The aquation of cis-Chlorodi(methyl sulphoxide)bisethylenediaminecobalt(III), cis-Chlorodimethylformamidebisethylenediaminecobalt(III), and cis-Chlorodimethylacetamidebisethylenediaminecobalt(III) ions

1966 ◽  
Vol 19 (10) ◽  
pp. 1821 ◽  
Author(s):  
IR Lantzke ◽  
DW Watts
Keyword(s):  
Solvent Molecule ◽  
Chloride Ion ◽  
Side Reaction ◽  
Base Hydrolysis ◽  
Alkaline Solutions ◽  
Replacement Reaction ◽  
Ph Values ◽  
Trigonal Bipyramidal ◽  
Entropy Of Activation ◽  
Solvent Replacement

The aquation of each of three octahedral chloro(solvent)bisethylene- diaminecobalt(III) ions, involving the solvent ligands dimethyl sulphoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMA), has been examined in solutions of different pH. In solutions of pH less than 6, the predominant reaction is replacement of the solvent molecule by water in an SN1 process, involving a trigonal bipyramidal transition state and resulting in a mixture of the trans- and cis- chloroaquo complexes. The slow loss of chloride ion is an accompanying side reaction. In solutions of pH greater than 6 base hydrolysis becomes important, and in alkaline solutions the rate of solvent loss is too fast to measure by conventional techniques. The rate of liberation of chloride ion is also greatly increased with increasing pH. Values of the activation energy, and entropy of activation, are reported for the solvent replacement reaction at a pH of 1.90.

scholarly journals Chloridobis(1,10-phenanthroline-κ2N,N′)copper(II) chlorido(1,10-phenanthroline-κ2N,N′)(pyridine-2,6-dicarboxylato-κ3O2,N,O6)manganate(II) methanol monosolvate

2014 ◽  
Vol 70 (4) ◽  
pp. m147-m148 ◽  
Author(s):  
Halyna I. Buvailo ◽  
Julia A. Rusanova ◽  
Valeriya G. Makhankova ◽  
Vladimir N. Kokozay ◽  
Roman I. Zubatyuk
Keyword(s):  
Solvent Molecule ◽  
Chloride Ion ◽  
Coordination Geometry ◽  
Π Interactions ◽  
Trigonal Bipyramidal ◽  
Distorted Octahedral Coordination Geometry ◽  
Distorted Octahedral ◽  
Cl Atom ◽  
Phenanthroline Ligands ◽  
Distorted Trigonal Bipyramidal

The title complex, [CuCl(C12H8N2)2][Mn(C7H3NO4)Cl(C12H8N2)]·CH3OH, consists of discrete [CuCl(phen)2]+cations (phen is 1,10-phenanthroline), [MnCl(pydc)(phen)]−anions (H2pydc is 2,6-pyridine-2,6-dicarboxylic acid) and one methanol solvent molecule of crystallization per asymmetric unit. It should be noted, that a solvent-masking procedure as implemented inOLEX2[Dolomanovet al.(2009).J. Appl. Cryst.42, 339–341] was used to remove the electronic contribution from one disordered solvent molecule, presumably methanol. Only the atoms used in the refined model are reported in chemical formula and related values. The CuIIion is five-coordinated by two phenanthroline ligands and one chloride ion in a distorted trigonal–bipyramidal geometry. The dihedral angle between the phen ligands is 65.21 (5)°. The MnIIion is six-coordinated by one Cl atom, two N atoms from a phen ligand, as well one N atom and two O atoms from pydc in a distorted octahedral coordination geometry, withcisangles ranging from 72.00 (8) to 122.07 (8)° andtransangles ranging from 143.98 (8) to 163.15 (6)°. In the crystal, C—H...O, O—H...O and C—H...Cl hydrogen bonds, cation–anion π–π interactions between the phen ring systems with centroid–centroid distances in the range 3.881 (34)–4.123 (36) Å, as well as cation–cation, anion–anion π–π interactions between the phen rings with centroid–centroid distances in the range 3.763 (4)–3.99 (5) Å and pydc rings with centroid–centroid distances 3.52 (5) Å link the various components.

