Removal of As(V) by Cu(II)-, Ni(II)-, or Co(II)-doped goethite samples

The present study reports removal of As(V) by adsorption onto laboratory-prepared pure and Cu(II)-, Ni(II)-, and Co(II)-doped goethite samples. The X-ray diffraction patterns showed only goethite as the crystalline phase. Doping of ions in the goethite matrix resulted in shift of d-values. Various parameters chosen for adsorption were nature of adsorbent, percentage of doped cations in goethite matrix, contact time, solution pH, and percentage of adsorbate. It was observed that the pH(pzc) of the goethite surface depended on the nature and concentration of metal ions. The surface area as well as the loading capacity increased with the increase of dopant percentage in goethite matrix. A maximum loading capacity of 19.55 mg/g was observed for 2.7% Cu(II)-doped goethite. The adsorption kinetics for Ni(II), Co(II) and for undoped goethite attained a quasi-equilibrium state after 30 min with almost negligible adsorption beyond this time. In case of Cu(II)-doped goethite samples, the quasi-equilibrium state for As(V) adsorption was observed after 60 min. At each studied pH condition, it was observed that the percentage of adsorption of As(V) decreased in the order Cu(II)-doped goethite > or = Ni(II)-doped goethite > Co(II)-doped goethite > pure goethite. The adsorption followed: Langmuir isotherm, indicating monolayer formation.     

Synthesis of stebisimine, (±)-obaberine,and (±)-isotetrandrine by Willgerodt-Kindler cyclobiscondensation. II

A synthesis of stebisimine, (±)-obaberine, and (±)-isotetrandrine has been performed by the cyclocondensation of 5-acetyl-2-methoxyphenyl 4-acetylphenyl ether and 5-(-aminoethyl)-2,3-dimethoxyphenyl 4-(-aminoethyl)-2-methoxyphenyl ether and sulfur through the stage of formation of the corresponding biscyclophenylthioacetamides which, by Bischler-Napieralski cyclization and reduction of the corresponding bismethiodides, have been converted into the desired compounds.Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia. All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 91–95, January–February, 1985.     

Polymerization of Bis(Pyridine)bis-(2,4,6-tribromophenoxo)copper(II) Complex (Py2Cu(TBrP)2) by Electrooxidation and Structural Characterization by 1H-NMR, 13C-NMR,and FTIR Spectroscopies

Abstract

Electroinitiated polymerization of bis(2,4,6-tribromophenoxo)- bis(pyridine)copper(II) complex was achieved in dimethylformamide-tetrabutylammonium tetrafluoroborate solvent-electrolyte couple under air or nitrogen at room temperature by constant potential electrolysis. Polymerization conditions were based on the peak potentials measured by cyclic voltammetry. The structural analyses of the polymers were done by ¹H-NMR, ¹³C-NMR, and FTIR spectral analyses along with molecular weight measurements by cryoscopy. The poly(dibromo phenylene oxide)s obtained only at oxidation potentials in either atmosphere were found to be highly linear, indicating mainly 1,4-catenation was taking place.     

Determination of boron by (p, a) reaction

Back-extraction of tri- and tetravalent actinides from diisodecylphosphoric acid (DIDPA) is studied using hydrazine carbonate as back-extractant. In experiments using 0.5M DIDPA–0.1M TBP n-dodecane solution, Am(III), Eu(III), Pu(IV) and Np(IV) are back-extracted, and the distribution ratios are decreased with an increase of hydrazine carbonate concentration. The back-extraction equilibria are confirmed by slope analysis in consideration of neutralization between DIDPA and hydrazine carbonate, which occurs quantitatively during back-extraction. In particular, oxidation of Np(IV) to Np(V) during back-extraction is observed by measuring absorption spectra. The hydrazinium ion acts as an oxidation reagent in the back-extraction of Np(IV). Separation factors of those metals are compared with the results of HDEHP. Hydrazine carbonate back-extracts Np(IV) more selectively from DIDPA than from HDEHP.     

Ion-exchange measurement in biological samples by (p,X) and (p,p) reactions

A method of analysis by ion-exchange in biological samples using (p, X) reactions and back-scattering of charged particles is proposed. Sensitivity and rapidity are the principal qualities of this method.     

Coordination and inclusion compounds formed by addition of quinoline (Q) or isoquinoline (Iq) to a metal(II) dibenzoylmethanate (Co, Ni, Zn, Cd)

Three isomorphous series of new compounds are reported: complexes [M(DBM)₂Q₂] and [M(DBM)₂Iq₂] (M = M(II) = Co, Ni, Zn, Cd; DBM is C₆H₅COCHCOC₆H₅ ^?) and inclusion compounds [M(DBM)₂Q₂]*Q (M = Co, Zn, Cd). All the compounds comprise a trans configured octahedral complex molecule. Inclusion compounds of modified Zn and Cd DBM complexes are reported for the first time and their inclusion ability is attributed to the trans isomeric state induced by the bulky Q or Iq ligand. The TG measurements indicate the following order of thermal stability of the complexes defined by the strength of the metal–ligand bonds: Ni > Co > Cd > Zn. The inclusion compounds do not follow this trend.     

