ⋅mol⁻¹; ΔS ^∘=152.88 J⋅mol⁻¹⋅K⁻¹ below the CMC and 25.70 kJ⋅mol⁻¹ and 243.14 J⋅mol⁻¹⋅K⁻¹, respectively, above the CMC) clearly indicate that the binding is entropy-driven and enthalpically disfavored. Based on F?rster’s theory of non-radiation energy transfer, the binding distance, r, between donor (BSA) and the acceptor (surfactant–cobalt(III) complex) was evaluated. UV–vis, CD and synchronous fluorescence spectral results showed that the binding of the surfactant–cobalt(III) complex to BSA induced conformational changes in BSA.     

Supramolecular catalytic systems based on anionic amphiphiles and polyethyleneimine for hydrolytic cleavage of phosphorus ester bonds

Self-organization in individual and binary systems based on polyethyleneimine (PEI) and amphiphilic sulfonatocalix[4]resorcinarene was studied by conductometry, tensiometry, dynamic light scattering, and ¹H NMR spectroscopy. The critical concentrations of micelle formation and aggregate sizes were determined. The enhancement of the catalytic effect on the hydrolysis of O-ethyl O-p-nitrophenyl chloromethylphosphonate was shown in the following series of the systems: PEI-water < PEI—calixarene-water < PEI—calixarene—La^III—water. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 366–373, February, 2008.     

Kinetics of alkaline hydrolysis of esters of phosphorus acids in micellar and hexagonal phases in the cetyldimethylethylammonium bromide—NaOH—water system

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.     

Potential surface topology of a butene—gold atom system in the ground state

Quantum chemical modeling of but-1-ene isomerization to cis-but-2-ene and trans-but-2-ene in the presence of a gold atom has been carried out in the framework of the density functional theory with an extended basis set, the PBE functional, and a pseudopotential with relativistic corrections included. Two possible mechanisms have been considered, viz., with the formation of an intermediate σ-complex with one C(sp²)—Au bond and with gold insertion into the C—H bond. In the former case, the calculated energy barriers to two isomerization stages are higher than 30 kcal mol⁻¹. In the latter case, the reaction involves three stages and proceeds via a metal hydride complex with low barriers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1330–1337, July, 2008.     

Die Wärmeleitfähigkeit von Polyäthylen im Temperaturbereich von 20 bis 200 °C

Zusammenfassung Die W?rmeleitf?higkeit von je einemPhillips-,Ziegler- und Hochdruckpoly?thylen mit hohem Molekulargewicht wurde im Temperaturbereich von 20 bis 200 ‡C gemessen. Von 20 ‡C bis zum Schmelzende zeigt sich bei den verschiedenen Poly?thylentypen ein um so gr?\erer Abfall der W?rmeleitf?higkeit, je h?her der Kristallisationsgrad bei 20 ‡C ist. Die W?rmeleitf?higkeit in der Schmelze betr?gt etwa 6 · 10⁻⁴ cal/‡C cm sec und steigt schwach mit der Temperatur an.

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Summary Thermal conductivity of three representative types of polyethylene —Phillips-, Ziegler- and high pressure-type — has been determined from 20 to 200 ‡C. The stationary method applied in this work limited the experiments to polyethylene with extremely high molecular weight. The decrease of thermal conductivity between 20 ‡C and the melting point is an increasing function of cristallinity at 20 ‡C, whereas in the liquid phase the value of about 6 · 10⁻⁴ cal/‡C cm sec is nearly the same for each of the three investigated substances; a slight increase with temperature can be observed.

     

Synthesis of optically active omeprazole by catalysis with vanadyl complexes with chiral Schiff bases

A new method for the preparation of optically active omeprazole, consisting in asymmetric oxidation of the corresponding sulfide with the use of vanadyl complexes with chiral Schiff bases as the catalysts has been elaborated. The best results of the oxidation were achieved by the use of the combination VO(acac)₂—2-[{(1S,2S,3R,5S)-3-hydroxymethyl-2,6,6-trimethyl-bicyclo[3.1.1]hept-2-ylimino}methyl]phenol—N-ethyl-N,N-diisopropylamine. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1648–1653, August, 2008.     

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.     

