Solid-phase Oxidation Research Articles

A Crosslinked Copolymer with N‐Bromosulfonamide Pendant Groups as Oxidant for Residual Sulfides in Alkaline Media

A redox copolymer, a macromolecular analogue of Bromamine T was prepared and developed as a solid phase oxidizing reagent for sulfides being in trace concentration in aqueous solutions. The resin was prepared starting from Amberlyst 15 by a four-step transformation of the sulfonic groups to N-bromosulfonamide. The product containing 3.30 meq active bromine/g showed strong oxidizing properties and was employed in batch as well as in flow processes for removal of sulfides from solutions by their transformation to sulfates. The starting solution contained 64.0 or 320.0 mg S 2- /dm 3 . The effects of various parameters on the reaction course have been studied (mole ratio of reagents, alkalinity of the reaction, media flow rate in the column processes). The solid phase oxidation carried out in a dynamic regime provided to drive the reaction to completion. Thus, sulfide free effluents (<10 μg S 2- /dm 3 ) were obtained in the column processes. The permissible flow rate, close to 10-12 bed volumes/h, was satisfactory. The sulfide oxidation proceeded quickly in aqueous media of various alkalinity, especially in those of strong alkalinity. As the transformation of sulfides to sulfates was accompanied by a drop of the pH value of the reaction medium, it was necessary to maintain it not lower than 6.0. Otherwise, the active bromine content in the resin decreased and the yield of the column process was unsatisfactory. Moreover, in acidic media a considerable part of sulfides transformed to elemental sulfur which contamined the resin phase and caused turbidity of the effluent. By reacting a stoichiometric amount of reagents in batch regime not only sulfate, but also various intermediate products were found in the solution. The exhausted copolymer contained unsubstitued sulfonamide groups; it could be regenerated and reused repeatedly for the next processes.

Anodic performance and insertion mechanism of hard carbons prepared from synthetic isotropic pitches

Anodic performances and structures of hard carbons prepared from synthetic isotropic pitches through solid phase oxidation were investigated to discuss their insertion sites for lithium ion and correlation between the capacity and structure. The derived hard carbons showed complicated voltage profiles of charge and discharge, indicating five kinds of insertion sites; partially charge transferring surface site (Type I), intercalation site like graphite (Type II), cluster gap between edges of carbon hexagon clusters (Type III), microvoid surrounded by hexagonal planes (Type IV) and atomic defect created by evolution of heteroatom (Type V). Types I–III are common to those found in the soft carbon. Very unique capacities of the present hard carbons calcined at 1000°C were found at the potentials of 0–0.13 V (Type IV) and 0.5–2.0 V (Type V) and varied markedly with oxidization extent and heteroatom contents of precursor pitch, respectively. The microvoid among the hexagonal planes and atomic defects created by evolution of heteroatom are suggested to serve such insertion sites of Types IV and V, respectively. The microvoid holds reduced lithium ions with different extents of charge transfer to the carbon, which exist independently at 140 K but exchange rapidly at room temperature to their averaged chemical shift in 7Li-NMR. Type V showed very similar charge–discharge behaviors to that of Type III, which was found more in the soft carbon carbonized at around 700°C and decreased sharply by the heat-treatment at 1000°C due to the coupling of hexagon clusters. The amount of microvoid or capacity at 0–0.13 V is correlated to XRD parameters and oxygen content of the precursors. Smaller crystal, lower stacking or more oxygen content in the precursor allows apparently larger capacity. Random assemble of smaller graphitic units may induce the microvoid among the cluster units, although the microvoid has not been specifically defined yet.

