Studies on Environmental Pollutants: Selective Separation and Recovery of Pb(II) on Ferric Phosphate Columns

Abstract

A new method is described for the recovery and selective separation of Pb(II). The following mixtures have been separated: Hg (II) -Pb (II), Zro(II) -Pb (II), Cd (II) -Pb (II), Cu (II) -Pb (II), Mn (II) -Pb(II), Zn (II) -Pb (II), Sr (II) -Pb(II) and Ni (II)-Pb (II), on ferric phosphate columns. Cu (II), Cd (II), Ni (II), Hg (II), Mn (II), Zn (II), Sr (II) and Zro(II) were eluted with 0.01M-NH₄NO₃ and Pb(II) with a mixture of 0.1M-HNO₃ + 1.0M-NH₄NO₃ solution. Proposed studies can be applied to pollution analysis and alloy analysis.     

Extraktionsmethode zur Trennung kleiner Tellurmengen von Begleitelementen

Zusammenfassung Zur Trennung von Tellur aus Lösungen mit komplizierter Zusammensetzung wurde eine kombinierte Extraktionsmethode entwickelt. Die Extraktion von Eisen(III), Arsen(V), Antimon(V), Gold(III), Thallium(III), Wismut(III), Zinn(IV) und Selen(IV) erfolgt mit Diisopropyläther aus 8 M Salzsäure, wobei das gesamte Te(IV) in der wäßrigen Phase verbleibt. Diese wird dann mit Methylisobutylketon aus 4 M Salzsäure extrahiert, während in der wäßrigen Phase Kupfer(II), Aluminium(III), Silber(I), Nickel (II), Kobalt(II), Zink(II), Cadmium(II) und Blei(II) verbleiben. Die vollständige Abtrennung der Begleitelemente des Tellurs erfolgt durch zusätzliche Extraktion ihrer Kupferronate mit Methylisobutylketon bei pH 3–5. Das vorgeschlagene Extraktionsverfahren kann mit jeder bekannten Methode zur Bestimmung geringer Tellurmengen kombiniert werden.

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Extraction method for the separation of small quantities of tellurium from accompanying elements

A new combined solvent extraction method is proposed for the separation of tellurium from solutions of complex composition. Iron(III), arsenic(V), antimony(V), gold(III), thallium(III)J bismuth(III), tin(IV) and selenium(IV) are extracted with diisopropyl ether from 8 M hydrochloric acid. Under these conditions tellurium(IV) is quantitatively retained in the aqueous phase. Subsequently tellurium(IV) is extracted from 4 M hydrochloric acid with methylisobutyl ketone, so that copper(II), aluminium(III), silver(I), nickel(II), cobalt(II), zink(II), cadmium(II) and lead(II) remain in. the aqueous phase. The complete separation of the accompanying elements is realized by an additional extraction of their cupferronates with methylisobutyl ketone at pH 3–5. The separation described can be combined with any known method for the determination of small amounts of tellurium(IV).

     

Thiacalix[4]arenetetrasulfonate as specific pre-column chelating reagent for nickel(II) ion in kinetic differentiation mode high-performance liquid chromatography

Thiacalix[4]arenetetrasulfonate (TCAS) has been examined as a pre-column chelating reagent for the determination of trace metal ions by kinetic differentiation mode (KD) ion-pair reversed-phase high-performance liquid chromatography (HPLC) with spectrophotometric detection. Among 14 kinds of common metal ions tested here, viz. Al(III), Ca(II), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Hg(II), Mg(II), Mn(II), Ni(II), Pb(II), V(V), and Zn(II) ion, only Ni(II) ion was detected as the TCAS chelate in the HPLC separation stage in spite of TCAS forming the chelates with various metal ions except for Al(III), Ca(II), and Mg(II) at the pre-column chelation stage. The undetected metal-TCAS chelates seemed to be dissociated on an HPLC column where no added TCAS was present in the mobile phase because of their kinetic unstability. The calibration graph for Ni(II) ion gave a wide linear dynamic range (40-20,000 nM) with the very low detection limit (DL) (3σ base-line fluctuation) to be 5.4 nM (0.32 ng ml⁻¹). The practical applicability of the KD-HPLC method with TCAS was demonstrated with the determination of trace Ni in coal fly ash.     

