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Zinc Chloride (zinc + chloride)
Selected AbstractsChemInform Abstract: p-Toluenesulfonic Acid Mediated Zinc Chloride: Highly Effective for the Beckmann Rearrangement.CHEMINFORM, Issue 2 2008Lin-fei Xiao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Alkyl Zinc Chlorides as New Initiators for the Polymerization and Copolymerization of IsobuteneMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2008Antonio Guerrero Abstract Mixtures of RZnCl and tBuCl (R,=,Et) initiate the polymerization of isobutene in the temperature range of (,35),(+35),°C. The order of addition of the reagents is important for effective polymerization. Increasing the solubility of the zinc reagent (R,=,n -octyl) and use of cumyl chloride as co-initiator provides a system that is active from (,90),(+35),°C. The molecular weights show a remarkably small temperature dependence, EDP,=,,3.3 kJ,·,mol,1, compared to EDP,=,,23 kJ,·,mol,1 in classical systems (AlCl3, EtAlCl2). The molecular weights increase with decrease in zinc concentration and are consistently higher for n -octyl zinc chloride, as expected for a bulkier, less coordinating counteranion. The polymerizations are not retarded by isoprene addition; homopolymers and copolymers show essentially identical conversions and molecular weights. [source] Low temperature hydrothermal growth and optical properties of ZnO nanorodsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2009J. H. Yang Abstract Well-faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90°C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride (ZnCl2, Aldrich, purity 98%) and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well-faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as-prepared ZnO was the single-phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface-related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis of Thio- and Selenoglycosides by Cleavage of Dichalconides in the Presence of Zinc/Zinc Chloride and Reaction with Glycosyl Bromides.CHEMINFORM, Issue 18 2006Chinmoy Mukherjee Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Crystal growth, crystal structure and physical properties of polar orthorhombic tris(glycine) zinc chlorideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2008M. Fleck Abstract Large single crystals of the polar (point group mm 2) compound tris(glycine) zinc chloride, (NH3CH2COO)3 · ZnCl2, were grown from aqueous solutions. The refractive indices were measured in the wavelength region from 365 nm to 1083 nm and an unpolarised absorption spectrum was recorded (transparency range from 260 to 1550nm). The phase matching conditions for second harmonic generation were analysed: both, type I (ss-f) and type II (sf-f) are possible in the red and near IR region. All five components of the piezoelectric tensor [dijk ] were determined; the maximum values of longitudinal and transverse piezoelectric effects are less than one half of d111 of ,-quartz. In addition, a redetermination of the crystal structure (including location of H atoms) is presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Toxicity of manufactured zinc oxide nanoparticles in the nematode Caenorhabditis elegansENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2009Hongbo Ma Abstract Information describing the possible impacts of manufactured nanoparticles on human health and ecological receptors is limited. The objective of the present study was to evaluate the potential toxicological effects of manufactured zinc oxide nanoparticles (ZnO-NPs; 1.5 nm) compared to aqueous zinc chloride (ZnCl2) in the free-living nematode Caenorhabditis elegans. Toxicity of both types of Zn was investigated using the ecologically relevant endpoints of lethality, behavior, reproduction, and transgene expression in a mtl-2::GFP (gene encoding green fluorescence protein fused onto the metallothionein-2 gene promoter) transgenic strain of C. elegans. Zinc oxide nanoparticles showed no significant difference from ZnCl2 regarding either lethality or reproduction in C. elegans, as indicated by their median lethal concentrations (LC50s; p = 0.29, n = 3) and median effective concentrations (EC50s; Z = 0.835, p = 0.797). Also, no significant difference was found in EC50s for behavioral change between ZnO-NPs (635 mg Zn/L; 95% confidence interval [CI], 477,844 mg Zn/L) and ZnCl2 (546 mg Zn/L; 95% CI, 447,666 mg Zn/L) (Z = 0.907, p = 0.834). Zinc oxide nanoparticles induced transgene expression in the mtl-2::GFP transgenic C. elegans in a manner similar to that of ZnCl2, suggesting that intracellular biotransformation of the nanoparticles might have occurred or the nanoparticles have dissolved to Zn2+ to enact toxicity. These findings demonstrate that manufactured ZnO-NPs have toxicity to the nematode C. elegans similar to that of aqueous ZnCl2. [source] X-Ray absorption fine structure analysis of the local environment