Basic Acetate Research Articles

Preparation of Neptunyl and Plutonyl Acetates To Access Nonaqueous Transuranium Coordination Chemistry.

Uranyl diacetate dihydrate is a useful reagent for the preparation of uranyl (UO22+) coordination complexes, as it is a well-defined stoichiometric compound featuring moderately basic acetates that can facilitate protonolysis reactivity, unlike other anions commonly used in synthetic actinide chemistry such as halides or nitrate. Despite these attractive features, analogous neptunium (Np) and plutonium (Pu) compounds are unknown to date. Here, a modular synthetic route is reported for accessing stoichiometric neptunyl(VI) and plutonyl(VI) diacetate compounds that can serve as starting materials for transuranic coordination chemistry. The new NpO22+ and PuO22+ complexes, as well as a corresponding molecular UO22+ complex, are isomorphous in the solid state, and in solution show similar solubility properties that facilitate their use in synthesis. In both solid and solution state, the +VI oxidation state (O.S.) is maintained, as demonstrated by vibrational and optical spectroscopy, confirming that acetate anions stabilize the oxidizing, high-valent +VI states of Np and Pu as they do for the more stable U(VI). All three acetate salts readily react with a model diprotic ligand, affording incorporation of U(VI), Np(VI), and Pu(VI) cores into molecular coordination compounds that occurs concomitantly with elimination of acetic acid; the new complexes are high-valent, yet overall charge neutral, facilitating entry into nonaqueous chemistry by rational synthesis. Computational studies reveal that the dianionic ligand framework assists in stabilizing the +VI O.S. via donation to the 5f shells of the actinides, highlighting the potential usefulness of protonolysis reactivity toward preparation of stabilized high-valent transuranic species.

PERSPECTIVE SEARCHES OF MEDICINAL PLANT RAW MATERIALS AS SOURCE OF POLYSACCHARIDES

The purpose of the conducted researches was studying of cones of a pine ordinary as source of polysaccharides in complex processing of raw materials. Cones of a pine ordinary were assembled during pollination. For the purpose of development of complex processing of raw materials researches on studying of the cones which remained after receiving pollen are conducted. Researches showed prospects of use of cones of a pine ordinary as source of polysaccharides after receiving pollen. The pectin content in ordinary pine cones, established by the oxalate method, was 1,2 ± 0,1%. Qualitative determination of pectin is proposed by colour reaction with solution of carbazole with alcohol 0,5%. Reaction with 10% lead (II) basic acetate was also used to identify pectin. One indicator of the detoxifying activity of pectin is the degree of esterification (ratio of esterified and free carboxyl groups). Low esterified pectins (esterification rate below 50%) are used as detoxicant. Important is the fact that the complex processing of ordinary pine cones will make it possible to obtain pectin actually from pollen production waste. In the developed scheme of complex processing of ordinary pine cones for hydrolysis-extraction of pectin-high substances from raw materials, it is proposed to use citric acid solution with pH 1,8-2,0. Methods for identifying and quantifying pectin in an object are valid. As a result of all the studies, a method was developed for producing pectin from ordinary pine cones in the complex processing of raw materials, the content of which was 1,2±0,1%, and the degree of esterification 13,20 ± 0,5%. The results of the conducted studies showed that the content of tannins in the studied raw materials of pine cones was 0,66±0,02%. As a result of all studies, a method of producing pectin from ordinary pine cones in complex processing of raw materials has been developed. The obtained results make it possible to recommend the obtained pectins as an effective detoxifying agent and a source of polysaccharides, tannins.

