Search

N-Methylmorpholine-N-oxide (NMMO) cannot be completely separated by extraction from mixtures with common 1,3-dialkylimidazolium ionic liquids (ILs) due to strong ionic interactions between the two components. At elevated temperatures, above approx. 90 °C, especially under dry conditions and in the presence of acid, alkylating or acylating agents, remaining NMMO in ILs tends to undergo autocatalytic degradation. This is a highly exothermic, unstoppable process that results in explosions, flames, and complete charring of the reaction mixtures. Thus, caution must be exercised when drying or heating ILs that were in previous contact with NMMO, and the absence of amine oxide must be confirmed to avoid potential danger.

Three kinds of alkylamide amine oxides having one, two, and three amides were synthesized, and their solution properties such as the surface tension and the viscosity were examined. The effects of the spacer group length n between amide and dimethyamine oxide group as well as the number of amide groups were examined with respect to the aggregation behavior. For short spacer lengths, amide groups join the hydrophilic head group, while for long spacer lengths, amide groups and a part of the spacer groups are suggested to reside in the micelle palisade layer. In a series of amphiphile having three amide groups, gels formed at a high concentration of 50 mM were tentatively grouped into two types: A and B, depending on the spacer length n. For Gel-A, the gelling temperature T gel increased linearly with n but it was scarcely affected by the protonation of amine oxide (AO) group. For Gel-A, fiber-like aggregates were observed in cryo-TEM images. For Gel-B, values of T gel were higher by 18 ± 2 K than those of Gel-A for a given n. Cryo-TEM images of Gel-B showed wide ribbon-like aggregates. On ionization of AO group, Gel-B transformed into Gel-A.

In this article, the enthalpy of dissolution for oxymatrine in 0.15 M citric acid solution is measured using a RD496-2000 Calvet Microcalorimeter at 36.5 °C under atmospheric pressure. The differential enthalpy (Δ dif H m) and molar enthalpy (Δ sol H m) were determined for oxymatrine dissolution in 0.15 M citric acid solution. On the basis of these experimental data and calculated results, the kinetic equation, half-life, Δ sol H m, Δ sol G m, and Δ sol S m of the dissolution process were also obtained.

A number of anions and cations have been incorporated into TiO2 as support for gold catalysts and also into as-prepared Au/TiO2 catalysts at levels of 0.4 mol% and 2.5 mol% with respect to the support. The activities of the catalysts for CO oxidation reveal that the at the higher concentration level of the ions, in all cases, a decrease in activity compared with unmodified Au/TiO2. However, and more interestingly, addition of only 0.4 mol% of the ions to the support, prior to gold addition, in most cases resulted in activity enhancement whilst similar addition to Au/TiO2 resulted in decrease in activity. Attempts have been made to understand the origin of these effects.

The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 °C and Fischer–Tropsch synthesis (FTS) at 170 °C in the [CH4/O2(or NO/H2 or CO/H2)/Ar//Pt (or Pt/Ru)//PBI(H3PO4)/H2, Ar] fuel cell. It has been shown that the partial methane oxidation to C2H2 and the C2 selectivity were electrochemically promoted by the negative catalyst polarization. This was also the case in NO reduction with hydrogen for low NO and H2 partial pressures. In both cases the catalytic reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H2 partial pressures the catalysis is promoted by the electrochemical pumping of H+ from the catalyst, i.e. at positive polarization. FTS demonstrated the highest methane production rate (11% of CO conversion) at zero fuel cell voltage.

Resistant strains of Escherichia coli were obtained by stepwise cultivation in media with increasing concentration of antimicrobially active 1-(methyldodecyl)dimethylamine oxide and 1-(methyldodecyl)trimethylammonium bromide. Adaptive changes were determined in the fatty-acid (FA) composition in an isolated lipopolysaccharide sample from the outer membrane of these strains. The composition of this FA mixture from adapted strains was compared with that of FA from a sensitive strain. The differences were found in level of palmitic, heptadecanoic, heptadecenoic, heptadecadienoic and nonadecenoic acids. In addition, the adapted strains differed from each other in the content of myristic, pentadecanoic, stearic and linoleic acids.