Study on desorption of Mn, Fe, and Mg from TMP and evaluation of the complexing strength of different chelating agents using side reaction coefficients 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Kim Granholm ◽  
Pingping Su ◽  
Leo Harju ◽  
Ari Ivaska
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Chelating Agents ◽  
Side Reaction ◽  
Sodium Dithionite ◽  
Thermomechanical Pulp ◽  
Peroxide Bleaching ◽  
Ph Values ◽  
Reducing Environment ◽  
Ph Range

Abstract Chelation of thermomechanical pulp (TMP) was studied in this work. The desorption of Mn, Fe, and Mg due to their impact on peroxide bleaching was investigated. The desorption experiments were performed with EDTA, citric acid, oxalic acid, and formic acid as chelating agents at different pH. Chelation experiments with EDTA were carried out at pH 3–11. Sodium dithionite was used as the reducing agent in studying chelation with EDTA in a reducing environment. Mn was very effectively desorbed with EDTA from TMP at pH <10 and the reducing environment further improved the removal of all the studied metal ions from TMP with EDTA. Citric acid also removed Mn effectively from TMP at pH 5. The thermodynamic stability constants of different metal chelates do not present the correct picture of how strongly the metal ions are bound by the chelating agents in different conditions. But by means of the side reaction coefficients (α M(L)-coefficients) it is also theoretically possible to evaluate and compare the real binding strengths between the metal ions and different chelating agents at varying pH values and other solution conditions. In this study, a theory is given for the calculation of side reaction coefficients. Values of the α M(L)-coefficients, for the pH range 0–14, are presented for EDTA, DTPA, and also for some other new potential environmentally friendly chelating agents.

scholarly journals Effect of alkaline solutions on the tensile properties of glass-polyester pipes

2011 ◽  
pp. 185-195 ◽  
Author(s):  
Slavisa Putic ◽  
Marina Stamenovic ◽  
Jelena Petrovic ◽  
Marko Rakin ◽  
Bojan Medjo
Keyword(s):  
Tensile Properties ◽  
Construction Materials ◽  
Ammonium Hydroxide ◽  
Longitudinal Direction ◽  
Testing Procedure ◽  
Circumferential Direction ◽  
Process Equipment ◽  
Alkaline Solutions ◽  
Ph Values ◽  
Definite Structure

Construction materials, traditionally used in process equipment, are today successfully replaced by composite materials. Hence, many pipes are made of these materials. The subject of this study was the influence of liquids on the state of stresses and tensile strengths in the longitudinal and circumferential direction of glass-polyester pipes of a definite structure and known fabrication process. These analyses are of great importance for the use of glass-polyester pipes in the chemical industry. The tensile properties (the ultimate tensile strength and the modulus of elasticity) were tested and determined for specimens cut out of the pipes; flat specimens for the tensile properties in the longitudinal direction and ring specimens for the tensile properties in the circumferential direction. First, the tension test was performed on virgin samples (without the influence of any liquid), to obtain knowledge about the original tensile properties of the material composite studied. Subsequently, the specimens were soaked in alkaline solutions: sodium hydroxide (strong alkali) and ammonium hydroxide (weak alkali). These solutions were selected because of their considerable difference in pH values. The specimens and rings were left for 3, 10, 30 and 60 days in each liquid at room temperature. Then, the samples were tested on tension by the standard testing procedure. A comparison of the obtained results was made based on the pH values of the aggressive media in which the examined material had been soaked, as well as based on the original tensile properties and the number of days of treatment. Micromechanical analyses of sample breakage helped in the elucidation of the influence of the liquids on the structure of the composite pipe and enabled models and mechanisms that produced the change of strength to be proposed.

scholarly journals Corrosion Inhibition Efficiencies of Polymeric Materials on Alloy Steel in Dilute Hydrochloric Acid and Sodium Hydroxide Solutions at Ambient Temperature