Single crystal growth, structural characterization and magnetic properties study of an antiferromagnetic trinuclear iron(III) acetate complex with uncoordinated hexamine

Structural characterization of novel Fe(III) basic acetate with 1,3,5,7-tetraazaadamantane (hexamine – HEX), [Fe3(μ3-O)(OAc)6(H2O)3)](NO3)(HEX)2(H2O)5] (1), revealed a molecular structure typical for Fe(III) basic carboxylates, with a triangular array formed by three iron atoms being equilateral and with an uncoordinated hexamine molecule and nitrate anion present in the crystal structure. Despite the hexamine molecule being uncoordinated, it plays a crucial role in the formation of a supramolecular network. The magnetic properties of the compound were characterized by magnetic susceptibility, Mössbauer and EPR spectroscopy. These studies indicate the presence of high-spin iron ions in +3 oxidation state with non-Curie-like behaviour. A small room temperature value of the effective magnetic moment and a decrease of the product χT with decreasing temperature both speak in favour of antiferromagnetic interactions between the three individual Fe(III) ions of complex 1 with a total ground state spin of St = 1/2 per trinuclear cluster. EPR spectroscopy confirmed the formation of a St = 1/2 ground state, but also suggested the presence of weak intermolecular exchange interactions between two (or more) clusters of neighbouring molecules. The temperature-dependent Mössbauer spectra show a slowing-down of the fast spin-lattice relaxation rates of the paramagnetic Fe(III) ion below about 60 K, however, yet no static spin regime is reached down to 3.6 K.

Tetrabutylphosphonium acetate and its eutectic mixtures with common-cation halides as solvents for carbon dioxide capture

The absorption and desorption isotherms of CO2 in the ionic liquid tetrabutylphosphonium acetate ([P4444][OAc]) were experimentally determined at 343.2 K in the pressure range 0–15 bar. Analysed in a mass basis, the CO2 absorption capacity of [P4444][OAc] is particularly competitive among that of phosphonium ionic liquids. A contribution of chemical absorption was evidenced from the shape of the isotherms, and a reaction scheme based on the abstraction of an acidic proton in the cation by the basic acetate anion, with a 1:2 (CO2 to ionic liquid) overall stoichiometry, was proposed. The investigation of the solid–liquid equilibria of the mixtures of [P4444][OAc] with its homologous halides, namely [P4444]Cl and [P4444]Br, led to the identification of eutectic behaviours, with the eutectic compositions having melting temperatures below 308.2 K, remarkably lower than the melting temperature of pure [P4444][OAc]. The CO2 absorption capacities of these eutectic compositions were then explored at 308.2 K, and also 343.2 K for comparative purposes. While advantageously allowing their utilisation as CO2-capturing solvents at lower temperatures, in comparison to pure [P4444][OAc] the eutectic mixtures did not lead to a major loss in CO2 absorption capacity, with greater physisorption compensating for the reduction in chemisorption.

Dependence of the Solubility of Basic Copper Acetate on the Concentration of the Solution and the pH of the Suspension

Physicochemical equilibria in an aqueous suspension of basic copper acetate are studied via ion-selective potentiometry at 20°С. Equations are obtained that link the solubility product for basic copper acetate to the total content of copper in the solution and the pH of the suspension.

Phytochemical and antimicrobial study of Pilocarpus pennatifolius Lemaire

The investigation of the crude extract of leaves and bark of Pilocarpus pennatifolius Lemaire allowed isolated of a not yet described coumarin, together with three known coumarins (bergapten, xanthotoxin and dimethyl allyl xanthyletin), and a not yet described imidazole alkaloid. All structures were established by means of spectral analysis, including extensive 2D NMR studies. In addition, the alkaloid had its absolute stereochemistry determined by X-ray diffraction. Meanwhile, extracts and pure compounds were tested against various strains of bacteria and fungi, showing promising antimicrobial activities. We highlight the activities of crude bark methanol extract (CBME), of the leaf basic acetate fraction (LBAcF), and of compound 2 against the Gram negative bacteria Shigella flexneri (MICs = 7.8, 7.8 and 3.12 μg·mL−1, respectively), of compound 5 against the Gram positive Enterococcus fecalis (MIC = 1.56 μg·mL−1), and against two Gram negative bacteria Salmonella enteritidis (MIC = 1.56 μg·mL−1), and Pseudomonas aeruginosa (MIC = 6.25 μg·ml−1). On the other hand, CBME and compounds 3–5 showed excellent activity against the fungus Candida krusei with MICs of 15.6, 1.56, and 3.12 μg·mL−1 respectively, as actives or better than the antifungal standard fluconazole (MIC = 3.12 μg·mL−1).

