Showing papers on "Ferric published in 1974"
TL;DR: In this article, a Losung von wasserfreiem Fe(III)-chlorid in Acetanhydrid werden Ather (I) uber die Zwischenstufen (III) zu den Acetaten (IV) bzw.
Abstract: Durch eine Losung von wasserfreiem Fe(III)-chlorid in Acetanhydrid werden Ather (I) uber die Zwischenstufen (III) zu den Acetaten (IV) bzw. (V) gespalten.
159 citations
TL;DR: In this paper, the authors explain the lack of equilibrium between dissolved and reactive O2 and the presence of ionic Mn species on seafloor sediments by using surface adsorption and cation substitution within disordered birnessite-todorokite structure.
155 citations
TL;DR: The application of magnetic resonance techniques to biological systems has permitted a detailed study of the nature of the active sites of many proteins that had not been possible previously, and the whole class of iron—sulphur proteins, the rubredoxins, are among them.
Abstract: The application of magnetic resonance techniques to biological systems has permitted a detailed study of the nature of the active sites of many proteins that had not been possible previously Among these is the whole class of iron—sulphur proteins which have been implicated as electron transport proteins in a variety of fundamental processes: photosynthesis, hydroxylation and nitrogen fixation to name but a fewThe single-iron proteins in this class, the rubredoxins, have been studied extensively by chemical, spectroscopic and X-ray crystallographic techniques (Lovenberg, 1973), and the active site is composed of a single iron atom bound in a distorted tetrahedron of cysteine sulphur ligands The iron is high-spin ferric in the oxidized state and high-spin ferrous in the reduced state This structure is shown in Fig I (α)
140 citations
TL;DR: It is proposed that heme or an iron-protein complex blocks the action of the enzyme(s) governing the synthesis of delta-aminolevulinic acid in etiolated leaves in the dark and that iron chelators antagonize this inhibition, leading to the biosynthesis of delta'-dipyridyl acid and porphyrins.
Abstract: Primary leaves of 7- to 9-day-old etiolated seedlings of Phaseolus vulgaris L. var. Red Kidney infiltrated in darkness with aqueous solutions of α, α′-dipyridyl, o-phenanthroline, pyridine-2-aldoxime, pyridine-2-aldehyde, 8-hydroxyquinoline, or picolinic acid synthesize large amounts of magnesium protoporphyrin monomethyl ester and lesser amounts of magnesium protoporphyrin, protoporphyrin, and protochlorophyllide. Pigment formation proceeds in a linear manner for up to 21 hours after vacuum infiltration with 10 mm α, α′-dipyridyl. Etiolated tissues of Zea mays L., Cucumis sativus L., and Pisum sativum L. respond in the same way to dipyridyl treatment. Compounds active in eliciting this response are aromatic heterocyclic nitrogenous bases which also act as bidentate chelators and form extremely stable complexes with iron; other metal ion chelators, such as ethylenediaminetetraacetic acid, salicylaldoxime, and sodium diethyldithiocarbamate, do not elicit any pigment synthesis. The ferrous, ferric, cobaltous, and zinc chelates of α, α′-dipyridyl are similarly ineffective. If levulinic acid is supplied to etiolated bean leaves together with α, α′-dipyridyl, porphyrin production is inhibited and δ-aminolevulinic acid accumulates in the tissue. Synthesis of porphyrins proceeds in the presence of 450 micrograms per milliliter chloramphenicol or 50 micrograms per milliliter cycloheximide with only partial diminution. We propose that heme or an iron-protein complex blocks the action of the enzyme(s) governing the synthesis of δ-aminolevulinic acid in etiolated leaves in the dark and that iron chelators antagonize this inhibition, leading to the biosynthesis of δ-aminolevulinic acid and porphyrins.
138 citations
TL;DR: Soybean lipoxygenase has now been shown to contain approximately 1 atom of iron per molecule, and all of the isoenzymes exhibit structure-less optical absorption spectra, detectable at 700 nm, and increasing continuously toward the blue.
136 citations
TL;DR: EPR and magnetic susceptibility measurements reported here indicate that in the pH range 1–11, the oxidized form of the protein can exist in four magnetically distinguishable states, quite similar in magnetic properties to the acid forms of metmyoglobin and methemoglobin.
129 citations
TL;DR: It was possible to picture simple models showing structural relations between five oxidation-reduction states of peroxidase.