Solid-phase oxidation of 2,4-Di-tert-butylphenol and 3,6-Di-tert-butylpyrocatechol in the presence of alkali and alkaline earth metal halides under elastic deformation

Solid-phase oxidation of 2,4-di-tert-butylphenol to give 2,2′,4,4′-tert-butyl-6,6′-bisphenol and of 3,6-di-tert-butylpyrocatechol to afford 3,6-di-tert-butyl-l,2-benzoquinone was performed in the presence of alkali and alkaline earth metals halides under conditions of modified extrusion. The formation of the corresponding metal 3,6-di-tert-butylsemiquinolates was registered by ESR method. The different behavior of chlorides, bromides, and iodides was observed and rationalized basing on the dissimilar complexing ability of halogens. The mechanism of activated oxidation was assumed.

Behaviour of materials for accelerator driven systems in stagnant molten lead

The behaviour of a modified F82H martensitic steel (both uncoated and aluminised) and tungsten was evaluated by immersion tests in stagnant, oxygen-saturated liquid lead at 793 K under an argon atmosphere, for exposure times up to 3700 h. The F82H steel is a candidate structural material for Accelerator Driven Systems (ADS), while tungsten is potentially suitable for a beam window working immersed in liquid lead. Layers of Me 3O 4 consisting of an inner sublayer with Me=Fe and Cr and an outer chromium-free sublayer of Fe 3O 4, formed on the surface of the uncoated steel while the aluminised steel showed no significant alteration. On tungsten, a compact and adherent layer of WO 3 formed and reacted with liquid lead leading to the formation of friable Pb–W–O ternary compounds. A two-step mechanism is proposed for interactions of metals and alloys exposed to oxygen-saturated molten lead: the first step is the solid phase oxidation of the base metal; the second is the interaction between liquid lead and the oxide layer formed on the metal surface.

ChemInform Abstract: A Mild and Selective Solid Phase Oxidation of Polythioether (III) to Octopus Polysulfoxide (IV) Using UHP under Supersonic Wave.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Mild and Selective Solid Phase Oxidation of Polythioether to Octopus Polysulfoxide Using UHP Under Supersonic Wave

UHP, a mild and selective oxidizing reagent, has been used to synthesis of octopus polysulfoxide in solid phase reaction under supersonic wave irradiation at room temperature with a high yield. Novel octopus polysulfoxide 2 has been synthesized by selective oxidation of octopus thioehter 1 in ≥95% yield using this method.

β-Lactams on Solid Support: Mild and Efficient Removal of Penicillin Derivatives from Merrifield Resin using Aluminum Chloride

Penicillin derivatives linked to Merrifield resin are efficiently released from this support under mild conditions using aluminum chloride in dichloromethane/nitromethane. Extension to Wang resin-linked analogues and studies on the solid-phase oxidation of penicillin is also reported. © 1997 Elsevier Science Ltd.

The formation of iminoxyl and nitroxyl radicals frompara-quinonedioxime

The formation of iminoxyl radicals in oxidation of oximes is described in the literature, i -6 We established that solid samples of commercially available paraquinonedioxime reprecipitated from alcohol (methanol or ethanol) give a weak ESR signal with a g-factor of 2.0052, which was primarily assigned to dopant paramagnetic centers. However, an attempt to purify paraquinonedioxime more carefully by vacuum (i0 -2 Tort) sublimation at 60 ~ resulted in quite unexpected phenomena: the intensity of the signal increased sharply to 2.8" 1018 sp/g, and the form of the signal corresponding to triaxial anisotropy became pronounced: gl = 2.0076, g2 = 2.0048, g3 = 2.002t, and a N = 2.6 mT. These parameters are close to those presented for iminoxyl radicals in the solid phase obtained by v-irradiation of polycrystalline oximes. 4 Double sublimation resulted in a subsequent 20-fotd increase in the intensity of the ESR signal. An attempt to perform the third sublimation resulted in the sell-ignition of the sample. The ESR spectrum of a solution of para-quinonedioxime in DMSO exhibits a nitrogen triplet with the constant a~ = 1.07 mT and g = 2.0059, which is typical of aromatic nitroxyl radicals. 7 Calculated per gram of the substance, the concentration of the radicals in a solt, tion of DMSO is twice as high as that in the solid sample. We suppose that the existence of iminoxyl radicals in para-quinonedioxime can be related to its solid-phase oxidation by air oxygen. The amount of the iminoxyl radicals formed can be accumulated only to a certain concentration below which a considerable removal of the radicals from each other still prevents their disproportionation. As indicated above, triple vacuum sublimation is accompanied by ignition of the sample. An attempt to sublime para-quinonedioxime in air also results in its ignition. Perhaps this is associated with the formation of energetically unfavorable iminoxyl radicals in a sufficiently high concentration. The disproportionation of these radicals is accompanied by the release of a great amount of heat. It is most probable that DMSO also oxidizes para-quinonedioxime to iminoxyl radicals, which then add to neutral molecules to tbrrn nitroxyl radicals of the supposed structure (1). This results in the fact that the concentration of the radicals in solution calculated per gram of the substance is somewhat higher than that in the solid state.

