Extraction of HCl,HBr, HNO3, HClO4, H2SO4 and CH3COOH by 4-(5-Nonyl)pyridine and 2-hexylpyridine in benzene and determination of their pKBH+ values

The extraction of HCl, HBr, HNO₃, HClO₄, H₂SO₄ and CH₃COOH into solutions of 4-(5-nonyl)pyridine (NPy) and 2-hexylpyridine (HPy) dissolved in benzene has been studied. The results show that the larger, less basic anions extract better (ClO ₄ ⁻ >CH₃COO⁻≥NO ₃ ⁻ >Br⁻>Cl⁻>HSO ₄ ⁻ ) due to their low aqueous hydration. The ionization constants of NPyH⁺ and HPyH⁺ as determined spectrophotometrically were found to be 5.97±0.06 and 5.94±0.05, respectively, at 25°C.     

Amidocrownophanes as Anion Receptor

Crownophanes composed of 28-membered ring atoms having two hydroxy groups, two amide groups, and aromatic parts such as naphthalene rings and either pyridine or benzene ring, can bind anions with high affinity and selectivity. The anion-coordination ability of these species has been observed by ¹H NMR techniques. As anion guest molecules, we selected some halides, dihydrogenphosphate and acetate ions. It has been found that amidocrownophanes, 3 and 4, can recognize anions in the order;H₂PO ₄ ⁻ >F⁻>CH₃COO⁻>Cl⁻>>Br⁻ and I⁻, while not only 1, 2, and 5 having no hydroxy group but also 6 having 27-membered ring have no ability for anion recognition under the same conditions. In order to exhibit the recognition ability for anion receptor, plural amide groups, hydroxy groups, and m-phenylene or 1,6-pyridyl rigid part play an important role in this macrocyclic system.     

Thermal Behaviour of New Zinc(II) Bromobutyrate Complex Compounds

New zinc bromobutyrate complexes of general formula ZnX₂·1−L·nH₂O (X=CH₂Br(CH₂)₂COO⁻; CH₃CH₂CHBrCOO⁻) containing one or two molecules of caffeine, nicotin-amide and phenazone as ligands (L) were prepared. The compounds were characterized by MS-, IR- spectroscopy, chemical and thermal analysis. The thermal decomposition of hydrated compounds starts by the release of water molecules. In anhydrous compounds the loss of organic ligands takes place followed by the decomposition of the bromobutyrate anion at higher temperatures. Zinc bromide was found among the final products of thermal decomposition. Water, carbon monoxide, propylaldehyde, vinylaldehyde and formaldehyde were detected in the gaseous products of the thermally decomposed samples on heating up to 700°C. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characteristic features of the synthesis, solubility products, and absorption spectra of basic cobalt(II) acetate, nitrate, and chloride salts

The solubility products of basic cobalt(II) salts Co(OH)_1.80(An)_0.20, where An are NO₃⁻ and CH₃COO⁻, and Co(OH)_1.50(CH₃COO)_0.50 were determined by the method of three variables. The stability of the salts Co(OH)_1.80(An)_0.20 against hydrolysis increases in the series < CH₃COO⁻ < Cl⁻. The absorption maxima of Co²⁺ ions in solutions, β-Co(OH)₂ powders, and the pink Co(OH)_1.50Cl_0.5 salt are located in the frequency regions typical of the octahedral coordination; those of CoOH⁺ ions in solutions and powders of green basic cobalt salts are in the frequency regions typical of the tetrahedral coordination. A model for the formation and interconversion of basic cobalt salts with single-charged anions is proposed.     

