Synthesis of nano‐niosomal deferoxamine and evaluation of its functional characteristics to apply as an iron‐chelating agent

Deferoxamine has been widely used as an iron‐chelating agent in patients with primary or secondary iron overload deficiency. Deferoxamine is typically administered subcutaneously, intramuscularly, or intravenously by the constant infusion of the drug over 8–12 h. This process is lengthy and uncomfortable for the patients. A nano‐niosomal form of deferoxamine was prepared using the reverse phase evaporation method and evaluated on the basis of morphology, drug release, cytotoxicity, and iron‐chelating efficacy to compare with free drug formulation. The unique structure of niosome enables sustained release of the drug over extended periods. The average particle size was 136 nm and the entrapment efficiency was about 96 %. The biocompatibility of the drug‐loaded nanoparticles showed that the encapsulation of the drug in nano‐niosomes reduces the toxicity of the drug significantly. Our results indicate that the iron‐chelating ability of the entrapped deferoxamine in hepatocytes is higher than the free drug. The nano‐niosomal drug form showed more efficacies versus the free one and it could be a promising clinical intravenous system for delivery of iron‐chelating drugs such as deferoxamine.     

Iron‐Catalyzed Synthesis of Allenes from 2‐Alken‐4‐ynoates and Grignard Reagents

Treatment of 2‐alken‐4‐ynoates with methyl‐ or aryl‐Grignard reagents and iron(II) chloride (10 mol%) afforded 5‐methyl‐ or 5‐aryl‐3,4‐alkadienoates in good yields as a single isomer after aqueous work‐up. Likewise, (2‐alken‐4‐ynoyl)oxazolidinones afforded (5‐methyl‐3,4‐alkadienoyl)oxazolidinones. The aldol‐type reaction with acetone was also possible in place of the hydrolytic work‐up.     

Iron‐Catalyzed Regioselective Oxo‐ and Hydroxy‐Phthalimidation of Styrenes: Access to α‐Hydroxyphthalimide Ketones

This paper describes the aerobic oxidation of styrenes catalyzed by iron(III) chloride (FeCl₃) to form β‐keto‐N‐alkoxyphthalimides in fair to good yields. This oxidative process employs mild conditions with green and atom efficient dioxygen (O₂) as the oxidant.

     

Scrap cast iron and copper‐modified cast iron for reductive degradation of 2,4‐dinitrotoluene

BACKGROUND: Little attention has been paid to the use of large‐sized scrap cast iron for reduction of refractory organic pollutants at neutral pH and in the presence of dissolved oxygen (DO). RESULTS: Scrap cast iron and copper‐modified cast iron with fresh surfaces have a high reactivity towards the reduction of 2,4‐dinitrotoluene (2,4‐DNT). The extent of conversion reached around 80% and 97% respectively, though it gradually decreased with repeated reactions to relatively stable values of 63% and 72%, and recovered once the reacted filings were cleaned by dilute acid. After 50 days reaction, no dissolved copper appeared in the copper‐modified cast iron process. The mass loss of copper due to physical detachment reached 1.1% of the total coated copper within the initial 20 reaction days, and only 0.3% appeared in the next 30 days. 2,4‐DNT oxidizes scrap cast iron to generate mainly FeFe₂O₄ with DO, however, it oxidizes scrap copper‐modified cast iron to generate mainly γ‐FeO(OH) and α‐FeO(OH). CONCLUSION: Both samples of cast iron were successfully applied in the treatment of neutral wastewater containing 2,4‐DNT with high reactivity and good repeatable efficiency. Electrode reaction rate was enhanced by the deposited copper, which has strong chemical and physical stability. Copyright © 2011 Society of Chemical Industry     

Assessment of aged biodegradable polymer‐coated nano‐zero‐valent iron for degradation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX)

BACKGROUND: This study reports on the effects of aging on suspension behavior of biodegradable polymer‐coated nano‐zero‐valent iron (nZVI) and its degradation rates of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) under reductive conditions. The polymers investigated included guar gum, potato starch, alginic acid (AA), and carboxymethyl cellulose (CMC). Polymer coating was used to mitigate nZVI delivery hindrance for in situ treatment of RDX‐contaminated groundwater. RESULTS: The RDX degradation rates by bare nZVI and starch‐coated nZVI suspensions were least affected by aging although these suspensions exhibited the least favorable dispersion behavior. CMC, AA, and guar gum coating improved nZVI rates of degradation of RDX but these rates decreased upon aging. The best suspension stability upon aging was achieved by CMC and AA. Guar gum with loadings rates one order of magnitude lower than that of CMC and AA achieved good iron stabilization but significantly higher RDX degradation rates. CONCLUSION: It is demonstrated that both migration and reactivity of polymer‐stabilized nZVI should be explicitly evaluated over a long period before application in the field. Guar gum coated nZVI appeared best suited for in situ application because it maintained good suspension stability, with RDX degradation rates least affected by aging compared with the other polymers tested. © 2012 Society of Chemical Industry     