Miscibility of Halogen-containing Polymethacrylates with Various Poly(alkyl acrylate)s

The miscibility behavior of a series of halogen-containing polymethacrylates with poly(methyl acrylate), poly(ethyl acrylate), poly(n-propyl acrylate) and poly(n-butyl acrylate) was investigated by differential scanning calorimetry and for lower critical solution temperature (LCST) behavior. Poly(chloromethyl methacrylate), poly(1-chloroethyl methacrylate), poly(2-chloroethyl methacrylate), poly(2,2-dichloroethyl methacrylate), poly(2,2,2-trichloroethyl methacrylate), poly(2-fluoroethyl methacrylate) and poly(1,3-difluoroisopropyl methacrylate) are miscible with some of the poly(alkyl acrylate)s. Most of the miscible blends show LCST behavior. However, poly(3-choloropropyl methacrylate), poly(3-fluoropropyl methacrylate), poly(4-fluorobutyl methacrylate), poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate), poly(2-bromoethyl methacrylate) and poly(2-iodoethyl methacrylate) are immiscible with any of the poly(alkyl acrylate)s studied. © 1997 John Wiley & Sons, Ltd.     

Thin Layer Chromatography of Metal Ions Complexed with Anils (VII) Detection,Separation, and Determination

Abstract

Dark colored chelates of p-dimethylaminoanil of 3-benzoyl-methylglyoxal bidentate ligand with Sb(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), ZrO(II), Y(III), La(III), Pr(III), Nd(III) Sm(III), Gd(III) and Dy(III) have been chromatographed on starch bound silica gel thin layers. New correlations of I.R. with R_f (resolving solvent) have been used to ascertain the colored spots.

Among various mixtures resolved qualitatively a few typical ones have been alanysed quantitatively. Errors in determinations and maximum separation limits have also been deduced.     

Hg(II), Tl(III), Cu(I), and Pd(II) Complexes with 2,2'-Diphenyl-4,4'-Bithiazole (DPBTZ), Syntheses and X-Ray Crystal Structure of [Hg(DPBTZ)(SCN)2]

Reaction of the ligand 2,2′-diphenyl-4,4′-bithiazole (DPBTZ) with Hg(SCN)₂, Tl(NO₃)₃, CuCl, and PdCl₂ gives complexes with stoichiometry [Hg(DPBTZ)(SCN)₂], [Tl(DPBTZ)(NO₃)₃], [Cu(DPBTZ)(H₂O)Cl]_, and [Pd(DPBTZ)Cl₂]. The new complexes were characterized by elemental analyses and infrared spectroscopy. The crystal structure of [Hg(DPBTZ)(SCN)₂] determined by X-ray crystallography. The Hg atom in the title monomeric complex, (2,2′-diphenyl-4,4′-bithiazole)mercury(II)bisthiocyanate, [Hg(C₁₈H₁₂N₂S₂)(SCN)₂], is four-coordinate having an irregular tetrahedral geometry composed of two S atoms of thiocyanate ions [Hg-S 2.4025(15) and 2.4073(15) Å] and two N atoms of 2,2′-diphenyl-4,4′-bithiazole ligand [Hg-N 2.411(4) and 2.459(4) Å]. The bond angle S(3)-Hg(1)-S(4) of 147.46(5)° has the greatest derivation from ideal tetrahedral geometry. Intermolecular interaction between Hg(1) and two S atoms of two neighboring molecules, 3.9318(15) and 3.9640(18) Å, make the Hg(1) distort from a tetrahedron to a disordered octahedron. The attempts for preparation complexes of Tl(I), Pb(II), Bi(III), Cd(II) ions with 2,2′-diphenyl-4,4′-bithiazole ligand were not successful and also the attempts for preparation complexes of 4,4′,5,5′-tetraphenyl-2,2′-bithizole ligand with Cu(II), Ni(II), Co(II), Co(III), Mn(II), Mn(III), Fe(II), Fe(III), Cr(III), Zn(II), Tl(III), Pb(II), Hg(II), Cu(I), Pd(II) were not successful. This point can be regarded as the initial electron withdrawing of phenyl rings and also their spatial steric effects.     