of zinc in dentine treated with zinc compoundsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2005Tsutomu Takatsuka It has been reported that zinc oxide (ZnO) inhibits dentine demineralization. By using the X-ray absorption fine structure (XAFS) technique, our aims in this study were to provide information about the local environment of zinc atoms in dentine that had been treated with zinc compounds. We measured the Zn K-edge X-ray absorption near-edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) of dentine specimens treated with zinc chloride or ZnO. In XAFS analyses, the spectra of dentine specimens treated with ZnO (D-ZO) or with zinc chloride (D-ZC) were similar and obviously different from the reference ZnO spectrum. This suggests that most of the zinc atoms detected in D-ZO are not derived from particles of ZnO. The spectra of D-ZO and D-ZC were similar to the spectrum of the synthetic, zinc-containing hydroxyapatite, but were not similar to that of zinc in ZnCl2 -treated collagen. The results of this study suggest that most of the zinc atoms detected were attached to hydroxyapatite and not to collagen. [source] Combustion properties of laminated veneer lumbers bonded with PVAc, PF adhesives and impregnated with some fire retardantsFIRE AND MATERIALS, Issue 3 2010eref Kurt Abstract In this study, the effects of impregnation materials di-ammonium phosphate, aluminium sulphate, potassium carbonate, calcium chloride, zinc chloride on combustion properties of 3 ply laminated veneer lumbers (LVL) produced from Walnut (Juglans regia L.) using phenol,formaldehyde (PF), poly (vinyl acetate) have been investigated. The pressure-vacuum method was used for impregnation process. Combustion test was performed according to the procedure of ASTM-E 69 standards. During the test, mass reduction, temperature and released gas (CO, NOX, SO2, O2) were determined every 30,s. As a result, zinc chloride was found to be the most successful fire-retardant chemical in LVL at PF adhesive. Since it diminishes combustion, the fire retardant of LVL produced from walnut using PF adhesive can be advised. Copyright © 2009 John Wiley & Sons, Ltd. [source] The european union risk assessment on zinc and zinc compounds: The process and the factsINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 4 2005Charles W.M. Bodar Abstract A risk assessment on zinc and zinc compounds was carried out within the framework of Council Regulation 793/93/EEC on Existing Chemicals. This risk assessment basically followed the European Union (EU) technical guidance documents (TGDs). These TGDs are built on the current knowledge on quantitative risk assessments, mainly for organic chemicals. This article describes the tailor-made approach for the zinc risk assessment. This work lasted almost a decade and involved the contributions of all EU member states and industry, who discussed the risk assessment during technical meetings. The risk assessment is initially based on scientific findings but is interrelated with pragmatic considerations. It follows a comprehensive approach, covering both environmental and human health. In the environmental part, new methodologies were developed to deal with the natural background of zinc, essentiality, speciation, and the use of species sensitivity distributions. The major results and the process of drawing conclusions of the risk assessment are outlined: potential environmental risks of zinc and zinc compounds may occur at local and regional scales in surfacewater, sediment, and soil. No potential health risks were identified for consumers and man indirectly exposed via the environment. For workers, potential health risks were identified only for zinc oxide and zinc chloride. [source] General Zinc-Catalyzed Conia-Ene Reactions of 1,3-Dicarbonyl Compounds with Alkynes Including the Classically Challenging Substrates under Neat ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Chen-Liang Deng Abstract A simple, versatile new approach to four-membered ring to six-membered ring products has been developed by zinc-catalyzed intramolecular Conia-ene reactions of 1,3-dicarbonyl compounds with alkynes. This new route allows a wide range of dicarbonyl compounds, including the classically challenging 1,3-diesters and N,N, -disubstituted 1,3-keto amides, to be used for the Conia-ene reaction with inexpensive zinc chloride (ZnCl2) under neat conditions. [source] The influence of the impregnating chemicals on the bonding strength of impregnated wood materialsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ayhan Özçifçi Abstract In this study, it is aimed to determine the bonding strength of white oak (Quercus petreae L.) and chestnut (Castanea sativa Mill.) woods impregnated with borax and zinc chloride. Within this purpose, the experimental samples were bonded with Polyvinyl-acetate and polyurethane based Desmodur-VTKA (D-VTKA) adhesives according to BS EN 205 standards