112 citations
TL;DR: In this paper, the sorption of iodide by several soil component materials was examined over a range of pH values and compared with sorption by a surface soil A compost, prepared from grass roots which had been allowed to decompose for 24 weeks, showed changes in sorption, due to pH and drying, similar to those shown by the soil.
Abstract: The sorption of iodide by several soil component materials was examined over a range of pH values and compared with sorption by a surface soil A compost, prepared from grass roots which had been allowed to decompose for 24 weeks, sorbed substantial amounts of iodide from solution and showed changes in sorption, due to pH and drying, similar to those shown by the soil Freshly precipitated hydrated ferric oxide also sorbed substantial amounts of iodide from solutions of pH < 55 but the amount decreased to zero as the pH approached 7 Sorption by freshly precipitated hydrated aluminium oxide was impossible to assess at pH < 5 owing to its solubility but at pH 55 to 75 its sorption was similar to that of ferric oxide No sorption of iodide was detected by kaolinite, montmorillonite, chalk or limestone
Drying markedly reduced the capacity for iodide sorption of the compost and soil and had a smaller effect on the ferric and aluminium oxides
96 citations
TL;DR: The b-type cytochrome P-450cam in the active ferric form, purified from camphor-grown Pseudomonas putida, has a Soret absorption band at 417 nm, and on addition of CO, to 446 nm.
83 citations
TL;DR: In this article, it was shown that ferromagnetic iron metal is formed in reduced PdFeAl2O3 catalysts as a result of the diffusion of hydrogen over the support surface from palladium particles to an oxide of iron.
79 citations
Journal Article•
TL;DR: It is demonstrated that changes in iron metabolism induced by bacterial endotoxin are a key factor in the mechanism of resistance to C. albicans infection in mice.
Abstract: Studies using an experimental model of the mouse and Candida albicans as the challenge organism attempted to define better the mechanism of nonspecific resistance to infection induced by bacterial endotoxins. In vitro studies showed a positive correlation between the growth of C. albicans in serum from mice obtained at daily intervals for 10 days after endotoxin or saline injection and the percentage iron saturation of the serum. In vivo studies in which one of four different concentrations of iron as ferric ammonium citrate was injected into control and endotoxin-treated mice at the time of challenge with C. albicans showed that the rate of mortality of the mice was directly related to the concentration of iron injected. The endotoxin-induced nonspecific resistance was negated and reversed by iron administration. These studies demonstrate that changes in iron metabolism induced by bacterial endotoxin are a key factor in the mechanism of resistance to C. albicans infection in mice.
Patent•
01 Apr 1974
TL;DR: Titanium dioxide is recovered from ilmenite in high purity and high yield as mentioned in this paper, where the ore is leached with concentrated hydrochloric acid at room temperature to dissolve at least 80% of the titanium and iron values of the ore and to leave gangue material substantially undissolved.
Abstract: Titanium dioxide is recovered from ilmenite in high purity and high yield. The ore is leached with concentrated hydrochloric acid at room temperature to dissolve at least 80% of the titanium and iron values of the ore and to leave gangue material substantially undissolved. After separation from solid gangue material and conversion of ferric iron to ferrous iron, the titanium chlorides are hydrolyzed and titanium oxyhydrate is precipitated. A substantial proportion of the ferrous chloride may be removed from the solution by crystallization prior to the hydrolysis of the titanium chlorides. The titanium oxyhydrate, after separation from the mother liquor, and purified, if necessary to remove traces of ferric materials, is dried and converted into substantially pure pigment grade titanium dioxide. The iron values may be recovered from the mother liquor and a closed hydrochloric acid cycle may be established.
TL;DR: Observations indicate that superoxide anion radical is an intermediate in the reduction of iron by xanthine oxidase in vitro but not in vivo.
Abstract: Superoxide dismutase exerted a pronounced inhibitory effect upon xanthine oxidase-mediated reduction of iron in ferritin, ferric chloride, or ferric ADP. Maximal inhibition was observed when the superoxide dismutase concentration was only about 1% of that found in normal porcine liver. These observations indicate that superoxide anion radical is an intermediate in the reduction of iron by xanthine oxidase in vitro but not in vivo.
TL;DR: In this paper, two quadrupole doublets were found at room temperature, one ferrous, the other largely ferric, and their intensity ratio is related to the crystallinity of the sediments, which is correlated with oxygen content, and inversely correlated with ferrous iron content of the overlying water.