Indirect cerimetric determination of gold at the milligram level

Summary A rapid volumetric method has been worked out for the indirect determination of 0.25–2.5 mg of gold in presence of many common ions. It is based on the reduction of gold(III) to metal with excess of cobalt(II) in the presence of 1,10-phenanthroline at pH 3 and 50°, and estimation of the unreacted cobalt(II) in the filtrate by visual, potentiometric or biamperometric titration with standardized cerium(IV) sulphate solution. It has been found that there is no interference from Ni(II), Pb(II), Zn(II), Cd(II), Mn(II), Mg(II), Ca(II), Al(III), Cr(III), Ti(IV), V(V) and W(VI). Interference due to Pd(II) and Ag(I) can be eliminated. Fe(III), Cu(II), Mo(VI), Hg(II) and Pt(IV) interfere, even present in small amounts.

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Zusammenfassung Ein schnelles maßanalytisches Verfahren zur indirekten Bestimmung von 0,25–2,5 mg Gold in Gegenwart vieler Ionen wurde ausgearbeitet. Es beruht auf der Reduktion zu metallischem Gold mit überschüssigem Kobalt(II) in Anwesenheit von 1,10-Phenanthrolin bei pH 3 und 50°. Die Rückbestimmung des unverbrauchten Kobalts im Filtrat erfolgt durch potentiometrische oder biamperometrische Titration mit Cer(IV)sulfat. Ni(II), Pb(II), Zn(II), Cd(II), Mn(II), Mg(II), Ca(II), Al(II), Cr(III), Ti(IV), V(V) und W(VI) stören nicht. Eine Störung durch Pd(II) oder Ag(I) kann man ausschalten. Fe(III), Cu(II), Mo(VI), Hg(II) und Pt(IV) stören auch in geringen Mengen.

     

FEATURES OF A FLEXIBLE BACKBONE IN THE COORDINATION COMPOUNDS OF A DIOXIME LIGAND: THE CHARACTERIZATION OF SUPRAMOLECULAR AND DINUCLEAR METAL COMPLEXES

Abstract

The grinding of a 2: 1 molar ratio mixture of isonitrosoacetylacetone and 1,3-diaminopropan-2-ol led to formation of the tribasic ligand (H₃L), (1) with two oxime groups and a flexible alcoholic backbone. The 1:2 molar ratio reaction of (1) with CuX₂ produced the planar dinuclear complexes LCu₂(X) nH₂O; × = acetate (2), phenylacetate (3), formate (4), monochloroacetate (5), dichloroacetate (6), trichloroacetate (7), benzoate (8), and p-hydroxybenzoate (9); n = 1 for (2) and (8); n = 2 for (3)-(7); and n = 4 for (9). The copper(II) ions are bridged by the carbox-ylate and the alcoholic oxygen. The strong antiferromagnetic interactions in (2)-(9) are impeded in (5)-(7) by the chloroacetate bridge withdrawing electron density from the carboxylate. The latter bridge is replaced by picrate in the 1:1 molar ratio reaction of (2) with picric acid (10). The 1:1 molar ratio reaction of (1) with copper(II) acetate produced the tetranuclear [HLCu]₂[LCu₂(OAc)] 5H₂O (11), whereas the 2:1 molar ratio reaction, similar to the reaction which led to (8), produced HLCu (12). The latter complex reacted (1:1 molar ratio) with either copper(ll) acetate or nickel(II) acetate to produce complexes (2) and the heterodinuclear LNi-Cu(OAc) 2H₂O (13), respectively. Similar reactions with (11) gave the same complexes (2) and (13). The acid adducts of (9) with p-hydroxybenzoic acid (14) and LCu₂(X)-HX (15); × = p-aminobenzoic acid were isolated. The cobalt(II) analogue of the mononuclear (12), HLCo 2H₂O (16) was obtained from the 1:1 molar reaction of (1) with cobalt(II) acetate. The supramolecular structure of (11), (12) and (16) took place via intermolecular hydrogen bonding of the alcoholic proton with the oximato oxygen of the adjacent molecule which mediated electron density and allowed for a magnetic exchange interaction. The suggested structures of the ligand and metal complexes are in accordance with analytical, spectral and magnetic moment data.     