Studies on the Reaction Kinetics and Mechanism of Iron(II) Reduction of the <Emphasis Type="Italic">cis</Emphasis>-Halogeno(cetylamine)bis(ethylenediamine)cobalt(III) Complex Ion in Aqueous Perchlorate Medium

The electron-transfer kinetics of the ionic surfactant complex cis-chloro/bromo(cetylamine)bis(ethylenediamine)cobalt(III) by iron(II) in aqueous perchlorate medium at μ=1.0 mol⋅dm⁻³ ionic strength have been studied at 303, 308 and 313 K by spectrophotometry under pseudo-first-order conditions using an excess of the reductant. The effects of [H⁺], ionic strength and [Fe²⁺] on the rate were determined. The reaction was found to be second order and showed to be independence of the acid concentration in the range [H⁺]=0.05–0.25 mol⋅dm⁻³. The second order rate constant increased with surfactant–cobalt(III) concentration and the occurrence of aggregation of the complex itself altered the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe²⁺(aq) with the cobal (III) complex proceeds by an inner-sphere mechanism. The critical micelle concentration (CMC) values of these surfactant–metal complexes were obtained in aqueous solution from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for the evaluation of the temperature-dependence of the critical micelle concentration (CMC) and the thermodynamics of micellization (ΔG _m^o,ΔH _m^o and ΔS _m^o).     

Dimerization and Coordination Properties of Zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine in Relation to DABCO in <Emphasis Type="Italic">o</Emphasis>-Xylene and Chloroform

For the first time the interactions between zinc(II)tetra-4-alkoxybenzoyloxiphthalocyanine (Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in o-xylene and chloroform have been studied by calorimetric titration and NMR and electron absorption spectroscopic methods. It has been found that in o-xylene at concentrations of Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc higher than 6×10⁻⁴ mol⋅L⁻¹ π–π dimers species are formed (λ _max= 685 nm). Additions of DABCO to the solution up to mole ratio 1 : 8 (Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc : DABCO) lead to a shift of the aggregation equilibrium towards monomer species due to formation of monoligand axial complexes. Further increasing the DABCO concentration results in formation of Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc—DABCO—Zn(4—O—CO—C₆H₄—OC₁₁H₂₃)Pc sandwich dimers (λ _max= 675 nm).     

Synthesis, characterization, and electron transfer reaction of some surfactant–cobalt(III) complex ions

Abstract  

The surfactant complex ion cis-[Co(tmd)₂(C₁₂H₂₅NH₂)₂]³⁺ (tmd = 1,3-propanediamine, C₁₂H₂₅NH₂ = dodecylamine) has been synthesized and characterized by elemental analysis and spectral data. In addition we have determined the critical micelle concentration of the surfactant–cobalt(III) complex and studied the kinetics and mechanism of the complex with ferrocyanide anion. The reaction is found to be second order, and the second-order rate constant increases with increasing initial concentration of the surfactant–cobalt(III) complex due to the presence of self-micelles formed by the complex itself. The thermodynamic parameters were determined. The results have been analyzed.     

Spectral elucidation of the acid metabolites of the four geometric isomers of trifloxystrobin

Four geometric isomers of trifloxystrobin (TFS)—namely EE, EZ, ZE, and ZZ—were hydrolyzed by 0.05 M NaOH, resulting in four corresponding acid metabolites. These compounds—namely EE-, EZ-, ZE-, and ZZ-acids—were purified by preparative HPLC and authentically characterized by a combination of infrared, Raman, GC–MS, LC–MS/MS, and NMR spectroscopies. The spectra were found to be very characteristic of the individual isomers, and so they could be used to distinguish the isomers from each other. The detailed spectral features of the individual isomers are presented and compared. EE-acid was identified as being the major metabolite of TFS in soil, which indicates that hydrolysis is the principal route of degradation of TFS. This finding further justifies the importance of the present study in relation to assessing the risk associated with the release of TFS into the environment.     

Activities of Co(II) Schiff base complexes in the redox carbonylation of aniline and nitrobenzene to methyl N-phenyl carbamate

The series of cobalt(II) complexes with different Schiff base ligands was synthesized and used as catalyst for the redox carbonylation of aniline and nitrobenzene. Effects of reaction temperature, CO pressure, promoter, and catalyst additions on the conversion of substrate were studied. When Co[(OH)₂saloph] — p-toluenesulfonic acid system was used as catalyst, the reaction was carried out at the next conditions: both Co[(OH)₂saloph] and p-toluenesulfonic acid—0.2 mmol, aniline—20 mmol, nitrobenzene—10 mmol, methanol—30 ml, Co—5 MPa, temperature 170°C, reaction time 7 h. The highest conversion of nitrobenzene and selectivity of methyl N-phenyl carbamate were 54.5 and 92.2%, respectively.     