after they had been prevacuumed with a pressure equal to 760 mmHg,1 with impregnating at 2 atm pressures for 60 min according to ASTM-D 1413 standards and applied vacuum-impregne-vacuum method. During the experiments, the retention amount, the retention proportion, and the bonding strength values of the samples were determined. According to the test results, the highest values of retention amount, and bonding strength were obtained from the wood material impregnated with zinc chloride. The impregnating materials had a negative effect on bonding strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] In vivo antimicrobial effectiveness of an essential oil-containing mouth rinse 12 h after a single use and 14 days' useJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 4 2005D. H. Fine Abstract Objectives: Two studies were conducted to determine the antimicrobial effect of rinsing with an essential oil-containing mouth rinse 12 h after a single rinse and 12 h after 2 weeks of twice daily rinsing, during the daytime and overnight. Materials and Methods: These studies utilized a randomized, double-blind, controlled crossover design. Following baseline sampling of bacteria from supragingival plaque and the dorsum of the tongue, subjects began twice-daily rinsing with either an essential oil mouth rinse containing 0.09% zinc chloride (Tartar Control Listerine® Antiseptic) or a negative control rinse. Bacterial sampling was repeated 12 h after the first rinse, and again 12 h after the final rinse 14 days later. The sampling schedule was adjusted according to whether the study was investigating daytime or overnight activity. Samples were plated on Schaedlers medium (total anaerobes), Schaedlers Nalidixic/Vancomycin medium (Gram-negative anaerobes), and OOPS medium (volatile sulphur compound (VSC)-producing organisms). Inter-group log10 transformed colony-forming units /ml counts from samples of supragingival plaque and tongue swabs on each of the three media were compared by analysis of covariance. Results: The mean bacterial counts in subjects using the essential oil mouth rinse were significantly lower (p0.005) than mean counts in subjects using the control rinse in all the comparisons, i.e., tongue and supragingival plaque samples on each of three media at two sampling periods in the daytime and overnight study, respectively. Mean bacterial count percent reductions for plaque samples ranged from 56.3 to 95.3; percent reductions for tongue samples ranged from 61.1 to 96.1. There was a trend to higher reductions after 14 days' rinsing than after the initial rinse. Conclusion: Rinsing with the essential oil mouth rinse can have long-lasting effects in reducing anaerobic bacteria overall as well as Gram-negative anaerobes and VSC-producing bacteria. The significant reductions in numbers of these bacteria produced by the essential oil mouth rinse, both in plaque and on the dorsum of the tongue, can play a key role in explaining the essential oil mouth rinse's effectiveness in reducing supragingival plaque and gingivitis as well as its effectiveness in controlling intrinsic oral malodor over prolonged periods. [source] COLOR and CHLOROPHYLL CONTENT CHANGES of MINIMALLY PROCESSED KIWIFRUITJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2000MARÍA ASUNCIÓN LEUNDA A combined factors preservation technology involving blanching and vacuum solutes (sucrose, potassium sorbate, ascorbic and citric acids, zinc chloride) impregnation was proposed to minimize color changes in minimally processed kiwifruit slices during one month storage. Atmospheric impregnation was also studied in order to compare both impregnation techniques. A Box-Behnken design was adopted and second order polynomial models were computed for different storage times to relate some process variables (blanching time, zinc content, storage temperature) to a color function (Brown Index). As the storage time increased, the response surfaces for vacuum treated fruits were vertically displaced to greater Brown Index values while the response surface behavior for atmospheric impregnated fruits were less dependent on storage time. For vacuum treated fruits, combinations of blanching and addition of zinc chloride improved the color of the finished product at all storage temperatures assayed, but these treatments were detrimental for atmospheric impregnated fruits, increasing significantly the Brown Index values. After storage, total chlorophyll had been degraded between 70 and 90% depending on the pretreatments. There did not appear to be any consistent relation between the changes which occurred in the total chlorophyll content and color. [source] Synthesis of ,3 adrenergic receptor agonist LY377604 and its metabolite 4-hydroxycarbazole, labeled with carbon-14 and deuteriumJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 6 2005Boris A. Czeskis Abstract Synthesis of 14C-radiolabeled 4-hydroxycarbazole was