Regioselective allylation reactions using crotyl Grignard reagent-CeCl3 systems

Regioselective allylation reactions using crotyl Grignard reagent-CeCl₃ systems are described. Regioselectivity depends on the lanthanide salts: α-product was predominantly produced with light rare earth elements such as La, Ce, Pr, Nd, whereas γ-product was formed when heavy rare earth elements were used.     

离子吸附型稀土矿中浸出相稀土元素含量的浸取方法研究

将风化壳离子吸附型稀土矿原矿样品加工至0.149 mm,使用35 g/L硫酸铵溶液(pH为4.0)作为浸取剂,提取浸出相稀土元素.考察了提取浸出相稀土元素时,样品粒度、浸取剂浓度及用量、浸取剂酸度、浸取方式、浸取时间等条件的影响,确定最佳试验条件,利用电感耦合等离子体质谱法(ICP-MS)测定样品溶液中浸出相稀土的总量...     

Elemental analysis of geological samples by cyclic activation using a 14 MeV neutron generator and applying flux corrections

The solvent extraction of the rare earth elements, yttrium and scandium with trioctylphosphine oxide in the presence of strong complexing and various salting-out agents has been studied. As a result, a technique was developed for the extractionchromatography recovery of the rare earth elements and yttrium with simultaneous purification practically from all the elements, including scandium, usually present in the mineral samples.     

用络合吸附色层法提纯稀土化合物的研究

本文提出了一种用络合吸附色层法从稀土化合物中除去铁、铜、钴、镍和铅等重金属杂质的方法。研究结果表明:将稀土化合物的溶液通过由掺和均匀的活性炭和络合剂组成的色层柱时,能从稀土化合物中除去上述杂质,到ppm数量级:Fe<0.57,Cu<0.5,Co<0.2,Ni<1.0,Pb<0.2,从而提供了一个高效率和大容量的提纯稀土化合物的方法。作者研究了各种络合剂的效率、色层柱的最佳工作条件,并提出了色层柱中反应的机理。     

Preorganized, cone-conformational calix[4]arene possessing four propylenephosphonic acids with high extraction ability and separation efficiency for trivalent rare earth elements

p-t-Octylcalix[4]arene with tetraphosphonic acid at lower rim in cone conformation has been designed and synthesized as a new extraction reagent to investigate the extraction behavior of the nine trivalent rare earth elements: La, Pr, Nd, Sm, Eu, Gd, Ho, Y, and Er. The extraction of rare earth metals with the present extractant occurs by a simple ion-exchange mechanism. The stoichiometry of the extractant to rare earth metal ion was determined to be 2:1 based on the extraction equation, half pH values, pH_1/2, and the difference in the values of the extraction equilibrium constants of nine trivalent rare earth elements and separation factors between adjacent rare earth elements. This allowed for comparison of the estimated extraction efficiency and selectivity. The present extractant exhibited extremely high extractability and sufficiently high separation efficiency of rare earth metals, compared with calix[4]arene tetraphosphonic acid at upper rim, calix[4]arene tetraacetic acid at lower rim as previously reported and the commercial extraction reagent. This results was attributed to size and multidentate effects based on the preorganized cyclic structure of calix[4]arene and to the original selectivity of functional group for heavier rare earth elements.     

Self-Assembled Heavy Lanthanide Orthovanadate Architecture with Controlled Dimensionality and Morphology

Nearly monodisperse YVO₄ architectures with persimmon-like, cube-like and nanoparticle shapes have been synthesised on a large scale by means of a complexing-agent-assisted solution route. The shape and size of these as-prepared architectures can be tuned effectively by controlling the reaction conditions, such as reaction time, the molar ratio of complexing agent/Y³⁺ and different complexing agents. As a typical morphology, the growth process of monodisperse nanopersimmons has been examined. To extend this method, other LnVO₄ (Ln=Ce, Gd, Dy, Er) complexes with well-defined shape and dimensionality can also be achieved by adjusting different rare earth precursors. Further studies reveal that the morphology of the as-synthesised lanthanide orthovanadate is determined mainly by the interaction between rare earth ion and the complexing agent. Ultraviolet (UV) absorption and photoluminescence spectra show that the optical properties of YVO₄ nanopersimmons are relevant to their size and shape. This work sheds some light on the design of well-defined complex nanostructures, and explores the potential applications of the as-synthesised architectures.     

