Ligand exchange separation of amines on copper (II) sorbed on zinc silicate

Summary Papers impregnated with Cu(II) sorbed on zinc silicate have been used to study the ligand exchange chromatographic behavior of amines. R_F values of 16 amines have been studied in 6 different systems. On the basis of differences in R_F values various analytically important qualitative separations of amines on impregnated papers and quantitative separations on columns of copper(II) sorbed on zinc silicate have been achieved.     

Zinc Silicate as a New Adsorbent for Paper Chromatographic Separation of Phenols

Abstract

A new adsorbent zinc silicate has been used for the paper chromatographic separations of different phenols. R_F values have been determined and compared with those obtained on plain papers. A new term R_i has been calculated for various phenols. The dependance of R_i and R_F on various factors have also been studied and discussed.     

Separation and Recovery of Some Metal Ions Using Pan Sorbed Zinc Silicate as Chelating Ion Exchanger

Abstract

A new inorganic ion exchanger zinc silicate has been synthesized. Its properties such as ion exchange capacity, heat effect and stability etc. have been studied. Sorption of PAN over zinc silicate formed a chelate ion exchanger which showed greater selectivity for some metal ions especially for Cu²⁺, Ni²⁺, Co²⁺, Fe³⁺, Ag⁺, Ag³⁺ and Pt⁴⁺. Selectivity has been determined on the basis of distribution coefficients of these metal ions. Separations of Pt(IV) from Fe(III), Au(III) from Fe(III), Ag(I) from Cu(II) and Au(III) from Cu(II) have been reported. The recovery of Pt(IV) and Au(III) from dilute solutions has also been studied.     

Thermal and spectral analyses of complexes of zinc(II)tetra-tertbutylphthalocyanine with amines

Spectral and thermochemical studies of complexes of zinc(II)tetra-tertbutylphthalocyanine (Zn(t-Bu)₄Pc) with some amines have been carried out. Spectral effects of the complex formation of the metallophthalocyanine with amines have been established. It has been found that an ability of Zn(t-Bu)₄Pc to coordinate amines depends on both their nature and conditions of preparation. Similarity of the crystal structures of biligand and monoligand of Zn(t-Bu)₄Pc complexes to individual β- and α-polymorphs of Zn(t-Bu)₄Pc, respectively is proved by IR spectroscopy and X-ray diffraction method.     

Zinc Recovery from Wulagen Sulfide Flotation Plant Tail by Applying Ether Amine Organic Collectors

Separating oxidized zinc minerals from flotation tailings is always a challenge. In this study, a flotation tailing from Wulagen zinc mine in China (Zn grade < 1%) was processed using froth flotation with combinations of amines (OPA 10, OPA 1214, OPA 13, DDA) and Na₂S to study the effects of these amines on the zinc recovery as well as their interactions with other reagents, aiming to screen out a proper reagent scheme to improve zinc separation from extremely low-grade zinc flotation tailings. The results show that different amines led to different flotation performance, and the collectors were ranked as OPA 1214, OPA 13, OPA 10 and DDA in a decreasing order based on flotation collectivity and selectivity. An increase in the concentration of each collector increased the zinc recovery but reduced the concentrate zinc grade. Interactions were also observed between different amines and Na₂S and Na₂SiO₃, and OPA 1214 outdid the others in saving the usage of both the Na₂S and Na₂SiO₃. The measured adsorption of collector onto smithsonite was found to correlate well with flotation test results. It was concluded that hydrocarbon chains can be held accountable for the difference in the flotation performance with different amines. The longer the hydrocarbon chain, the stronger the hydrophobic association ability of amine, which is conducive to the selective amine adsorption onto sulfurized smithsonite particles and hence the smithsonite flotation.     

A study of the differential capacitance of zinc in aqueous solution with potassium silicate additions

The differential capacitance of the polycrystalline zinc electrode has been studied in aqueous solutions of KCl, KNO₃ and KOH both with and without the addition of potassium silicate. Double layer capacitance measurements can be made in KCl and KNO₃ without the interaction of OH^? at low pH values < 3.0. The reduction of the nitrate ion takes place at the zinc electrode in aqueous potassium nitrate.The silicate ion is adsorbed on the zinc electrode in aqueous KOH solutions at a potential close to the dissolution potential. This results in inhibition of metal dissolution, due to limited interaction of OH^? with the metal surface. The electrode resistance is increased by this adsorbed layer of silicate ion. In alkaline solution the h.e.r. is stimulated by the addition of potassium silicate.     