Abstract: Dried surface sediment from various Canadian lakes was characterized by X-ray diffraction and Mossbauer spectroscopy. At most two quadrupole doublets were found at room temperature, one ferrous, the other largely ferric. Their intensity ratio is related to the crystallinity of the sediments. It is also correlated with oxygen content, and inversely correlated with ferrous iron content of the overlying water. The major iron phase in the sediments is X-ray amorphous ferric hydroxide. Chlorite is the major ferrous mineral.
TL;DR: It was concluded that crude common salt could be fortified with 0.1% iron as FePO, and 1.25% ascorbic acid and stored under all but the most extreme tropical conditions, and that such fortification would significantly improve the iron nutrition in countries where the staple food is rice or maize.
Abstract: Summary. Common salt fortified with ascorbic acid or iron compounds became discoloured on storage, the reaction being accelerated by heat and humidity. Soluble iron compounds such as FeSO4 caused discoloration more readily than insoluble compounds such as ferric orthophosphate (FePO4). Fortification with both ascorbic acid and iron led to more rapid discoloration than fortification with either alone. Colour developed more rapidly in coarse salt than in refined commercial salt, while chemical NaCk developed a faint discoloration only under very hot and humid conditions. Discoloration was inhibited if starch was mixed with the salt: coarse salt mixed with 2.5% starch, 1.25% ascorbic acid and 0.1% iron as FePOI retained an acceptable appearance during storage under subtropical conditions (Durban) for more than I yr. A double isotope red cell utilization method was employed to assess the absorption of iron from maize porridge and from a standard rice meal cooked with fortified salt. The absorption of both the intrinsic food iron and the iron in the fortified salt was increased threefold if the salt contained 50 mg ascorbic acid as well as FePO4. The amount of iron absorbed was similar whether the salt contained 50 mg ascorbic acid and 4 mg iron as FePO4 or 50 mg ascorbic acid and 4 mg iron as FeSO4. It was concluded that crude common salt could be fortified with 0.1% iron as FePO, and 1.25% ascorbic acid and stored under all but the most extreme tropical conditions, provided that 2.5% starch was added to prevent the development of discoloration, and that such fortification would significantly improve the iron nutrition in countries where the staple food is rice or maize.
TL;DR: In this article, the reactions of trialkylboranes with ferric chloride and thiocyanate in an aqueous tetrahydrofuran solution give the corresponding alkyl chlorides and thIocyanates in good yields.
Abstract: The reactions of trialkylboranes with ferric chloride and thiocyanate in an aqueous tetrahydrofuran solution give the corresponding alkyl chlorides and thiocyanates in good yields. It was found that two equivalents of ferric salts per alkyl group of organoborane are required, and not only the first alkyl group of trialkylborane but other alkyl groups are also used.
TL;DR: A modification of the EDTA method of determining ion activities in soil developed by Norvell was used to measure the solubility of various ferric hydroxides as mentioned in this paper, which gave pK° values of 39.02 ±.35 and 42.48 ±.23, respectively.
Abstract: A modification of the EDTA method of determining ion activities in soil developed by Norvell was used to measure the solubility of various ferric hydroxides. The solubility products of jarosite (KFe₃(SO₄)₂(OH)₆) and amorphous Fe(OH)₃ were also determined on a natural jarosite nodule taken from an acid sulphate soil. For amorphous ferric hydroxide and lepidocrocite, the method gave pK° values of 39.02 ± .35 and 42.48 ± .23, respectively. Hematite and goethite were too inert to yield reproducible solubilities. For a mixture of jarosite and ferric hydroxide, the respective pK° values were 98.56 and 39.93. These values were used to develop an Eh-pH stability diagram that helps to explain the occurrence of jarosite under acid oxidizing conditions in soils.
Journal Article•
TL;DR: In this article, the generation and removal of optical absorption bands in natural amethyst and in synthetic a-quartz doped with either Fe'* or Fe\"* ions has been surveyed.
Abstract: The generation and the removal of the various optical absorption bands in natural amethyst and in synthetic a-quartz doped with either Fe'* or Fe\"* ions has been surveyed. Fositive rhombohedral growth regions of synthetic a-qvattz containing Fe'* ion proved to be related to the generation of the amethyst color upon treatment with ionizing radiation. It is believed that the interstitial Fe'* ions in voids perpendicular to positive rhombohedral faces furnish charge compensation for substitutional Fe\"* ion. This combination is the precursor of several color centers responsible for the production of the amethyst color.
