Complexes of thorium(IV) and uranium(IV) with some Schiff bases

Complexes of thorium(IV) and uranium(IV) with Schiff bases derived from salicylaldehyde have been prepared and characterised. The metal tetrachlorides react directly with quadridentate Schiff bases in ethanol to yield the complexes but bidentate Schiff bases yield hydrolysed products under the same conditions. Complexes of the bidentate Schiff bases are obtained by reaction of ligand with metal tetraacetate in a melt or by ligand exchange with the thallium-Schiff base complex. Absorption spectra are reported and band assignments are discussed.     

One-pot synthesis of 1,3-bis(cytisinyl)propan-2-ol

Russian Journal of Organic Chemistry -     

Extraction studies of uranium(VI) and thorium(IV) with tributylphosphine oxide

Clay minerals occur widely in nature and play a very important role in agriculture, mineral recovery and chemical manufacturing. Among the many properties which affect clay behaviour, water binding and ion exchanging appear to be the most important. The study of the cation exchange capacity of soils is of great theoretical and practical importance since the CEC determines in many ways the behavior of nutrients, chemical amendments, and many toxic compounds entering the sols. Sorption interactions with montmorillonite and other clay minerals in soils are potantially important mechanisms for attenuating the mobility of heavy metal cations through the subsurface environment. In this work the cation exchange capacity (CEC) of montmorillonite from west Anatolia, and sorptions with montmorillonite for attenuating the mobility of uranium were studied. The CEC value was found to be 77 meq/100 g montmorillonite. The relative importance of test parameters e.g., contact time, particle size, pH and U(+6) aqueous speciation was determined. The results show that sorption on montmorillonite is a funtion of pH depending strongly on the aqueous U(+6) species. It reaches a maximum at near neutral pH(pH}7). At low and at high pH solutions the sorption values of uranium are poor. These sorption values were attributed to the formation of aqueous U(+6) carbonate complexes in alkaline conditions and the ionexchange process between UO₂ ⁺² species and interlayer cations on montmorillonite in acidic solutions.     

Structure and molecular interactions in {ethanol + (propan-1-ol/propan-2-ol)} mixtures at 303.15 K

In view of industrial importance of binary {ethyl alcohol + (propan-1-ol/propan-2-ol)} mixtures, the densities (ρ) and refractive indices (n _D ) of these alkanols mixtures were measured for different compositions at 303.15 K. Molar volumes (V _m) and excess molar volumes (V ^E) of these binary mixtures were calculated from experimental density data of pure solvents and solvents mixtures. The measured refractive index and density data was used to calculate specific refractions (R _D ), molar refractions (R _M) and apparent molar refractions (R _{φ, i} ) of binary mixtures. From mole fraction dependence of apparent molar refractions, the limiting apparent molar refractions (R _{φ, i} ^○ ) of propan-1-ol and propan-2-ol have been determined. The graphical values of R _{φ, i} ^○ for propan-1-ol and propan-2-ol were found to be 9.5664 and 7.405 cm³ mol^?1 respectively. Structural changes, geometrical fittings and molecular interactions in binary mixtures of these alkanols have been discussed.     

Relativistic density functional study on uranium(IV) and thorium(IV) oxide clusters of zonohedral geometry

Free and ligated oxide clusters of thorium(IV) and uranium(IV) were studied with density functional theory using all-electron scalar relativistic method, as well as energy-consistent relativistic f-in-core pseudopotentials. The main driving force for the cluster formation is the sintering of the dioxoactinide moieties, which is more favorable for thorium(IV) than for uranium(IV) because, for the latter, a penalty for bending of the uranyl(IV) is to be paid. We assumed that the rhombic structural motif that exists already in the (AnO(2))(2) dimer could be a guide to explaining the preference for the existing An(6)O(8)-type clusters. On the basis of this, we have theoretically explored the possibility of the existence of similar (zonohedric) polyhedral actinide oxide clusters and found that the next possible cluster would be of An(12)O(20) stoicheometry. We have predicted by our DFT computations that the corresponding zonohedral clusters would be minima on the potential energy surface. The alternating An-O rhombic structural motif also offers a possible explanation of the existence and stoichiometry of the only nonfluorite cluster thus far, the An(12)O(20), which is nonzonohedral, nonconvex, but still a rhombic polyhedron. Our relativistic all electron DFT computations of both free cationic and ligated clusters predict that preparation of the larger clusters is not forbidden thermodynamically. We have also found that for the uranium(IV), oxide dimer and hexamer clusters are antiferromagnetic, broken spin singlet in their ground state, while ligated [U(6)O(8)] clusters prefer an all high-spin electronic configuration.     

