Extraction of zirconium(IV) from HCl solutions by mixtures of Aliquat-336 and Alamine-336 with TBP

Synergism has been observed in the extraction of zirconium(IV) by mixtures of Aliquat 336 or Alamine 336 with a neutral donor TBP from aq. HCl solutions. Although the extractant dependency for Zr(IV) is found to be nearly second power with respect to TBP alone, monosolvate is found to be formed for extraction by its mixture with Aliquat 336 or Almine 336. Quantitative extraction is observed with mixtures at a lower acidity than that with individual extractants. The species formed is tentatively assigned to be Q₂ZrCl₆. TBP, where for Aliquat 336 and for Alamine 336.     

Radiolysis of p-benzoquinone solutions

The products of the continuous radiolysis of p-benzoquinone (Q) at different concentrations of H₂SO₄, Q and Cl^– are p-hydroquinone (H₂Q) and 2-hydroxy-p-benzoquinone (2-Q-OH). In the presence of some alcohols, a carbonyl compound is produced in addition to H₂Q and 2-Q-OH. The dependence of G values of the products on these factors is described. The material balance between G(-Q) and G(H₂Q)+G(2-Q-OH) is maintained. The experimental results indicate the occurrence of the following reaction: . By competition studies, it was possible to evaluate the rate coefficients for the following reactions: .     

Synthesis and CH-acidity of N,N-disubstituted aminotriphenylphosphonium salts

Several substituted methylaminotriphenylphosphonium salts (APS) of general formula have been synthesized. The CH-acidities of some of the prepared APS have been measured by the indicator method in DMSO, with K⁺ counterion and 9-phenylfluorene (pK 18.5) as standard, showing a pK range of 14.7–24.8. The acidification effect of and groups has been evaluated. The results obtained suggest that there is an effective charge on the nitrogen atom in the APS studied and an increased multiplicity of the N-P bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1598–1604, July, 1991.     

Oscillatory variation in yields of I2 and the reactivity of γ-irradiated TiO2 in KI solution

The reactivity of preheated and -irradiated TiO₂ was observed in KI solution by studying the kinetics of liberation of I₂. The rate of the reaction was found to be low. species proposed on the surface of oxide probably dissociate into . surface sites which oxidize I^– ions to produce free I₂. During irradiation and are produced which are reducing in nature and therefore very low yields of I₂ are observed for low -doses. In further irradiation the reformation of –O–O–, peroxy linkages is proposed hence the observed higher yields. All the processes ultimately lead to an oscillatory variation in yields of I₂ with -doses.     

Vibrational spectra and structure of sulfonium nitroimides

Vibrational spectroscopy and x-ray structure analysis have been used to investigate three new types of sulfonium nitroimides: N-nitrosulfylimides, N-nitrosulfoximides, and N,N-dinitrosulfodiimides. Structural parameters have been determined for the molecules , , and .Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2489–2496, November, 1991.     

ZumHunsdiecker-Abbau von 2-Acylcyclopropancarbonsäuren

2-Acylcyclopropane carboxylic acids (1) are degraded by aHunsdiecker reaction using red HgO/Br₂ to mixtures oftrans- andcis-2-bromo-cyclopropyl alkanones, the former being the major component. The starting materials may be easily prepared by reaction of stabilised S-ylides with ,-unsaturated oxo compounds or -acylvinyltriphenylphosphonium bromides.     

Studies on ion exchange equilibria and kinetics

¹⁶⁰Tb was used as radiotracer and the equilibria and kinetics of cation exchange with zeolite-Y were studied. The ion exchange isothems and the Kielland plots at 298 and 303 K were obtained. It was found that the ion exchange rate is controlled by particle diffusion. The integral interdiffusion coefficients for the direct and reverse exchanges at 298 K and 303 K were calculated. In addition, the isotopic ion exchange was studied too.     

Effect of dissolved oxygen on the inactivation of bacteriophages in water by gamma radiation: Important role ofH\dot O_2 radicalsradicals

The inactivation of bacteriophages by -radiation was studied in 0.1M Na phosphate buffer and in deionized water in the presence and absence of dissolved oxygen. From the results obtained it is possible to make conclusion that radicals /which are formed in radiolysis of water in the presence of oxygen/ have a marked inactivating effect on bacteriophages, but in the simultaneous presence of radicals an inactivation takes place between them.     

