Sorption Studies in DMSO-NITRIC Acid and DMSO-Acetic Acid Systems and Separation of Metal Ions on TIN(IV)-Iodophosphate

Abstract

Some new samples of tin(IV)-iodophosphate have been synthesized and their ion exchange properties have been studied. Adsorption behaviour of different metal ions on tin(IV)-iodophosphate (TIP₅), in H⁺ form, in different solvent systems have been examined. Kd values of few metal ions, in 4M DMSO medium, have also been determined on the same ion-exchanger in NH⁺ ₄ form. Effect of particle size of tin(IV)-iodophosphate (TIP₅), in H⁺ form, on the Kd values of metal ions has been studied. Separations of a number of metal ions have been achieved on tin(IV)-iodophosphate (TIP₅) columns.     

Chromatography of Some Metal Ions on Silica Gel Thin Layers in Butanol-Formic Acid Media

Abstract

Chromato graphic behaviour of some metal ions on silica gel thin layers has been studied in butanol—formic acid media. The results have been compared with those obtained in aqueous formic acid medium. Many important and analytically difficult separations have been achieved. Some thin layer chromato graphic parameters for the separation of Vo²⁺ from numerous metal ions using 20.0 M formic acid in butanol have been determined.     

Extraction of Lanthanide Nitrates in Multicomponent Aqueous-Organic Two-Phase Systems with D2EHPA

Lanthanum nitrate distribution in three-component aqueous-organic systems with D2EHPA from acetate or acetic acid–acetate solutions has been studied, it has been shown that variation in sodium acetate concentration or composition of CH₃COONa–CH₃COOH mixture can affect metal distribution ratios. It has been found that extraction in three-component mixture of 1: 1: 1 composition (aqueous solution Ln(NO₃)₃ + CH₃COONa + CH₃COOH–D2EHPA in hexane–isopropyl alcohol) can provide lanthanide separation, which is dependent on the ratio of sodium acetate and acetic acid in aqueous phase and on D2EHPA concentration in organic phase. Lanthanide–lanthanum separation factors have been calculated for the extraction of lanthanide nitrates from acetic acid–acetate solutions.     

微波辅助合成双1,2,4-三嗪化合物及其荧光特性研究

以联苯甲酰、二甲酰肼为原料, 采用微波技术合成了5个双1,2,4-三嗪化合物3, 产率72%～85%, 利用元素分析、MS, IR, ¹H NMR和荧光光谱对其结构进行了表征, 并研究了金属离子对化合物3a的荧光性质的影响. 结果表明, 微波合成具有缩短反应时间、提高产率的优点; Cu^2＋, Ni^2＋等金属离子对化合物3a产生明显的荧光猝灭作用.     

Complexing Properties of Phenolic Diazacrown Ethers with Transition and Heavy Metal Ions

The complexation equilibria of the phenolic diazacrown ether derivatives L1–L11 with transition and heavy metal ions (Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Pb²⁺) have been studied in methanol using UV absorption spectrophotometry. A majority of the systems studied formed only ML complexes. Using a ligand with a different position of the substituents on the phenolic side arms (denoted L7) leads to ML₂ formation with most of the metal ions. Every ligand forms very strong ML and ML₂ complexes with Pb²⁺, and, in nearly all cases, only a lower limit could be derived for the stability constant. The stability of the complexes generally increases as the length of the para-substituents on the phenol groups increases. Among the metal ions tested, Zn²⁺ and Hg²⁺ are the least preferred by alkyl and alkoxy derivatives, respectively.     

Interaction between ozone and the chloride ion in sulfuric acid solutions up to 6-M concentration

The effect of sulfuric acid concentration on Cl₂ evolution in the reaction between O₃ and Cl^? has been investigated. The catalytic effects of metal ions in this reaction have been studied as a function of solution acidity. The chlorine evolution rate increases markedly with increasing acid concentration. At acid concentrations below 4 mol/l, the most effective catalyst is Co²⁺. The catalytic activities of Fe³⁺ and Cu²⁺ peak at $C_{H_2 SO_4 } $ = 4.8 mol/l. In passing to highly acidic solutions ( $C_{H_2 SO_4 } $ > 5 mol/l), the catalytic activity of the metal ions decreases, but the chlorine evolution rate remains high owing to the high acidity. Kinetics of VO²⁺ oxidation with ozone in acid media have been studied, and the ozone solubility in aqueous sulfuric acid has been measured.     