Preparation and certification of arsenobetaine reference material NMIJ CRM 7901-a

An arsenobetaine [(CH₃)₃As⁺CH₂COO⁻] solution reference material, NMIJ CRM 7901-a, intended for use in the speciation of arsenic compounds, was developed and certified by the National Metrology Institute of Japan (NMIJ), part of the National Institute of Advanced Industrial Science and Technology (AIST). The high-purity arsenobetaine powder was synthesized from trimethylarsine [(CH₃)₃As], and it was dissolved in water in order to prepare 20 mg kg⁻¹ of arsenobetaine standard solution. The solution was bottled in 500 bottles (each containing 10 ml). Certification of the CRM for arsenobetaine was conducted by NMIJ. The concentration of As was determined by four independent analytical techniques (ICP–MS, ICP–OES, GFAAS and LC–ICP–MS), and each result was converted to the arsenobetaine concentration by applying an appropriate factor. The arsenobetaine concentration in the CRM was thus certified.     

The Effect of Different Aqueous Ionic Media on the Acid-Base Properties of Some Open Chain Polyamines

Acid-base properties of some open-chain polyamines (ethylenediamine, diethylenetriamine, triethylenetetramine, spermine, tetraethylenepentamine and pentaethylenehexamine) were studied at different ionic strengths in different aqueous ionic media at 25 °C. Measured were: (i) the protonation constants of triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine from potentiometric measurements [0 ≤I≤2.5 mol⋅L⁻¹ in NaCl and (CH₃)₄NCl)]; and (ii) protonation enthalpies of ethylenediamine, diethylenetriamine, and spermine from calorimetric measurements [NaCl: 0≤I≤1 mol⋅kg⁻¹ for ethylenediamine, diethylenetriamine, 0 ≤I≤2 mol⋅kg⁻¹ for spermine; (C₂H₅)₄NI: 0≤I≤1 mol⋅kg⁻¹; (CH₃)₄NCl: 0 ≤I≤2.5 mol⋅kg⁻¹ only for diethylenetriamine]. Previously published protonation data for these polyamines in aqueous NaCl, (CH₃)₄NCl and (C₂H₅)₄NI, were also examined. The general trends for the Gibbs energy and entropic contributions are, for ΔG: NaCl>(CH₃)₄NCl>(C₂H₅)₄NI, and for TΔS: (C₂H₅)₄NI>(CH₃)₄NCl>NaCl. This trend is more pronounced for the first protonation step. The dependences of these quantities on ionic strength were modeled with the SIT (Specific ion Interaction Theory) equations, and differences found among the different media were interpreted in terms of weak complex formation.     

ESR study of free-radical intramolecular transfer of a hydrogen atom: mechanisms and kinetics of the reactions

A method for preparing >Si(R₁(R₂ ^.) structures (R₁=CH₃, CD₃, or CH₂−CH₃, R₂ ^.=CH₂−CH₂ ^. or CD₂−CD₂ ^.) grafted to a silica surface is developed. The reactions of intramolecular transfer of H (D) atoms between the R₁ and R₂ ^. fragments were studied by ESR. The directions and kinetic parameters of these reactions were established. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1468–1471, August, 1997.     

Non-alkane behavior of cyclopropane and its derivatives: characterization of unconventional hydrogen bond interactions

Eight cyclopropane derivatives (Δ − R) have been modeled, with R = −H, −CH₃, −NH₂, −C ≡ CH, −C ≡ CCH₃, −OH, −F and −C ≡ N. All geometries have been fully optimized at the MP2/ AUG-cc-pVTZ level of calculations. Natural bond orbital analyses reveal extra p character (sp^λ, λ > 3) in the C-C bonds of the cyclopropyl rings. The banana-like σ _CC bonds in the rings are described in detail. Alkene-like complexes between Δ − R molecules and hydrogen fluoride are identified. These weakly bonded complexes are formed through unconventional hydrogen bond interactions between the hydrogen atom in the HF molecule and the carbon–carbon bonds in the cyclopropane ring. A topological analysis of the electronic charge density and its Laplacian has been used to characterize the interactions. The possible relevance of such complexes in the modeling of substrate–receptor interactions in some anti-AIDS drugs is discussed. Contribution to the Serafin Fraga Memorial Issue.     