A generalized separation reaction scheme for assessment of the radioanalytical method of concentration dependent distribution

For the assessment of the analytical error of concentration dependent distribution (CDD), complex-forming separation reaction was proposed in a generalized form of equilibrium , where n is the effective stoichiometric coefficient, i.e. the difference of mean ligand numbers and <n> of a mixture of complexes of analyte M with reagent L in the respective groups (distinguished by bars above the symbols) of the separation system. Calibration curve is derived from measurement of gross activity of complexes, A=A(ML_<n>) and . Theoretical relative error is expressed as a product of three terms, x/x=f₁f₂f₃. The first term f₁ depends on the degree of isotopic dilution, and the recommended ratio of amounts of nonradioactive (x) and radioactive (y) substance M is x/y(1;4). The second term f₂ depends first of all on the slope of distribution ratio (yield of separation ) vs. the analyte; reagent ratio, n(Z+1)/T. The form of slope is analyzed on the basis of the generalized separation reaction. Optimal conditions were discussed from this point of view and the ideal case is at f₂=1. The third term f₃ depends on the activities A and , i.e. on the distribution ratio, sample volumes, and the manner of counting. The ideal ratio of sample activities is A= and the optimal interval (0.2;0.8) is suggested     

A method for experimental determination of effective resonance energies related to (n, γ) reactions

When making use of some single comparator or absolute standardization methods in reactor neutron and in epicadmium neutron activation analysis, the knowledge of the effective resonance energy ( ) is essential to correct for the effect of the nonideal epithermal flux distribution on the analysis result. can be calculated from neutron resonance data, but when these are incomplete, not accurate or even not known at all, experimental determination should be considered. Such a method, providing both and the resonance integral to 2200 ms^–1 cross-section ratio (Q_O), is described in this paper. Results are given for 11 isotopes.     

Critical evaluation of the effective resonance energy concept and the epithermal neutron spectrum shape-factorα for reactor NAA purposes

The epithermal reactor neutron spectrum shape-factor, and the associated effective resonance energy for a given nuclide, are examined theoretically in great detail. First the necessity, meaning and importance of the choice of a reference neutron energy in a non-ideal spectrum (0) are explained. Next, the definition and practical calculation of are discussed, showing that the relation between the reasonance integrals in ideal and non-ideal spectra cannot be described adequately by two independent parameters and . The exact meaning of the logarithmic expression defining an independent of is clarified, its limits of validity are established as a function of and, as a result, it follows that relatively large systematic errors on can be introduced by its use. It is shown that is dominated by the first lowest resonance energies for a given nuclide, making its vulnerability to literature updates of resonance parameters almost equal to those of individual resonances. The effect, on the epithermal and total activation of specific nuclides, of large systematic and statistical errors on and, is calculated for a series of nuclides (different I₀/₀ and ) and irradiation facilities (different and _the), and represented graphically.Finally, the effect of important errors on and is calculated for final NAA results in terms of concentrations, botained by a comparator technique based on the¹⁹⁷Au reference nuclide. Conclusions are drawn concerning the impact of the foregoing on the usefulness of comparator type reactor NAA as an alternative to classical NAA using multi-element standards.     

Applicability of the 1/E1+α epithermal spectrum representation and the effective resonance energy\bar E_r in NAA

The practical applicability of the 1/E¹⁺ epithermal spectrum representation and of the effective resonance energy in NAA is investigated. Attention is paid to fundamental considerations such as definitions and approximations, error propagation functions, uncertainty statements, reliability of nuclear data and formal dimensioning problems. As to the latter, it is concluded that the applicability of the -concept is not dependent on the choice of a reference energy. The usefulness of the parameters and in NAA is demonstrated by new experimental evidence obtained from and Q₀ determinations in three different reactors: the WWR-M reactor (Budapest, Hungary), the THETIS reactor (Gent, Belgium) and the DR-3 reactor (Risø, Denmark).     

Some analytical results forABC,ABCD, andXBCD coupled spin 1/2 systems. I

By choosing a suitable linear combination of the constants of the motion , it is shown that the calculation of the density matrix(t) can be simplified by subdividing the Hamiltonian into . In particular, this technique can be used to obtain closed form solutions for the eigenfunctions and eigenvalues of spin 1/2ABC andXBCD spin systems, evolving in the presence of Zeeman offsets, scalar coupling and dipolar interactions. In general, the eigenvalues and eigenvalues of are very transparent, while those of require more effort. Nevertheless, simplifications can be made. Firstly, the effective size of the Hamiltonian matrix which needs to be considered, is reduced fromN ×N to at least (N – 2) × (N – 2), while forXBC ... systems it is reduced to (N – 4) × (N – 4). Secondly, the highest rank and highest/lowest order tensor operators available to the spin ensemble are constants of the motion under . Finally, by exploiting the fact that is a good quantum number, it is possible to block-diagonalize the matrix into no more than 3 × 3 matrices.     