Thermochemistry of heteroatomic compounds 26.* Calculation of the combustion and formation enthalpy of carbohydrate bicyclophosphites

The enthalpies of combustion for five noncyclic and cyclic phosphites in the condensed state were calculated from the derived equation ΔH_comb/kJ mol^-1 = —860.7 — 107.0(N — n), where N is the number of bonding valent electrons, and c is the number of lone electron pairs of heteroatoms. The dependence presented was used to calculate the combustion enthalpy of five phosphorylated carbohydrates, because these thermochemical values are often difficult to determine by reaction calorimetry. The enthalpies of formation of carbohydrate cyclophosphites were calculated by Hess’s law for the first time.     

Allylic isomerization of dichlorobutenes catalyzed by iron-containing nanoparticles stabilized in polymeric matrices

Iron-containing clusters obtained by the decomposition of iron complexes in a solutionmelt of a polymeric matrix exhibit catalytic activity in the isomerization of dichlorobutenes. The activity of the clusters stabilized in the polytetrafluoroethylene and polyethylene matrices depends on the nature of the stabilizing matrix and the content of the metal in it,i. e., on the size and structure of the cluster, and substantially exceeds the activity of supported metals and powders. The clusters in the polytetrafluoroethylene matrix are more active than those in polyethylene. The dependence of the catalytic activity on the metal content has an extreme character, and for the polyethylene matrix it achieves a maximum at a metal content of ≈10%. In catalysts with this composition, the particle size increases to 4–5 nm, and the distance between them is shortened, on the average, to 10 nm, which leads to interaction of the cluster particles with each other. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 854–857, May, 2000.     

Studies on the interactions between anionic surfactants and polyvinylpyrrolidone: Surface tension measurement, 13C NMR and ESR

 The interaction between anionic surfactants and polyvinylpyrrolidone (PVP) are investigated using ¹³C NMR, ESR spectroscopy and surface tension measurements at the air/water interface. The behavior of single-chained surfactant, sodium dodecyl sulphonate (AS), is compared with that of the double-chained surfactant, sodium bis(2-ethylhexyl) phosphate (NaDEHP). The results showed that a surfactant–polymer complex of “necklace and head structure” is formed in AS aqueous solutions in the presence of PVP due to the hydrophobic interaction between PVP and AS. The AS micelles nucleate on the polymer hydrophobic sites, and the mobility of the AS head groups is not affected. But, for NaDEHP surfactant, it was found that PVP is little effective in influencing the monomer–micelle equilibrium and no surfactant– polymer complex formed in the NaDEHP aqueous solution. Received: 8 May 1996 Accepted: 14 August 1997     

UPLC–MS as a powerful technique for screening the nonvolatile contaminants in recycled PET

The possibility of using recycled polyethylene terephthalate as a food contact material is being seriously considered, but the potential migration of nonvolatile compounds from it must be assessed to ensure that it is safe to do so. In the study presented here, four samples of recycled PET were each exposed to three food simulants under the harsh extraction conditions stipulated by European legislation regarding migration tests. The nonvolatile compounds that migrated from them were determined by ultra performance liquid chromatography–mass spectrometry using three different cone voltages, and both positive and negative ionization modes. A total of 36 chemical compounds were detected, some of which were identified, including common additives such as N,N′-di-beta-naphthyl-p-phenylenediamine (antioxidant) and 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (light stabilizer) as well as degradation compounds such as ethylene terephthalate dimers and trimers. In addition, specific migration values of three common components of polyethylene terephthalate (diethylene glycol, terephthalic acid, and isophthalic acid) were determined and found to occur at levels of <1 mg/kg—much lower than the specific migration limits stipulated by European legislation.     

Allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(<Emphasis Type="Italic">S</Emphasis>)-(—)-BINAP complex

The allylation of prochiral C-nucleophiles catalyzed by the Pd(0)—(S)-(—)-BINAP complex (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) was studied. The enantioselectivity of the allylation was found to be low. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1753—1755, August, 2008.     

The inverted micellar catalysis of the reaction of 2-aminomethylphenols with 4-nitrophenyl bis(chloromethyl)phosphinate

The parameters of the reaction ofpara-substituted 2-aminomethylphenols with 4-nitrophenyl bis(chloromethyl)phosphinate in toluene catalyzed by reversed micelles of polyethylene glycol-600 monolaurate depend on the nucleophile structure. The efficiency of the catalytic action increases in the series of substitutes C₉H₁₉ ⁱ<H<Cl. An increase in the catalytic activity of micelles in the region of structural rearrangement of micelle aggregates was observed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 275–278, February, 1999.