The nature of ion exchange selectivity of phenol-formaldehyde sorbents with respect to cesium and rubidium ions

The structure of aqua complexes of alkali metal ions Me⁺(H₂O) _n , n = 1−6, where Me is Li, Na, K, Rb, and Cs, and complexes of 2,6-dimethylphenolate anion (CH₃)₂PhO⁻ selected as a model of the elementary unit of phenol-formaldehyde ion exchanger with hydrated alkali metal cations Me⁺(H₂O) _n , n = 0−5, was studied by the density functional method. The energies of successive hydration of the cations and the energies of binding of alkali metal hydrated cations with (CH₃)₂PhO⁻ depending on the number of water molecules n were calculated. It was shown that the dimethylphenolate ion did not have specific selectivity with respect to cesium and rubidium ions. The energies of hydration and the energies of binding of alkali metal cations with (CH₃)₂PhO⁻ decreased in the series Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺ as n increased. The conclusion was drawn that the reason for selectivity of phenol-formaldehyde and other phenol compounds with respect to cesium and rubidium ions was the predomination of the ion dehydration stage in the transfer from an aqueous solution to the phenol phase compared with the stage of binding with ion exchange groups.     

Reaction of a naphthalene complex C10H8Yb(THF)2 with cyclopentadienyl-substituted alcohols and amines as a convenient synthetic route to the half-sandwich complexes of divalent ytterbium

The reactions of ytterbium naphthalene complex C₁₀H₈Yb(THF)₂ with 2-cyclopentadienylethanol, 1-cyclopentadienylpropan-2-ol, 3-cyclopentadienyl-1-butoxypropan-2-ol, and cyclopentadienyldimethylsilyl-tert-butylamine were studied. The bivalent ytterbium complexes with chelate bifunctional cyclopentadienyl ligands [(η⁵−C₅H₅)CH₂CH₂(η¹−O)]Yb(THF), [(η⁵−C₅H₅)CH₂CH₂(η¹−O)]Yb(DME). [(η⁵−C₅H₅)CH₂CH(Me)(η¹−O)]Yb(THF), [(η⁵−C₅H₅)CH₂CH(CH₂OC₄H₉)(η¹−O)]Yb(THF), and [(η⁵−C₅H₅)SiMe₂(η¹−N(Bu¹))]Yb(THF) were obtained and characterized. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 742–745, April, 2000.     

Design and evaluation of highly sensitive luminescent terbium sensor for hypochlorite in water

A novel terbium 2-methyl-benzoimidazole-5-carboxylic acid complex was prepared and incorporated into silica matrix (tetraethoxysilane) using a mild sol–gel technique. We then successfully fabricated a terbium luminescent xerogel, which maintained intense green emission even in pure water. The emission was rapidly (~1 s) quenched by ClO⁻ (detection limit 10⁻⁵ M) but not NO₃ ⁻, CH₃COO⁻, F⁻, Cl⁻, Br⁻, I⁻, CO₃ ⁻, and OH⁻. The selectivity appears to be due to the high vibrational energy of ClO⁻ as well as its strong oxidation capability.     

Novel Co(II) and Cd(II) complexes with non-steroidal anti-inflammatory drugs

New metal(II) complexes with empirical formulae Co(ibup)₂·4H₂O, Cd(ibup)₂·3H₂O, Co(nap)₂·H₂O, Cd(nap)₂·3H₂O (where ibup=(CH₃)₂CHCH₂C₆H₄CH(CH₃COO⁻) and nap=CH₃O(C₁₀H₆)CH(CH₃COO⁻)) were isolated and investigated. The complexes were characterized by elemental analysis, molar conductance, IR spectroscopy and thermal decomposition. The thermal behavior was studied by TG, DTG, DTA methods under non-isothermal conditions in air atmosphere. The hydrated complexes lose water molecules in first step. All complexes decompose via intermediate products to corresponding metal oxides CoO and CdO. A coupled TG-MS system was used to detect the principal volatile products of thermolysis and fragmentation processes of Co(nap)₂·H₂O. The IR spectra of studied complexes revealed also absorption of the carboxylate group. Principal concern with the position of asymmetric, symmetric frequencies. The value of their separation allow to deduce about type of coordination these groups.     