混合稀土离子的毛细管电泳电导法分离检测

采用高效毛细管电泳电导检测法分离检测了稀土离子。以醋酸-醋酸钠为背景电解质,4-吗啉乙磺酸（MES）为络合剂,在24kV的高压下,7种稀土离子得到子较好的分离。考察了背景电解质的pH和浓度,络合剂的浓度,分离电压等对稀土离子分离的影响。在选定的实验条件下,7种烯土离子在10min内守成分离检测。     

Luminescence studies on europium-strontium phthalate system

New lanthanide luminescence materials were prepared. The main component lanthanide chelates generally need a relatively high content of rare earth. Inorganic luminescence materials only need low rare earth concentration using doped method. Similarly, lanthanide chelates can be added to complex matrix by doped method. In this way, low rare earth concentration emission was successful in the lanthanide chelates system as well. The influence of europium ion concentration on luminescence intensities was discussed. When the europium ion weight in the complex is only about 0.6%, the sample exhibits good luminescence properties. The fluorescence, Fourier transform infrared spectra, micro-Raman and electron spin resonance spectra of the samples were measured. And a possible luminescence mechanism was suggested by the inorganic doped mechanism and the luminescence of lanthanide complexes together.     

A convenient route to lanthanide triiodide THF solvates. Crystal structures of LnI(3)(THF)(4) [Ln = Pr] and LnI(3)(THF)(3.5) [Ln = Nd, Gd, Y

The reaction between 1.5 equiv of elemental iodine and rare earth metals in powder form in THF at room temperature gives the rare earth triiodides LnI(3)(THF)(n)() in good yields. Purification by Soxhlet extraction of the crude solids with THF reliably gives the THF adducts LnI(3)(THF)(4) [Ln = La, Pr] and LnI(3)(THF)(3.5) [Ln = Nd, Sm, Gd, Dy, Er, Tm, Y] as microcrystalline solids. X-ray crystallography reveals that the early, larger lanthanide iodide PrI(3)(THF)(4) crystallizes as discrete molecules having a pentagonal bipyramidal structure, whereas the later, smaller lanthanide iodides LnI(3)(THF)(3.5) [Ln = Nd, Gd, Y] crystallize as solvent-separated ion pairs [LnI(2)(THF)(5)][LnI(4)(THF)(2)] in which the cations adopt a pentagonal bipyramidal geometry and the anions adopt an octahedral geometry in the solid state.     

Determination of rare earth elements and heavy metals in river water by preconcentration on chelex 100 and neutron activation

The neutron activation determination of rare earth elements and heavy metals in river water has been studied with Chelex 100 resin as a preconcentration agent. The resin is applied directly as a support for irradiation and for radiochemical separation. The radioactive rare earth elements are recovered selectively and quantitatively from the irradiated resin by elution with hot 1 M sodium carbonate solution; radioactive heavy metals are recovered with 2 M nitric acid. Activities from each eluate are counted with a Ge(Li) detector connected to a multichannel analyzer; La, Sm, Eu, Dy, Mn, Cu and Zn can be determined. The recoveries were almost quantitative and the measurement of chemical yield was unnecessary.     

Selective precipitation of rare earth orthophosphates with hydrogen peroxide from phosphoric acid solutions

It has been shown for the first time that the use of hydrogen peroxide allows precipitation of rare earth orthophosphates (La–Tb) from phosphoric acid solutions at temperatures below 100°C. Either anhydrous or hydrated orthophosphates with monazite or rhabdophane structure, respectively, can be obtained depending on rare earth element position in lanthanide series and precipitation conditions (orthophosphoric acid and hydrogen peroxide concentration). Hydrated orthophosphates with rhabdophane structure can be prepared by precipitation with hydrogen peroxide for all studied rare earth elements.     

Extraction of rare earth elements with 1-(diphenylphosphorylmethoxy)-2-diphenylphosphoryl-4-ethylbenzene with the use of 1,1,7-trihydrododecafluoroheptanol as a solvent

Extraction of rare earth elements from nitric acid solutions in a 1,1,7-trihydrododecafluoroheptanol-water system with the use of phosphoryl-containing podand 1-(diphenylphosphorylmethoxy)-2-diphenylphosphoryl-4-ethylbenzene (L) was studied. The content of metals in organic phase was shown to be negligible at nitric acid concentration lower 1 mol/L. Distribution ratio sharply increases with nitric acid concentration from 1 mol/L and reaches 5.5 for the yttrium subgroup elements at HNO₃ concentration of 6 mol/L. The rare earth elements of the yttrium subgroup were found to be extracted much better than the rare earth elements of the cerium subgroup under the same conditions, the distribution ratios in both subgroups smoothly rise with atomic number of element. It was shown using the shift of extraction equilibrium that the M: L ratio in extracted complexes is 1: 2 irrespective of the nature of rare earth element. The structure of complex {Yb[η²-(O,O′)-L]₂(η²-O₂NO)₂}(O₂NOHNO₃), whose single crystals were isolated from extraction solution, was established by X-ray diffraction study. The system can be used for the isolation and separation of rare earth elements.     