Quantitative analysis by (p,X) and (p, γ) reactions at low energies

Production of atomic X-rays and nuclear γ-rays by bombardment with 0–3 MeV protons of thick targets is described. In the case of low-Z atomic X-rays, the absorption in the target is very large, while in the case ofK X-rays from high-Z atoms or for γ-rays, this phenomenon is negligible. Both of these reactions can be used for analysis of elements from F to U, and the sensitivities and the accuracies of the determinations are discussed. A table is given showing the γ-ray energies observed in 11 substances and the limits of sensitivity.     

Spectrophotometric determination of chromium(III, VI) by use of chromium(III, VI)-Chrome AzurolS-cetylpyridinium bromide-hydroxylamine hydrochloride-zinc(II) system

This paper shows that the sensitivity of the Cr(III, VI)—Chrome Azurol S (CAS)-cetylpyridinium bromide (CPB)—hydroxylamine hydrochloride system can be increased and the wavelength of maximum absorption slightly shifted by addition of zinc(II) and that the analytical data are practically identical for both Cr(III) and Cr(VI), indicating that under the conditions used both initial oxidation states of chromium yield the same final oxidation state, Cr(III). On the basis of the Cr(III, VI)—CAS—CPB—NH₂OH·HCl—Zn systems a new, highly sensitive and selective method for spectrophotometric determination of microamounts of Cr(III, VI) has been developed, with molar absorptivity of 1.27 × 10⁵ 1. mole⁻¹ . cm⁻¹ for the complex at 620 nm and linear calibration up to 0.4 μg/ml chromium. Various foreign ions do not interfere. The method can be applied to direct determination of chromium in steels.     

Bis(dimethylmetall(III)glyoximato)metallate(II) (metall(III) = Al,Ga, In,metall(II) = Ni,Pd, Pt,Cu)

When the trimethyl derivatives of aluminium, gallium and indium react with glyoximato metallates, (R₂C₂N₂(O)OH)₂Met^II (R = H, CH₃; Met^II = Ni, Pd, Pt, Cu), in a $\text{2}\text{1}$ molar ratio, 2 mol of methane are evolved and monomeric bis(dimethylmetal(III)glyoximato)metallates(II) (metal(III) = Al, Ga, In) are formed in high yields. The vibrational and NMR spectra of the new complexes were measured and were partly resolved. The X-ray structure determinations of two of these compounds show non-planar structures of approximate C_2h and C₂ symmetry, respectively, with weak metal(III)?metal(II) π-interactions.     

1，4-苯二硫乙酸配体构筑的锌(Ⅱ)及镉(Ⅱ)配合物的合成、晶体结构及荧光性质

基于1,4-苯二硫乙酸(H2L)及中性含氮配体,水热法合成了两个新的d10金属配合物[ZnClL0.5(bpp)](1)和[Cd2L(phen)4(H2O)2].L.2.78H2O(2)(bpp=1,3-di(4-pyridyl)propane,phen=1,10-phenanthroline),并通过单晶X-射线衍射、元素分析、红外光谱和热重对其结构进行了表征。结构分析表明,在配合物1中,Zn(Ⅱ)呈现四配位的扭曲四面体构型,进一步连接形成一维双链状结构。在配合物2中,Cd(Ⅱ)呈现六配位的扭曲八面体构型,并通过可能存在的氢键及π-π堆积作用,形成最终的三维超分子结构。同时,讨论了两种配合物的固体荧光性质。     

α-Amido(thioamido)alkylation of dithiocarbamic,O-ethyldithiocarbonic,and arylsulfinic acids by 4-hydroxy(alkoxy)hexahydropyrimidine-2-thiones(ones)

The reaction of dithiocarbamic, O-ethyldithiocarbonic, and arylsulfinic acids with 4-hydroxy(methoxy)hexahydropyrimidine-2-thiones(ones) results in the regio- and stereoselective formation of 4-(aminothiocarbonylthio)-,4-(ethoxythiocarbonylthio)-, and 4-(arylsulfonyl)hexahydropyridimidinethiones(ones) for which the reaction with O-nucleophiles was studied. It was found that the axial orientation of the functional groups at the C₍₄₎ atom is preferential in the molecules of the compounds obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 228–236, February, 1991.     

Preparation of organogold(III) complexes by oxidizing dichloro-, or bis(pentafluorophenyl)-μ-bis(diphenylphosphino)ethanedigold(I)

The oxidation of compounds of the type XAu(dpe)AuX [dpe = 1,2-bis(diphenylphosphino)ethane] leads to organogold(III) complexes. When X is Cl, treatment with BrTl(C₆F₅)₂ leads to oxidative addition of two C₆F₅ groups to each gold atom and formation of Cl(C₆F₅)₂ Au(dpe)Au(C₆F₅)₂Cl, which by metathesis with KBr or KI gives the corresponding bromo (or iodo) derivative. When X is C₆F₅ oxidation with halogens leads in the case of X′ = Cl or Br to formation of X′₂ (C₆F₅)Au(dpe)Au(C₆F₅)X′₂ whereas, for X′ = I reductive elimination of IC₆F₅ takes place to give IAu(dpe)AuI.     