The alkaline lamellar titanates (K 2 Ti 4 O 9 and Na 2 Ti 3 O 7 ) obtained from solid state reactions react with acid solutions producing a partial ion exchange of the ions K + and Na + present in the interlamellar region by protons H + , producing the titanate acid forms. These materials were characterized by X-ray diffraction, infrared spectroscopy and thermal analyses (TG/DTA).

pH-induced transformation between a hemicylindrical aggregate and a laterally homogeneous layer at the graphite-solution interface was demonstrated in micellar aggregates of dodecyldimethylamine oxide (C12DMAO) using atomic force microscopy (AFM). Nonionic C12DMAO (pH~8) and fully-ionized cationic C12DMAO (pH~1.5) both formed hemicylindrical aggregates on graphite, similar to aggregates formed by many other ionic (or nonionic) surfactants on graphite. However, a laterally homogeneous layer was observed in the case of nearly half-ionized C12DMAO around pH~4 (a 1:1 mixture of the nonionic and the cationic species). These results indicated that the surface curvature of the C12DMAO aggregates on graphite was the smallest around the degree of ionization α=0.5, despite charging up the nonionic hemicylindrical aggregates. Using AFM images and the corresponding force curves, the transformation between the hemicylindrical aggregate and the laterally homogeneous layer was found to be reversible via a change in pH. The formation of the laterally homogeneous layer of nearly half-ionized C12DMAO is explained by hydrogen bond formation between the nonionic and the cationic headgroups.

Dielectric relaxation was examined for aqueous trimethylamineoxide (TMAO) solutions over a wide concentration (c) range. The dielectric relaxation of TMAO was described by a Debye-type function with a relaxation time of about 3 × 10−11 s, with the strength proportional to c. The number of water molecules tightly hydrated to unprotonated TMAO was estimated to be two. Ab initio calculations predict the magnitudes of the dipoles for individual TMAO and TMAO tightly hydrated by two water molecules, to be 4.9 and 4.2 D, respectively. When the amount of HBr added was increased, dielectric spectra were described by two modes with relaxation times, about 3 × 10−11 and the about 8 × 10−10. The fast relaxation was assigned to the rotational mode of unprotonated TMAO tightly hydrated by two water molecules, and the slow mode to the rotational mode of dimers formed between a protonated and unprotonated TMAO due to hydrogen bonding.

Ionic/nonionic mixed micelle formation of dodecyldimethylamine oxide (DDAO) was studied by measuring the activities of DDAO+ ions and Cl− ions using surfactant-selective electrodes and Ag/AgCl electrodes at three pH values in the absence of added salt. DDAO monomer exists as either a nonionic or a cationic species depending on the pH of the aqueous solution and hence the two species are not independent of each other. A new relation between the activity of the surfactant ions and that of the counterions is presented which differs from the corresponding relation valid for ionic/nonionic mixed micelles consisting of independent components.

Cationic heteroconjugation equilibria of more than ninety systems consisting of substituted pyridines, their N-oxides, and trimethylamine N-oxide, i. e., in systems with “mixed” hydrogen bridges of type OHN+ (NHO+) were studied in propylene carbonate. Both experimental systems without proton transfer, BH+/B1, and those with proton transfer, B1H+/B, were explored. The stability of the “mixed” hydrogen bridges, OHN+ (NHO+), is compared with that of the OHC+-type bridges. The influence of the difference in basicity of the conjugate base of the proton donor and the proton acceptor on the presence of the proton transfer equilibria, and, consequently, the possibility of determination of the cationic heteroconjugation constant values is discussed.

The examined method of processing cellulose can be used to conduct solid-phase EDA-complexation of cellulose with high-melting MMO hydrates in conditions of the effect of shear strains and pressure. The method allows: expanding the concentration range of the solubility of cellulose in MMO to 50% and obtaining highly concentrated spinning solutions with a concentration of up to 30%; decreasing the duration of dissolution to 5–10 min; regulating the process of thermal degradation of MMO and cellulose: fabricating “Orcel®” fibre with a high degree of orientation and high strength and modulus of elasticity. The solid-phase amine oxide method of processing cellulose was developed by the contract group at the All-Russian Scientific-Research Institute of Polymer Fibres (VNIIPV): Candidate L. K. Golova (director), candidate N. V. Vasil'eva, Candidate L. K. Kuznetsova. Candidate T. A. Lyubova, Research Associate O. E. Borodina, and Research Associate T. B. Krylova with the participation of leading specialists at the Institute's BI Center (director of the Center, Candidate I. Z. Eifer). The studies of the properties and structure of Orcel® fibre were conducted by leading specialists at the Institute's BIFIM Complex (Professor M. M. Iovleva. Director). Candidates V. N. Smirnova, S. I. Banduryan, T. A. Belousova, L. P. Mil'kova, I. N. Andreeva, L. P. Konovalova, V. G. Brusentsova, Dr. A. T. Kalashnik, Research Associate G. Ya. Rudinskaya, and Dr. A. Sh. Goikhman.