Dimethylberyllium + CO2 → Fire! A DFT and ab Initio Study into the Photon Emission Observed in a Gas Phase Carbon Dioxide Activation Reaction

Dimethylberyllium, Me2Be, is known to ignite when the neat compound is reacted with CO2. In this contribution, we present evidence from DFT and ab initio calculations demonstrating that, while the two-stage gas phase carboxylation of Me2Be to yield beryllium acetate is strongly exothermic, it is not sufficiently so to result in the formation of excited states, as required by a combustion process. The reaction, however, will liberate sufficient heat to drive endothermic unimolecular decomposition reactions. In the case of the reaction of diethylberyllium Et2Be, this results in the formation of beryllium hydride via a β-hydride elimination reaction, and potentially of Be atoms. Pyrolysis of Me2Be, which lacks β-hydrogen atoms, is predicted to give the extremely reactive methyleneberyllium CH2═Be, a ground state triplet species. All reactive intermediates generated by pyrolysis of either Me2Be or Et2Be are calculated to react with CO2 in exothermic reactions. With one possible exception, however, none of the...

A DFT/B3LYP study of the mechanisms of the O2 formation reaction catalyzed by the [(terpy)(H2O)MnIII(O)2MnIV(OH2)(terpy)](NO3)3 complex: A paradigm for photosystem II

We present a theoretical study of the reaction pathway for dioxygen molecular formation catalyzed by the [(terpy)(H2O)MnIII(O)2MnIV(OH2) (terpy)](NO3)3 (terpy=2,2′:6′,2″-terpyridine) complex based on DFT-B3LYP calculations. In the initial state of the reaction, a partial oxido radical (0.44 spins) is formed ligated to Mn. This radical is involved in a nucleophylic attack by bulk water in the OO bond reaction formation step, in which the oxido fractional unpaired electron is delocalized toward the outermost Mn of the μ-oxo bridge, instead of the ligated Mn center. The reaction then follows with a series of proton-coupled electron transfer steps, in which the oxidation state, as well as the bond strength of the OO moiety increase, while the OOMn(1) bond gets weaker until O2 is released. In this model, basic acetate ions from the buffer solution capture protons in the proton-transfer steps. In each step there is reduction of the OOMn(1) binding strength, with concomitant increase of the OO bond strength, which culminates with the release of O2 in the last step. This last step is entropy driven, while formation of hydroperoxide and superoxide moieties is enthalpy driven. According with experiments, the rate-limiting step is the double oxidation of Mn(IV,III) or peroxymonosulfate binding, which occur prior to the OO bond formation step. This supports our findings that the barriers of all intermediate steps are below the experimental barrier of 19–21kcal/mol. The implications of these findings for understanding photosynthetic water-splitting catalysis are also discussed.

Selective Nitrate Recognition by a Halogen‐Bonding Four‐Station [3]Rotaxane Molecular Shuttle

The synthesis of the first halogen bonding [3]rotaxane host system containing a bis‐iodo triazolium‐bis‐naphthalene diimide four station axle component is reported. Proton NMR anion binding titration experiments revealed the halogen bonding rotaxane is selective for nitrate over the more basic acetate, hydrogen carbonate and dihydrogen phosphate oxoanions and chloride, and exhibits enhanced recognition of anions relative to a hydrogen bonding analogue. This elaborate interlocked anion receptor functions via a novel dynamic pincer mechanism where upon nitrate anion binding, both macrocycles shuttle from the naphthalene diimide stations at the periphery of the axle to the central halogen bonding iodo‐triazolium station anion recognition sites to form a unique 1:1 stoichiometric nitrate anion–rotaxane sandwich complex. Molecular dynamics simulations carried out on the nitrate and chloride halogen bonding [3]rotaxane complexes corroborate the 1H NMR anion binding results.

