Ferric Acetate Research Articles

Hydrazine-Assisted, Low-Temperature Aerosol Pyrolysis Method to Synthesize γ-Fe2O3

Oxides of iron in different crystalline forms such as hematite, maghemite, and magnetite have been used in number of industrial and biomedical applications in recent years. These materials are often synthesized in multiple-step processes in which simultaneous control of particle size, shape, morphology, and crystallinity is difficult. A single-step, low-temperature spray pyrolysis of iron precursors with hydrazine in a furnace aerosol reactor (FuAR) is described. To help select viable precursors and guide selection of operating conditions for the aerosol process, hydrazine derivatives of iron precursors are prepared in batch and analyzed with TGA, FTIR, and XRD. These results were also used to identify the chemical formula of hydrazinated precursors and elucidate the reaction pathway for the precursors such as ferrous acetate, ferric nitrate, and ferrous oxalate that are suitable for single-step aerosol reactor synthesis. These iron precursors are aerosolized and reacted in situ with hydrazine vapor to demonstrate the single-step, low-temperature production of metarstable γ-Fe2O3. Structurally similar cubic intermediates (FeO, Fe3O4, γ-FeOOH·H2O) are the key decomposition intermediates observed during the synthesis of γ-Fe2O3. It is shown that hydrazinated iron precursors decompose at a lower temperature compared to the same unhydrazinated precursors to produce pure γ-Fe2O3. The localized exothermal reaction of hydrazine released from the hydrazinated precursor with oxygen along with a controlled supply of energy assists in the production of the metastable γ-Fe2O3. Hydrazine oxidation releases moisture and nitrogen as reaction byproduct, which further enhances the stability of γ-Fe2O3.

Highly efficient catalytic system for hydrosilylation of ketones with iron(II) acetate–thiophenecarboxylate

A combination of a catalyst derived from ferrous acetate and sodium thiophene-2-carboxylate efficiently promoted hydrosilylation of aromatic and aliphatic ketones to give the corresponding secondary alcohols in high yields with extremely high selectivity.

Crystal structure and ligand binding properties of the truncated hemoglobin from Geobacillus stearothermophilus

A novel truncated hemoglobin has been identified in the thermophilic bacterium Geobacillus stearothermophilus (Gs-trHb). The protein has been expressed in Escherichia coli, the 3D crystal structure (at 1.5 Å resolution) and the ligand binding properties have been determined. The distal heme pocket displays an array of hydrogen bonding donors to the iron-bound ligands, including Tyr-B10 on one side of the heme pocket and Trp-G8 indole nitrogen on the opposite side. At variance with the highly similar Bacillus subtilis hemoglobin, Gs-trHb is dimeric both in the crystal and in solution and displays several unique structural properties. In the crystal cell, the iron-bound ligand is not homogeneously distributed within each distal site such that oxygen and an acetate anion can be resolved with relative occupancies of 50% each. Accordingly, equilibrium titrations of the oxygenated derivative in solution with acetate anion yield a partially saturated ferric acetate adduct. Moreover, the asymmetric unit contains two subunits and sedimentation velocity ultracentrifugation data confirm that the protein is dimeric.

Preparation of superhydrophilic α-Fe 2O 3 nanofibers with tunable magnetic properties

The paper describes a simple, effective method for producing α-Fe 2O 3 nanofibers by electrospun poly(vinyl alcohol)/ferrous acetate composite nanofibers precursors and high-temperature calcination in air. The experimental results show that the morphology and crystalline phase of α-Fe 2O 3 nanofibres are influenced by the content of ferrous acetate in composite nanofibres and the calcination temperature. The α-Fe 2O 3 nanofibres can generate superhydrophilic surface displaying the contact angle of water as 0°. By controlling the calcination temperature of electrospun composite nanofibers in the air, the magnetic property of α-Fe 2O 3 nanofibres could be tuned from superparamagnetic to ferromagnetic.

