Lewis acidity dependency of the electrochemical window of zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquids

Negative ion fast atom bombardment mass spectra (FAB-MS) recorded for ZnCl₂-1-ethyl-3-methylimidazolium chloride (ZnCl₂-EMIC) ionic liquids with various compositions indicate that various Lewis acidic chlorozincate clusters (ZnCl₃⁻, Zn₂Cl₅⁻ and Zn₃Cl₇⁻) are present in ZnCl₂-EMIC ionic liquids depending on the percentage of ZnCl₂ used in preparing the ionic liquids; higher ZnCl₂ percentage favors the larger clusters. Cyclic voltammetry reveals that the potential limits for a basic 1:3 ZnCl₂-EMIC melt correspond to the cathodic reduction of EMI⁺ and anodic oxidation of Cl⁻, giving an electrochemical window of approximately 3.0 V which is the same as that observed for basic AlCl₃-EMIC ionic liquids. For acidic ionic liquids that have a ZnCl₂/EMIC molar ratio higher than 0.5:1, the negative potential limit is due to the deposition of metallic zinc, and the positive potential limit is due to the oxidation of the chlorozincate complexes. All the acidic ionic liquids exhibit an electrochemical window of approximately 2 V, although the potential limits shifted in the positive direction with increasing ZnCl₂ mole ratio. Underpotential deposition of zinc was observed on Pt and Ni electrodes in the acidic ionic liquids. At proper temperatures and potentials, crystalline zinc electrodeposits were obtained from the acidic ionic liquids.     

Thallium complexes of meso-tetra-(p-chlorophenyl)porphyrin: trifluoroacetato-[meso-tetra(p-chlorophenyl)porphyrinato]thallium(III) and pentafluoropropionato-[meso-tetra(p-chlorophenyl)porphyrinato]thallium(III)

The crystal structures of trifluoroacetato-[meso-tetra(p-chlorophenyl)porphyrinato]thallium(III), Tl[(p-Cl)₄tpp](O₂CCF₃) (1), and pentafluoropropionato-[meso-tetra(p-chlorophenyl)porphyrinato]thallium(III) Tl[(p-Cl)₄tpp](O₂CCF₂CF₃) (2), were determined. The coordination sphere around the Tl³⁺ ion is described as five-coordinate regular square-based pyramid (RSBP) in which the apical site is occupied by an unidentate CF₃CO₂⁻ ligand for 1 whereas the unidentate CF₃CF₂CO₂⁻ ligand occupies the axial site for 2. The plane of the four pyrrole nitrogen atoms [i.e., N(1)–N(4)] strongly bonded to Tl³⁺ is adopted as a reference plane 4N. The Tl³⁺ is moderately out of the 4N plane; its displacement of 0.58 Å (or 0.59 Å) for 1 (or 2) is in the same direction as that of the trifluoroacetate oxygen for 1 (or pentafluoropropionate oxygen for 2). The free energy of activation at the coalescence temperature T_c for the intermolecular trifluoroacetate exchange for 1 in CD₂Cl₂ is found to be ΔG^≠₁₇₈=36.6 kJ/mol whereas the intermolecular pentafluoropropionate exchange for 2 in CD₂Cl₂ is determined to be ΔG^≠₂₁₃=41.5 kJ/mol through ¹⁹F and ¹³C NMR temperature-dependent measurements.     

Copper-selective chelating resins. I. Batch extractions

Eleven novel metal ion-chelating resins based upon porous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) have been prepared by direct reaction of the polymer with ligands containing an amino group. Those species involving a 2-pyridyl-2-imidazole and a 2-aminomethylpyridine proved to be the most interesting and, for comparison, polystyrene resin analogues of these were also produced. As expected from the literature, the above pyridine-containing ligands remained effective for the extraction of Cu²⁺ down to pH 2. Despite having superficially similar overall physical characteristics (particle size, surface area, porosity) the glycidyl methacrylate-based resins showed remarkably enhanced kinetic behaviour in the batch extraction of base metal ions such as Cu²⁺, with an extraction half life as low as ∼ 8 minutes, four times faster than a polystyrene-based analogue.In addition the glycidyl methacrylate-based resins displayed superior selectivity in the extraction of particular metal ions from feed liquors containing a mixture of metal ions. The most remarkable separation discovered was that of Cu²⁺ from Zn²⁺ where the glycidyl methacrylate-based species with the above ligands achieved essentially quantitative separation of Cu²⁺, even with Zn²⁺ present in 250 times excess. Extracted metal ions were rapidly and quantitatively eluted from these resins with 2 M H₂SO₄, and in the case of Cu²⁺ an acid strength of only 0.25 M was adequate.     