2020 ◽  
Vol 7 (2) ◽  
pp. C27-C32
Author(s):  
I.E. Ekengwu ◽  
O.G. Utu ◽  
K.O. Anyanwu
Keyword(s):  
Corrosion Rate ◽  
Ambient Temperature ◽  
Alloy Steel ◽  
Corrosion Inhibition ◽  
High Density Polyethylene ◽  
Inhibition Efficiency ◽  
Polymeric Materials ◽  
High Density ◽  
Alkaline Solutions ◽  
Ph Values

A corrosion control test was conducted on alloy steel, using polymeric coatings (polyurethane, bitumen (medium airing), and high-density polyethylene) in dilute HCl solutions of pH values 4, 7, and 12, respectively for acid, neutral and alkaline solutions at ambient temperature. In the study, Eighty-four coupons of alloy steel were used. The coupons were mechanized, ground, polished, etched with natal, and weighed using a digital weighing balance (Beva 206B). The mass of each coupon was recorded according to the tag number on them. Twenty-one of the coupons were coated with polyurethane, 21 coated with medium curing bitumen (MC), and 21 coated with high-density polyethylene, while 21 were left uncoated. Seven polyurethane-coated samples, bitumen coating, and uncoated coupons were suspended in dilute HCl solutions of pH values 4, 7, and 12. Every week, one sample is taken from each of the solutions, the coatings and the corrosion products were removed, and the coupons were etched with natal. Then the coupons were reweighed, and their masses were recorded in accordance with their tag number. The weight loss per unit area of the coupons, corrosion rate, and percentage corrosion inhibition efficiencies of the coatings was calculated over seven weeks. The results obtained were tabulated and represented graphically. From the results obtained, it is seen that the corrosion inhibition efficiency of polyurethane coatings is higher compared with bitumen and polyethylene. It is also seen from the graphs that the corrosion rate of the coupons is higher in acid, a little bit lower in alkaline, and much lower in neutral solution. It is also observed that the corrosion rates fall with time as the inhibition efficiency also falls with time.

scholarly journals Chiral crystallization of a zinc(II) complex

2021 ◽  
Vol 77 (5) ◽  
pp. 542-546
Author(s):  
Shabana Noor ◽  
Shintaro Suda ◽  
Tomoyuki Haraguchi ◽  
Fehmeeda Khatoon ◽  
Takashiro Akitsu
Keyword(s):  
Hydrogen Bond ◽  
Schiff Base ◽  
Complex Molecule ◽  
Solvent Molecule ◽  
Hirshfeld Surface ◽  
Supramolecular Interactions ◽  
Orthorhombic Space Group ◽  
Complex Molecules ◽  
Trigonal Bipyramidal ◽  
Distorted Trigonal Bipyramidal

The compound, {6,6′-dimethoxy-2,2′-[(4-azaheptane-1,7-diyl)bis(nitrilomethanylidyne)]diphenolato}zinc(II) methanol monosolvate, [Zn(C22H27N3O4)]·CH3OH, at 298 K crystallizes in the orthorhombic space group Pna21. The Zn atom is coordinated by a pentadentate Schiff base ligand in a distorted trigonal–bipyramidal N3O2 geometry. The equatorial plane is formed by the two phenolic O and one amine N atom. The axial positions are occupied by two amine N atoms. The distorted bipyramidal geometry is also supported by the trigonality index (τ), which is found to be 0.85 for the molecule. In the crystal, methanol solvent molecule is connected to the complex molecule by an O—H...O hydrogen bond and the complex molecules are connected by weak supramolecular interactions, so achiral molecules generate a chiral crystal. The Hirshfeld surface analysis suggests that H...H contacts account for the largest percentage of all interactions.