Kinetics and mechanism of oxidation of anisole and substituted anisoles by acid bromate in acetic acid-water mixture

Oxidation of anisoles by acid bromate has been studied in acetic acid-water system in the presence of sulphuric acid. The reaction is first order each in [anisole] and [Br(V)]. The rate of reaction increased with increase in [H⁺] and percentage of acetic acid. The products of oxidation have been identified as ortho and para hydroxyanisoles. From the effect of [H⁺] and [acetic acid] on rate, H ₂ ⁺ BrO₃ has been established as the reactive species. Anisoles having electron-donating substituents in the benzene ring accelerate the rates and vice versa with a Hammett ρ value of −0.6. A mechanism involving the attack of H ₂ ⁺ BrO₃ on ortho/para position of the anisole in the rate-determining step has been proposed.     

Copper and Nickel Removal from Aqueous Solutions Using New Chelating Poly[Acrylamide/N‐vinyl pyrrolidone/3‐(2‐hydroxyethyl carbamoyl)acrylic acid] Hydrogels

New poly[Acrylamide/N‐vinyl pyrrolidone/3‐(2‐hydroxyethyl carbamoyl)acrylic acid], poly [AAm/NVP/HECA], chelating hydrogels with different composition of HECA monomer have been prepared via free radical solution polymerization using N,N‐methylene bisacrylamide as a crosslinker. The hydrogels obtained were loaded with metal ions and characterized by FT‐IR spectroscopy, Scanning Electron Microscope (SEM) and Thermogravimatric analysis (TGA). The removal of Cu²⁺ and Ni²⁺ from aqueous solutions by the hydrogel was examined by a batch equilibrium method. The influence of treatment time, pH, initial concentration of the metal ions and HECA content in the feed compositions on the amount of adsorbed metal ions was studied. Swelling of the hydrogel was also carried out in distilled water and metal ion solutions. The removal of the metal ions followed the following order: Ni²⁺>Cu²⁺. The amount of metal ions removed increased with increasing HECA content in the feed composition, treatment time, pH of the medium and initial concentration of metal ions. The desorption of metal ions were carried out using 1 N HCl and 0.5 N H₂SO₄. The poly[AAm/NVP/HECA] hydrogels could be used many times without significantly decreasing their adsorption capacity.     

Sorption and desorption of UO2 2+, Th4+ and Ru3+ on the synthetic analogue of muscovite</p> </p>

Summary Sorption and desorption of UO₂²⁺, Th⁴⁺ and Ru³⁺ on the synthetic analogue of the mica mineral muscovite has been studied by a batch technique. The synthesized gel was characterized by XRD, EDXRFS, FTIR, TGA and SEM and was found to have a composition K_1.4Al_4.2(Si₆Al₂O₂₀)(OH)₄ ^. 2H₂O. Different parameters like acid concentration, contact time, amount of gel, composition of gel: OPC admixture, effect of temperature, desorption of metal ions from loaded muscovite and effect on crystal morphology due to loading of metal ions were studied. The results has been expressed in terms of distribution coefficient (K_d).</p> </p>     

A Convenient,Highly Efficient One-Pot Preparation of Peracetylated Glycals From Reducing Sugars

ABSTRACT

A convenient, highly efficient, one-pot, three-step procedure has been developed for the synthesis of peracetylated glycal derivatives from various reducing sugars including D-glucose, D-galactose, L-rhamnose, L-arabinose, D-maltose, D-lactose, and maltotriose. This procedure involves peracetylation of the reducing sugars with acetic anhydride and HBr/acetic acid followed by the transformation of the anomeric acetates to the corresponding bromides with additional HBr/acetic acid and finally reductive elimination of the 1-bromo and 2-acetoxy groups with Zn/CuSO₄·5H₂O in acetic acid/water containing sodium acetate. The overall yields of purified peracetylated glycals from the corresponding sugars range from 50 - 98%.

     

Metal Complexes of Saccharin with the N-(2-hydroxyethyl)-ethylenediamine Ligand: Synthesis,Characterization and Spectroscopic Examination. Crystal Structures of trans- Bis(Saccharinato)Bis{N-(2-hydroxyethyl)-Ethylenediamine} copper(II) and Cadmium(II)

The novel transition metal saccharinato complexes of N-(2-hydroxyethyl)-ethylendiamine (HydEt-en) have been synthesized and characterized by elemental analyses, magnetic moments, UV-Vis and IR spectra. Coordination behaviour of HydEt-en has been studied. The Mn(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) form mononuclear complexes, while the Fe(II) and Co(II) complexes are dimeric. The crystal structures of the [Cu(sac)₂(HydEt-en)₂] and [Cd(sac)₂(HydEt-en)₂] complexes, where sac is the deprotonated form of saccharin, were determined by x-ray diffraction. The metal ions are octahedrally coordinated by these ligands. The amine ligand acts as a bidentate N-donor ligand and its ethanol group is not involved in coordination. The sac ions coordinate through the deprotonated N as a monodentate ligand. The NH and OH groups of the amine ligand are involved in intra- and intermolecular hydrogen bonding with the carbonyl and sulphonyl oxygens of the sac ions to form a three-dimensional infinite network.     

