Synthesis and characterisation of bis(pentafluorophenyl)antimony(V) cations, [(C6F5)2SbL3]

Pentacoordinate complex cations of the general formula [(C₆F₅)₂SbL₃]³⁺ stabilized as solid salts in combination with tetraphenylborate (BPh₄), tetrafluorobroate (BF₄) anions, where L=DMSO, Ph₃AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required.     

Two New Xanthone Glycosides from Polygala tenuifolia

Two new xanthone glycosides,polygalaxanthone IV and V were isolated from the roots of Polygala tenuifolia Willd. Their structures were established as 6-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]-1-hydroxy-3,7-dimethoxyxanthone(polygalaxanthone IV), and 6-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]-1,3-dihydroxyl-7-methoxyxanthone (polyga-laxanthone V),respectively, on the basis of chemical and spectral evidence.     

Simultaneous determination of cobalt,copper, iron and vanadium in crude petroleum oils by HPLC

Summary A method has been developed for the simultaneous formation and solvent extraction of cobalt (II), copper (II), iron (II) and vanadium (IV) complexes of bis (acetylpivalylmethane)ethylenediamine (H₂APM₂en) in methyl isobutyl ketone. The complexes are eluted from a reversed phase HPLC column with a mixture of methanol:water:acetonitrile and detection was at 260 nm. The method has been applied to the simultaneous determination of cobalt, copper, iron and vanadium in crude petroleum oils at the ng level.     

Extraction-spectrophotometric study on the vanadium(V)-2,3-dihydroxynaphthalene — iodonitrotetrazolium chloride — water — chloroform system and its analytical application

The formation of a new ternary ion-associate complex of vanadium(V) with 2,3-dihydroxynaphthalene and iodonitrotetrazolium chloride with a composition ratio of 1:2:1 is reported. The complex is quantitatively extracted from water into chloroform. The molar absorptivity (ɛ) of the extract at λ _max=340 nm is 2.5 × 10⁴ dm³/mol cm, and Beer’s law is obeyed for concentrations ranging from 0.1 to 0.9 μg/cm³ V(V). The following constants are determined: the extraction constant, the association constant, the distribution constant, and the recovery factor. The effects of foreign ions and reagents are studied. A selective and sensitive method is developed for determination of vanadium in steels.     

Lanthanide nitrate complexes with 2-azacyclononanone

Thermal behavior of rare earth nitrate complexes with 2-azacyclononanone (AZA) with Ln(NO₃)₃·3(AZA) composition (where Ln=Gd, Er and Ho) was analyzed in kinetic point of view. Kinetic parameters were calculated from thermogravimetric data. All obtained results were similar. The first decomposition step was representative to the loss of ligand and the residue was essentially Ln₂O₃. Furthermore, a reaction path was proposed for the thermal decomposition of the Ln(NO₃)₃·3(AZA).     

V_2O_5/C催化氧化乙二醛制备乙醛酸

利用等体积浸渍法制备了V2O5/C催化剂,并应用于乙二醛的液相氧化反应,采用XRD、TEM手段对催化剂进行了物化性质表征.结果表明,V2O5/C对乙二醛的氧化表现出较高的催化活性和乙醛酸选择性,反应10h,乙二醛的转化率达29.2%,乙醛酸得率13.6%.与贵金属Pd-Bi/C催化剂相比,V2O5/C催化剂的稳定性和重复使用效果都比较好.     

d,h-m̈-Alkoxoalkylphosphonato-e-m̈-alkoxo-f-m̈-oxo-bis[trichloroantimon(V)]-Verbindungen

d,h-m?-Alkoxoalkylphosphonato-e-m?-alkoxo-f-m?-oxo-bis[trichloroantimony(V)] Compounds The binuclear antimony(V) complexes Cl₃Sb(O)[R³(R¹O)PO₂](OR²)SbCl₃ 1 to 7 with R¹, R² and R³ = Me or Et in solution slowly exchanges the R² groups between the equatorial oxygen atoms of the Sb₂O₂ ring. The SbO(3)PO(3)Sb ringsystem makes rapid pseudorotation. The resulting isomeres are detected by nmr spectroscopy.     

植入用Co—Cr—Mo合金与Ti—6Al—4V合金的电偶腐蚀研究

组件式设计常被用地人工髋关节，钴络钼合金（Ｃｏ－Ｃｒ－Ｍｏ）与钛合金（Ｔｉ－６Ａｌ－４Ｖ）的压配最常用，本文应用电化学方法研究了静态条件下两种合金的电偶腐蚀行为，浸泡实验表明，钴络钼合金为阳极，但电偶电流与其维钝电流相近，并无明显加速度腐蚀效应，钛合金为阴极，受到保护，失重及金相观察结果显示，在４５天的浸泡实验周期内，未发现腐蚀痕迹，混合电位理论和电位处于两种合金的钝化电位区，电偶电流为合金的维钝     

Preparation of polyfluorinated cycloalk-1-enyl-, alk-1-enyl-, and alkyliodine tetrafluorides using XeF2 in the presence of appropriate Lewis acids as fluorooxidant

Previously unknown polyfluorocyclohexenyl, and acyclic perfluoroalkenyliodine tetrafluorides were prepared in high yields. Perfluorocyclohex-1-enyliodine tetrafluoride was obtained from pentafluoroiodobenzene using XeF₂-NbF₅ in aHF. The reaction of C₆F₅I with the weaker fluorooxidant XeF₂-BF₃ in 1,1,1,3,3-pentafluorobutane (PFB) yielded C₆F₅IF₂, perfluorocyclohexa-1,4-dienyliodine difluoride, C₆F₅IF₄, perfluorocyclohexa-1,4, and 1,3-dienyliodine tetrafluoride as intermediate products on parallel reaction routes. Both perfluoroalkenyl iodides, cis- and trans-(CF₃)₂CFCFCFI, reacted with XeF₂-BF₃ in PFB to give the corresponding perfluoroalkenyliodine tetrafluorides, cis- and trans-(CF₃)₂CFCFCFIF₄. Even perfluoroalkyl iodides can be fluorinated by this reagent as was demonstrated by the preparation of C₆F₁₃IF₄ from C₆F₁₃I. Generally, the CFCIF_n fragment (n = 0, 2, or 4) in cyclic or acyclic perfluoroalkenyliodine compounds R_FIF_n did not undergo a transformation to the corresponding perfluoroalkyliodine compound. Furthermore, no perfluoroorganoiodine hexafluorides were detected in reactions with the fluorooxidant XeF₂-aHF or BF₃ or NbF₅.     

Determination of methylated dibenzothiophenes in environmental sarnples by on-line HPLC-CGC

Concurrent solvent evaporation with a loop-type interface was used for on-line HPLC-CGC in the analysis of methylated dibenzothiophene (DBT) isomers in oil samples. The chromatographic behavior of 20 methyl DBT's was studied by HPLC on an aminopropylsilane DBTA phase and by GC on a selective methyl-phenylsilicone phase. That provided a method for analyzing by GC-flame photometric detection, the individual components of the DBT family, previously picked out of the crude oil matrix by HPLC. The GC oven temperature was shown to be critical during HPLC eluent introduction into the GC pre-column. Too high a temperature induced a severe broadening of early eluted peaks whereas a temperature too close to the boiling point of the liquid at the inlet pressure induced double peaks. Optimized conditions were retained on this basis and may be used for the analysis of other families of polyaromatic hydrocarbons.