Ligand Exchange Chromatography Separations of Some Phenolic Compounds on Zinc Silicate in Fe(III) Form

Abstract

The high sorption capacity of zinc silicato for Fe(III) has been utilized for the separation of phenolic compounds on the basis of ligand exchange. The coordination of ligands with the central metal ion occurs through oxygen. Ligand sorption capacity, rate of sorption and break-through capacity have been studied. The distribution coefficients (Kd values) of 21 phenols have been determined in five different systems. Selectivity has been determined on the basis of Kd values of these phenols. On the basis of differences in Kd values various analytically important quantitative binary and ternary separations on columns of zinc silicate in Fe(III) form have been achieved.     

Enhancing the Photo and Biomedical Activity of ZnO by Incorporation with Zinc Silicate Nanocomposites

Highly active and non-toxic ZnO incorporated with zinc silicate (zinc silicate/ZnO) nanocomposites are synthesized via a simple and low-cost hydrothermal method followed by heat treatment. Different molar ratios from Si to Zn [1:20], [1:10], [1:8] and [1:6] are used to prepare different zinc silicate/ZnO nano composite materials which are assigned to ZS1, ZS2, ZS3 and ZS4 samples, respectively. The effect of calcination times and temperatures have been investigated on the crystallographic and morphological properties of the synthesized nano composite materials. The XRD analysis show that at very low molar ratios, zincite (ZnO) is the most predominant phase. However, at higher molar ratios, there are two phases coexist; hemimorphite (Zn₄Si₄O₇) and zincite. The TEM images show a uniform nanoplate-like shaped morphology from ZnO with well dispersed Zn₂SiO₄ nanoparticles. The S_BET is remarkably increased from 18.14 to 176.5 m².g⁻¹ by calcination up to 400 °C and then decreased to 72.2 m². g⁻¹ by further increasing in the calcinations temp up to 1,000 °C. The bio and photocatalytic activities of the composite nanomaterials have been investigated. Compared with the pure ZnO, the nano composites have been demonstrated as better photocatalysts for the degradation of Levafex golden yellow (LGY) dye as a model of organic dye pollutant under simulated sunlight irradiation. Moreover, the nano composites were evidenced to possess better and non-toxic antitumor activity towards hepatocellular carcinoma cell lines with (IC₅₀ = 11.2 μg.ml⁻¹ and LD₅₀ ˃ 50 mg. Kg⁻¹).     

Zinc Powder Catalysed Formylation and Urealation of Amines Using CO2 as a C1 Building Block†

Transformation of CO₂ into valuable organic compounds catalysed by cheap and biocompatible metal catalysts is one of important topics of current organic synthesis and catalysis. Herein, we report the zinc powder catalysed formylation and urealation of amines with CO₂ and (EtO)₃SiH under solvent free condition. Using 2 mol% zinc powder as the catalyst, a series of secondary amines, both the aromatic ones and the aliphatic ones, can be formylated into formamides. When primary aromatic amines were used as the substrates, the reactions produce urea derivatives. The electronic and steric effects from the substrates on the formylation and urealation reactions were observed and discussed. The recovery and reusability of zinc powder were investigated, showing the zinc powder can be reused in the formylation reaction without loss of catalytic activity. The analysis on the reactants/products mixture after filtering out the zinc powder showed the zinc concentration in the mixture is low to 1 ppm. The pathways for the formylation and urealation of amines with this catalytic system were also investigated, and related to the different substrates.     

THE SULFUR (11)-NITROGEN BOND. PART IV1. AMINOSULFENATES

Abstract

Aminosulfenates R₂NSOR' have been prepared from aminosulfenyl chlorides and tin alkoxides. They form sulfenyl chlorides with chlorosilanes, bisaminosulfides with secondary amines and polysulfides with thiols.     

Controlled Reduction of Carboxamides to Alcohols or Amines by Zinc Hydrides

New protocols for controlled reduction of carboxamides to either alcohols or amines were established using a combination of sodium hydride (NaH) and zinc halides (ZnX₂). Use of a different halide on ZnX₂ dictates the selectivity, wherein the NaH‐ZnI₂ system delivers alcohols and NaH‐ZnCl₂ gives amines. Extensive mechanistic studies by experimental and theoretical approaches imply that polymeric zinc hydride (ZnH₂)_∞ is responsible for alcohol formation, whereas dimeric zinc chloride hydride (H?Zn?Cl)₂ is the key species for the production of amines.     

