Showing papers on "Ferric published in 1969"

On the nature of the high iron diamine method for sulfomucins

Abstract: Spectrophotometric and chromatographic studies on Spicer’s high iron diamine reaction suggest that new red and blue oxidation products are formed, which become rapidly aggregated mainly to ferrous ions. Model experiments with pure substrates of known physical and chemical nature at pH 1.3-1.5 indicate that this reaction selectively demonstrates compounds carrying ester sulfate groups. Substrates with the highest charge density (e.g., heparin and dextran sulfates) give dark purple or violet colors, where4s others with lower charge density give brownish reddish or purplish shades. The empirical high iron diamine (HID) method of Spicer (3) for the histologic demonstration of sulfomucins raises some questions as to the nature of the reaction. Spicer assumed that the two dye isomers become oxidized and form colored positively charged aggregates. The ferric ions added would catalyze the oxidation and possibly partake in the aggregation formation. By choosing an acid pH of 1.3 the ionization of carboxyl and phosphate radicals on the substrate is avoided, leaving only ester sulfate groups available for interaction with the dye aggregates. All shades between grayish and

Heterogeneity in silicon-iron mixed hydroxides

Abstract: Summary Several mixed hydroxides obtained by co-precipitation of FeCl2 or FeCl2 with Na2SiO2 followed by ageing and purification were studied by X-ray diffraction, infra-red spectroscopy, and surface-area measurements. The compounds with molecular ratios SiO2/Fe2O3 ranging from 0·1 to 1·17 are essentially amorphous. Silica, which is not to be considered as an integral part of the gel, is chemi-sorbed on the ferric or‘ferrosic’ phase. The good agreement between IR, DTA, and surface-area measurements with increasing molecular ratios permits the distinction between two ranges of silica contents. In the first range, MR 0·1 range, silica polymerizes as a separate phase growing upon the‘ferrosic’ or‘ferric’ phase.

Pulse-radiolysis study of some unstable complexes of iron

Abstract: Pulse radiolysis of oxygen-containing solutions of ferrous perchlorate in perchloric acid (l M) enables the formation and disappearances of a ferric hydroperoxide complex, Fe3+HO–2, to be observed. The rate constant for its formation by reaction of HO2 radicals with free ferrous ions is 2.1 ± 0.4 × 106 M–1s–1 in the pH range 0–2.1. The complex disappears in a first-order reaction with a rate constant independent of pH in the range 0–2.1. It exhibits a broad absorption in the region 280–600 nm, with Iµ430 nm= 280 ± 30 M–1 cm–1. In the absence of oxygen, a different absorbing species can be seen, attributed to a ferric hydride complex, Fe3+H–. This is formed by the reaction of hydrogen atoms with free ferrous ions with k= 7.5 ± 2 × 106 M–1 s–1. It disappears by reaction with hydrogen ions, with k= 1.06 ± 0.1 × 104 M–1 s–1. Its absorption spectrum exhibits a maximum at 325 nm, Iµ325= 650 ± 65 M–1 cm–1.

Role of cations in radiation grafting and homopolymerization

Abstract: The grafting of acrylic acid in aqueous solution to nylon 6 film has been studied in the presence of ferrous, ferric, and cupric salts. The mutual irradiation technique was adopted using a 60Co source. The anions were found to have no effect on the grafting or homopolymerization, but both of these processes were suppressed by the cations in the following order of effectiveness: Cu2+ > Fe2+ > Fe3+. The rate constant for the capture of hydroxyl radicals by acrylic acid has been determined as 6 × 109 1. mole−1 sec−1 by pulse radiolysis using the CNS− competition method. By invoking this result, mechanisms have been suggested for the process of chain termination by metal cations.

Hemoglobin a: an electron paramagnetic resonance study of the effects of interchain contacts on the heme symmetry of high-spin and low-spin derivatives of ferric alpha chains

Abstract: Hemoglobin, the oxygen-binding heme protein of blood is composed of four subunits of two types, alpha and beta. Although the protein when isolated is diamagnetic, by oxidation it can be converted to various paramagnetic ferric forms exhibiting specific electron paramagnetic resonance (EPR) spectra. Using electron paramagnetic resonance, we have shown that the symmetry of the heme of isolated ferric alpha chains is different from that of the heme of these same subunits when associated with ferric beta chains in the parent tetramer. The high-spin form of the isolated ferric alpha chains shows a clearly resolved departure from tetragonal symmetry in contrast to ferrihemoglobin A, where the environment of the iron of all four chains is nearly tetragonal. This difference in heme symmetry suggests that the maintenance of tetragonal symmetry in the hemoglobin tetramer must be brought about by the configuration the alpha chains assume due to their contact with the beta chains. When isolated from the tetramer, some parts of the alpha chain must undergo physical displacement from a configuration that had been stabilized by the beta chains. Although differences in symmetry between monomer and tetramer are seen with high-spin forms, no such difference exists with two low-spin ferric forms. Here the symmetries of iron are primarily governed by the immediate ligand environment of the iron and not by the state of association of the protein.