Synthesis of Arenethiolate Complexes of Divalent and Trivalent Lanthanides from Metallic Lanthanides and Diaryl Disulfides: Crystal Structures of [{Yb(hmpa)(3)}(2)(&mgr;-SPh)(3)][SPh] and Ln(SPh)(3)(hmpa)(3) (Ln = Sm, Yb; hmpa = Hexamethylphosphoric Triamide)

A convenient and one-pot synthetic method of lanthanide thiolate compounds was developed. An excess of metallic samarium, europium, and ytterbium directly reacted with diaryl disulfides in THF to give selectively Ln(II) thiolate complexes, [Ln(SAr)(&mgr;-SAr)(thf)(3)](2) (1, Ln = Sm; 2, Ln = Eu; Ar = 2,4,6-triisopropylphenyl), Yb(SAr)(2)(py)(4) (3, py = pyridine), and [{Ln(hmpa)(3)}(2)(&mgr;-SPh)(3)][SPh] (6, Ln = Sm; 7, Ln = Eu; 8, Ln = Yb; hmpa = hexamethylphosphoric triamide). Reaction of metallic lanthanides with 3 equiv of disulfides afforded Ln(III) thiolate complexes, Ln(SAr)(3)(py)(n)()(thf)(3)(-)(n)() (9a, Ln = Sm, n = 3; 9b, Ln = Sm, n = 2; 10, Ln = Yb, n = 3) and Ln(SPh)(3)(hmpa)(3) (11, Ln = Sm; 12, Ln = Eu; 13, Ln = Yb). Thus, Ln(II) and Ln(III) thiolate complexes were prepared from the same source by controlling the stoichiometry of the reactants. X-ray analysis of 8 revealed that 8 has the first ionic structure composed of triply bridged dinuclear cation and benezenethiolate anion [8, orthorhombic, space group P2(1)2(1)2(1) with a = 21.057(9), b = 25.963(7), c = 16.442(8) ?, V = 8988(5) ?(3), Z = 4, R = 0.040, R(w) = 0.039 for 5848 reflections with I > 3sigma(I) and 865 parameters]. The monomeric structures of 11 and 13 were revealed by X-ray crystallographic studies [11, triclinic, space group P&onemacr; with a = 14.719(3), b = 17.989(2), c = 11.344(2) ?, alpha = 97.91(1), beta = 110.30(2), gamma = 78.40(1) degrees, V = 2751.9(9) ?(3), Z = 2, R = 0.045, R(w) = 0.041 for 7111 reflections with I > 3sigma(I) and 536 parameters; 13, triclinic, space group P&onemacr; with a = 14.565(2), b = 17.961(2), c = 11.302(1) ?, alpha = 97.72(1), beta = 110.49(1), gamma = 78.37(1) degrees, V = 2706.0(7) ?(3), Z = 2, R = 0.031, R(w) = 0.035 for 9837 reflections with I > 3sigma(I) and 536 parameters]. A comparison with the reported mononuclear and dinuclear lanthanide thiolate complexes has been made to indicate that the Ln-S bonds weakened by the coordination of HMPA to lanthanide metals have ionic character.     