The evolution, chemistry and applications of chelated iron hydrogen sulfide removal and oxidation processes

The evolution of the use of Fe(III) as a regenerable oxidant for the conversion of H 2S to S is traced from inception as solid phase oxidation processes employing Fe 2O 3, through aqueous, alkaline Fe(OH) 3 suspensions and [Fe(CN) 6] based processes to modern, aqueous, homogeneous redox catalysts using amino polycarboxylate chelated iron. In the current process, H 2S bearing gas streams are contacted with a dilute ([Fe] = 5 mM to 0.5 M), aqueous, mildly alkaline (pH 7 to 9) amino or polyamino polycarboxylato iron (III) solution using a variety of application dependent gas-liquid contactors. S is precipitated and continuously removed. The Fe(III)L is concomitantly reduced to Fe(II)L and is regenerated by aeration in the same or a separate vessel, depending on the need to prevent admixture of reoxidation air with the H 2S free process gas stream. Basic process chemical reactions are reviewed and both beneficial and troublesome side reactions, including ligand degradation by dioxygen reduction products and control thereof by in-situ generated S 2O 2− 3, are discussed together with associated mechanistic studies. Selection criteria for ligands suitable for use in this process are described and new chelating agents with significantly increased in-process stability are disclosed. The current global scope of applications is presented, advantages and limitations of the process relative to alternate technologies are discussed and the present status and future expectations are reviewed.

Development of a manganese dioxide solid-phase reactor for oxidation of toxins associated with paralytic shellfish poisoning

Using manganese dioxide as a solid-phase oxidant, a post-column HPLC reactor for paralytic shellfish poison toxins was constructed and evaluated. Operating parameters such as reaction temperature and pH, flow-rate, reactor column size, and MnO 2 particle size were studied. Based on a 3:1 signal-to-noise ratio, the limits of detection for the non-hydroxylated toxins were in the sub-nanogram range, while the hydroxylated toxins were ten times less detectable. The limit of detection for saxitoxin was about 0.1 ng per injection. The repeatability of replicate injections was ≤10% (relative standard deviation). The system was used to analyze extracts of shellfish and plankton, yielding results that were in agreement with those obtained by established analytical methods. Extracts of shellfish contaminated at the regulatory limit of 0.8 μg/g were successfully analyzed.

Synthetic studies on 4,5-dihydro-3H-1,2,4-triazole-3,5-diones bearing fluorogenic residues at N-4

A number of fluorescent 4,5-dihydro-3H-1,2,4-triazole-3,5-diones have been made. Intra-inter-electrophilic substitution by the triazoledione moiety on the activated naphthalene ring of 4-[6-(5-dimethylamino-1-naphthylsulfonamido)hexyl]-4,5-dihydro-3H-1,2,4-triazole-3,5-dione 4a3 leads to rapid decomposition. The dienophilicity of the triazoledione moiety in 4-pyren-1-yl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione 4d is dramatically lowered by steric shielding. Insertion of a three-carbon spacer unit into the latter compound, to give the 3-pyren-1-ylpropyl analogue 4e, affords a valuable fluorogenic reagent for the analysis of trace levels of 1,3-dienes. Powdered barium manganate is shown to be an excellent solid-phase oxidant for conversion of urazoles into 1,2,4-triazole-3,5-diones.