Studies on selective adsorption resins. XXI. Preparation and properties of macroreticular chelating ion exchange resins containing phosphoric acid groups

Macroreticular cation exchange resins containing phosphoric acid groups (RGP) were prepared by the reaction of glycidyl methacrylate–divinylbenzene copolymer [or poly(glycidyl methacrylate)]beads (RG) with phosphoric acid or phosphorous oxychloride, and the adsorption behavior of metal ions on the RGP was investigated. The phosphorylation of the polymer beads could be effectively carried out by treatment of the polymer beads with 85% phosphoric acid at 80°C for 3 h. The RGP obtained from glycidyl methacrylate–divinylbenzene (2 mol %) copolymer beads showed high cation exchange capacity, salt splitting capacity, and adsorption capacity for Cu²⁺, Zn²⁺, Cd²⁺, Ca²⁺, and Ag⁺. On the other hand, the RGP obtained from poly(glycidyl methacrylate)beads had high adsorption capacity for Al³⁺, Fe³⁺, and UO₂²⁺. The RGP prepared by treating the RG with phosphoric acid had a higher selective adsorption for Li⁺ than for Na⁺.     

Polymerization of styrene with a simple rare earth metal initiator

The catalytic activity in the polymerization of styrene has been examined using commercially available simple rare earth metal compounds such as Sm(OiPr)₃, Sm(acac)₃, Sm(OCOMe)₃, SmI₂(THF)₂ or SmCl₃ coupled with Et₃Al or methylaluminoxane (MAO). Among these compounds, the Sm(OiPr)₃/AlEt₃ system shows the highest catalytic activity, especially in the presence of a minor amount of toluene at 60 °C. The random copolymerization of styrene with methyl methacrylate suggests that the present polymerization proceeds with a radical polymerization mechanism. (C₅Me₅)SmCl₃Na(THF) and (C₅Me₅)SmCl₃Li(THF) systems exhibit relatively low catalytic activity, even in the presence of AlEt₃. © 2001 Society of Chemical Industry     

Effects of Lewis acid catalysts on the hydrogenation and cracking of three-ring aromatic and hydroaromatic structures related to coal

Little is known about the hydrogenation and cracking of fused aromatic nuclei during the liquefaction of coal under the influence of Lewis acid catalysts. This study was conducted to establish the effects of catalyst acidity on the activity and selectivity of Lewis acid catalysts, the sources of hydrogen involved in hydrogenation and cracking, and the relationships between reactant structure and reactivity. Three-ring aromatic and hydroaromatic compounds were used to simulate some of the structural units present in coal. The catalysts examined were ZnCl₂ and AlCl₃. It has been established that the rates of both processes are strongly influenced by the Brönsted acidity of the active catalyst, e.g. H⁺ (MX_nY)^?, and the Brönsted basicity of the aromatic portions of the reactant. The source of the hydrogen used for hydrogenation depends on the choice of catalyst. In the presence of AlCl₃, Scholl condensation of aromatic nuclei serves as the principal source of hydrogen. Molecular hydrogen is used exclusively, however, when hydrogenation is catalysed by ZnCl₂. The formation of reaction products and the trends in reactant reactivity are discussed on the basis of cationic mechanisms. The results of this study contribute to an understanding of the processes which occur during the liquefaction of coal using ZnCl₂ or AlCl₃.     

Crystallization behavior and melt structure of typical CaO–SiO2 and CaO–Al2O3-Based mold fluxes

Crystallization behavior and melt structure of two typical mold fluxes A (CaO–SiO₂-based) and B (CaO–Al₂O₃-based) for casting high-aluminum steel were investigated using double hot thermocouple technology (DHTT), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results suggest that the crystallization temperature of Flux B is higher, and its crystallization incubation time is shorter compared with Flux A. The precipitated phase in Flux A is CaSiO₃, whereas BaAl₂O₄ and Ca₂Al₂SiO₇ form in Flux B. The structure analyses suggest that the degree of polymerization of Flux A is larger than that of Flux B. In addition, the major structural units of Flux A are Si–O–Si, Q₀^Si, Q₁^Si, Q₂^Si and Q₃^Si, but those of Flux B are mainly aluminate (Al–O–Al, Al–O^-), aluminosilicate (Al–O–Si) and silicate units (Q₀^Si, Q₁^Si, Q₂^Si and Q₃^Si). These different melt structures are the main reasons why the precipitated phases in these two mold fluxes are different, and the crystallization ability of Flux A is weaker than Flux B.     