Extraction study of uranium(VI) and thorium(IV) salicylates with triphenylarsine oxide

Triphenylarsine oxide is proposed as an extractant for the solvent extraction of uranium and thorium salicylates. The optimum extraction conditions are established by studying the various parameters such as pH, sodium salicylate concentration, triphenylarsine oxide concentration, diluents and shaking time. The probable extracted species as ascertained by logD-logC plots are UO₂(Hsal)₂·2TPAsO and Th(Hsal)₄·2TPAsO. The method is simple, fast, precise and permits the determination of uranium and thorium in monazite sand samples.     

Photoelectron spectroscopy of f-element organometallic compounds II. Tricyclopentadienyl derivatives of uranium(IV) and thorium(IV)

The photoelectron spectra of some cyclopentadienyI derivatives of uranium(IV) and thorium(IV), namely (C₅H₅)₃ ThCl, (C₅H₅)₃ UCl, (C₅ H₄ CH₃)₃ ThCl, (C₅ H₄ CH₃)₃ UCl, (C₅ H₄ CH₃)₃ UBr and (C₅ H₄ CH₃ )₃ UBH₄, are reported the metal 5f ionization has been detected in all the uranium derivative spectra and a simple molecular orbital scheme qualitatively accounts for the number and position of the observed low energy bands.     

Preconcentration techniques for uranium(VI) and thorium(IV) prior to analytical determination-an overview

The need for the preconcentration of trace and ultratrace amounts of uranium(VI) and thorium(IV) in conjunction with various detection techniques was clearly brought out in the introductory part. Subsequently, various off-line and on-line procedures developed for uranium(VI) and thorium(IV) prior to their analytical determination since 1990 were critically reviewed in terms of enrichment factor, retention/sorption capacity, validation using certified reference materials and application to complex real samples. The relative merits and demerits of various preconcentration and/or separation of uranium(VI) and thorium(IV) prior to quantitation by a plethora of analytical techniques are discussed in concluding part of the review article.     

Extraction of uranium(VI) and thorium(IV) from nitric acid solution by N-alkylcaprolactam

Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO₃ as a function of aqueous NHO₃ concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions.     

Liquid-liquid extraction of thorium(IV) and uranium(VI) with three ether-amide type tripodands

N,N,N',N',N',N'-Hexaethyl-2,2′,2'-(nitrilotrisethyleneoxy-2-benzyloxy)tris(acetamide) (L3) has been prepared and characterized by using IR, ¹H NMR and positive-ion FAB mass spectra. The extraction of Th⁴⁺ and UO₂ ²⁺ with N,N,N',N',N',N'-hexaethyl-2,2',2'- (nitrilo-trisethyleneoxy)tris(acetamide) (L1), N,N,N',N',N',N'-hexaisopropyl-2,2',2'-(nitrilotrisethyleneoxy)tris(acetamide) (L2), and L3 was studied at 20±1 °C as a function of diluent, concentration of free extractant in organic phase and concentration of picrate in aqueous phase. It was found that the extracting powers of L1 and L2 for Th⁴⁺ are almost identical. The extracting power of L2 for UO22+ was slightly higher than that of L1. The difference in terminal groups (ethyl or isopropyl) of the extractants (L1 and L2) with same backbone has a little effect on the extracting power for both Th4+ and UO22+. The extracting powers of L3 for both Th4+ and UO22+ were larger than those of L1 and L2. The extractants (L1 and L3) having the same terminal group (ethyl) with different backbones have obviously different extracting powers for Th4+ or UO22+. The extracting powers of all three extractants L1, L2, and L3 for Th4+ were larger than those for UO22+. The compositions of extracted species in organic phase were predominantly ThL(Pic)3NO3 and UO2L(Pic)NO3, respectively (L denotes L1, L2 and L3). This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic studies on the solvent extraction of uranium (IV), thorium (IV) and uranium (VI) from nitric acid solutions with tributyl phosphate

The kinetics of solvent extraction of U (IV), Th (IV) and U (VI) from nitric acid solution with tributyl phosphate (TBP) in kerosene and cyclohexane have been studied using the single drop technique. The effects of concentrations of U (IV), Th (IV), U (VI), nitric acid, nitrate, TBP and temperature on the extraction rates of U (IV), Th (IV) and U (VI) have been examined. The mechanisms for the three extraction processes are discussed.     