It has been reported that the stability of a 1.11-GBq (30 mCi) technetium-99m d,l-hexamethyl-propylene amine oxime (HMPAO) preparation can be improved to up to 5 h by the addition of 200 micrograms CoCl2.6H2O within 2 min after reconstitution. However, it is not clear whether this method is also efficient for high-activity preparations (5.55 GBq) and whether this modified 99mTc-d,l-HMPAO has the same biological properties and can safely be used. We have now studied CoCl2-stabilised 99mTc-d,l-HMPAO preparations containing different amounts of "in-house" HMPAO ligand and SnCl2 and reconstituted with activities from 1.11 GBq to 5.55 GBq 99mTc. The characteristics of the generator eluates were also divergent, ranging from fresh eluates from a generator eluted less than 2 h previously to 4-h-old eluates from a generator not eluted during the preceding 72 h. Preparations containing up to 5.55 GBq 99mTc and as low as 2 micrograms SnCl2.2H2O can be efficiently stabilised for at least 6 h by the addition of CoCl2 shortly after reconstitution. Interestingly, it was found that the stabilisation method is not efficient if the cobalt ions are added prior to reconstitution of the preparation. This implies that the cobalt chloride cannot be incorporated in the labelling kit. Also, preparations with amounts of the ligand lower or higher than 0.5 mg formed the 99mTc-d,l-HMPAO complex with low radiochemical yield or showed rapid degradation. Therefore, combination of a subdivision and storage of Ceretec kits in fractions (as reported in the literature) is contra-indicated with this CoCl2 stabilisation method. CoCl2-stabilised Ceretec kits reconstituted with 5550 MBq 99mTcO4- and used 4-5 h after preparation retain the diagnostic usefulness of the fresh 1110-MBq preparation with regard to leucocyte labelling and brain imaging. Although baboon brain uptake of the stabilised preparation was 6%-9% lower, this small difference could not be distinguished in the tomographic images. The data obtained with both inhouse prepared d,l-HMPAO and Ceretec kits suggest that the eluate restrictions recommended by the Ceretec manufacturer can be neglected if the preparation is stabilised with Co2+ ions. Studies with 57Co-spiked CoCl2 added to d,l-HMPAO preparations demonstrated that the Co2+ ions clearly interact with the d,l-HMPAO ligand, probably to form one or more complexes. From biodistribution studies in mice it became evident that the toxicological profile of the Co2+ ions in the presence of d,l-HMPAO should be more favourable than that of cobaltous ions. For these reasons, it seems justifiable that CoCl2-stabilised 99mTc-d,l-HMPAO preparations should undergo rigorous studies to elucidate their clinical usefulness and pharmacological safety.

The effects of subinhibitory concentrations (1/4, 1/8, 1/16 of the MIC) of 12 organic ammonium salts of A (hard-alkyltrimethylammonium bromides) and B (soft--2-(dodecanoylamino)ethylalkyldimethylammonium bromides) homologous series on phospholipase C, proteinase, elastase and permeability activity were studied. The substances with longer substituents were more effective in reducing phospholipase C activity (hard and soft series) as well as proteinase (hard series). Phospholipase C was the most frequently and the most markedly inhibited enzyme. The organic ammonium salts were less effective in inhibiting elastase and permeability activity. Only one of the substances under study reduced all the tested activities.