More on the poly(L‐lactide) prepared using ferrous acetate as catalyst

AbstractPolylactides were prepared by ring‐opening polymerization (ROP) in bulk using as catalyst either stannous 2‐ethylhexanoate at a monomer to catalyst ratio of 2000, or ferrous acetate (Fe(OAc)2) at monomer to catalyst ratios of 500, 1000, 2000 and 3000. The crystallization behaviour was studied for the prepared polymers as well as the degradation behaviour both in laboratory and natural compost environments by using differential scanning calorimetry, size exclusion chromatography, X‐ray diffractiometry and microscopy. No differences were apparent due to the choice or amount of catalyst used, except for those which could be related to the increased racemization when the Fe(OAc)2 was used. Copyright © 2004 Society of Chemical Industry

Blends of poly(ε‐caprolactone‐b‐lactic acid) and poly(lactic acid) for hot‐melt applications

AbstractThe condensation reaction product of poly(lactic acid) (PLA) and a hydroxyl‐terminated four‐armed poly(ε‐caprolactone) (PCL) was studied by size‐exclusion chromatography, DSC, and NMR. The use of both L‐lactic acid (LLA) and rac‐lactic acid (rac‐LA) was studied and the use of two different catalysts, stannous 2‐ethylhexanoate [Sn(Oct)2] and ferrous acetate [Fe(OAc)2], was also investigated. The thermal stability and adhesive properties were also measured for the different formulations. The characterization results suggested the formation of a blend of PLA and a block‐copolyester of PLA and PCL. The results further indicated partial miscibility in the amorphous phase of the blend showing only one glass‐transition temperature in most cases, although no randomized structures could be detected in the block‐copolymers. The polymerization in the Fe(OAc)2‐catalyzed experiments proceeded slower than in the Sn(Oct)2‐catalyzed experiments. The discoloring of the polymer was minor when Fe(OAc)2 was used as catalyst, but significant when Sn(Oct)2 was used. The ferrous catalyst also caused a slower thermal degradation. Differences in the morphology and in the adhesive properties could be related to the stereochemistry of the poly(lactic acid). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 196–204, 2004

A modified mordant technique for staining plant chromosomes.

The ability to produce ferric acetate in house has provided a new mordant source for use in Newcomer's fluid (6:3:1:1:1 isopropanol, propionic acid, acetone, petroleum ether, 1,4-dioxane) for species with small chromosomes. This method improves on one first published in 1970.

A mechanistic model on methane oxidation in a rice rhizosphere

A mechanistic model is presented on the processes leading to methane oxidation in rice rhizosphere. The model is driven by oxygen release from a rice root into anaerobic rice soil. Oxygen is consumed by heterotrophic and methanotrophic respiration, described by double Monod kinetics, and by iron oxidation, described by a second order reaction. Substrates for these reactions - ferrous iron, acetate and methane - are produced by an exponential time dependent organic matter mineralisation in combination with modified Michaelis Menten kinetics for competition for acetate and hydrogen. Compounds diffuse between rhizosphere, root and atmosphere. A diffusion resistance between the rice root and shoot is included. Active transport across the root surface occurs for root exudation and plant nutrient uptake. Iron adsorption is described dependent on pH. The model predicts well root oxygen release, compound gradients and compound concentrations in a rice rhizosphere. Methane oxidation estimates are comparable to experimental estimates. A sensitivity analysis showed however that methane oxidation is highly dependent on model initialisation and parameterisation, which is highly dependent on the history of the rhizosphere and root growth dynamics. Equi- librium is not obtained within the period that a single root influences a soil microsite and results in a large change in methane storage. Equilibrium is moreover dependent upon the diffusion resistance across the root surface. These factors make methane oxidation dynamics highly variable in space and time and dependent on root dynamics. The increased under- standing of methane oxidation does not directly lead to increased predictive abilities, given this high variability and the uncertainties involved in rhizosphere dynamics.