Absorption and luminescence spectra and photodecomposition of zinc(II) complex with bis(1,2,3,7,9-pentamethyldipyrrin-8-yl)methane in solution and polymer matrix

New polymeric materials containing dinuclear double-stranded zinc(II) helicate with bis(1,2,3,7,9-pentamethyldipyrrin-8-yl)methane have been prepared on the basis of poly(methyl methacrylate) and tetraethoxysilane. The zinc(II) complex [Zn₂L₂] retains its fluorescence properties in a poly(methyl methacrylate) film. The photostability of [Zn₂L₂] in poly(methyl methacrylate) is higher by a factor of ≈2.5 than in the benzene solution. Conditions have been found for the preparation of [Zn₂L₂]-doped silicate matrix based on tetraethoxysilane via the sol–gel method. The [Zn₂L₂] complex in the tetraethoxysilane solid matrix shows a weak fluorescence with its maximum at λ = 545–549 nm.     

Sterically-Hindered Amines for Acid-Gas Absorption

Abstract

This paper reviews sterlcally-hindered amines for removal of add gases such as CO₂ and H₂S from gaseous streams. Steric hindrance of amines reduces carbamate stability. Moderately hindered amines are characterized by high rates of CO₂ absorption and high capacities for CO₂. The moderately hindered amine in use with organic solvent has considerably higher capacity than the conventional amine-solvent system for simultaneous removal of CO₂and H₂S from synthesis gas and natural gas. A severely-hindered-amine absorbent, characterized by a very low rate of CO₂absorption, has much higher capacity and selectivity than the current industry standard, methyldiethanolamine, for selective removal of H₂S from CO₂-containing streams. Use of hindered amines represents new advances in gas treating. Hindered amines save energy and capital in gas treating significantly. In addition, hindered amines used commercially have much better stability than conventional amines. As of today, fourteen commercial plants use hindered amines.     

Two self-assembled supramolecular solar cells sensitized via axial coordination with zinc porphyrin

In this work, two new self-assemblies based on zinc porphyrins substituted at the meso-positions with different donor units (denoted as ZnP1 and ZnP2) and anchor porphyrin (ZnPA) dyads formed by the coordination bonds of Zn-to-ligand have been prepared. Further, the assemblies were absorbed on semiconducting TiO₂ electrode surfaces by the carboxylic groups of anchor porphyrin (ZnPA), and their photovoltaic performances in solar cells were performed under 100 mW cm^?2 AM 1.5G sunlight. Photoelectrochemical studies reveal a significantly improved photovoltaic behavior for the dyad of triphenylamine-based zinc porphyrin (ZnP1) compared to the dyad with trimethylamine-based zinc porphyrin. The results were verified by electrochemical impedance spectroscopy, calculations, and optical performance. In addition, the modes of the assemblies immobilized on TiO₂ electrode surfaces were also verified by transmission electron microscopy.     

Extraction of Ce(III), Gd(III) and Yb(III) from Citrate Medium by High Molecular Weight Amines

Abstract

High molecular weight amines have been used for the extraction of citrate complexes of Ce(III), Gd(III) and Yb(III). The effect of different variables on extraction has been studied. The citrate species extracted in the organic phase have been proposed as [(RNH₃ ⁺)₃] [M(Cit)₂]^3-.     

Syntheses, structure and intercalation properties of low-dimensional phenylarsonates, A(HO3AsC6H5)(H2O3AsC6H5) (A = Tl, Na, K and Rb)

Four new low-dimensional phenylarsonates, A(HO₃AsC₆H₅)(H₂O₃AsC₆H₅) (A = Tl(1), Na(2), K(3) and Rb(4)), have been synthesized and characterized by X-ray diffraction, spectroscopic and thermal studies. They crystallize in triclinic unit cells and have approximately planar arrangement of A⁺ ions, coordinated to oxygen atoms of phenylarsonates, on both sides. Structure of thallium phenylarsonate as determined by single crystal X-ray diffraction, is one-dimensional, whereas those of alkalimetal analogues are two-dimensional. Successful intercalation reactions of compounds1 and2 with primaryn-alkyl amines have been demonstrated. Dedicated to Prof J Gopalakrishnan on his 62nd birthday.     

