Separation of actinide and fission product elements by means of thermochromatography and fractional sublimation of their β-diketonates

The heterogeneous ligand exchange synthesis of volatile -diketonates of some actinides /²³⁰Th,²³³U,²³⁹Pu,²⁴¹Am/ and fission product elements /⁹⁰Sr,⁹⁰Y,¹¹³Sn,^113mIn/ and their separation by means of thermochromatography and fractional sublimation are reported. The methods are efficient for the separation of elements of different oxidation states.     

Separation of some organic mixtures by fractional entrainment sublimation

Fractional entrainment sublimation has been successfully applied to mixtures of sublimable organic compounds. The components of the mixtures were obtained in well-defined crystalline zones, sufficiently pure for identification by melting points and spectroscopic analysis. The highest temperature limit of any zone was reproducible and may be comparable to the well known R_F value for qualitative analytical purposes. The technique was employed for the separation of 11 artificial mixtures and the purification of 5 crude reaction products. Samples of 10–60 mg were easily separated. The apparatus, operating procedures, and some of the factors which influence the separations are discussed.     

Mutual effect of elements in the separation by sublimation of their chlorides

The transfer and separation of the chlorides of a number of rare-earth and actinide elements and their mixtures has been investigated in the flow of gas-carrier along a quartz tube under temperature gradient. The dependence of the position (characteristic temperature) and shape of the condensation (or sorption) peak of cerium chloride in the gradient region of the tube on the amount of substance in the starting zone has been studied. Weight limits determining the behaviour of the substance as micro- or macrocomponent and its transfer by adsorption or condensation mechanism have been established. The mutual effect of elements in the La?Ce, Am?U, Np?U systems has been studied. It is shown that in the case, when the condensation peak of the macrocomponent overlaps the adsorption zone of the microcomponent, the position of the adsorption peak is shifted and the effectivity of the micro- and macrocomponent separation deteriorates in comparison with the separation of microamounts of elements. If the condensation of the macrocomponent occurs in temperature zones distant from that of the microcomponent adsorption, the position of the latter does not change and the degree of purification of the microcomponent increases.     

β-二酮化合物光稳定行为的研究

研究了β-二酮类化合物二苯甲酰甲烷、苯甲酰丙酮、对苯二甲酰乙酸乙酯的光稳定行为,在β-二酮类化合物的溶液中存在着烯醇式和酮式平衡。当以紫外光进行辐照时,烯醇式异构体不断减少,酮式的含量则不断增多。由于这些化合物有不同的互变异构化过程以及不同的氢键形成能力,因此,它们对高聚物有着不同的稳定化能力。我们提出的二苯甲酰甲烷的光稳定机理,不同于Otterstedt提出的机理。新的统一的光稳定机理尚待进一步深入研究.     

Separation of rare-earth fission product elements from106Ru and137Cs by chloride sublimation

The possibility has been investigated of separating rare-earth fission fragment elements from¹⁰⁶Ru and¹³⁷Cs by high-temperature sublimation (950°C) of chlorides, with their subsequent gas adsorption separation in a quartz tube under a temperature gradient in a flow of the carrier-gas Ar+SOCl₂. The temperature corresponding to the maxima of the element precipitation zones are: 630–660°C (¹⁴⁴Ce), 770–780°C (0.7–6 μg¹⁴⁰La+La), 920°C (1.5 mg Ce or La), 420–450°C (¹⁰⁶Ru), 280–300°C (¹³⁷Cs). The coefficients of element separation have been calculated. For the separation of indicator amounts of rare-earth elements and¹⁰⁶Ru and¹³⁷Cs, fractional sublimation of the chlorides of the latter at 650°C has been used. Rate constants and effective activation energies of the overall processes of chlorination-sublimation of the elements have been determined.     

Studies in fluorinated 1,3-diketones and related compounds Part X. Synthesis of some new polyfluorinated 1,3-diketones,their copper 1,3-diketonates and spectral studies

The reaction of tetrafluoro-1,2-diiodobenzene with tellurium yields an oil which, on treatment with bromine yields perfluorotelluranthrene- 9,9,10,10-tetrabromide. The latter is reduced by sodium sulfide to perfluorotelluranthrene. The crystal structure of perfluorotelluranthrene is reported.     