Simulation of donor-acceptor electron-transport systems in the example case of the oxidation of copper in media of organic solvents

The interaction of the onium salts [Me₂ Et=O]BF₄ ^–, [Me₂ =CH-OEt]BF₄ ^–, and [Me₃ =O]I^– with metallic copper in DMSO, DMF, and acetonitrile (AN) has been investigated. It has been shown that the reaction takes place with an intermediate step involving the formation of Cu(I) compounds. The complexes [Cu^I(AN)₄]BF₄, [Cu^II(DMSO)₅](BF₄)₂, [Cu^II(DMSO)₄(AN)₂](BF₄)₂, [Cu^II(DMSO)₂(DMF)(AN)](BF₄)₂, and [ME₃ ]₃Cu^II₄ · [Me₃ =O]I^– have been isolated and characterized. It has been established that dipolar onium compounds which simulate the intermediate products of the interaction of the components of donor-acceptor electron-transport systems are responsible for the oxidation of metals in organic complex-forming media.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1325–1330, June, 1991.     

Neutron generation in massive Cu-targets during the irradiation with 22 and 44 GeV carbon ions

An extended Cu-target was irradiated with 22 and 44 GeV carbon ions for about 11.3 and 14.7 hours, respectively. The upper side of the target was in contact with a paraffin-block for the moderation of secondary neutrons. Small holes in the moderator were filled with either lanthanum salts or uranium oxide. The reaction was studied via the decay of¹⁴⁰La(40h) using radiochemical methods, as has been published. The reaction was studied via the decay of²³⁹Np(2.3 d) as well as the reaction U(n,f) using radiochemical methods. In addition, solid state nuclear track detectors were used for fission studies in gold. The yields for the formation of (n,) products agree essentially with other experiments on extended targets carried out at the Dubna Synchrophasotron (LHE, JINR). To a first approximation, the breeding rate of (n, ) products doubles when the carbon energy increases from 22 to 44 GeV. If, however, results at 44 GeV are compared in detail to those at 22 GeV, we observe an excess of (37±9)% in the experimentally observed²³⁹Np-breeding rate over theoretical estimations. Experiments using solid state nuclear track detectors give similar results. We present a conception for the interpretation of this fact: There is the evident connection between anomalies we observe in the yield of secondary particles in relativistic heavy ion interactions above a total energy of approximately 30–35 GeV and increased yield of neutrons in this energy region.     

Intramolecular alkylation of anions of nitramines

Conclusions The intramolecular alkylation of the anions of nitramines of type goes by the O-alkylation scheme with the formation of the derivatives of 4,5-dihydro-1,2,3-oxadiazole 2-oxides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1294–1298, June, 1973.     

Kinetics of the reaction of superoxide anion-radical with olefins

Kinetic investigation of the reaction of electrochemically generated with perfluorooctene, styrene, and cyclohexene in acetonitrile, in the presence of tetraethylammonium perchlorate used as a background electrolyte, revealed that reacts with styrene and perfluorooctene at the double bond, and the reactivity of the olefins with respect to decreases with decrease in the electrophilicity of the substituents at the double bond: perfluorooctene > styrene > cyclohexene. The main transformation products of styrene are phthalic and benzoic acid esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 733–737, April, 1990.The authors thank V. B. Bol'evoi for his contribution to the discussion of the results obtained.     

Theoretical conformational analysis of some agonists of the H1- and H2-receptors of histamine

The conformational equilibrium of -(aminoethyl)pyridines has been studied by molecular-mechanics using the geometry optimization. It has been determined that the equilibrium is characterized by the nearly statistical distribution of the ap- and sc-conformers about the bond. Substitution of the dimethylamino-group for the amino-group results in a slight shift of the equilibrium toward the ap-rotamers. The global minimum in -(ammoniumethyl)pyridines corresponds to the conformation with the +sc-orientation about the central C-C bond and the -sc-orientation (in the case of the dimethylammonium derivatives) about the bond. In the latter conformation, the bond of the ammonium group is oriented toward the pyridine cycle. For charged compounds, the regular orthogonal conformation of the aromatic-ring plate is distorted (the vicinal C-C bond becomes eclipsed).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1833–1840, August, 1991.The authors are grateful to P. P. Shagidullin and A. Kh. Plyamovatyi for their interest in this work and for fruitful discussions.     

Mass transfer in shell-core inorganic TIP1 ion exchanger

The ion exchange processes of (OAc^–) and (OAc^–) proceeding in shell-core inorganic ion exchanger Ti (HPO₄)₂·1/2H₂O has been studied and the diffusion equation whose boundary conditions are satisfied by a shell-core model was solved. Based on the equation solved and experimental data, the diffusion coefficients corresponding to the exchange process (OAc^–) and Li⁺–H⁺ (OAc^–) at 17°C are found to be 7.7×10^–9 and 6.2×10^–8 cm² s^–1 and the activation energies 3.4×10⁴ and 5.0×10³ J mol^–1, respectively. Compared to the gel type of styrene-divinylbenzene strong acid exchanger with 20% cross linking, it can be concluded that the rate of or exchange is 3.5 times faster than that in the organic exchanger.TIP was obtained from the Salt Lake Institute of the Academy of Science of China.