Hydrogen‐bonded structures of the isomeric compounds of quinoline with 2‐chloro‐5‐nitrobenzoic acid, 3‐chloro‐2‐nitrobenzoic acid, 4‐chloro‐2‐nitrobenzoic acid and 5‐chloro‐2‐nitrobenzoic acid

The structures of four isomeric compounds, all C₇H₄ClNO₄·C₉H₇N, of quinoline with chloro‐ and nitro‐substituted benzoic acid, namely, 2‐chloro‐5‐nitrobenzoic acid–quinoline (1/1), (I), 3‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (II), 4‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (III), and 5‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (IV), have been determined at 185 K. In each compound, a short hydrogen bond is observed between the pyridine N atom and a carboxyl O atom. The N...O distances are 2.6476 (13), 2.5610 (13), 2.5569 (12) and 2.5429 (12) Å for (I), (II), (III) and (IV), respectively. Although in (I) the H atom in the hydrogen bond is located at the O site, in (II), (III) and (IV) the H atom is disordered in the hydrogen bond over two positions with (N site):(O site) occupancies of 0.39 (3):0.61 (3), 0.47 (3):0.53 (3) and 0.65 (3):0.35 (3), respectively.     

Miscible blends of amorphous polymers

Thirty-five polymethacrylate/chlorinated polymer blends were investigated by differential scanning calorimetry. Poly(ethyl), poly(n-propyl), poly(n-butyl), and poly(n-amyl methacrylate)s were found to be miscible with poly(vinyl chloride) (PVC), chlorinated PVC, and Saran, but immiscible with a chlorinated polyethylene containing 48% chlorine. Poly(methyl) (PMMA), poly(n-hexyl) (PHMA), and poly(n-lauryl methacrylate)s were found to be immiscible with the same chlorinated polymers, except the PMMA/PVC, PMMA/Saran, and PHMA/Saran blends, which were miscible. A high chlorine content of the chlorinated polymer and an optimum CH₂/COO ratio of the polymethacrylate are required to obtain miscibility. However, poly(methyl), poly(ethyl), poly(n-butyl), and poly(n-octadecyl acrylate)s were found to be immiscible with the same chlorinated polymers, except with Saran, indicating a much greater miscibility of the polymethacrylates with the chlorinated polymers as compared with the polyacrylates.     

The spectrophotometric determination of vanadium after extraction as vanadium(III) ferronate by tribenzylamine

Vanadium(III) obtained by dithionite reduction of vanadium(V) can be extracted as its ferron complex with tribenzylamine in chloroform from 0.05 M sulphuric acid. Vanadium (0–5 μg ml^-1) is determined spectrophotometrically at 430 nm with a sensitivity of 0.0028 μg V cm^-2. Al(III), Co(II), Ni(II), Fe(II, III), Hg(II), Si(IV), Be(II), Mg(II), Ca(II), Sr(II), Ba(II), Cr(VI, III), W(VI), Zn(II), U(VI), Mn(II). Pb(II), Cu(II), Cd(II) and Th(IV) do not interfere; only Mo(VI), Ti(IV), Zr(IV). Bi(V) and Sn(II) interfere. A single determination takes only 7 min. The extracted complex is V^III (R-3H.TBA)₃ where R = C₉H₄O₄NSI. The method is satisfactory for the determination of vanadium in steels, alum and other samples without preliminary separations.     

Electron-transfer polymers. XXIX. Copolymerizability of vinylhydroquinone derivatives