Ethylene polymerization with iron‐based diimine catalyst supported on MCM‐41

A mesoporous molecular sieve MCM‐41 supported iron‐based diimine catalyst ( MC ) was prepared for the first time. The kinetic behavior of ethylene polymerization with MC was studied. The effects of Al/Fe molar ratio and various cocatalysts on the catalytic activity and properties of the polyethylene obtained were investigated. The results showed that good catalytic activities can be reached with cocatalyst methylaluminoxane (MAO) and triethylaluminium (TEA). Ethylene polymerization with MC gave polymers with higher molecular weight, melting temperature and onset temperatures of decomposition (T_onset) and better morphology than those obtained with the corresponding homogeneous catalyst. Copyright © 2004 Society of Chemical Industry     

Polymerisation of ethylene catalysed by mono‐imine‐2,6‐diacetylpyridine iron/methylaluminoxane (MAO) catalyst system: effect of the ligand on polymer microstructure

The complex, {1‐{6‐[(2,6‐diisopropylphenyl)‐ethaneimidoyl]‐2‐pyridinyl}‐1‐ethanone}iron(II) dichloride ( 2 ), has been synthesised and characterised. Treatment of complex 2 with methylaluminoxane resulted in a very active catalytic system for the preparation of polyethylene (PE). The system shows activities in the order of magnitude 10⁷ g (PE) mol^?1(Fe) h^?1 bar^?1. Characterisation by ¹³C NMR indicated that branched PE was obtained and that experimental conditions affect polymer microstructure. PE produced contained six to eight branches per 100 carbons. © 2002 Society of Chemical Industry     

Synthesis and characterization of poly(2‐hydroxyethyl methacrylate)‐functionalized Fe‐Au/core‐shell nanoparticles

Disulfide‐bearing poly(2‐hydroxyethyl methacrylate) (DT‐PHEMA) was synthesized by atom transfer radical polymerization technique, which was subsequently immobilized onto core‐shell structured Fe‐Au nanoparticles (Fe‐AuNPs) by applying a “grafting to” protocol to afford new PHEMA‐grafted Fe‐AuNPs (PHEMA‐g‐Fe‐AuNPs). The Fe‐AuNPs having the iron core of 20–22 nm and the gold layer of 1–2 nm were initially prepared by inverse micelle technique and characterized by XRD and high‐resolution transmission electron microscopy (HR‐TEM). The grafting of DT‐PHEMA on the Fe‐AuNPs was confirmed by Fourier transformed infrared spectrophotometer, thermogravimetric (TGA), X‐ray photoelectron spectroscopy, and energy dispersive X‐ray analyses. The average diameter of polymer coated Fe‐AuNPs was determined to be 28 nm by HR‐TEM analysis. The amount of the polymer on the surface of Fe‐AuNPs was calculated to be about 50% by TGA analysis. The studies of magnetic property by the superconducting quantum interference devices indicate the superparamagnetic property of Fe‐AuNPs and PHEMA‐g‐Fe‐AuNPs. The optical property of the PHEMA‐g‐Fe‐AuNPs was recorded by UV–visible absorption spectroscopy, and a redshift in the absorption was observed, which further suggests the PHEMA attachment on the surface of Fe‐AuNPs. The magnetic nanocomposites demonstrate good dispersibility in common polar solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhancing separation of titanium and iron by three‐liquid‐phase extraction with 1,10‐phenanthroline as additive