Kinetics and mechanism of oxidation of sugars by quinquevalent vanadium in binary mixture solvents of DMSO–water and acetic acid–water in H2SO4 medium

The kinetics of oxidation of aldosugars and ketosugar by quinquevalent vanadium in binary mixtures of DMSO–water and acetic acid–water in sulfuric acid medium have been studied. The reaction is first order in both oxidant and substrate. The effect of acidity on the reaction kinetics has been determined. The effect of acidity shows a clear difference. The ketose has a unit dependence, whereas aldoses have a 0.5 dependence in H₀. The role of solvent in these reactions has also been studied, and the effect of temperature on these reactions has been determined. A suitable mechanism has been postulated taking all the observed facts into consideration.     

Extraction of sulfuric acid with TOPO

A study on solvent extraction of sulfuric acid by tri-octylphosphine oxide (TOPO) in n-heptane has been made. Extraction coefficients of H₂SO₄ as a function of H₂SO₄ concentration in aqueous phase, and extractant concentrations in organic phase have been studied. The composition of extracted species, equilibrium constants of extraction reaction have been evaluated. These results are important for interpreting extraction equilibrium data of uranium(VI) or other metal ions with TOPO in sulfuric acid media.     

Paper Chromatographic Separations of Metal Ions on Collidinium Tungstoarsenate Papers

Abstract

A systematic study of the chromatography of metal ions on collidinium tungstoarsenate papers has been performed using seven different mixed solvent systems. R_f values of 30 metal ions have been determined by ascending technique and are discussed. The study demonstrates that specific extraction of both Sn(ii) and Sn(iv) is possible in 0.1 mol dm^?3 HNO₃ in 80% (v/v) 1-propanol and their mutual separation can be carried out in solvent system 1 mol dm^?3 HCl in 33% (v/v) 1-propanol. In addition some binary and ternary separation of metal ions have also been achieved on these papers. For a comparison R_f values on plain papers have also been determined in all the solvent systems.     

Phosphinate Analogues of Ida and Nta with Low Basicity of Nitrogen Atom: Acid-Base and Complexation Properties

Abstract

Analogues of iminodiacetic acid (H₂IDA) and nitrilotriacetic acid (H₃NTA) bearing two (hydroxomethyl)methylphosphinate or (2-carboxyethyl)methylphosphinate groups were synthesized. Their acid-base and coordination properties with divalent metal ions (Cu²⁺, Ni²⁺ and Zn²⁺) were studied by potentiometry. The compounds exhibit very low basicity of the amino groups (pK_a = 6.2–7.6) due to presence of two electron-withdrawing methylphosphinate groups and, consequently, a low stability of the complexes. In the case of IDA-analogues, the low complex stability results in precipitation of metal hydroxides in neutral region. As expected, NTA-analogues form more stable complexes and, thus, they were also studied in the alkaline region. Presence of additional carboxylate in the 2-carboxyethylphosphinic acid groups results in the formation of dinuclear complexes. Solid-state structures of two compounds were determined by X-ray diffraction analysis. The compounds are protonated on the nitrogen atom and the structures are stabilized by rich hydrogen bond network.     

A porous zinc(II) metal–organic framework exhibiting high sensing ability for ferric and nitroaromatics as well as photocatalytic degradation activities against organic dyes

A NbO-type Zn(II) metal–organic framework of {[Zn₂(HL)(H₂O)₂]?H₂O}_n (1) has been developed using a pentacarboxylate 2,5-bis(3′,5′-dicarboxylphenyl)-benzoic acid (H₅L) ligand and characterized. The single-crystal X-ray diffraction studies indicate that 1 comprises free –COOH groups and Zn(II) centers bridged by four carboxylate groups to form a paddle wheel SBU which is further connected by L^5? ligands to build a 3-D porous network with two types of cages. The chemically stable MOF 1 behaves as a highly selective and sensitive fluorescent chemosensor for the detection of Fe³⁺ ions, 2,4,6-trinitrophenol (TNP), which is known to be an extremely hazardous and strong explosive. Furthermore, the photocatalytic properties of 1 for degradation of methyl violet (MV) and Rhodamine B (RhB) have been explored. The possible emission quenching mechanism in the presence of nitro-aromatics (NACs) has been addressed by theoretical calculations and photocatalytic activity of 1 against organic dyes has been supported using density of states (DOS) calculations.     