Use of chelates in preparing polycyanurates

Abstract: POLYCYANATES SUCH AS AROMATIC DICYANATES AND CYANATOMETHYL-TERMINATED FLUOROALIPHTAIC COMPOUNDS, ARE MIXED WITH METAL CHELATE CATALYST, SUCH AS ZINC OR FERRIC ACETYLACETONATE, AND HEATED TO FORM CYANURATE POLYMERS. THE POLYMERS ARE USEFUL IN THE PREPARATION OF ADHESIVES, BINDERS, COATING, AND TOOLING COMPOUNDS.

Solid-state reaction between zinc oxide and ferric oxide

Abstract: The solid-state reaction ZnO + Fe2O3→ ZnFe2O4 has been studied by means of magnetic and thermo-gravimetric measurements and by X-ray analysis. Because of the diamagnetic nature of the Zn2+ ion, intermediate products can be identified and a mechanism proposed by Reijnen has been confirmed for this reaction. Magnetization-temperature curves of mixed zinc iron ferrites are reported.

Oxidation states and site symmetries of iron in ilvaite using Mössbauer spectrometry

Abstract: The Mossbauer spectrum of ilvaite has been measured at room temperature, and indicates the presence of both high-spin ferrous and ferric iron. Two distinguishable ferrous sites are detected, with the proportion of Fe2+ ions differing by about 20%. The ferric site is highly distorted.

Mössbaur Studies of Iron in Illite and Montmorillonite

Abstract: Three-layer type iron bearing clay minerals, Illite and Montmorillonite, have been analyzed by Mossbauer effect with a view to find the oxidation state, coordination symmetry and site distortion of the iron ion. Furthermore, these samples were treated with concentrated solutions of Fe(NO 3 ) 3 , pH 0.1 to study the exchange of cations. It is concluded that in the natural samples of Montmorillonite and Illite, Fe 3+ ion is in the alumina octahedra in place of Al 3+ ion. In the case of Montmorillonite, treated with ferric nitrate solution, the iron ion is taken up in three inequivalent sites of cubic symmetry: into the vacant sites of Si tetrahedra as [FeO 4 ] - , in the basal plane and on the broken edges. In the case of Illite, the main exchange location for Fe 3+ is the broken edge and only a small amount goes into the basal plane.

Investigation of the MgO∶Fe system using the Mössbauer effect

Abstract: The MgO∶Fe system as subjected to a variety of heat-treatments has been studied using the Mossbauer effect for Fe57 On firing the MgO∶Fe samples in air, iron initially dissolves in the lattice in its ferric state and is associated with a charge-compensating vacancy However, on exceeding a certain concentration, magnesioferrite precipitates out Hydrogen firing of these samples tends to create clusters of metallic iron and Fe2+ at Mg2+ sites On refiring the samples in air, metallic iron is converted to Fe2O3 and Fe2+ to Fe3+ which subsequently reacts with the lattice to give magnesioferrite and a small fraction of Fe3+ dissolved in the lattice These changes are found to be completely reversible In some cases the magnesioferrite particle size is so small that it exhibits superparamagnetism Although there is a limit to the solubility of Fe3+ in MgO, Fe2+ can be dissolved to any extent

The crystal structure of tris(tropolonato)iron(III)(“ferric tropolone”)

Abstract: X-Ray crystallographic analysis of ferric tropolone establishes that the iron co-ordination deviates considerably from octahedral, and, in contrast to the cupric tropolone structure, all C–C bonds, apart from the long C(1)–C(2) bond, have lengths near to the aromatic value.

The Enfrared Spectra of tris (Methyl Methylphosphonate) Iron(III), Tris (Ethyl Ethylphosphonate) Iron(III), and Tris (Isopropyl Methylphosphonate) Iron(III)

Abstract: The literature contains few references to the reactions of phosphonate esters with iron salts. Guilbault et al. 1 recently studied the infrared spectrs of diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DIMP) chemisorbed on solid FeCl 3 and made infrared band assignments. We wish to report the results of a study of the products of the homogeneous reaction of DIMP, DMMP and diethyl ethylphosphonate (DEEP) with ferric chloride. On the basis of elemental analysis and infrared absorption data, the products isolated were identified as tris (methylmethylphosphonate) iron (III), tris (ethyl ethylphosphonate) iron (III), and tris (isopropyl methylphosphonate) iron (III).