Synthesis, characterisation and chemical reactivity of some new dioxouranium(VI) complexes of 2-aminobenzoylhydrazone of butane-2,3-dione

A new series of dioxouranium(VI) complexes of a potential ONNO tetradentate donor 2-aminobenzoylhydrazone of butane-2,3-dione (L₁H₂) have been synthesized. At pH 2·5–4·0, the donor (L₁H₂) reacts in the keto form and complexes of the type [UO₂(L₁H₂)(X)₂] (X⁻=Cl⁻, Br⁻, NO ₃ ⁻ , NCS⁻, ClO ₄ ⁻ , CH₃COO⁻, 1/2SO ₄ ²⁻ ) are obtained. At higher pH (6·5–7), the complex of the enol form having the formula [UO₂(L₁)(H₂O)] has been isolated. On reaction with a monodentate lewis base (B), both types of complexes yield adducts of the type [UO₂(L₁)(B)]. All these complexes have been characterised adequately by elemental analyses and other standard physicochemical techniques. Location of the bonding sites of the donor molecule around the uranyl ion, status of the uranium-oxygen bond and the probable structure of the complexes have also been discussed.     

Contributions of hydrocarbon radicals and functional groups of organic molecules to enthalpies of their solvation in mixed water—tert-butyl alcohol solvents

The contributions of hydrocarbon radicals (−CH₃, >CH₂, >CH−, >C<) and functional groups (−OH, −OCOO−, −NO₂, −CN, >SO) to the enthalpies of solvation of organic molecules in mixed water—tert-butyl alcohol solvents were calculated in the whole range of compositions at 298.15 K. The influence of the composition and properties of the mixture on the solvation of different functional groups is discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1811–1814, October, 1997.     

Synthesis and magnetic properties of polymeric complexes containing ruthenium(II)-ruthenium(III) tetracarboxylato units linked by cyanato,thiocyanato, and selenocyanato ligands

Polymeric complexes of ruthenium(II)-ruthenium(III) tetracarboxylato units linked by cyanato, thiocyanato, and selenocyanato ligands [Ru₂{O₂C(CH₂)_mCH₃}₄(L)] _n (m = 0, 4–7; L = OCN⁻, SCN⁻, and SeCN⁻) were prepared and characterized based on the elemental analyses, IR, and diffuse reflectance spectra. Magnetic susceptibilities were measured at the temperature range of 4.5 K to 300 K, where the interdimer antiferromagnetic interactions were revealed. The strongest interaction was exhibited in case of m = 7 and L = OCN⁻. ¹H-NMR spectra of [Ru{O₂C(CH₂)₇CH₃}₄(SCN)] _n in CD₂Cl₂ showed broad signals which can be ascribed to polymeric species, as the addition of tetrabutylammonium thiocyanate caused sharper signals due to the formation of [Ru₂{O₂C(CH₂)₇CH₃}₄(SCN)₂]⁻ adduct as the main species in the solution. Dedicated to Professor Milan Melník on the occasion of his 70th birthday     

Reduction of Ag<Superscript>I</Superscript> complexes with malonate ions in aqueous solution studied by pulse radiolysis

The formation of clusters CH₂(COO⁻)(COOAg₃ ⁺) (absorption bands at 280 and 460 nm) by the reduction of silver ions in the presence of malonate ions in an aqueous solution was studied by pulse radiolysis. The disappearance of the clusters affords colloidal silver. The mechanism of silver nucleation was discussed, and the rate constants of some reactions were determined. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1819–1822, August, 2005.     