Prediction and Analysis of Reinforcement Corrosion in Simulated Concrete Pore Solution Based on Neural Network

2020 ◽  
Vol 34 (14) ◽  
pp. 2059047
Author(s):  
Fengjiao Jiang ◽  
Jinxin Gong ◽  
Jichao Zhu ◽  
Huan Wang ◽  
Weibo Song
Keyword(s):  
Neural Network ◽  
Equivalent Circuit ◽  
Pore Solution ◽  
Equivalent Circuit Model ◽  
Chloride Ion ◽  
Ion Concentration ◽  
Equivalent Circuits ◽  
Chromium Alloy ◽  
Ph Values ◽  
Impedance Characteristics

The corrosion of reinforcement has always been a problem to be solved in the field of architecture. In this paper, the corrosion characteristics of chromium alloy steel under different pH conditions are studied. The impedance characteristics and equivalent circuit are predicted by neural network model. First of all, in simulated pore solution with different pH values, the characteristics of Nyquist impedance spectroscopy of the whole chromium alloy under passivation stage and the damaged passivation film of reinforcing bars under initial corrosion stage have been found. Then, according to the difference of impedance characteristics under different pH values, different equivalent circuits have been established and [Formula: see text] values of different equivalent circuits under different chloride ion concentration have been calculated. By fitting the electrochemical parameters of the equivalent circuit with [Formula: see text] values, the equivalent circuit model which can be predicted by neural network has good consistency with the equivalent circuit which can be predicted by [Formula: see text] values.

THE ELECTRODE POTENTIAL OF IRON IN RELATION TO HYDROGEN ION CONCENTRATION

1936 ◽  
Vol 14b (1) ◽  
pp. 31-40 ◽  
Author(s):  
J. W. Shipley ◽  
J. H. Shipley
Keyword(s):  
Electrode Potential ◽  
Chloride Ion ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Iron Electrode ◽  
General Corrosion ◽  
Citrate Buffer ◽  
Hydrogen Ion Concentration ◽  
Electrically Conducting ◽  
Ph Values

The electrode potential of iron immersed in phosphate, borate and citrate buffers of varying hydrogen ion concentration was measured, using a normal calomel electrode as the second half of the cell. Breaks in the potential of the iron electrode amounting to as much as 0.7 volts were found to occur at definite pH values for each series of buffers. The electrode exhibited an "initial" and "final" potential depending on the pH of the electrolyte and the time of immersion, the "final" value requiring several days to become established. The "final" break in the electrode potential of 0.74 volts in the pure phosphate buffer occurred between a pH of 3.1 and 4.0, that in the pure borate buffer, of 0.75 volts, occurred between a pH of 4.3 and 4.6, and in the pure citrate buffer, of 0.77 volts, between a pH of 10.1 and 10.9. The effect of chloride ion and de-aeration on the electrode potential was observed. It is suggested that the potential of the iron electrode is determined by the presence or absence of a non electrically conducting film or deposit on the iron, the formation of which is a function of the nature of the electrolyte and its hydrogen ion concentration. De-aeration apparently had no effect on the electrode potential, but the presence of chloride ion affected the establishing of the "final" potential and caused the break in voltage to appear irregularly at a much lower hydrogen ion concentration.At pH values below that at which the break in potential occurred, corrosion of the iron electrode was marked, and the electrode potential remained high, while, at pH values above the break, corrosion was virtually inhibited or confined to local spots on the electrode, and the electrode potential remained low. The presence of the chloride ion stimulated local corrosion and permitted general corrosion to proceed at a lower hydrogen ion concentration.

Zur Chemie der l,3,5-Triaza-2-phosphinan-4,6-dione. Teil VI. Darstellung von 1,3,5-Triaza-2 λ3-, 1,3,5-Triaza-2 λ4- und 1,3,5-Triaza-2 λ5-phosphinan-4,6-dionen / Chemistry of the 1,3,5-Triaza-2-phosphinane-4,6-diones. Part VI. Synthesis of 1,3,5-Triaza-2λ3-, 1,3,5-Triaza-2λ4- and 1,3,5-Triaza-2λ5-phosphinane-4,6-diones