At a given surfactant-surfactant ratio, the enthalpies of transfer ΔH (W→W+S) of pentanol 0.03m from water to sodium dodecylsulfate (NaDS)-dodecyldimethylamine oxide-water mixtures as functions of the surfactants mixture concentration (m t) were determined. ForX NaDS=0.9, ΔH (W→W+S) increases monotonically withm t such as observed for pure surfactants. ForX NaDS=0.12 and 0.3, ΔH (W→W+S) increases withm t up to 0.12m beyond which it decreases withm t. AtX NaDS=0.6, two monotonic curves can be distinguished in the ΔH (W→W+S)vs. m t trend. Experimental data were fitted through an equation previously reported for additives in pure surfactants derived by assuming the pseudo-phase transition model for the micellization and a mass action model for the distribution of the additive between the aqueous and the micellar phases. This method did permit to simultaneously obtain the distribution constant of the alcohol between the aqueous and the micellar phase (and, then, the standard free energy of transfer) and its enthalpy of transfer from the aqueous to the micellar phases. By combining these properties the standard entropies of transfer were calculated. From these results, the excess properties of pentanol in the mixed micelles were calculated as a function of the mixture composition. The excess enthalpies and entropies are positive and compensate with each other leading to null values for the excess free energies in the whole range of the mixed micelles composition.

An attempted synthesis of [Re(CO3) (μ-OH)]4,1, by reacting Re2(CO)10 with an excess of NMe3O in THF resulted instead in isolation of a disproportionation product, [fac-Re(CO)3(ONMe3)3][ReO4],2. The structure of2 was determined via X-ray crystallography: tri-clinic,P1¯,a=9.499(5),b=9.841(2),c=13.448(2)A,α=109.92(2),β=106.89(3), γ=93.15(4)°,Dcalc=2.22 g−3 andZ=2. Least-squares refinement based on 1606 observed (I>3σ(I)) reflections gave final values ofR=0.040 andRw=0.047. The cation is a distorted octahedron that exhibits several structural manifestations of steric crowding among the bulky NMe3O ligands.

Biodegradation of two amphiphilic "soft" antimicrobially active derivatives of lauric (dodecanoic) acid, a quaternary ammonium salt and an amine oxide bearing an amide or ester group, was followed using microorganisms from activated sludge. Primary biodegradation was determined by ion-selective electrodes, total biodegradation as the chemical oxygen demand. Though organic ammonium salts quickly undergo primary biodegradation, the rest of the molecule is difficult to destroy. In contrast, amine oxides are easily biodegradable.

The behavior of polymeric chains in dilute cellulose solutions in triethylamine oxide or in mixtures of this solvent with dimethylformamide under intense lengthwise flow, where the product of the velocity gradient by the chain relaxation time is approximately equal to unity, has been studied. It has been shown that under these conditions, the macromolecules go over into a practically completely uncoiled state.

Bacterial strains with a high biodegradation potential were isolated from activated sludge. Their ability to decompose the hard bis-quaternary ammonium salt FB was determined by the method of chemical oxygen demand (COD) in a mineral medium, where the compound FB was the only source of carbon. The COD values were very low after 21 d and in the course of this period they reached zero level twice. The contribution of adsorption to decrease the COD value was small. The maximum COD decrease was accompanied by an increase of cell respiration. It is suggested that FB is effectively decomposed in spite of the fact that according to its structure it is a typical hard detergent.

New H + -selective ion carriers suitable for imprenating in liquid membrane as the active component of the pH electrodes are described. It has been found that lipophilic amine oxide and phosphine oxide behaved as neutral carrier for proton with excellent selectivities at basic side or acidic side, respectively. The observed ion selectivities for the new electrodes utilizing the proton carriers were superior to those of previously reported pH-sensitive liquid membrane electrodes

Complexes of 2,6-dimethylpyridine 1-oxide with lanthanide iodides of the formulaeLn(2,6-LTNO)5I3 whereLn=La, Tb and Yb,Ln(2,6-LTNO)4I3 whereLn=Pr and Nd and Er(2,6-LTNO)4.5I3 have been prepared and characterised by chemical analysis, infrared and conductance studies. Infrared and conductance data have been interpreted in terms of dimeric (or polymeric) structures involving bridging amine oxide groups.