Characterization of recombinant soybean leghemoglobin a and apolar distal histidine mutants

The cDNA for soybean leghemoglobin a (Lba) was cloned from a root nodule cDNA library and expressed in Escherichia coli. The crystal structure of the ferric acetate complex of recombinant wild-type Lba was determined at a resolution of 2.2 Å. Rate constants for O2, CO and NO binding to recombinant Lba are identical with those of native soybean Lba. Rate constants for hemin dissociation and auto-oxidation of wild-type Lba were compared with those of sperm whale myoglobin. At 37°C and pH 7, soybean Lba is much less stable than sperm whale myoglobin due both to a fourfold higher rate of auto-oxidation and to a ∼600-fold lower affinity for hemin. The role of His61(E7) in regulating oxygen binding was examined by site-directed mutagenesis. Replacement of His(E7) with Ala, Val or Leu causes little change in the equilibrium constant for O2 binding to soybean Lba, whereas the same mutations in sperm whale myoglobin cause 50 to 100-fold decreases in KO2. These results show that, at neutral pH, hydrogen bonding with His(E7) is much less important in regulating O2 binding to the soybean protein. The His(E7) to Phe mutation does cause a significant decrease in KO2 for Lba, apparently due to steric hindrance of the bound ligand. The rate constants for O2 dissociation from wild-type and native Lba decrease significantly with decreasing pH. In contrast, the O2 dissociation rate constants for mutants with apolar E7 residues are independent of pH, suggesting that hydrogen bonding to the distal histidine residue in the native protein is enhanced under acid conditions. All of these results support the hypothesis that the high affinity of Lba for oxygen and other ligands is determined primarily by enhanced accessibility and reactivity of the heme group.

A Hexairon(III) Complex with Three Nonplanar η2-μ4-Peroxo Ligands Bridging Two Basic Iron Acetate Units

The novel η2-μ4-peroxo hexairon(III) complex, [Fe6(O)2(O2)3(OAc)9]-, was prepared as its [Fe3O(OAc)6(H2O)3]+ salt by addition of H2O2 to basic iron acetate in the presence of NaOCH3. The compound [Fe3O(OAc)6(H2O)3][Fe6(O)2(O2)3(OAc)9]·8H2O crystallizes in the hexagonal space group, P63/m with unit cell parameters of a = 14.276(5), c = 18.935(3) A, V = 3342.0(1) A3, and Z = 2; the structure was solved and refined to a final residual of R = 0.044. The anionic component of the salt contains two trinuclear {Fe3O}7+ units arranged in a face-to-face manner. The resulting trigonal prism has η2-μ4-peroxo ligands bridging each rectangular face and η2-μ2-acetates bridging each edge of the rectangular and triangular faces. Two distinguishing structural features are an elongated O−O bond distance of 1.472(9) A for the bridging peroxo ligand and significant displacement of this group by 1.05 A out of the plane of the four iron atoms that it links. The νO-O stretching mode is readily observed by Raman spectroscopy at 8...

On the Reduction of Basic Iron Acetate: Isolation of Ferrous Species Mediating Gif-Type Oxidation of Hydrocarbons

On the Reduction of Basic Iron Acetate: Isolation of Ferrous Species Mediating Gif-Type Oxidation of Hydrocarbons

Synthesis, Structure, and Electronic Properties of a Mixed-Valent Dodecairon Oxo Complex, a Model for the Biomineralization of Ferritin

The mixed-valent polyiron oxo complex [Fe III 4 Fe II 8 (O) 2 (OMe) 18 (OAc) 6 (MeOH) 4.67 ] (1) was prepared through the controlled oxidation of a methanol solution of ferrous acetate and lithium methoxide. The structure of 1, revealed in a single-crystal X-ray diffraction experiment, consists of a face-centered cubic array of oxygen atoms with iron(II) and iron(III) ions in the octahedral interstices. Two μ 6 -oxo ligands, to which ten of the twelve from atoms are coordinated, form the core of the structure. The iron atoms have distorted octahedral coordination geometries with oxo, methoxide, methanol, and acetate ligands