Cyclometallated platinum(II) complexes: oxidation to, and C-H activation by, platinum(IV)

A series of cyclometallated phenylpyridine platinum(II) complexes have been synthesised with a systematic variation in both the phenylpyridine and the ancillary ligand. Oxidation of one of the cyclometallated species leads to a number of isomeric platinum(IV) complexes, all of which eventually isomerize to a single compound. The route to these new compounds has been demonstrated to involve an initial slow oxidation followed by a rapid C-H activation to give doubly cyclometallated complexes. The solid state structures of a number of both the platinum(II) and the platinum(IV) species have been solved; many of the structures exhibited extended interactions that result in complex three dimensional packing.     

Oxidation of sulfoxides by hydrogen peroxide,catalyzed by methyltrioxorhenium(VII)

Dialkyl and diaryl sulfoxides are oxidized to sulfones by hydrogen peroxide using methyltrioxorhenium as the catalyst. The reaction rate is negligible without a catalyst. The kinetics study was performed in CH3CN-H2O (4:1 v/v) at 298 K with [H+] at 0.1 M, conditions which make the equilibration between MTO and its peroxo complexes more rapid than the oxygen-transfer step. The values for the rate constant for the oxygen-transfer step lie in the range 0.1-3 L mol-1 s-1. The rate constants were significantly smaller than for the oxidation of sulfides to sulfoxides. A study of ring-substituted diaryl sulfoxides yielded kinetics results that are consistent with nucleophilic attack of the sulfur atom on the peroxide oxygen group since rho = -0.65. The results cited refer to the reactions of the diperoxo from the catalyst, MeRe(O)(eta 2-O2)2H2O. The monoperoxo complex showed no measurable reactivity toward sulfoxides, in contrast with the situation for nearly every other substrate. That unusual finding suggests a hydrogen-bonded interaction between the substrate and the diperoxorhenium compound which cannot exist with the monoperoxo compound.     

Manganese(III,IV) and manganese(III) oxide clusters trapped by copper(II) complexes

Reactions of quinquedentate Schiff base ligands with Mn and Cu ions afforded icosa- and hexadecanuclear mixed-metal clusters in which dinuclear CuII complexes trapped oxo-bridged [MnIII8MnIV4O12] and [MnIII6O6] cores, respectively. Maximum entropy method analysis for synchrotron X-ray diffraction data was used to determine the oxidation states of the Mn ions.     

Chromium(II) and chromium(III) complexes supported by tris(2-pyridylmethyl)amine: synthesis, structures, and reactivity

This report describes the synthesis, structural characterization, and polymerization behavior of a series of chromium(II) and chromium(III) complexes ligated by tris(2-pyridylmethyl)amine (TPA), including chromium(III) organometallic derivatives. For instance, the combination of TPA with CrCl(2) yields monomeric (TPA)CrCl(2) (1). A similar reaction of CrCl(2) with TPA, followed by chloride abstraction with NaBPh(4) or NaBAr(F)(4) (Ar(F) = 3,5-(CF(3))(2)C(6)H(3)), provides the weakly associated cationic dimers [(TPA)CrCl](2)[BPh(4)](2) (2A) and [(TPA)CrCl](2)[BAr(F)(4)](2) (2B), respectively. X-ray crystallographic analysis reveals that each chromium(II) center in 1, 2A, and 2B is a tetragonally elongated octahedron; such Jahn-Teller distortions are consistent with the observed high spin (S = 2) electronic configurations for these chromium(II) complexes. Likewise, reaction of CrCl(3)(THF)(3) with TPA, followed by anion metathesis with NaBPh(4) or NaBAr(F)(4), yields the monomeric, cationic chromium(III) complexes [(TPA)CrCl(2)][BPh(4)] (4A) and [(TPA)CrCl(2)][BAr(F)(4)] (4B), respectively. Treatment of 4A with methyl and phenyl Grignard reagents produces the cationic chromium(III) organometallic derivatives [(TPA)Cr(CH(3))(2)][BPh(4)] (5) and [(TPA)CrPh(2)][BPh(4)] (6), respectively. Similar reactions of 4A with organolithium reagents leads to intractable solids, presumably due to overreduction of the chromium(III) center. X-ray crystallographic analysis of 4A, 5, and 6 confirms that each possesses a largely undistorted octahedral chromium center, consistent with the observed S = (3)/(2) electronic ground states. Compounds 1, 2A, 2B, 4A, 4B, 5, and 6 are all active polymerization catalysts in the presence of methylalumoxane, producing low to moderate molecular weight high-density polyethylene.