Angular dependence of light scattering has been measured for aqueous solutions of dimethyloleylamine oxide in the presence of HCl and NaCl. In micellar solutions more concentrated than 0.1×10−2 g cm−3, rodlike micelles are dominantly formed, and their properties are strongly reflected in the characteristics of the solutions. The aggregation number, radius of gyration and even flexibility of the rodlike micelles increase with the addition of HCl as well as NaCl. The increase of HCl concentration up to 10−3 N makes the aggregation number of rodlike micelles as large as 58,000, when 0.01 M NaCl is present. The large micelle size would be stabilized by the dehydration of the amine oxide group and the hydrogen bonding between nonprotonated and protonated molecules in a micelle.

A solvent extraction technique using 0.01M solution of trilaurylamine N-oxide in benzene as extractant has been used to concentrate mercury efficiently from water solutions with or without the presence of 0.02M KI in weakly acidic media. In addition to unmodified aqueous solutions, mercury can be extracted quantitatively from aqueous iodide solutions that are up to 1M in HCl, H2SO4, and HNO3 in a single equilibration. Distribution coefficients and separation factors of several elements relative to mercury(II) are reported for media that contain 0.1 M HCl and 0.02M KI. The reagent is superior to aliphatic amines and quaternary amines for the extraction of mercury from aqueous iodide solutions.

Intracytoplasmic membranes isolated from Rhodospirillum rubrum, mutant strain VI, were extracted with the detergent lauryl dimethyl amine oxide. Subsequently two fractions were isolated, one of which contained reaction centers and the other contained light-harvesting bacteriochlorophyll of the photosynthetic apparatus. The two fractions are compared with unextracted membranes on the basis of protein patterns obtained by different methods of polyacrylamide gelelectrophoresis. Electron micrographs of the light-harvesting bacteriochlorophyll fraction reveal the presence of vesicular membrane structures. The only difference between such membranes and unextracted membranes is identified after freeze etching. While unextracted membrane surfaces are studded with particles extracted membranes exhibit a smooth surface.

Compounds of composition MCl5−n(OPh)n · L (M = Nb or Ta; n = 1 or 2 and L = monodentate ligand) have been prepared by reacting phosphoryl and amine oxide ligands with phenoxy-niobium(V) and -tantalum(V) chlorides and characterized by their analytical data, molecular weights, molar conductance and i.r. spectra.

A micromethod for the determination of the amine oxide group in organic compounds is described. It is based on the reduction with an excess of titanium(III) reagent at pH 5–6, which is quantitative at room temperature within 5 min. Excess titanium(III) is back-titrated with iron(III) solution. The accuracy is about ±0.5%. Amine oxide and nitro groups are determined together. An assembly for the preparation and storage of the titanium(III) solution is also described.

IN 1957, Haley et al. 1 found that quinoxaline-1,4-di-N-oxide reduced X-radiation mortality in mice by 50 per cent. Two mechanisms were involved, reduction of bacteraemia1 and interaction with X-ray-produced oxidizing radicals2. Comparisons have been made of other N-oxides (Table 1) using groups of 20 CF-1 mice and the same radiation conditions as before1. The 250 mgm./kgm. oral dose of drugs was given 24 hr. prior to irradiation with 550 r. The two quinoxaline derivatives significantly increased the ST 50 day but had less effect on total survival than quinoxaline-1,4-di-N-oxide. Erythromycin N-oxide significantly reduced the ST 50 day and total survival while its anhydro derivative was equivalent to quinoxaline-1,4-di-N-oxide as a radiation prophylactic. All the above compounds are readily absorbed, excreted slowly in the urine and exert antibiotic effects so the radiation bacteraemia could be reduced. On the other hand not all of them can interact with equal facility with the radiation-produced oxidizing radicals. Examination of the chemical structures involved indicated that an amine oxide either in an unsaturated ring, for example, quinoxaline or within one carbon atom of a double bond, for example, anhydroerythromycin is necessary if oxidizing radicals are to be prevented from exerting their deleterious effects. In the dimethyl-substituted quinoxaline compounds difficulties in oxidizing the methyl groups are probably the reason for the decrease in protectant activity even though Francis et al. 4 showed that hydroxylation in the 2 position occurs in vivo. With erythromycin N-oxide, the double bond is lacking and the compound can be oxidized only with difficulty even in vitro 5. Thus, it would appear that amine oxides with the above chemical structures can reduce mortality from ionizing radiation when administered orally 24 hr. prior to exposure.