Ten vinylhydroquinone and one vinyl resorcinol derivatives are compared, particularly with respect to NMR spectra and copolymerizability with styrene. They are vinylhydroquinone dimethyl ether (I), vinyl-O,O′-bis(1-ethoxyethyl)hydroquinone (II), vinylhydroquinone di(2-pentyl)ether (III), 4-vinyl resorcinol bismethoxymethyl ether (IV), 2-vinyl-5-methylhydroquinone dimethyl ether (V), 2-vinyl-5-methyl-O,O′-bis(1-ethoxyethyl)hydroquinone (VI), 2-vinyl-6-methylhydroquinone dimethyl ether (VII), 2-vinyl-5-tert-butylhydroquinone dimethyl ether (VIII), 2-vinyl-5-chlorohydroquinone dimethyl ether (IX), 2-vinyl-3,6-dimethylhydroquinone dimethyl ether (X), and 2-vinyl-3,5,6-trimethylhydroquinone dimethyl ether (XI). All the vinyl protons have almost the same coupling constants. Though subtle distinctions are found among all the spectra, they can in general be put into two groups on the basis of the chemical shifts. Let the hydrogen on carbon-1 of the vinyl group be A, the hydrogen cis to A be B the hydrogen trans to A be C, then in the first group, (I) through (IX), the chemical shifts (τ) are (A) 3.02 ± 0.08, (C) 4.41 ± 0.05, and (B) 4.87 ± 0.07, and in the second group, (X) and (XI), they are (A) 3.30 ± 0.03, (C) 4.49 ± 0.01, and (B) 4.59 ± 0.03. It is supposed that in (X) and (XI) the vinyl group is out of the plane of the ring, because of the two ortho substituents, and this conformation is reflected in the NMR data. Ultraviolet spectra are consonant with this interpretation, since the λ_max of (X) and (XI) correspond closely with those of nonvinyl reference compounds, while those of (II), (V), and (VIII) are shifted to longer wavelengths. When these compounds are copolymerized separately with styrene, the behaviors are classifiable into the following three groups, where r₁ and r₂ are monomer reactivity ratios with styrene as the first monomer: (i) r₁ < 1 and r₂ < 1 for compounds (II) and (III) and the reference compound O,O′-dibenzoylvinylhydroquinone, (ii) r₁ < 1 and r₂ > 1 for compounds (I), (V), (VII), (VIII), (IX), and (iii) r₁ > 1 and r₂ = 0 for compounds (X) and (XI). These behaviors are correlated with the effect of electronegativity of groups on the stability of the radical at the growing end of the chain and with the simultaneous effects of steric hindrance.     

Metal String Complexes: Synthesis,Crystal Structures and Magnetic Properties of Heptanuclear Nickel(II) Complexes, [Ni7(μ7-teptra)4X2] (teptra = tetrapyridyltriamido,X = Cl−, NCS−)

The synthesis, crystal structures and magnetic properties of linear heptanuclear nickel(II) complexes [Ni₇(μ₇-teptra)₄X₂], (teptra = tetrapyridyltriamido), with the axial ligand X = Cl^? ( 1 ), NCS^? ( 2 ), are reported. The hepta-nuclear metal chain is helically wrapped by four syn-syn-syn-syn-syn-syn teptra^3? ligands. Both of the [Ni₇(μ₇-teptra)₄]²⁺ moiety are isostructural involving a Ni₇ linear chain unit with all of the ∠Ni-Ni-Ni being 180°, terminated by two axial ligands. Three types of Ni? Ni distances are found in these complexes. The longest ones bonded with the axial ligands are 2.383(1), 2.374(2) and 2.375(2), 2.354(2), and the intermediate ones are 2.310(1), 2.304(1) and 2.300(2), 2.303(2) Å for ( 1 ) and ( 2 ), respectively. The innermost Ni? Ni distances are the shortest ones with the distances of 2.226(2), 2.214(2) and 2.194(2), 2.206(2) Å for ( 1 ) and ( 2 ), respectively. Two terminal Ni(II) ions bonded with the axial ligands are in a square-pyramidal (NiN₄X) environment and exhibit long Ni? N bonds (?2.10 Å) which are consistent with a high-spin Ni(II) configuration. The inner five Ni(II) ions displayed short Ni? N (～1.90 Å) bond distances which are consistent with a square-planar (NiN₄), diamagnetic arrangement of a low-spin Ni(II) configuration. The magnetic measurement of ( 1 ) shows an antiferromagnetic interaction of two terminal high-spin Ni(II) ions with the coupling constant J = ?3.8 cm^?1. The Ni? Ni, Ni? N distances and magnetic behavior among tri-, penta-, and hepta-nickel(II) complexes are compared and discussed.     