BACKGROUND: A three‐liquid‐phase system (TLPS) composed of an organic solvent‐rich top phase, a polymer‐rich middle phase and a salt‐rich bottom phase is a newly emerging separation medium. Due to low affinity of the polymer‐rich phase for metals it is necessary and important to search for a suitable complexing agent that has a definite affinity for the polymer‐rich middle phase and a high selectivity for the metal ion of interest. RESULTS: Addition of 1,10‐phenanthroline (phen) is effective in enhancing the separation of titanium and iron from magnesium in the TLPS consisting of trialkylphosphine oxide (TRPO)‐PEG 2000‐(NH₄)₂SO₄. Hydrogen‐bonding interactions between PEG 2000 and phen molecules are the driving force for anchoring tri(phen)‐iron(II) sulfate complexes in the middle phase. Under the conditions (pH = 1.5, molar ratio of phen to iron(II) = 3.4:1), nearly 86% of titanium was extracted into the top phase while 100% of iron(II) was distributed in the middle phase, without any interference between the metal species. The separation factor of titanium and iron in the upper two phases was greater than 20 000. CONCLUSIONS: A single step of extraction and separation of titanium and iron from magnesium was realized in the TRPO‐PEG 2000‐(NH₄)₂SO₄ TLPS with phen as additive. It highlights the effectiveness of TLPS in dealing with multi‐metal solutions and suggests a potential use of TLPS in the separation of iron and other target metals. As iron is ubiquitous the separation of iron is often needed in both analytical processes and the hydrometallurgical industry. Copyright © 2012 Society of Chemical Industry     

The Interaction of Isopenicillin N Synthase with Homologated Substrate Analogues δ‐(L‐α‐Aminoadipoyl)‐L‐homocysteinyl‐D‐Xaa Characterised by Protein Crystallography

Isopenicillin N synthase (IPNS) converts the linear tripeptide δ‐(L ‐α‐aminoadipoyl)‐L ‐cysteinyl‐D ‐valine (ACV) into bicyclic isopenicillin N (IPN) in the central step in the biosynthesis of penicillin and cephalosporin antibiotics. Solution‐phase incubation experiments have shown that IPNS turns over analogues with a diverse range of side chains in the third (valinyl) position of the substrate, but copes less well with changes in the second (cysteinyl) residue. IPNS thus converts the homologated tripeptides δ‐(L ‐α‐aminoadipoyl)‐L ‐homocysteinyl‐D ‐valine (AhCV) and δ‐(L ‐α‐aminoadipoyl)‐L ‐homocysteinyl‐D ‐allylglycine (AhCaG) into monocyclic hydroxy‐lactam products; this suggests that the additional methylene unit in these substrates induces conformational changes that preclude second ring closure after initial lactam formation. To investigate this and solution‐phase results with other tripeptides δ‐(L ‐α‐aminoadipoyl)‐L ‐homocysteinyl‐D ‐Xaa, we have crystallised AhCV and δ‐(L ‐α‐aminoadipoyl)‐L ‐homocysteinyl‐D ‐S‐methylcysteine (AhCmC) with IPNS and solved crystal structures for the resulting complexes. The IPNS:Fe^II:AhCV complex shows diffuse electron density for several regions of the substrate, revealing considerable conformational freedom within the active site. The substrate is more clearly resolved in the IPNS:Fe^II:AhCmC complex, by virtue of thioether coordination to iron. AhCmC occupies two distinct conformations, both distorted relative to the natural substrate ACV, in order to accommodate the extra methylene group in the second residue. Attempts to turn these substrates over within crystalline IPNS using hyperbaric oxygenation give rise to product mixtures.     

Fe(2‐EHA)3/Al(i‐Bu)3/hydrogen phosphite catalyst for preparing syndiotactic 1,2‐polybutadiene

Polymerizing 1,3‐butadiene into syndiotactic 1,2‐polybutadiene with an iron(III) catalyst system has been investigated. Activity of the catalyst was affected by the type of cocatalyst alkylaluminum and the phosphorus compound as an electron donor, molar ratio of catalyst components, and their aging sequence and aging time of the catalyst. The microstructure and configuration of the polymer was decided by the catalyst components, the higher [Al]/[Fe] molar ratio tending to yield syndiotactic 1,2‐polybutadiene, while the higher [P]/[Fe] molar ratio favors the formation of amorphous 1,2‐polybutadiene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4265–4269, 2006     

Iron‐Catalysed sp3–sp3 Cross‐Coupling Reactions of Unactivated Alkyl Halides with Alkyl Grignard Reagents

Iron‐catalysed sp³–sp³ Kumada coupling with primary and secondary alkyl halides (RX) and alkyl Grignard reagents has been achieved in low to good yields depending on the nature of the R group.     

Catalytic Decarboxylative Cross‐Ketonisation of Aryl‐ and Alkylcarboxylic Acids using Magnetite Nanoparticles

In the presence of catalytic amounts of magnetite nanopowder, mixtures of aromatic and aliphatic carboxylic acids are converted selectively into the corresponding aryl alkyl ketones. As by‐products, only carbon dioxide and water are released. This catalytic cross‐ketonisation allows the regioselective acylation of aromatic systems and, thus, represents a sustainable alternative to Friedel–Crafts acylations.