Studies in fluorinated 1,3-diketones and related compounds Part XII. Synthesis and spectroscopic studies of some new polyfluorinated 1,3-diketones,and their copper 1,3-diketonates

New polyfluorinated 1,3-diketones have been prepared from polyfluorinated acetophenones and appropriate esters in the presence of sodamide. The corresponding copper 1,3-diketonates have been obtained by treating a methanolic solution of polyfluorinated 1,3-diketone with methanolic solution of copper acetate. The polyfluorinated 1,3-diketones have been characterized by elemental as well as by spectral studies, viz: I.R., ¹H N.M.R. and ¹⁹F N.M.R. In I.R., characteristic absorptions observed are: CF stretching bands (1300 ? 1000) cm^?1, CF deformation modes (900 ? 700 cm^?1) and intramolecular hydrogen bonding (3000 ? 2500 cm^?1). In ¹H N.M.R. methine ( = C$\text{H}$) signal is observed at δ 6.2 ? 6.8 ppm and enolic proton resonance signal at δ 13 ? 15 ppm indicating the presence of strong hydrogen bonding in such polyfluorinated 1,3-diketones.     

Separation of bismuth from lead, copper and other elements by means of anion exchange

The anion-exchange behaviour of bismuth and various other elements has been investigated in media consisting of methyl glycol and nitric acid. Through the determination of the distribution coefficients in such mixtures, a method for the anion-exchange separation of bismuth from many metal ions has been developed. A mixture of 90% methyl glycol and 10% 5M nitric acid is a suitable medium for this separation on the strongly-basic anion exchanger Dowex 1, X8. Only bismuth, thorium and lanthanum are strongly retained on the resin in these conditions. All other elements investigated, such as lead, copper, iron, etc., are either only weakly adsorbed or are not absorbed. By means of this ion-exchange procedure, a series of analyses of copper-base alloys for bismuth has been carried out. The results show that this method can be used successfully for the quantitative isolation of bismuth from such materials. The final determination of bismuth in the eluates is performed by complexometric titration.     

Separation of actinides by means of HPLC

A procedure is described separating, identifying and determining the actinides (An) U, Np, Pu, Am and Cm in the presence of the lanthanides (Ln) La, Ce, Pr, Nd, Pm, Sm, Eu and Ho on an analytical scale. It is based on high-pressure liquid chromatography (HPLC) combined with a dual on-line detection system and is accomplished within a short time, in one step and under isocratic conditions (for An). The separation was carried out on a strongly acidic and highly capacitive cationic exchange resin on a polystyrene divinylbenzene copolymer (Aminex A9, co. BioRad) basis. Radionuclides emitting α- and β-particles are detected on-line using a custom-made solid scintillation flow-through cell. Inactive components are monitored by colour reagent complex detection (Arsenazo III, λ-648 nm) with a VIS detector placed in series.     

Separation of rhodium and iridium by multiple fractional extraction

Mixtures of the chloro complexes of rhodium(III) and iridium(IV) were resolved by a nine stage multiple extraction technique. The solutes are partitioned in a hydrochloric acid-tributyl phosphate system. Rhodium is concentrated in the raffinate while iridium is concentrated in the extractant. 99% of the rhodium and 94% of the iridium are recovered free of the other metal. Experimental results agree reasonably well with the results predicted by a theoretical treatment of the distribution data.     

Separation of geometric isomers of metal β-diketonates by supercritical fluid chromatography

The separation of the geometric isomers of chromium and rhodium chelates of trifluoroacetylacetone and thenoyltrifluor-oacetone was investigated using packed column supercritical fluid chromatography. Mobile phases consisting of neat and alcohol-modified carbon dioxide were used, and the most favorable isomeric resolution was obtained with a phenyl stationary phase. The chromatographic performance was better for chelates with trifluoroacetylacetone than for the corresponding chelates with thenoyltrifluoroacetone. Chromatographic peak area analysis of the metal chelates investigated showed appropriate isomeric concentrations in the final diastereomeric products resulting from the synthetic procedures.     