1994 ◽  
Vol 49 (2) ◽  
pp. 145-164 ◽  
Author(s):  
Michael Farkens ◽  
Thomas G. Meyer ◽  
Ion Neda ◽  
Ralf Sonnenburg ◽  
Christian Müller ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Solvent Molecule ◽  
Oxidation Products ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Phenyl Azide ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Trifluoromethyl Groups ◽  
Bifunctional Compound

The reactions of 1,3,5-trimethylbiuret with dicyclohexylaminodichlorophosphine and with pyrrolidinodichlorophosphine furnished the triazaphosphinane-diones 1 and 2. Oxidation reactions of the 2-diorganoam ino-1,3,5-triorgano-1,3,5-triaza-2 λ3-phosphinane-4,6-diones 1, 2, and 4-9, as well as 2-fluoro-1,3,5-trimethyl-1,3,5-triaza-2λ3-phosphinane-4,6-dione 10 with hydrogen peroxide, elemental sulphur, phenyl azide, 1-adamantyl azide,p-nitrobenzoyl azide, tetrachloro-orthobenzoquinone, tetrabromo-orthobenzoquinone, 3,5-di-t-butyl-orthobenzoquinone, and hexafluoroacetone led to the respective oxidation products, 12-32, involving either λ4P or λ5P. In the reaction o f the P(III)C1 derivative 11 with 3-m ethyl-l,5-diphenyl-l,5- bis(trimethylsilyl)biuret the bifunctional compound 33 was produced. The new com pounds 1,2 and 12-33 were characterized via their 1H, 13C and 31P and, where appropriate, 19F NMR spectra. In the case o f the four compounds, 3 (previously described in the literature [2]), 13, 31, and 33, single crystal X-ray diffraction studies were conducted. Unusually for this type of heterocycle 3 displays a 1,4-diplanar ring conformation because o f the bulky aromatic substituents. 13 shows an envelope conformation. The hydrogen peroxide solvent molecule has crystallographic inversion symmetry, but may be disordered. In 31 the coordination geometry at phosphorus is trigonal bipyramidal. The five-membered ring shows a twist conform ation associated with the bulky trifluoromethyl groups. The exocyclic P-N bonds in 33 are unusually long.

Preparation and stability of indomethacin solutions

1982 ◽  
Vol 60 (7) ◽  
pp. 988-992 ◽  
Author(s):  
Stephen H. Curry ◽  
Edgar A. Brown ◽  
Hilken Kuck ◽  
Sidney Cassin
Keyword(s):  
High Pressure ◽  
Ductus Arteriosus ◽  
Alkaline Solutions ◽  
Related Research ◽  
Ph Values ◽  
Peg 400 ◽  
Biological Studies ◽  
Two Temperatures ◽  
Stable Solutions ◽  
Near Term

Indomethacin is used in closure of the ductus arteriosus in newborn humans as well as in related research in near-term sheep and goats. Conflicting data in these studies have led to a reexamination of indomethacin stability. Solutions at various pH values, at two temperatures, and in polyethylene glycol (PEG-400), were assessed by high-pressure liquid chromatography for indomethacin and its products. Solutions below pH 7.4 were stable. Decomposition was rapid in alkaline solutions. Solutions at pH 7.4 showed no changes up to 24 h. Solutions of sodium indomethacin, and of indomethacin in PEG were stable. Solutions in aqueous Na2CO3 were variably stable depending on the mode of mixing. A solution prepared directly in 0.1 M Na2CO3 (pH 10.7) lost 75% of its content in 80 min; a similar solution diluted immediately with two volumes of pH 7.4 buffer (final pH 9.9) showed less decomposition. A solution in Na2CO3 adjusted to pH 7.4 with HCl was stable (at least 24 h). Solutions prepared by suspending indomethacin in 0.9% NaCl and adding Na2CO3 slowly were stable for 80 min; rapid mixing led to decomposition. Solutions in plasma were stable at −20 °C (2 months). Lack of indomethacin activity in some biological studies may have resulted from injection of inactive solutions.

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