TL;DR: A Raman study of FCHH in 11.5M HCl solutions has shown the presence of tetrahedral FeCl4− ion as the most prominent species as discussed by the authors.
Abstract: A Raman study of ferric chloride hexadydrate (FCHH) in 11.5M HCl solutions has shown the presence of tetrahedral FeCl4− ion as the most prominent species. An appreciable concentration of a polymeric species, which is composed of higher chloroferrate groups of the type FeCl5 · H2O, and a small concentration of lower chloro‐aquoferrate complex ion of the type Fe(H2O)4Cl2+ are also present in the solutions. The saturation of FCHH‐11.5M HCl solution with dry HCl is observed to convert both the polymeric species and the lower chloro‐aquoferrate ions into FeCl4− ions. In hydrated ferric chloride melts the most prominent species exists in the form of tetrahedral FeCl4− ion along with an appreciable concentration of Fe(H2O)4Cl2+ ion. Hydrated ferric chloride melts saturated with LiCl or dry HCl gas, contains only FeCl4− ions. In the case of moderately acidic (≤ 6M HCl) ferric chloride solutions Raman evidence has revealed the presence of a polymeric species along with significant concentrations of lower chloro‐aq...
TL;DR: In testing the ability of ferricyanide to prevent the azo-coupling reactions of enterochromaffin cells and of the noradrenaline islets of the adrenal medulla, ferricianide proved to be an effective oxidant in alkaline solution, but failed to quinonize the two catechols below pH 6.5.
Abstract: The ferric ferricyanide reaction has been generally considered to depend on the reduction of ferricyanide to ferrocyanide and, in the presence of the ferric ion, the consequent production of Prussian Blue. In testing the ability of ferricyanide to prevent the azo-coupling reactions of enterochromaffin cells and of the noradrenaline islets of the adrenal medulla, ferricyanide proved to be an effective oxidant in alkaline solution, but failed to quinonize the two catechols below pH 6. Similar results are obtained in oxidative blocking of cutaneous sulphydryl sites against the ferric ferricyanide reaction and against staining by the mercaptide acid azo-coupling reaction of Lillie & Glenner (1965). Ferric ferricyanide solutions are used at pH 2–2.5 and the ferric ion is an effective quinonizing and thiol-oxidizing agent at this pH level; the ferricyanide ion is not. The ferric ferricyanide reaction depends on the reduction of ferric to ferrous ions in the presence of ferricyanide, with the production of Turnbull's Blue.
TL;DR: A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO(4) (2+) and hydrogen ion concentrations.
Abstract: A method for direct, continuous determination of ferric ions produced in autotrophic iron oxidation, which depends upon the measurement of ferric ion absorbance at 304 nm, is described. The use of initial rates is shown to compensate for such changes in extinction during oxidation, which are due to dependence of the extinction coefficient on the ratio of complexing anions to ferric ions. A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO(4) (2+) and hydrogen ion concentrations. Some examples are discussed of the applicability of these methods to study of the rates of ferrous ion oxidation related to sulfate concentration.
Patent•
10 Sep 1974
TL;DR: In this article, the purity of titanium dioxide obtained by the acid leaching of a titaniferous iron ore, such as ilmenite, is improved by heating the ore prior to acid extraction with a reducing agent mixture of a carbonaceous reducing agent and/or hydrogen and sulfur to convert and lower the ferric oxide contaminant content of the ore to acid-soluble ferrous oxide and ferrous sulfide.
Abstract: The purity of titanium dioxide obtained by the acid leaching of a titaniferous iron ore, such as ilmenite, is improved by heating the ore prior to acid leaching with a reducing agent mixture of (a) a carbonaceous reducing agent and/or hydrogen and (b) sulfur to convert and lower the ferric oxide contaminant content of the ore to acid-soluble ferrous oxide and ferrous sulfide.
TL;DR: In this paper, the redox behavior of Fe(III) porphyrins and hemipeptides has been investigated polarographically as a fonction of axial coordination in dimethylformamide.