Determination of trace metals by ICP-OES in plant materials after preconcentration of 1,10-phenanthroline complexes on activated carbon

In this work, 1,10-phenanthroline was used as a complexing agent for the separation and preconcentration of Cd(II), Co(II), Ni(II), Cu(II) and Pb(II) on activated carbon. The metals were adsorbed on activated carbon by two methods: static (1) and dynamic (2). The optimal condition for separation and quantitative preconcentration of metal ions with activated carbon for the proposed methods was for (1) in the static methods in the pH range 7-9. The desorption was found quantitative with 8 mol dm⁻³ HNO₃ for Cd(II) (92.6%), Co(II) (95.6%), Pb(II) (91.0%), and with 3 mol dm⁻³ HNO₃ for Cd(II) (95.4%), Pb(II) (100.2%). The preconcentration factor was 100 with R.S.D. values between 1.0 and 2.9%. For (2), the dynamic method (SPE), the pH range for the quantitative sorption was 7-9. The desorption was found quantitative with 8 mol dm⁻³ HNO₃ for Cd(II) (100.6%), Pb(II) (94.4%), and reasonably high recovery for Co(II) (83%), Cu(II) (88%). The optimum flow rate of metal ions solution for quantitative sorption of metals with 1,10-phenanthroline was 1-2 cm³ min⁻¹ whereas for desorption it was 1 cm³ min⁻¹. The preconcentration factor was 50 for all the ions of the metals with R.S.D. values between 2.9 and 9.8%.The samples of the activated carbon with the adsorbed trace metals can be determined by ICP-OES after mineralization by means of a high-pressure microwave mineralizer. The proposed method provides recovery for Cd (100.8%), Co (97.2%), Cu (94.6%), Ni (99.6%) and Pb (100.0%) with R.S.D. values between 1.2 and 3.2%.The preconcentration procedure showed a linear calibration curve within the concentration range 0.1-1.5 μg cm⁻³. The limits of detection values (defined as “blank + 3s” where s is standard deviation of the blank determination) are 5.8, 70.8, 6.7, 24.6, and 10.8 μg dm⁻³ for Cd(II), Pb(II), Co(II), Ni(II) and Cu(II), respectively, and corresponding limit of quantification (blank + 10s) values were 13.5, 151.3, 20.0, 58.9 and 33.2 μg dm⁻³, respectively.As a result, these simple methods were applied for the determination of the above-mentioned metals in reference materials and in samples of plant material.     

On the Ambiphilic Reactivity of Geometrically Constrained Phosphorus(III) and Arsenic(III) Compounds: Insights into Their Interaction with Ionic Substrates

The ambiphilic nature of geometrically constrained Group 15 complexes bearing the N,N‐bis(3,5‐di‐tert‐butyl‐2‐phenolate)amide pincer ligand (ONO^3?) is explored. Despite their differing reactivity towards nucleophilic substrates with polarised element–hydrogen bonds (e.g., NH₃), both the phosphorus(III), P(ONO) ( 1 a ), and arsenic(III), As(ONO) ( 1 b ), compounds exhibit similar reactivity towards charged nucleophiles and electrophiles. Reactions of 1 a and 1 b with KOtBu or KNPh₂ afford anionic complexes in which the nucleophilic anion associates with the pnictogen centre ([(tBuO)Pn(ONO)]^? (Pn=P ( 2 a ), As ( 2 b )) and [(Ph₂N)Pn(ONO)]^? (Pn=P ( 3 a ), As ( 3 b )). Compound 2 a can subsequently be reacted with a proton source or benzylbromide to afford the phosphorus(V) compounds (tBuO)HP(ONO) ( 4 a ) and (tBuO)BzP(ONO) ( 5 a ), respectively, whereas analogous arsenic(V) compounds are inaccessible. Electrophilic substrates, such as HOTf and MeOTf, preferentially associate with the nitrogen atom of the ligand backbone of both 1 a and 1 b , giving rise to cationic species that can be rationalised as either ammonium salts or as amine‐stabilised phosphenium or arsenium complexes ([Pn{ON(H)O}]⁺ (Pn=P ( 6 a ), As ( 6 b )) and [Pn{ON(Me)O}]⁺ (Pn=P ( 7 a ), As ( 7 b )). Reaction of 1 a with an acid bearing a nucleophilic counteranion (such as HCl) gives rise to a phosphorus(V) compound HPCl(ONO) ( 8 a ), whereas the analogous reaction with 1 b results in the addition of HCl across one of the As?O bonds to afford ClAs{(H)ONO} ( 8 b ). Functionalisation at both the pnictogen centre and the ligand backbone is also possible by reaction of 7 a / 7 b with KOtBu, which affords the neutral species (tBuO)Pn{ON(Me)O} (Pn=P ( 9 a ), As ( 9 b )). The ambiphilic reactivity of these geometrically constrained complexes allows some insight into the mechanism of reactivity of 1 a towards small molecules, such as ammonia and water.     