Two novel trinuclear cluster-based coordination polymers with 2,6-Di-imidazol-1-yl-pyridine: solvothermal syntheses,crystal structures,properties and Hirshfeld surface analysis

Two novel trinuclear cluster-based coordination polymers {[M₃(dip)(AcO)₆]·(X)}_n (1, M = Cu, X = CH₃OH; 2, M = Co, X = 2H₂O) (dip is 2,6-Di-imidazol-1-yl-pyridine), have been synthesised and structurally determined by single crystal X-ray diffraction, element analysis. Crystallographic unit of 1 consists of three Cu(II), six acetic ions, one dip ligand and one methanol molecule, which formed 1D chain through acetic bridges. The 1D chain further constructed 2-D network through dip ligand bridge which formed 3-D network through π···π interaction. Crystallographic unit of 2 consists of three Co(II), six acetic ions, one dip ligand and two water molecules. The trinuclear unit further formed a dimmer through dip ligand bridge which constructed 1-D through dip ligand bridge. The 1D chain further constructed 2-D network through π···π interaction. IR and UV–vis spectrum properties of 1 and 2 were studied. In addition, Hirshfeld surface analysis was also studied for 1.     

A kinetic study of the oxidation of hydroxamic acids by compounds I and II of horseradish peroxidase: Effect of transition metal ions

Abstract

Oxidation of hydroxamic acids (HXs) generates HNO, and it is not clear whether it is formed also in the presence of metal ions. The kinetics of the oxidation of HXs, such as acetohydroxamic acid, suberohydroxamic acid, and suberoylanilide hydroxamic acid (SAHA), by compounds I and II of horseradish peroxidase (HRP) at pH 7.0 and 25?°C have been studied using rapid-mixing stopped-flow. The kinetics of these reactions were compared to those observed in the presence of Cu(ClO₄)₂, NiSO₄, or ZnSO₄. The rates decrease upon increasing [Cu^II] at constant [HXs], and no oxidation of HX occurs when [HX]/[Cu^II] ≈ 2, implying that HX oxidation in the presence of Cu^II proceeds through the free ligand since the predominant complex is CuX₂. In the case of Ni^II, the oxidation rate decreases upon increasing the ratio [Ni^II]/[HX] beyond 1, where the predominant complex is Ni^IIX⁺, implying that its oxidation is feasible. The effect of Zn^II could be studied only on the rate of HXs oxidation by compound II demonstrating similar behavior to that of Ni^II. HXs were also oxidized catalytically by HRP/H₂O₂ at pH 7.0, demonstrating that metal ions facilitate the formation of HNO while hardly affecting its yield and the extent of HX oxidation.     

Chromatographic behaviour of metal ions on tin(IV) and titanium(IV) antimonate papers

Summary The chromatographic behaviour of 49 metal ions has been studied on papers impregnated with Sn(IV) and Ti(IV) antimonates in aqueous HNO₃ and mixed solvent systems containing dimethyl sulphoxide. Numerous separations have been achieved and the Alberti equation, for Sn(IV) and Ti(IV) antimonate papers, in the modified form: –nloga K⁺=R_M + constant (a K⁺=activity of K⁺), has been verified. The effect of the concentration of impregnating reagents on these papers has been determined and compared with other papers. The effect of pH on R_f, R_i, log R_f and R_M values of metal ions has also been examined in aqueous systems.     

基于紫精组分构筑的三种光致变色共晶体

在碱性条件下,将1,2,4,5-均苯四甲酸(H4BTEC)与过渡金属离子配位,并引入中性紫精组分1-羧乙基-4,4′-联吡啶(CEbpy),构筑了3个同构共晶体[M(H₂O)_5(BTEC)_0.5]·(CEbpy)(M=Mn(1)、Zn(2)、Co(3))。在紫外灯照射下,3个化合物都发生明显的光致变色现象,这归因于光诱导的电子转移并产生了紫精自由基。同时,在加热的情况下,化合物3还表现出不可逆的失水致变色行为,而化合物1和2则没有。我们讨论了金属离子对变色行为的影响。