TL;DR: In this paper, the chelation of iron by D -gluctose and D -glucose led to definable conditions for the preparation of ferric- D -fructose and ferric D -lucose-D -fructose complexes that could be isolated and redissolved to give neutral solutions.
Patent•
14 Nov 1974
TL;DR: In this article, a separator between the anolyte and catholyte compartments of the electrolytic cell is introduced to prevent passage of ions of copper and iron between the catholytes and anolytes, and the residue is treated with regenerated ferric chloride of a concentration to insure there is no cuprous copper in the resulting solution.
Abstract: An improvement in the process for recovering copper from its sulfide ores or concentrates thereof which comprises treating the ore with cupric chloride and/or ferric chloride to form a copper chloride electrolyte and a residue, electrolytically recovering copper from the electrolyte and further treating the residue with ferric chloride to solubilize substantially all of the copper remaining therein for conversion to copper chloride electrolyte, with ferrous chloride from the electrolyte being regenerated to ferric chloride for leaching the residue, the improvement which comprises conducting the electrolysis without the conversion of any cuprous copper to cupric copper, using a separator between the anolyte and catholyte compartments of the electrolytic cell to prevent passage of ions of copper and iron between the catholyte and anolyte, continuously further treating the residue with regenerated ferric chloride of a concentration to insure there is no cuprous copper in the resulting solution and regenerating ferric chloride from ferrous chloride in the solution free of cuprous chloride by passing the solution through the anolyte compartment of the electrolytic cell as copper is continuously being recovered at the cathode of the cell.
TL;DR: In this article, 1-hydroxy-1-methylethyldioxyl radicals react with oxygen with a rate constant of 4.5 ± 0.9 J °C−1 mol−1.
Abstract: 1-Hydroxy-1-methylethyl radicals react with oxygen with a rate constant of 4.5 ± 0.5 × 109 dm3 mol–1 s–1. The resulting dioxyl radicals react with ferrous ions with a rate constant at 25°C of 1.7 ± 0.2 × 106 dm3 mol–1 s–1, entropy of activation + 99 J °C–1 mol–1. Pulse radiolysis data are consistent with the product of the reaction being a complex, Fe3+RO–2, which is in equilibrium with a bridge compound, Fe3+RO–2Fe2+. The complex disappears in a first order manner with a rate constant at 25°C of 3.85 ± 0.15 × 103 s–1, entropy of activation –82 J °C–1 mol–1. The bridge compound disappears in a first order manner with a rate constant at 25°C of 2.1 ± 0.1 × 104 s–1, entropy of activation –0.9 J °C–1 mol–1. The 1-hydroxy-1-methylethyldioxyl radical has a weak absorption with a peak at 250 nm. Fe3+RO–2 has a weak absorption extending through the visible region of the spectrum. Fe3+RO–2Fe2+ has a stronger absorption with a broad peak at 320 nm. 1-Hydroxy-1-methylethyl radicals react with ferric ions with a rate constant of 4.5 ± 0.5 × 108 dm3 mol–1 s–1.
01 Jan 1974
TL;DR: An understanding of iron transport in the phenolate-producing organism Bacillus subtilis is hampered by lack of information on possible synthesis of a trimer of 2, 3-dihydroxybenzoylglycine.
Abstract: Publisher Summary This chapter focuses on iron transport in gram-positive and acid-fast bacilli. The need for continued flow of iron into rapidly dividing cells, together with the pronounced tendency of iron to form unavailable complexes at environmental conditions preferred by most biological species, have required microbial cells to construct unique iron-gathering systems. Many microorganisms release chelating agents with a high and specific affinity for iron, and they can recognize and transport the resulting iron chelate into or across the lipid-protein boundary of the cell. In Bacillus megaterium, which produces the ferric chelating secondary hydroxamate schizokinen, transport of iron as the schizokinen-iron chelate appears to be the primary mode of iron uptake. The iron transport cofactor produced by the mycobacteria is unusual in that it is the only known natural secondary hydroxamate that is soluble in lipid solvents. Moreover, mycobactin is not excreted by the cells and is probably bound in the membrane fraction. An understanding of iron transport in the phenolate-producing organism Bacillus subtilis is hampered by lack of information on possible synthesis of a trimer of 2, 3-dihydroxybenzoylglycine. The cells release a ferric chelating secondary hydroxamate, which binds iron, and the ferric hydroxamate is bound and transported into the cells by a special hydroxamate transport system within the membrane.