Selective esterification of tert-butanol by acetic acid anhydride over clay supported InCl3, GaCl3, FeCl3 and InCl2 catalysts

Clay (kaolin, mont-K10 and mont-KSF) supported InCl₃, GaCl₃, FeCl₃ and ZnCl₂ catalysts (metal chloride loading=1.1 mmol g⁻¹) show high selectivity (⩾98%) at high conversion in the esterification of tert-butanol by acetic anhydride to tert-butyl acetate (t-BA) and very low activity for the dehydration of tert-butanol at ⩽50°C. For all the catalysts, mont-K10 is the best support and the order of their esterification activity (at 26°C) is: InCl₃/mont-K10 (TOF=0.025 s⁻¹) > GaCl₃/mont-K10 (0.023 s⁻¹) > FeCl₃/mont-K10 (0.02 s⁻¹) ⩾ ZnCl₂/mont-K10 (0.019 s⁻¹). InCl₃/mont-K10 is highly active, selective and reusable catalyst for the esterification.     

Redox processes as a route for the formation of an unusual structure of the Co(II)/Zn(II) complex isolated from the system: [Co(0)/Zn(II)-1-hydroxymethyl-3,5-dimethylpyrazole]

The in situ preparation of the unique complex [CoClL¹][ZnI₃L²] (1) (L¹ = tris(1-(3,5-dimethylpyrazolyl)-methyl)amine, L² = hexamethylenetetramine) via redox and condensation processes of zerovalent cobalt, ZnCl₂ and 1-hydroxymethyl-3,5-dimethylpirazole has been reported. The crystal structure of 1, determined by single-crystal X-ray diffraction exhibited a distorted trigonal bipyramidal coordination sphere for [CoCl(L¹)]⁺ ion and a distorted tetrahedral arrangement of the [ZnI₃(L²)]^? anion, both of the C₁ point group symmetry. The structure of 1 was confirmed by IR, FTIR, UV–Vis, magnetic and thermal investigations.     

Studies on the kinetics and mechanism of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride

Radical copolymerization of acrylonitrile (AN) with styrene (Sty), using x,x′-azobisisobutyronitrile as initiator, was carried out in the presence of zinc chloride (ZnCl₂) dilatometrically at 65/pm 0.1 C for 120min. The rate of polymerization was a direct function of the concentrations of ZnCl₂, AN and Sty, and polymerization temperature. The viscosity-average molecular weight of the copolymer increased with ZnCl₂ concentration. The energy of activation in the presence and absence of the complex was evaluated as 82.5 kJ mol^?1 and 115.5 kJ mol^?1, respectively. The copolymerization of AN with Sty proceeded via the radical-complex mechanism.     

Ionic liquid crystals from β-diketonyl containing pyridinium cations and tetrachlorozincate anions

In this work, an approach towards ionic liquid crystals is strategically designed. A pyridine group has been attached to an 1,3-diketone containing an alkyloxyphenyl R substituent (R = C₆H₄OC_nH_2n+1; n = 10–18) and protonated with hydrochloric acid towards the formation of the chloride salts of 2-[3-(4-n-alkyloxyphenyl)propane-1,3-dion-1-yl]pyridinium cations [OO^R(n)py]Cl (I), which have been proved to be non-mesomorphic. Reaction of these organic–inorganic compounds (I) with ZnCl₂ yields to the ionic liquid crystals of the type bis{2-[3-(4-n-alkyloxyphenyl)propane-1,3-dion-1-yl]pyridinium}tetrachlorozincate [OO^R(n)py]₂[ZnCl₄] (II).The crystalline structure of compounds [OO^R(12)py]Cl and [OO^R(10)py]₂[ZnCl₄] as representative examples of both kinds of salts have been solved and discussed. Both compounds exhibit layered structures containing cationic and anionic sublayers. In addition for the tetrachlorozincate salt [OO^R(16)py]₂[ZnCl₄] structural relationships between the mesophases and the crystalline phase are proposed on the basis of the variable-temperature small-angle X-ray diffraction studies.     

Six- and four-coordinated zinc(II) complexes exhibit strong blue fluorescent properties

A new ligand, 4-(p-chlorophenyl)-1,2,4-triazole (^pCltrz), and its complexes, [Zn(^pCltrz)₆]₂(ClO₄)₂ · H₂O (1) and [Zn(^pCltrz)₂Cl₂] (2), were synthesized. The structure of 1 exhibits the first case that zinc(II) ion coordinated with six triazole ligands to form octahedral environment. Both 1 and 2 display very strong blue photoluminescence as the result of the fluorescence from the intraligand emission excited state.     