第五 六族元素的有机化合物在有机合成中应用的研究XXXI. 应用稳定胂叶立德合成β-酮酸酯和β-二酮的一种简便方法

本文报道一种在温和条件下使稳定胂叶立德(1)砷-碳键断裂的方法,从而合成了β-酮酸酯和β-二酮类化合物,特别是相应的含氟化合物,该方法操作简便,产物容易分离提纯,得率较好。     

Fractional sublimation of the β-diketone chelates of the lanthanide and related elements

Various β-diketone chelates of Sc(III), Y(III), Th(IV), U(IV). U(VI), Zr(IV) and the lanthanides have been prepared, characterized and investigated to determine if they were volatile and stable. The ligands employed were acetylacetone(AA), trifluoroacetylacetone(TFAA), hexafluoroacetylacetone(HFAA), and dipivaloyl-methane(DPM). The chelates were sublimed in a fractional vacuum sublimator and the recrystallization temperature zones recorded for individual chelates. None of the lanthanide acetylacetonates arc volatile but the Sc(III), Th(IV), U(IV) and dioxouranium(VI) acetylacetonates are thermally stable and quite volatile below 150° at 1 mm mercury pressure. The lanthanide, Sc(III), Y(III), and dioxouranium(VI) trifluoroacetylacetonates are volatile and can be vacuum-sublimed below 150°, but are thermally unstable; only the Th(IV) chelate is sufficiently stable to be quantitatively recovered by sublimation. The Sc(III), Y(III), Th(IV), and lanthanide hexafluoroacetylacetonates are thermally stable and easily sublimed below 125° in vacua or at atmospheric pressure. All the dipivaloylmethanates studied were thermally stable and volatile and could be quantitatively recovered by vacuum sublimation below 140°.The volatility of the HFAA and DPM lanthanide chelates increased with an increase in atomic weight (a decrease in ionic radii) of the lanthanides. The lack of volatility observed for the lanthanide AA and TFAA chelates is attributed to the fact that only hydrates of the chelates were formed, which decomposed at elevated temperatures in vacuo to form basic polymeric compounds.Separations are proposed for numerous binary mixtures of the β-diketone chelates of the lanthanide and related elements. Recrystallization temperature zones are given for the following binary mixtures which were quantitatively resolved by the fractional sublimation technique; 118-88° for Nd(DPM)₃ and 84-48° for Tm(DPM)₃; 72-49° for Sc(DPM) and 120-88° for Pr(DPM); 128-79° for La(DPM)₃ and 79-47° for Yb(DPM)₃; 70-47° for Th(TFAA)₄ and 116-96° for Gd(TFAA)₃; 52-42° for Th(HFAA)₄ and 120-80° for La(HFAA)₃.     

Separation of group five elements by reversed-phase chromatography

A chemical separation method based on reversed-phase chromatography has been developed to separate the group five elements from the reaction products produced in the bombardment of ²⁴³Am with ⁴⁸Ca ions. Decontamination factors on the order of 10⁶ were achieved for group-three elements such as americium, and 10⁷ or more for selected reaction products as measured by gamma-ray spectrometry pre-and post-chemistry. Details of the chemical separation scheme are discussed and compared to previously reported results.     

Separation of reboxetine enantiomers by means of capillary electrophoresis

The novel antidepressant reboxetine, a selective norepinephrine reuptake inhibitor, is increasingly used in the treatment of different forms of major depression. Reboxetine is a chiral compound, and is marketed as a racemic mixture of (R,R)- and (S,S)-reboxetine; however, the pharmacokinetic and toxicological profiles of the two enantiomers are rather different. For this reason, a simple capillary electrophoretic method for the separation of reboxetine enantiomers has been developed. Sulfobutyl ether-beta-cyclodextrin was chosen as the chiral selector, and several parameters, such as cyclodextrin and buffer concentration, buffer pH and capillary temperature were investigated in order to obtain good separation and acceptable run times. Using an uncoated, fused-silica capillary (internal diameter 50 microm, total length 48.5 cm, effective length 40.0 cm) and a background electrolyte consisting of a pH 3.0, 100 mM phosphate buffer containing 1.25 mM cyclodextrin, reboxetine enantiomers were baseline separated (resolution > 4) with a voltage of 20 kV in less than 16 min. Since pure enantiomers of reboxetine were not available, they were obtained from the racemic powder by means of direct-phase, high-performance liquid chromatography and their identity confirmed by circular dichroism spectra.     

Optical absorption by rare-earth β-diketonates in the excited state

Reabsorption of the emission from Tb³⁺ in 4f ⁸ 4f ⁷5d transitions is examined for coordination compounds of the ion with \-diketones. The energy levels are calculated by MOLCAO methods. The Tb³⁺ (4f ⁷5d) is assumed to interact only with adjacent oxygen atoms; the effects of the other atoms are allowed for via a preliminary calculation of the charge distribution in the \-diketone anions. The energy spectrum is deduced as a function of the charge on the oxygen atoms in the \-diketone anion.Read at the Symposium on Quantum Chemistry, Palanga, June 1965