Solid‐phase oxidation of polyethylene coatings on metals

AbstractThe paper considers the problem of solid‐phase oxidation for cases of polyethylene coatings applied onto active (copper) and passive (aluminum) substrates. Oxidation of PE coatings on copper, unlike that of PE coatings on aluminum, is shown to develop in two stages separated by a time period of autoinhibition. During this time period the concentration of carboxyl groups does not in fact change. In a similar manner copper‐containing compounds accumulate in the coating, which fact supports the relation between metal transfer and polymer oxidation processes. © 1994 John Wiley &amp; Sons, Inc.

Macrokinetics of thermal and thermooxidative destruction of organic-reinforced plastic on heating in a gas flow

The thermochemical failure of organic-reinforced plastic in a high-temperature gas flow (nitrogen, air) is studied experimentally. The activation energy, preexponential factors, thermal effects, and orders of the solid-phase and heterogeneous oxidation reactions are determined by methods proposed previously.

Solid phase oxidation of iodide ion and the role of gamma radiation

Solid phase oxidation of iodide ion by bromate, chlorate and perchlorate has been investigated at different temperatures. The bromate-iodide oxidation with equimolecular mixture is independent of temperature. The period of half-oxidation is limited to 5 minutes. Gamma-radiation has no significant effect on the temperature independence of the oxidation process of this particular composition, although delayed oxidation appears with irradiated mixtures. With increase of bromate, the iodide is completely oxidized and the rate is dependent on temperature. However, with chlorate and perchlorate, there is no prescription of composition for oxidation with 1∶1 mixture. The reaction proceeds with an appreciable oxidation. The rate increases with the temperature and goes to completion. In the case of irradiated mixtures delayed oxidation appears. The kinetics of iodide ion oxidation follows conventional first order.

Solid phase oxidation of arsenite and the effect of gamma radiation

The oxidation of solid arsenite by bromate, chlorate and perchlorate ions has been studied at different temperatures and at a constant composition of 1∶2. Arsenite is completely oxidized to arsenate. The fraction oxidized /α/ — time /t/ data are reproducible. The rate of oxidation increases with an increase in temperature. Gamma radiation has no significant effect on the temperature independence of the oxidation process of this particular composition, although delayed oxidation appears with irradiated systems. The kinetics of oxidation process follows the conventional first order. The activation energies for the oxidation of As/III/ to As/V/ are 30.5, 44.0 and 67.9 kJ mol−1, respectively, for bromate, chlorate and perchlorate systems, and for irradiated 29.8 and 67.3 kJ mol−1, respectively, for bromate and perchlorate systems.

Degree of solid-phase oxidation of nickel and cobalt phthalocyanines by halogens

Electronic and IR transmission spectroscopy and ESR have been used to investigate the products obtained in the oxidation of layes of nickel and cobalt phthalocyanines by halogen vapors. It has been established that cobalt phthalocyanine in chlorine or bromine vapor forms stable cation radicals in which one electron has been detached from the cobalt and the other from the phthalocyanine ligand; in iodine vapor, a partially oxidized product is formed, with a positive charge on the ligand. Nickel phthalocyanine in bromine vapor at high pressure of bromine, and also in chlorine or iodine vapor, nickel phthalocyanine forms partially oxidized products with various degrees of oxidation of the ligand. An interpretation is given for the spectra of the ionic species that have been investigated; the interpretation can be used in particular to determine the degree of the ionic species on the basis of their spectra.