Effectiveness of both ZnCl2- and SnCl2-containing molten salt catalysts for hydrogenation of Big Ben coal in the absence of a solvent

Hydrogenation of Big Ben coal (Australian bituminous coal) with 9.8 MPa H₂ for 3h at 400 °C has been carried out using a batch autoclave system in the presence of a molten salt catalyst such as ZnCl₂, SnCl₂, ZnCl₂-KCl-NaCl (3:1:1 mol ratio) and SnCl₂-KCl (3:2). The hexane-soluble (HS) yield decreases in the order: SnCl₂-KCl, SnCl₂, ZnCl₂-KCl-NaCl, ZnCl₂. The use of SnCl₂-containing melt is characterized by higher yields of both HS and benzene-soluble (BS) fractions and the suppression of gas yield compared with the use of ZnCl₂. The average aromatic unit and the molecular weight of HS increase in the order: ZnCl₂, ZnCl₂-KCl-NaCl, SnCl₂, SnCl₂-KCl. Chromatographic separation of HS fractions indicates that the saturate content is lowest and polar-material content is highest with the SnCl₂-KCl melt: this fact coupled with the structural parameters suggests that HS material with SnCl₂-KCl melt has, on average, a reasonably-high-molecular-weight skeleton which has more alkyl chains and heteroatoms. Micrographs of resulting benzene-insoluble (Bl) materials clearly indicated that the Bl particles were larger when ZnCl₂ was used than when the other melts were used, the Bl particles in these cases being of similar size. Lewis acidity and the viscosity of the molten salt appear to be related, in part, to the size of the Bl particles.     

Treating contaminated soil by conversion into carbonaceous adsorbents: an investigation of activation procedures

The well established activated carbon manufacturing process has been investigated as a novel treatment for contaminated soil from gaswork sites by converting it into a porous carbonaceous solid with adsorbent properties. Several activation methodologies were evaluated: CO₂, air, ZnCl₂, H₂SO₄, H₃PO₄, FeSO₄ and HNO₃. Thermal analysis of the soil provided information regarding appropriate carbonisation and activation conditions. Bulk samples were prepared using contaminated soil samples, with ZnCl₂ being found to be the most effective agent for the process, producing an adsorbent which possessed a BET surface area of 131m²g⁻¹. The aqueous adsorption ability of the soil carbons was studied using phenol and 4‐nitrophenol as representative micropollutant organic molecules. The Langmuir monolayer capacity of the ZnCl₂‐activated soil was found to be 0.12 mmg⁻¹ for phenol and 0.23 mmg⁻¹ for 4‐nitrophenol. © 2000 Society of Chemical Industry     

Synthesis of Diphenyl Carbonate from Phenol and Carbon Dioxide in the Presence of Carbon Tetrachloride and Zinc Chloride

Diphenyl carbonate (DPC) was synthesized from phenol and dense phase CO₂ in the presence of CCl₄ and K₂CO₃ using different catalysts of ZnCl₂, ZnBr₂, Lewis acid ionic liquids including 1-butyl-3-methylimidazolium chloride (BMIMCl) and bromide (BMIMBr). It was found that K₂CO₃ was not required, ZnCl₂ and ZnBr₂ were similar in the catalytic performance, and the use of BMIMCl and BMIMBr was not effective for the production of DPC. For the reactions with ZnCl₂ in CCl₄, the effects of such reaction variables as temperature, CO₂ pressure, the amount of ZnCl₂, and the volume of CCl₄ were studied in detail. It was shown that the pressure was less influential while a larger amount of ZnCl₂, a smaller volume of CCl₄, and a low temperature of around 100°C were beneficial for the synthesis of DPC. On the basis of the results obtained, possible reaction mechanisms were discussed.     

Linear low‐density polyethylene‐g‐poly(acrylic acid)/(organo‐montmorillonite) hydrogel composite as hydrogel electrolytes for zinc–carbon batteries