Imidazolium-Based Poly(Ionic Liquid)s Featuring Acetate Counter Anions: Thermally Latent and Recyclable Precursors of Polymer-Supported N-Heterocyclic Carbenes for Organocatalysis.

Statistical copoly(ionic liquid)s (coPILs), namely, poly(styrene)-co-poly(4-vinylbenzylethylimidazolium acetate) are synthesized by free-radical copolymerization in methanolic solution. These coPILs serve to in situ generate polymer-supported N-heterocyclic carbenes (NHCs), referred to as polyNHCs, due to the noninnocent role of the weakly basic acetate counter-anion interacting with the proton in C2-position of pendant imidazolium rings. Formation of polyNHCs is first evidenced through the quantitative formation of NHC-CS2 units by chemical postmodification of acetate-containing coPILs, in the presence of CS2 as electrophilic reagent (= stoichiometric functionalization of polyNHCs). The same coPILs are also employed as masked precursors of polyNHCs in organocatalyzed reactions, including a one-pot two-step sequential reaction involving benzoin condensation followed by addition of methyl acrylate, cyanosilylation, and transesterification reactions. The catalytic activity can be switched on and off successively upon thermal activation, thanks to the deprotonation/reprotonation equilibrium in C2-position. NHC species are thus in situ released upon heating at 80 °C (deprotonation), while regeneration of the coPIL precursor occurs at room temperature (reprotonation), triggering its precipitation in tetrahydrofuran. This also allows recycling the coPIL precatalyst by simple filtration, and reusing it for further catalytic cycles. The different organocatalyzed reactions tested can thus be performed with excellent yields after several cycles.

Effect of Mixing Methods on the Precipitation of Basic Copper Acetate

Basic copper acetate can be obtained by mixing copper acetate with sodium hydroxide solutions. However, the quality of the resulting crystals is usually poor. An unknown peak appears in its X-ray diffraction pattern, and moreover, the intensity of the peak varies from sample to sample. In this study, effect of mixing methods on the quality of the basic copper acetate crystals was studied. The crystals were synthesized by employing three different mixing methods, which were batch, semi-batch system, and micromixer. The intensity of the unknown peak weakened when the semi-batch system was employed. The results implied that the mixing rate gave strong influence on the quality of the resulting basic copper acetate crystals.

An abnormal N-heterocyclic carbene-carbon dioxide adduct from imidazolium acetate ionic liquids: the importance of basicity.

In the reaction of 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N-heterocyclic carbene (NHC)-CO2 adduct I, but also isomeric aNHC-CO2 adducts II and III were obtained. The abnormal NHC-CO2 adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC-CO2 adduct I, which can then be converted in the presence of the excess of CO2 to the more stable 2-deprotonated anionic abnormal NHC-CO2 adduct via the anionic imidazolium-2,4-dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation.

Electrochemical gas sensors based on paper-supported room-temperature ionic liquids for improved analysis of acid vapours

A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon which three electrodes are screen printed by carbon ink profiting from a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs and of their easy immobilization into a porous and inexpensive supporting material such as paper. The performance of this device, used as a wall-jet amperometric detector for flow injection analyses of headspace samples in equilibrium with aqueous solutions at controlled concentrations, was evaluated for phenol and 1-butanethiol vapours which were adopted as model acid gaseous analytes. The results obtained showed that the quite high potentials required for the detection of these analytes are lowered significantly, thanks to the addition of the basic acetate RTIL. In such a way, overlap with the medium discharge is avoided, and the possible adverse effect of interfering species is minimised. The sensor performance was quite satisfactory (detection limits, ca. 0.3 μM; dynamic range, ca. 1-200 μM, both referred to solution concentrations; correlation coefficients in the range 0.993-0.997; repeatability, ± 6% RSD; long-term stability, 9%); thus suggesting the possible use of this device for manifold applications.