Evaluation of cation-exchange iron for catalytic liquefaction of a subbituminous coal

The total conversion and the oil yield in liquefaction tests of iron ion-exchanged Black Thunder coal were found to increase by up to 23 and 18 %, respectively, relative to the untreated coal. The ion-exchanged coal samples were prepared by stirring a slurry mixture of the coal and ferric acetate [Fe(OOCCH 3 ) 3 ] ina 10-L fermenter. The ion-exchange process, in which iron was exchanged primarily for calcium and magnesium, yielded a highly dispersed catalytic iron species for coal liquefaction. 57 Fe Mossbauer and X-ray absorption fine structure (XAFS) spectroscopies and electron probe microanalysis (EPMA) X-ray mapping were used to characterize this iron species after the ion-exchange process. The results indicate that the added iron is present in bimodal form

Liquefaction of lignite containing cation-exchanged iron

A significant enhancement of the liquefaction yields and desirable products from two lignites has been achieved by incorporating iron in the lignites by an ion-exchange process. The total conversion of iron ion-exchanged Hagel and Beulah lignites was found to increase by up to 25% and the oil yield by 10% relative to the untreated lignites. The ion-exchanged lignites were prepared by stirring a slurry mixture of the lignite and ferric acetate [Fe(OOCCH 3 ) 3 ] in a 10-L fermenter. The ion-exchange process, in which iron was exchanged primarily for calcium, yielded a highly dispersed catalytic iron species for coal liquefaction

An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300°C

The formation of the monochloroiron(II) complex, FeCl +, was studied potentiometrically from 125 to 295°C at 25 degree intervals at one molal ionic strength in aqueous solutions containing acetic acid, sodium acetate, and sodium trifluoromethanesulfonate. In this method, competition between chloride and acetate ions for the ferrous cation resulted in a change in solution pH, which in turn was monitored in situ in a hydrogen-electrode, concentration cell. A simple empirical approach was used to extrapolate these formation quotients to infinite dilution. The resulting constants proved to be in excellent agreement with previous spectrophotometric results obtained from 25 to 200°C. Thus, the present study confirms the validity of the conclusions made based on these earlier data concerning the solubility of Fe-containing minerals in hydrothermal brines. Formation constants at infinite dilution for FeCl + are compared with the stability of ferrous acetate and hydroxide complexes. The original potentiometric titration data for ferrous acetate complex formation were combined in a new fit with values determined from the present study at unit ionic strength. Two empirical treatments (namely the isocoulombic method and the temperature/water density function) were considered for fitting and extrapolating the infinite dilution formation constants to 350°C.

A Mixed-Valent Polyiron Oxo Complex that Models the Biomineralization of the Ferritin Core

A novel polyiron oxo complex, [FeIII4FeII8(O)2(OCH3)18(O2CCH3)6(CH3OH) 4.67] (1), has been prepared from ferrous acetate and lithium methoxide in methanol by slow addition of dioxygen. The three-dimensional close-packed layered structure found in 1 closely mimics that proposed for the inorganic core in the iron storage protein ferritin. The Mössbauer spectra of 1 reveal superparamagnetic relaxation at temperatures below 15 K, a property characteristic of the ferritin core. The small size and mixed-valent nature of 1 suggest that it is a reasonable model for intermediates formed in the biomineralization of iron during ferritin core formation. A related compound, with the same iron-oxygen framework found in 1 but containing only two ferric ions, has also been structurally characterized. Because the clusters exhibit properties of both discrete molecules and extended solids, they are representative of a new class of nanometer-sized compounds that bridge the molecular solid-state boundary.