Simultaneous determination of uranium(IV) and thorium(IV) ions with Arsenazo III by partial least squares method

A multivariate calibration method, Partial Least Squares Type 1 (PLS-1), is proposed for simultaneous spectrophotometric determination of uranium and thorium ions as their complexes with arsenazo III in hydrochloric acid medium. Several data characteristics are taking into account in order to minimize the optimum number of factors required for the construction of calibration model, while using various statistical criterions of selection. Finally, the evaluated calibration model is satisfactorily applied to determination of these ions in samples that resemble sulfuric acid leach solution obtained from a uranium ore.     

Manganese ferrite (MnFe2O4) as potential nanosorbent for adsorption of uranium(VI) and thorium(IV)

Journal of Radioanalytical and Nuclear Chemistry - The adsorption behavior of U(VI) and Th(IV) metal ions by MnFe2O4 NPs was studied as a function of pH, mass of sorbent, contact time, and...     

CO2 laser-induced decomposition of propan-2-ol,butan-2-ol,pentan-2-ol,pentan-3-ol,and hexan-2-ol

The pulsed CO₂ laser-induced decompositions of propan-2-ol, butan-2-ol, pentan-2-ol, pentan-3-ol, and hexan-2-ol in the gas phase have been investigated. Like ethanol which we examined previously [1] the absorption cross section of propan-2-ol for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole-filling. In contrast the absorption cross section of butan-2-ol (10R24) has only a small pressure dependence and those of pentan-2-ol (9R26), pentan-3-ol (10R14), and hexan-2-ol (9P20) show little or no variation with pressure in the range 0.1–5.0 torr. Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and C? C fission channels, with minor contributions from other molecular eliminations. © 1994 John Wiley & Sons, Inc.     

Simultaneous determination of uranium(VI) and thorium(IV) with carminic acid by derivative spectrophotometry

The reactions of uranium(VI) and thorium(IV) ions with carminic acid have been investigated. These ions react with carminic acid in neutral medium, forming colored complexes. The dark purple or red wine complexes show a high absorption in the visible region (597 nm U(VI) and 616 nm Th(IV)). Chemical variables that affect the reaction have been optimized. The spectral overlapping of the color of complexes has been resolved by first-derivative spectrophotometry. The simultaneous determination of uranium(VI) and thorium(IV) mixtures is accomplished by taking the derivative signal (zero crossing) at 597 nm for U(VI) determination and at 616 nm for Th(IV) determination, respectively. The method has been applied to Tyuyamonite ore, containing in the matrix both ions.     

Kinetic studies on the stripping of thorium (IV) and uranium (IV) from tributylphosphate-kerosene with dilute nitric acid solution

The cold solution of a pyrophosphate kit was prepared and dispensed into 2-ml fractions which were stored at −20°C for one week. The solution was prepared by using two protection methods. The first was nitrogen purging to exclude air and the second one the addition of the well known antioxydant ascorbic acid. The aim was to determine the stability of^99mTc(Sn)-PyP obtained by labeling these fractions prepared under the given experimental conditions. The content of^99mTc-pertechnetate in the unprotected samples raises with time. Nitrogen purging provides some protection but already after a few days the content of pertechnetate exceeds 5%. The addition of ascorbic acid gave good results. The content of pertechnetate was 1–2% after seven days in the presence of 50 μg of acid per ml of the cold kit.     

合成(R)-2-异戊氧基丙醇的新方法

以(R)-1,2-丙二醇为原料,经伯醇羟基保护、仲醇O-异戊基取代、脱羟基保护三步反应合成了手性醇(R)-2-异戊氧基丙醇,其结构经NMR和MS确证.     

Vibrational spectra of uranium (IV) borohydride and uranium (IV) borodeuteride

The compositions of the equilibrium vapors above U(BH₄)₄ and U(BD₄)₄ at 23° were analyzed by mass spectrometry and only monomeric molecular ions, U(BH_4-x)_y⁺, were detected. Infrared spectra for the molecules were recorded in the frequency range 4000-200 cm⁻¹ for vapors contained in a variable path (1–20m) cell at 23°, from inert gas, low temperature matrices and low temperature thin-films. The data collected in this study are correlated with previously recorded data from vapors of U(BH₄)₄ generated at 40–50°. Several spectral features pertinent to the eventual complete vibrational spectroscopic definition of U(BH₄)₄ and U(BD₄)₄ are discussed.