Preparation and properties of barium-ferrite-containing glass ceramic fibers via an electrospinning/sol–gel process

Barium-ferrite-containing glass ceramic fibers were successfully prepared by the combination of a sol–gel process and electrospinning technique using basic iron formate, barium acetate and boric acid as the starting materials. After leaching of barium borate matrix, pure phase BaFe12O19 fibers were obtained. The relationship of aged time and viscosity of the precursor solution was studied and the results showed that the viscosity corresponding to the spinnable state was 1–4 Pa s. The morphology, structure and magnetic properties of the obtained fibers were characterized with scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis–differential scanning calorimetry, vibrating sample magnetometer. The X-ray diffraction results indicate that only the M-type Ba-ferrite and Ba-borate exist. The fibers had rough surface and hollow structure with the diameter no more than 1 μm. The fibers were composed of 40 nm BaFe12O19 nanoparticles embedded in the borate matrix. The coercivity and saturation magnetization of the synthesized fibers were 4,106.9 Oe and 17.8 emu/g, respectively.

Efficacy of surface sampling methods for different types of beryllium compounds

The objective of the research work was to evaluate the efficiency of three different sampling methods (Ghost Wipe™, micro-vacuum, and ChemTest®) in the recovery of Be dust by assessing: (1) four Be compounds (beryllium acetate, beryllium chloride, beryllium oxide and beryllium aluminium), (2) three different surfaces (polystyrene, glass and aluminium) and (3) inter-operator variation. The three sampling methods were also tested on site in a laboratory of a dental school for validation purposes. The Ghost Wipe™ method showed recovery ranging from 43.3% to 85.8% for all four Be compounds and for all three quantities of Be spiked on Petri dishes, while recovery with the micro-vacuum method ranged from 0.1% to 12.4%. On polystyrene dishes with 0.4 µg Be, the recovery ranged from 48.3% to 81.7%, with an average recovery of 59.4% for Operator 1 and 68.4% for Operator 2. The ChemTest® wipe method with beryllium acetate, beryllium chloride, and AlBeMet® showed analogous results that are in line with the manufacturer's manual, but collection of beryllium oxide was negative. In the dental laboratory, Ghost Wipe™ samplings showed better recovery than the micro-vacuum method. The ratios between the recovered quantities of Be in each location where the Ghost Wipe™ was tested differed substantially, ranging from 1.45 to 64. In the dental laboratory, a faint blue color indicating the presence of Be was observed on the ChemTest® wipes used in two locations out of six. In summary, the Ghost Wipe™ method was more efficient than micro-vacuuming in collecting the Be dust from smooth, non-porous surfaces such as Petri dishes by a factor of approximately 18. The results obtained on site in a dental laboratory also showed better recovery with Ghost Wipes™. However, the ratio of Be recovered by Ghost Wipes™ versus micro-vacuuming was much lower for surfaces where a large amount of dust was present. Wet wiping is preferred over micro-vacuuming for beryllium forms, but this conclusion probably applies to the ultra-low particulate loading levels (0.4 micrograms or less) which was tested in this study.

Mechanism of thermal decomposition of cobalt acetate tetrahydrate

AbstractThe thermal decomposition of cobalt acetate tetrahydrate (Co(CH3COO)2 · 4H2O) has been studied via thermogravimetric (TG) analysis, in situ X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results of TG and XRD showed that the parent salt melted and then the dissolved crystalline water was vaporized in two steps. The dehydration process was followed by a major step concerning the decomposition of the acetate group, leading to basic acetate as an intermediate, which then produced CoO and Co in N2 and H2 atmosphere, respectively. Three decomposition intermediates Co(CH3COO)2 · 0.5H2O, Co(CH3COO)2, and Co(OH)(CH3COO) were presumed. In situ XRD experiments revealed that the intermediate basic acetate was poorly crystallized or even amorphous. Evolved gases analysis indicated that the volatile products of acetate decomposition were water vapor, acetic acid, ethylenone, acetone, and CO2. A detailed thermal decomposition mechanism of Co(CH3COO)2 · 4H2O was discussed.