仲辛基苯氧基乙酸萃取稀土(Ⅲ)的机理

氯化稀土;萃取机理;仲辛基苯氧基乙酸萃取稀土(Ⅲ)的机理     

RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE USING LANTHANIDE TRIS（N-PHENYL-3,5-DI-T-BUTYLSALICYLALDIMINATO）S AS SINGLE COMPONENT CATALYST

Ring-opening polymerization ofε-caprolactone has been carried out by using rare earth Schiff base complexes: lanthanide tris(N-pheny1-3,5-di-t-butylsalicylaldiminato)s[Ln(OPBS)_3]as single component catalyst for the first time.The influences of different rare earth elements,monomer and catalyst concentration as well as reaction time on the polymerization were investigated.Mechanism studies showed that monomer inserts into the active site with the acyl-oxygen bond scission rather than the break of alkyl-oxygen bond.     

Synthesis of organophosphorus ligands with a central oxygen atom and their applications in solvent extraction

Various structurally related glycolamide compounds were synthesised and evaluated by solvent extraction experiments for the separation of rare earth elements (REEs) from aqueous acid solutions using dodecane as the diluent. We describe herein the full synthesis of a family of bifunctional ligands with a central oxygen and focus our investigation on the effects of structural modification on the extraction efficiencies. The combination of an amide, a PO donor site, and a central oxygen in such a glycolamide ligand showed interesting extraction properties for heavy rare earth elements from phosphoric acid solutions.     

RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE USING LANTHANIDE TRIS(N-PHENYL-3,5-DI-T-BUTYLSALICYLALDIMINATO)S AS SINGLE COMPONENT CATALYST

Ring-opening polymerization of ε-caprolactone has been carried out by using rare earth Schiff base complexes:lanthanide tris(N-phenyl-3,5-di-t-butyisalicylaldiminato)s [Ln(OPBS)3]as single component catalyst for the first time.The influences of different rare earth elements,monomer and catalyst concentration as well as reaction time on the polymerization were investigated.Mechanism studies showed that monomer inserts into the active site with the acyl-oxygen bond scission rather than the break of alkyl-oxygen bond.     

萃取分离电感耦合等离子体原子发射光谱法测定钢中的微量稀土元素

本文采用苯甲酰苯胲(BPHA)-甲基异丁基酮(MIBK)溶剂萃取方法将钢中基体元素Fe,Ti,Mo,V等大量非稀土元素萃入有机相中,稀土元素留于水溶液中.由电感耦合等离子体原子发射光谱(ICP-AES)仪直接测定水溶液中的微量稀土元素La,Ce,Pr,Nd.Sm,Y和Gd,实验结果与推荐值基本相符,方法的回收率为96％～108％,相对标准偏差低于5％.     

Sorption in the chemistry of rare earth elements

Sorption methods for the concentration and separation of rare earth elements are reviewed. Sorbents based on organic polymers, specifically strongly and weakly acidic cation exchangers, anion exchangers, and complexing sorbents, are successively considered. Data on the use of inorganic sorbents and solid phase extractants in the rare earth chemistry are also given. Considerable attention is paid to hybrid organomineral materials constituting a promising class of sorbents. Advantages and disadvantages of using biosorbents, molecularly imprinted sorbents, and nanosorbents for the concentration and separation of rare earths are discussed.     

桦甸油页岩中稀土元素赋存状态研究

以吉林省桦甸油页岩为研究对象,采用电感耦合等离子质谱( ICP-MS)和化学逐级提取方法相结合,对油页岩中稀土元素的分布特征以及油页岩中稀土元素的赋存状态进行研究.结果表明,相对于中国煤,桦甸油页岩表现为轻稀土元素富集程度高于重稀土元素.油页岩中稀土元素与陆源碎屑岩关系密切,且陆源物质的供应相对比较稳定.轻重稀土间分馏...     

FT-IR study of rare earth 4-aminobenzenesulfonate complexes

The crystal structure of lanthanum 4-amino-benzenesulfonate complex has been determined by X-ray diffraction. The crystal data indicate that lanthanum and neodymium 4-amino-benzenesulfonates are isomorphous. The FT-IR spectroscopic study of rare earth 4-amino-benzenesulfonate complexes showed that the spectra of light rare earth (La, Nd, Sm, Eu) complexes are similar and so are the spectra of heavy rare earth (Dy, Er, Y) complexes. There are remarkable differences between the spectra of light rare earth and heavy rare earth complexes. Based on above results, we infer that light rare earth (La, Nd, Sm, Eu) complexes are isomorphous and three heavy rare earth (Dy, Er, Y) complexes are of a different structure but also isomorphous.