Ligand trans-effect in octahedral complexes of 3d metals and its manifestation in the synthesis of metalloporphyrins in solution

We study features of the indicator kinetic reaction of meso(tetraphenyl)tetrabenzoporhine with cobalt(II), nickel(II), and manganese(II) acetates in electron-donating organic solvents (N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and pyridine (Py)) and in their binary mixtures at temperatures in the range 348–368 K. Specific features of the trans-effect of solvent molecules on the rate and activation parameters of formation of manganese(II), cobalt(II), nickel(II), and copper(II) complexes with porphyrin are noted.     

Alkaloids from the Leaves of Fissistigma Glaucescens

Two new alkaloids, glaucenamide ( 1 ) and fissiceine ( 2 ), along with fifteen known ones, liriodenine ( 3 ), oxocrebanine ( 4 ), kuafumine ( 5 ), oxoxylopine ( 6 ), atherospermidine ( 7 ), (‐)‐xylopine ( 8 ), (‐)‐N‐acetylxylopine ( 9 ), N‐trans‐feruloyltyramine ( 10 ), aristololactam BII ( 11 ), aristololactam BIII ( 12 ), aristololactam AII ( 13 ), piperolactam A ( 14 ), goniothalactam ( 15 ), norcepharadion B ( 16 ), and noraristolodione ( 17 ) were isolated from the methanolic extracts of the Fissistigma glaucescens. The structures of these compounds were established by means of spectral analysis.     

Structures of triphenylbismuth dicarboxylates

Tripheylbismuth bis(trichloroacetate) (I), triphenylbismuth bis(chloroacetate) (II), and triphenylbismuth bis(bromoacetate) (III) were synthesized by the reaction of triphenylbismuth with carboxylic acid. The Bi atoms of the synthesized compounds have a distorted trigonal-bipyramidal coordination with phenyl ligands in equatorial positions. The Bi-C bond lengths lie within intervals 2.194(2)–2.201(2), 2.193(8)–2.223(7), 2.191(4)–2.220(3) Å, the distances Bi-O and Bi···O(=C) are equal 2.308(2), 2.315(2), and 2.896(2), 2.931(2); 2.289(6), 2.302(6), and 2.891(6), 2.910(6); 2.295(3), 2.312(3), and 2.893(3), 2.920(3) Å in I, II, and III, respectively. Molecules of triphenylbismuth dicarboxylates show linear dependence between the maximum equatorial angle CBiC (on the side of a contact) and intramolecular distance Bi···O(=C).     

Separation of rhenium by thin-layer chromatography with polyethyleneimine cellulose in hydrochloric acid media

Summary The thin-layer chromatographic behavior of 49 inorganic ions on polyethyleneimine (PEI) cellulose has been investigated in hydrochloric acid media (0.01–1.0 mol dm⁻³). The sorption on the cellulose decreases with increasing acid concentration for most of the ions, but As(III), Ti(IV) and Te(VI) do not exhibit any R_f variation with the acid concentration. The R_f spectra of TI(I), Cd(II), Pb(II) and Zn(II) have a maximum. Ag(I), Bi(III), Nb(V), Ta(V), Mo(VI) and W(VI) are retained tightly on the layer, due to either insoluble salt formation or extensive hydrolysis. The extremely low R_f values of Hg(II), Pd(II), Au(III), Ru(III) and Pt(IV) are accounted for by stability of their chlorocomplexes. Re(VII) distributes chromatographically, having moderate R_f values between 0.3 and 0.6, so that the selective separation of Re(VII) from the other ions is feasible.