Surfactant-assisted fabrication PbS nanorods, nanobelts, nanovelvet-flowers and dendritic nanostructures at lower temperature in aqueous solution

PbS nanostructures with different morphologies, such as rod-like, belt-like, downy-velvet-flower-like and dendrite-like, were fabricated successfully under varied reaction conditions in aqueous solution at lower temperature by the assistance of surfactant CTAB. Especially, among all the synthesis methods for PbS nanocrystals, this is the first report using basic acetate of lead, which was formed at initial reaction stage, as a precursor to control the crystal nucleation rate. This synthesis method is a promising one to metal sulfide for its easy control, low-cost and large-scale production. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), field-emission scanning electron microscopy (FE-SEM) and UV–visible spectrophotometer (UV–vis) were used to characterize the products. A rational mechanism is proposed and three control factors to the crystal directional growth are also concluded.

Novel Lewis-base ionic liquids replacing typical anions

We have synthesized two kinds of new Lewis-base ionic liquids (ILs); one is based on the relatively strong Lewis basic acetate anion, and the other is a salt composed of a mono-alkylated diamine such that the Lewis base site is incorporated in the cation. 1-Octyl-4-aza-1-azonia-bicyclo[2.2.2]octane bis(trifluoromethanesulfonyl)amide, [C 8dabco]TFSA, and N-butyl- N-methylpyrrolidinium acetate, [p 1,4]OAc, melted into fluid liquids at 26 and 81 °C, respectively. The thermal decomposition of [p 1,4]OAc started at around 150 °C, whereas the thermal stability of [C 8dabco]TFSA was almost equal to that of typical TFSA-based ILs in spite of the Lewis base site. This suggests that if the Lewis base site is incorporated into the cation the IL can maintain higher thermal stability. In addition, as a further result of the presence of the basic nitrogen, [C 8dabco]TFSA can dissolve hydrated Cu(NO 3) 2 whereas the other TFSA-based ILs cannot.

Dimethylsuphoxide and its roles in the coordination chemistry of the uranyl ion

Structure determinations for the dimethylsulphoxide (DMSO) solvates of uranyl triflate, nitrate, picrate and a tetranuclear basic acetate show DMSO to be bound in all cases as an O-donor ligand but with the sulphur atoms involved in a variety of close approaches which may be significant in determining details of the complex ion structures. These close approaches, which generally mean that S may be considered to have ‘3 + 2’ coordination, usually involve O of an adjacent DMSO or oxyanion ligand, but can also involve uranyl-O and can be both intra- and inter-molecular. To cite this article: J.M. Harrowfield et al., C. R. Chimie 8 (2005) .

Thermal decomposition of nickel acetate tetrahydrate: an integrated study by TGA, QMS and XPS techniques

The thermal decomposition of nickel carboxylates is a feasible route to synthesize metal nanoparticles suitable for catalytic purposes. The aim of this work is the characterization of the thermal decomposition course of nickel acetate tetrahydrate, Ni(CH 3COO) 2·4H 2O. A thermogravimetric (TGA) decomposition study carried out in three different atmospheres (air, helium and hydrogen) showed that the dehydration of the parent salt occurs between 118 and 137 °C. However, irrespective of the chosen atmosphere, the sample weight loss registered in this stage remains invariable, suggesting the formation of a an intermediate basic acetate with the formula 0.86Ni(CH 3COO) 2·0.14Ni(OH) 2. The dehydration step was followed at ca. 350 °C by the subsequent one-step major decomposition of the acetate group, producing NiO and Ni, in treatment atmospheres of air and hydrogen, respectively, but there was some indication of an additional step when the thermolysis was conducted in helium. The conclusions possible from thermal analysis were confirmed by monitoring evolved gases employing quadrupole mass spectrometry (QMS), and a set of reactions linked to the decomposition of the acetate group has been proposed to account for most of the gas products detected. X-ray photoelectron spectroscopy (XPS) was used to investigate the solid phases obtained during the thermal decomposition of the salt in He atmosphere.