Distonic ions of the “ate” class

The gas phase synthesis, structure, and reactivity of distonic negative ions of the “ate” class are described. “Ate”-class negative ions are readily prepared in the gas phase by addition of neutral Lewis acids, such as BF₃, BH₃, and AlMe₃, to molecular anions, carbene negative ions, and radical anions of biradicals. The ions contain either localized σ- or delocalized π-type radical moieties remote from relatively inert borate and aluminate charge sites. The free radical reactivity displayed by these ions appears to be independent of the charge site. As an example, the distonic alkynyl radical (·C≡CBF₃⁻) is highly reactive and undergoes radical coupling reactions with NO₂, NO, H₂C=CH-CN, and H₂C=CH-CH₃. Radical-mediated group and atom transfers are observed with O₂, CS₂, and CH₃SSCH₃. Furthermore, H-atom abstraction reactions are observed, in accordance with the predicted high C-H bond strength of this species [DH₂₉₈(H-C₂BF₃⁻)=130.8 kcal mol⁻¹]. High level ab initio molecular orbital calculations on the prototype “ate”-class distonic ion · CH₂BH₃⁻ and its conventional isomer CH₃BH₂^·− reveal that CH₃BH₂^·− is 3.2 kcal/mol more stable than the α-distonic form. However, the calculations also show that CH₃BH₂^·− is unstable with respect to electron detachment, and only the α-distonic form ·CH₂BH₃⁻ should be experimentally observed in the gas phase.     

Liquid Densities and Excess Molar Volumes for Binary Systems (Ionic Liquids + Methanol or Water) at 298.15, 303.15 and 313.15 K,and at Atmospheric Pressure

Binary excess molar volumes, V _m ^E, have been evaluated from density measurements, using a vibrating tube densimeter over the entire composition range for binary liquid mixtures of ionic liquids 1-ethyl-3-methyl-imidazolium diethyleneglycol monomethylethersulphate [EMIM]⁺[CH₃(OCH₂CH₂)₂OSO₃]⁻ or 1-butyl-3-methyl-imidazolium diethyleneglycol monomethylethersulphate [BMIM]⁺[CH₃(OCH₂CH₂)₂OSO₃]⁻ or 1-methyl-3-octyl-imidazolium diethyleneglycol monomethylethersulphate [MOIM]⁺[CH₃(OCH₂CH₂)₂OSO₃]⁻+methanol and [EMIM]⁺[CH₃(OCH₂CH₂)₂OSO₃]⁻+water at 298.15, 303.15 and 313.15 K. The V _m ^E values were found to be negative for all systems studied. The V _m ^E results are explained in terms of intermolecular interactions and packing effects. The experimental data were fitted by the Redlich-Kister polynomial.     

功能化酸性离子液体脱除模拟油品中的非碱性氮

合成了一系列功能化酸性离子液体并用于模拟油品中非碱性氮-吲哚的脱除。结果表明,离子液体的阴离子对脱氮率有较大影响,离子液体的酸性越强,对吲哚的选择性脱除效果越好,不同阴离子的脱氮率顺序为：HSO₄^- > CF₃COO^- > H₂PO₄^- > CH₃COO^-。以（CH₃CH₂）₃N（CH₂）₃SO₃HHSO₄为例,考察了剂油比、剂水比、沉降时间、反应时间和温度对油品脱氮率的影响。结果表明,在优化的工艺路线下,（CH₃CH₂）₃N（CH₂）₃SO₃HHSO₄对油品中的吲哚脱除率可达99.12%,重复使用六次后,脱氮活性未见明显降低,具有良好的稳定性,。     

The synthesis of13N-labelled nitrite of high specific activity and purity

An improvement in a method for the synthesis of¹³NO ₂ ⁻ from¹³NO ₃ ⁻ with specific activity>30 mCi/mL and radiochemical purity>99% is described.¹³NO ₃ ⁻ is produced by the¹⁶O(p, α)¹³N reaction using a recirculating water target and 20 MeV protons.¹³NO ₂ ⁻ is synthesized by reduction of¹³NO ₃ ⁻ in a cadmium-copper column. Contaminating¹³NH ₄ ⁺ is removed by rotatory evaporation at pH>11.0. The synthetic procedure takes less than 20 minutes from collection of irradiated target water to sterilization of the radiopharmaceutical.