accomplished starting from aniline-[U- 14C], based on zinc chloride initiated Fischer cyclization of the phenylhydrazone prepared from phenylhydrazine-[U- 14C] and cyclohexane-1,3-dione. The resulting tetrahydrooxocarbazole was subjected to dehydrogenation,aromatization using palladium on carbon. The aromatized 4-hydroxycarbazole-[4b,5,6,7,8,8a- 14C] was then used for the synthesis of 14C-labeled ,3 adrenergic receptor agonist LY377604. The introduction of four deuteria in the carbazole fragment of LY377604 accomplished by its initial bromination and subsequent catalytic deuteration of the resulting tetrabromide. A similar approach was used for the conversion of 4-hydroxycarbazole into its tetradeutero-isotopomer. Copyright © 2005 John Wiley & Sons, Ltd. [source] Zn2+ mediates ischemia-induced impairment of the ubiquitin-proteasome system in the rat hippocampusJOURNAL OF NEUROCHEMISTRY, Issue 5 2009Min Chen Abstract Deposition of ubiquitinated protein aggregates is a hallmark of neurodegeneration in both acute neural injuries, such as stroke, and chronic conditions, such as Parkinson's disease, but the underlying mechanisms are poorly understood. In the present study, we examined the role of Zn2+ in ischemia-induced impairment of the ubiquitin-proteasome system in the CA1 region of rat hippocampus after transient global ischemia. We found that scavenging endogenous Zn2+ reduced ischemia-induced ubiquitin conjugation and free ubiquitin depletion. Furthermore, exposure to zinc chloride increased ubiquitination and inhibited proteasomal enzyme activity in cultured hippocampal neurons in a concentration- and time-dependent manner. Further studies of the underlying mechanisms showed that Zn2+ -induced ubiquitination required p38 activation. These findings indicate that alterations in Zn2+ homeostasis impair the protein degradation pathway. [source] Speciation of zinc in secondary fly ashes of municipal solid waste at high temperaturesJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2009Meijuan Yu The evaporation aerosols produced during the vitrification process of municipal solid waste incinerators (MSWI) fly ash represent a potential environmental risk owing to their high content of heavy metals. In this research, high-temperature heating processes were carried out on fly ashes collected from bag houses in a Chinese MSWI plant and the secondary fly ashes (SFA) were separately collected at three high temperatures (1273,K, 1423,K and 1523,K) below the melting range. Elemental analysis showed that high contents of both zinc and chlorine were present in these SFA samples and, according to the standard of the heavy metals industrial grade of ore, SFAs can be re-used as metallurgical raw materials or rich ore. Moreover, as shown by XAS analysis and for different high temperatures, zinc environments in the three SFA samples were characterized by the same local structure of the zinc chloride. As a consequence, a zinc recycling procedure can be easily designed based on the configuration information. [source] Alkyl Zinc Chlorides as New Initiators for the Polymerization and Copolymerization of IsobuteneMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2008Antonio Guerrero Abstract Mixtures of RZnCl and tBuCl (R,=,Et) initiate the polymerization of isobutene in the temperature range of (,35),(+35),°C. The order of addition of the reagents is important for effective polymerization. Increasing the solubility of the zinc reagent (R,=,n -octyl) and use of cumyl chloride as co-initiator provides a system that is active from (,90),(+35),°C. The molecular weights show a remarkably small temperature dependence, EDP,=,,3.3 kJ,·,mol,1, compared to EDP,=,,23 kJ,·,mol,1 in classical systems (AlCl3, EtAlCl2). The molecular weights increase with decrease in zinc concentration and are consistently higher for n -octyl zinc chloride, as expected for a bulkier, less coordinating counteranion. The polymerizations are not retarded by isoprene addition; homopolymers and copolymers show essentially identical conversions and molecular weights. [source] The Pigmentation of Human Iris Influences the Uptake and Storing of ZincPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2004Despina Kokkinou Age-related macular degeneration (AMD) is more prevalent among the elderly Caucasians than in Africans. A significant association between light iris colour, fundus pigmentation and incidence of AMD is reported, suggesting a possible correlation with melanin pigment. Zinc is known to bind to melanin in pigmented tissues and to enhance antioxidant capacity by function as a cofactor or gene expression factor of antioxidant enzymes in the eye. In this in vitro study, we investigated the uptake and storage of zinc in human irides. Irides of blue and brown human eyes were used. The number of melanocytes was measured. Tissues without any treatment served as controls. The irides were incubated with 100 ,M zinc