"Ferric wheel" molecule characterized at MIT

Sometimes chemistry is fun just because molecules are beautiful. At Massachusetts Institute of Technology, chemistry professor Stephen J. Lippard and graduate student Kingsley L. Taft have discovered such a molecule. has no known utility, but it sure is pretty. They call it a molecular ferric wheel. The molecule, [Fe(OCH 3 ) 2 (O 2 CCH 2 - Cl)] 10 , is a decairon molecule that forms a nearly perfect circle [ J. Am. Chem. Soc. , 112 , 9629 (1990)]. assembles spontaneously in methanolic solutions of diiron(III) oxo complexes that Lippard and Taft are studying. The studies are part of a research program to elucidate the chemistry of polyiron oxo protein cores such as those that occur in the proteins hemerythrin, ribonucleotide reductase, methane monooxygenase, and ferritin. We were not trying to make this particular compound, Lippard says. It was a completely serendipitous discovery. The compound was prepared by allowing the monochloroacetate analog of basic iron acetate, [Fe 3 O(O 2 -CCH 2 Cl) 6...

Effect of Extrusion on Lipid Oxidation

ABSTRACTTo examine extrusion temperature effects on oil stability, corn meal/ starch with soybean oil was extruded, frozen immediately in liquid nitrogen, freeze‐dried and ground. The conjugable oxidation products (COP), oxodiene values (OV), peroxide values (PV) and conjugated dienes were determined during storage. There was an increase in COP, OV, PV, and conjugated dienes with an increase in extrusion temperature. An increase in transition metal content, particularly iron, occurred with an increase in extrusion temperature. Starch and soybean oil were extruded with 50 ppm ferrous acetate (dry weight) and 50 ppm butylated hydroxyanisole (BHA) (oil weight). Ferrous acetate reduced the oxidation relative to the control, which contained neither antioxidant nor iron, and relative to the sample containing BHA.

Potentiometric determination of the molal formation constants of ferrous acetate complexes in aqueous solutions to high temperatures

The formation quotients of ferrous acetate complexes were determined in aqueous solutions from 50 to 295/degrees/C at ionic strengths of 0.03, 0.1, 0.3, and 1.0 m using sodium trifluoromethanesulfonate as the supporting electrolyte. The potentiometric titrations were carried out in a Teflon-lined concentration cell fitted with hydrogen electrodes. Three complexes, namely, Fe(CH/sub 3/COO)/sub n//sup 2-n/, where n = 1, 2, and 3, were identified by regressional analysis of the data. The relevant thermodynamic quantities were calculated for the first two species.

Spectrophotometric evaluation of interferences in three iron reactions for the determination of serum total cholesterol

A spectrophotometric and chemical evaluation of reported interferences for three iron reactions for the determinations of serum cholesterol has been presented. It has been shown that all three reactions are affected by various interfering substances, such as 2-thiouracil, nitrate, azide, bromide, diethylstilbesterol, and steroids. Spectral differences between the reactions are probably due to solvent and anion effects. The incorporation of uranyl acetate as a precipitating agent into the ferric acetate-uranyl acetate procedure did not make the results obtained comparable with the Abell-type extract of a very icteric serum. Incorporation of ferrous sulfate does not noticeably affect the intensity or stability of color development with standards. As proposed, the ferric acetate-uranyl acetate procedure for the determination of cholesterol represents a modified iron reagent, but the reaction mechanism and the procedure described for it is neither new nor direct. The use of the ferric acetate reagent for serum cholesterol as opposed to ferric chloride, ferric ammonium chloride, or ferric perchlorate appears to have no real advantages as a color reaction. In fact the reaction is less sensitive while reagent preparation is more tedious, time consuming, and expensive than the ferric chloride procedure. Although no quantitative studies were performed, the only effects that chloride had on the reactions were in the region of 400 nm, a wavelength sufficiently far enough away from the 560-nm peak that it did not affect determinations. The concept that the ferric acetate-uranyl acetate reagent contains only acetate and sulfate anions is nullified as soon as one adds serum to the reagents.