Kinetics of reaction of iron(III) with some aliphatic acids in aqueous solution at 20°C

Abstract: The temperature-jump relaxation technique has been used to study the kinetics of the reaction of iron(III) with acetic, propionic, and chloroacetic acids in aqueous solution at 20°C and I= 1.0 M over the acidity range 0.010 M ⩽[H+]⩽0.95 M. The kinetic data show that the formation of the iron(III) acetate and propionate complexes occur via an acid-independent path, and, simultaneously, via a second path dependent on the hydrogen ion concentration. A third path, inversely proportional to the hydrogen ion concentration, also contributes to the formation of the ferric chloroacetate complex. The estimated rate constants are similar to those previously found for analogous reactions of complex formation of iron(III). This provides additional support to the hypothesis that the rate-determining step is the loss of a water molecule coordinated to the iron(III).

Coatings for steel

Abstract: A FERROUS OXALATE COATING ON FERROUS METAL RESULTS FROM CONTACTING THE METAL WITH AN AQUEOUS SOLUTION OF FERROUS OXALATE, FERRIC ION, FLUORIDE ION, OXALIC ACID AT A PH OF 0-2.5 AND A TEMPERATURE OF 130* TO ABOUT 190*F. A MIXTURE FOR PREPARING AND REPLENISHING THE BATH CONSISTS OF OXALIC ACID, FERRIC SULFATE AND ALKALI METAL BIFLUORIDES.

A Mössbauer study of biotite weathering

Abstract: Fresh and weathered biotites have been studied using Mossbauer, chemical, and X-ray analytical techniques. In the Mossbauer spectra the complete interference of both low-spin ferric lines by one of the high-spin ferrous lines and the existence of high-spin ferric iron in the weathered biotite has been demonstrated. In view of this interference, which appears to be common, allowances must be made in spectral interpretation if chemical analysis reveals ferric iron to be present in detectable amounts. Hypothetical extension of the weathering trends observed suggests that high-spin ferric iron is the only stable iron species in the end product. During weathering marked loss of ferrous iron occurs, whereas the ferric iron content remains approximately constant. As a result of the instability of ferrous iron in the weathering environment there is a significant rearrangement of the octahedral layer.

Production of iron oxide pigments

Abstract: Pigment-grade ferric oxide is precipitated from a solution of a ferrous salt by aerating at ambient temperature while introducing substantially two equivalents of base at such rate as to maintain the pH between 5 and 6.

Comparison of Fe2+ ? H2O2 and Fe3+ ? H2O2 initiation systems in graft copolymerization of cellulosic materials

Abstract: Studies were carried out on decomposition of hydrogen peroxide by ferrous and ferric ions adsorbed on cellulosic materials (SP, SCP), scission of the cellulose chain and formation of grafts by graft copolymerization. As a result, it was found that the activity of ferrous ion is always higher than that of ferric ion, but there exists a common relation between the amount of decomposition of hydrogen peroxide and the number of grafts for all cellulose samples and kinds of metallic ions, and it was inferred that essentially, copolymerization takes place by the same mechanism irrespective of the kind of metallic ions. Consequently, it can be considered that the difference in degree of activity between ferrous ion and ferric ion is due to the difference in the decomposition mechanism of hydrogen peroxide by these metallic ions and it is assumed that the high activity of ferrous ion in graft copolymerization is due to the high hydrogen peroxide decomposition effect.

Method of making iron dextran-preparations

Abstract: A substantially pure iron-dextran preparation is produced by a specific and simple process of reacting ferric chloride and dextran in aqueous solution in the presence of citric acid while maintaining the reaction temperature between about 50* C. and about 100* C. and the pH-value of the reaction mixture at a pH between about 9.0 and 10.0. The resulting iron-dextran preparation is substantially free of chloride ions. The novel process permits the preparation of iron-dextran preparations with a predetermined iron content.

Temperature-jump Studies of the Kinetics of the Formation of the Monochloro and Monobromo Complexes of Iron(III)

Abstract: The temperature-jump method was used to study the kinetics of FeCl2+ and FeBr2+ complex formations in aqueous solutions. Complex formation is composed of two paths. In the acid-independent path, the rate-determining step of complex formation may be the reaction between Fe(H2O)53+ and X− (X−=Cl−, Br−). The other path is that via the hydrolysis of ferric ions, and the rate-determining step is the loss of a water molecule from the inner coordination sphere of the metal ion. The kinetic values obtained are in good agreement with the results obtained by the flow method.