chloride in culture medium for 24 h. Specimens of the tissues were stored for the uptake examination. The remained pieces were further incubated for 3 and 7 d to investigate the storage of zinc. The concentration of zinc was measured by inductively coupled plasma mass spectrometry (ICP-MS). Melanocytes count was significantly higher in the brown tissues (P < 0.0001). Zinc concentration of blue coloured irides after 24 h zinc treatment was close to the controls. We did not observe any significant storing. In contrast, the concentration of zinc in brown irides was significantly increased after 24 h (P , 0.01) and remained at a high level for 7 d. The uptake of zinc is likely dependent on the amount of pigmentation in human iris. Therefore, we assume that in patients suffering from AMD the degree of pigmentation of the irides and eventually fundi should be under consideration when the patients are treated with zinc supplementation. [source] Degradation of polyamide-6 by using metal salts as catalyst,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002a Klun Abstract Polyamide-6 (PA-6) is a widely used polycondensation polymer that can be recycled by hydrolysis to its monomer ,-caprolactam. The reaction is normally catalyzed by mineral acids. Using microwaves as the source of heating, zinc chloride, acetate and triflate were evaluated as non-acid catalysts for the reaction. Gravimetric and electron spray ionization mass spectrometry analysis of reaction products showed ZnCl2 as the most effective salt catalyst. A 50wt% (versus PA-6) addition gave 75% water-soluble, low-molecular-weight oligomers, which is approximately 25% lower than when using phosphoric acid. The triflate salt was effective only when used as an addition to a mineral acid, whereas the acetate was ineffective. FTIR and NMR spectroscopy of degradation products showed that dissociated ions from ZnCl2 bind to the amide group of the polymer. Using the triflate salt no such interaction could be observed, indicating that the degradation and catalysis mechanisms differ with the chloride and triflate salt. Five water-stable lanthanide triflates showed no catalytic effect on the reaction. Copyright © 2003 John Wiley & Sons, Ltd. [source] Halogeno(triazolyl)zinc complexes as molecular building blocks for metal,organic frameworksACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Jörg Lincke The isomorphous title complexes, dichlorido[4-(3,5-dimethyl-4H -1,2,4-triazol-4-yl)benzoic acid-,N1]zinc(II) dihydrate, [ZnCl2(C11H11N3O2)2]·2H2O, and dibromido[4-(3,5-dimethyl-4H -1,2,4-triazol-4-yl)benzoic acid-,N1]zinc(II) dihydrate, [ZnBr2(C11H11N3O2)2]·2H2O, were synthesized and crystallized by slow evaporation of the solvent from a solution of the ligand and either zinc chloride or zinc bromide, respectively, in water/ethanol. The ZnII ions occupy twofold axes in the noncentrosymmetric orthorhombic space group Fdd2. The metal ion is approximately tetrahedrally coordinated by two monodentate triazole groups of the ligands and additionally by two halide ions. The water molecules incorporate the complexes into a three-dimensional framework made up by hydrogen bonds. Furthermore, each complex possesses two hydrogen-bond-donor sites represented by the carboxy groups and two acceptor sites at the noncoordinating N atoms of the triazoles. [source] Total Spontaneous Resolution of Chiral Covalent Networks from Stereochemically Labile Metal ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2005Anna Johansson Abstract Stereochemically labile copper and zinc complexes with the N,N, -dimethylethylenediamine ligand (dmeda) have been shown to be promising precursors for the total spontaneous resolution of chiral covalent networks. (N,N,)-[Cu(NO3)2(dmeda)], crystallises as a conglomerate and yields either enantiopure (R,R)- 1 or enantiopure (S,S)- 1. A mixed-valence copper(I/II) complex, [{CuIIBr2(dmeda)}3(CuIBr)2], (2), which crystallises as a pair of interpenetrating chiral (10,3)- a nets, is formed from CuBr, CuBr2 and dmeda. One net contains ligands with solely (R,R) configuration and exhibits helices with (P) configuration while the other has solely (S,S)-dmeda ligands and gives rise to a net in which the helices have (M) configuration. The whole crystalline arrangement is racemic, because the interpenetrating chiral nets are of opposite handedness. With zinc chloride (R,S)-[ZnCl(dmeda)2]2[ZnCl4] (3) is obtained, which is a network structure, although not chiral. Total spontaneous resolution of stereochemically labile metal complexes formed from achiral or racemic building blocks is suggested as a viable route for the preparation of covalent chiral networks. Once the absolute structure of the compound has been determined by X-ray crystallography, a quantitative determination of the enantiomeric excess of the bulk product can be undertaken by means of solid-state CD spectroscopy. [source] | ||||||||||||||||||||||||||||||||||