A hydrogel composite that has been prepared by using waste linear low‐density polyethylene, acrylic acid, and organo‐montmorillonite (LLDPE‐g‐PAA/OMMT) is used as a hydrogel electrolyte. An absorbency test was used to determine the percentage of ZnCl₂ solution absorbed by the hydrogel composite. The swelling behavior of the hydrogel composite in the ZnCl₂ solution was then studied. The highest absorbency was recorded when the concentration of ZnCl₂ solution was 3 M. The conductivity of ZnCl₂‐hydrogel composite electrolytes is dependent on the solution's concentration. A mixture of ZnCl₂ solution with hydrogel composite yields a good hydrogel composite electrolyte with a conductivity of 0.039 S cm^?1 at 3 M ZnCl₂. The hydrogel composite electrolyte was used to produce zinc‐carbon cells. The fabricated cell gives capacity of 7.8 mAh, has an internal resistance of 9.9 Ω, a maximum power density of 15.78 mWcm^?2, and a short‐circuit current density of 43.75 mAcm^?2 for ZnCl₂‐hydrogel composite electrolytes. J. VINYL ADDIT. TECHNOL., 22:279–284, 2016. © 2014 Society of Plastics Engineers     

Polymerization of 1-butyne and isopropylacetylene by transition metal catalysts and geometric structure of polymers

Polymerization of 1-butyne and isopropylacetylene was studied using MoCl₅, WCl₆, and two Ziegler catalysts [Fe(acac)₃-Et₃Al, Ti(On-Bu)₄-Et₃Al]. 1-Butyne was polymerized in high yields with WCl₆ and Fe(acac)₃-Et₃Al to give a yellow, air-sensitive polymer. The cis content of poly(1-butyne), evaluated by ¹³C n.m.r., was about 80% irrespective of polymerization conditions. Isopropylacetylene was polymerized well by any of MoCl₅, WCl₆, and Fe(acac)₃-Et₃Al; the polymer formed was a light yellow air-sensitive powder. The cis content of poly(isopropylacetylene) varied from 65% to 90% according to polymerization conditions. Substituent effects on polymerization and polymer structure are discussed.     

With different structure ligands heterogeneous Ziegler-Natta catalysts for the preparation of copolymer of ethylene and 1-octene with high comonomer incorporation

Comparison with the conventional Ziegler-Natta catalyst TiCl₄/MgCl₂ (I), the modified supported Ziegler-Natta catalysts (iso-PentylO)TiCl₃/MgCl₂ (II) and (BzO)TiCl₃/MgCl₂ (III) were prepared as efficient catalysts for copolymerization of ethylene with 1-octene. The complexes (II) and (III) were desirable for the production of random ethylene/1-octene copolymers coupled with higher molecular weight, higher comonomer incorporation within copolymer chain and good yield even at high temperature 80 ^°C and fairly low Al/Ti molar ratio of 100. The effects of catalysts ligands, Al/Ti molar ratio, polymerization temperature, as well as concentration of 1-octene on the catalytic activity, molecular weight and microstructure of the copolymer were investigated in detail. The structure and properties of the copolymers were characterized with ¹³C NMR, GPC, DSC and WAXD. The kinetic results also indicate that these catalysts (II) and (III) show higher catalytic activity and the produced polymers feature higher molecular weight, because of lower ratio of K_trm/K_p and K_tra/K_p, and higher ratio of K_tra/K_trm which indicates that chain transfer to cocatalyst is predominant.     

emf Studies of zinc halides ln concentrated aqueous NH4NO3CA(NO3)2 solutions

The formation constants of the species ZnC⁺, ZnCl₂, ZnBr⁺ and ZnBr₂ were determined from emf measurements in suitable concentration cells. Mixtures of NH₄NO₃Ca(NO₃)₂ with a molar ratio 0.844/0.156 containing variable amounts of water (from 0 to 1.2 moles per mol of salt) were used as a solvent. The bromide complexes were found to be more stable than the chloride complexes in the anhydrous melt, while the opposite was found in the concentrated aqueous solutions. The results are discussed on the basis of models for chemical equilibria in molten salts and aqueous melts.     

Role of amino acids and micronutrients on biosynthesis of spiramycins

The production of spiramycin using a synthetic basal medium, to which amino acids, vitamins and metallic ions were added, was investigated. L -Tryptophan was found to be the amino acid which best increased the antibiotic yield. Addition of vitamins to the fermentation medium did not increase the antibiotic output, while the addition of different concentrations of trace elements such as Co(NO₃)₂ ZnCl₂ (NH₄)₂Mo₇O₂₄ and MnCl₂ improved the antibiotic yield. High concentrations of these trace elements decreased the antibiotic yield and directed the microbial activities towards biosynthesis of spiramycin II and III—these are less toxic than spiramycin I. Optimum concentrations of Co(NO₃)₂, ZnCl₂, (NH₄)₂Mo₂₄O₇, MnCl₂ which supported the antibiotic yield were 5 × 10^?1, 5 × 10^?3, 5 × 10^?3 and 5 × 10^?3 g dm^?3, respectively.