Viscosity of Aqueous Solutions of n-butylamine,sec-butylamine and tert-butylamine

Abstract

Viscosities of the systems, water (W) + n-butylamine (NBA), W + sec-butylamine (SBA) and W + tert-butylamine (TBA) have been measured in the temperature range 298.15–323.15K. The viscosities (η) and excess viscosities (η^E) have been plotted against mole fraction of amines (X ₂). On addition of amines to water, viscosities first increase rapidly, then pass through maxima at 0.2 mole fraction of amines and then decline continuously as the addition of amines is continued. η^E show large positive values, with maxima also at 0.2 mole fraction of amines. The maxima of the curves of η and η^E vs. mole fraction of butylamines follow the order, W + TBA > W + SBA > W + NBA. The ascending part of the η vs. X ₂ curves in the water-rich region is explained by the hydrophobic hydration caused by the hydrocarbon tails and the hydrophilic effect due to — NH₂ group of amines. Following the maxima, amine - amine association is preferred, which accounts for the steady decrease of viscosity up to the pure state of amines.     

Einige Neue N,S-Substituierte 2-Nitrodienverbindungen Aus Reaktionen Von Mono(p-fluorarylthio)substituierten Dienen Mit Aminen

2-Nitrodiene compound 1 was stirred with p-fluorothiophenol for a long time and compound 3 was obtained. Compound 1 gave bis(thio)substituted 2-nitrodiene compound 4 and tris(thio)substituted compound 5 with 2 moles of p-fluorothiophenol in the presence of NaOH in ethanol. The compounds 9a–g have been prepared from 8a–g and 3. Compound 7 was obtained from the reaction of mono(thio)substituted 2-nitrodiene with morpholine. Compound 3 gives 11a–d in the reaction with piperidines in CH₂Cl₂ (or ether). Compound 13a–b have been obtained from the reaction of compound 3 with primary amines 12a–b. Compound 3 gives 15 and 16 in the reaction with 2,5-dimethylpiperazine in CH₂Cl₂.

     

Multidentate bis(pyrazolylmethyl)pyridine ligands: coordination chemistry and binding properties with zinc(II) and cadmium(II) cations

The coordination chemistry and cationic binding properties of 2,6-bis(pyrazol-1-ylmethyl)pyridine (L1), 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L2), and 2,6-bis(3,5-ditertbutylpyrazol-1-ylmethyl)pyridine (L3) with zinc(II) and cadmium(II) have been investigated. Reactions of L2 with zinc(II) and cadmium(II) nitrate or chloride salts produced monometallic complexes [Zn(NO₃)₂(L2)] (1), [ZnCl₂(L2)] (2), [Cd(NO₃)₂(L2)] (3), and [CdCl₂(L2)] (4). Solid state structures of 1 and 3 confirmed that L2 binds in a tridentate mode. While the nitrates in the zinc complex (1) adopt monodentate binding fashion, in cadmium complex (3), they exhibit bidentate mode. L1–L3 show binding efficiencies of 99% for zinc(II), 60% for lead(II), and 30% for cadmium(II) cations from aqueous solutions of the metal ions. Theoretical studies using Density Functional Theory were consistent with the observed extraction results.     

Simple generation of neutral bimetallic aluminium and zinc alkyls Schiff bases bridged by a central resorcinol moiety

Aluminium and zinc complexes bearing the N,O-chelating Schiff base ligand 4,6-bis-1-(2-(dimethylamino)ethylimino)ethyl)benzene-1,3-diol, (C₆H₂(OH)₂(NCH₂CH₂NMe₂)₂) (1a), have been synthesized. Bimetallic aluminium and zinc alkyl complexes (2a–4a) were prepared by treatment of the hexadentate 1a with the appropriate amount of AlMe₃, ZnMe₂ and ZnEt₂, respectively. 2a has been characterized crystallographically, it lies on a crystallographic two-fold rotation axis and each aluminium centre adopts a five coordinate geometry. Complex 2a was tested as a catalyst in the ring-opening polymerisation of ɛ-caprolactone. We describe here the synthesis of two neutral ligands (1a and (C₆H₂(OH)₂(C₆H₅NH₂) (C=O(CH₃)) (1b)) and demonstrate their application in the synthesis of molecular aluminium and zinc derivatives.