Preparation and characterization of a new cholecystokinin receptor probe that can be oxidatively radioiodinated

Oxidative iodination is the simplest, most efficient, and least expensive method for radiolabeling peptide hormones. It has not been applied to cholecystokinin (CCK), however, because this peptide lacks an unsubstituted tyrosine residue and oxidation abolishes its biologic activity. We report the synthesis, purification, and characterization of the first derivative of CCK that can be radioiodinated with an oxidative method while maintaining full biologic activity and receptor binding affinity. Boc-Tyr-[Thr28, Nle31)CCK-25-33] was synthesized, iodinated using a solid-phase oxidant, and purified on reverse-phase high-pressure liquid chromatography to a specific activity of 2125 Ci/mmol. Both native and iodinated Boc-Tyr-[(Thr28, Nle31)CCK-25-33] exhibited efficacy and potency for stimulation of in vitro pancreatic enzyme secretion that were identical to CCK-8. Binding of Boc-125I-Tyr-[(Thr28, Nle31)CCK-25-33] to rat pancreatic plasma membranes was rapid, reversible, temperature-dependent, saturable, and specific. The abilities of various molecular forms of CCK to compete for this binding paralleled their potencies for stimulation of pancreatic secretion (Kd: CCK-8, 0.8 nM; CCK-33, 3 nM; CCK-8DS, 1 μM; CCK-4, 50 μM), whereas structurally unrelated pancreatic ligands (1 μM) demonstrated no significant competition. These findings suggest that Boc-125I-Tyr-[(Thr28, Nle31)CCK-25-33] interacts with the same high-affinity pancreatic receptor as the CCK receptor probes previously reported, i.e., the Bolton-Hunter-labeled CCK-33 and CCK-8. This probe also possesses the major advantages of simplicity, efficiency, and cost of the labeling procedure, and the stability and relative oxidation-resistance of the product. Boc-125I-Tyr-[(Thr28, Nle31)CCK-25-33] will be useful for the characterization of binding interactions between CCK and its target tissues.

Oxidation of Mn(II): Initial mineralogy, oxidation state and ageing

The initial solid phase oxidation products formed during the oxidation of aqueous Mn(II) at 25°C were studied as a function of time. The analyses included morphology (TEM), mineralogy (x-ray diffraction), O Mn ratio (iodometric method), oxidation state of manganese (XPS), and dissolved manganese. The initial solid formed under our conditions was Mn 3O 4 (hausmannite) which converted completely to γMnOOH (manganite) after eight months. βMnOOH (feitknechtite) appeared to be an intermediate in this transformation. The O Mn ratio was initially 1.37 and increased to 1.49 over the same time span. Throughout the course of this study the XPS analyses showed that the surface of the solids (<50 Å) was dominated by Mn(III). The solution pH and dissolved manganese concentrations were consistent with disproportionation and oxidation reactions that favor the transformation of Mn 3O 4 to γMnOOH but not to γMnO 2.

Topology and immunoreactivity of capsid proteins in hepatitis A virus.

Hepatitis A virus (HAV) was propagated in a hepatoma cell line and complete viral particles with a density of 1.34 g/ml were purified from cell extracts. The topography of the viral proteins (VPs) was studied by surface labelling with 125I and a solid-phase oxidant. The order of labelling intensity in complete particles was VP1 much greater than VP3 greater than VP2; labelling of VP4 was undetectable. When the particles were denatured with sodium dodecyl sulfate at 100 degrees C before iodination, the labelling efficiency was 6 times higher and the order of labelling intensity was VP3 greater than VP2 greater than VP1. After denaturation, the viral proteins no longer reacted with human anti-HAV antibody. The results suggest that (i) as with other picornaviruses, HAV exposes an essential part of VP1 at its surface whereas VP3 and especially VP2 are more hidden; (ii) naturally immunized individuals do not form detectable amounts of antibodies against the denatured capsid proteins. The apparent molecular weights of the VPs were 33000, 29000 and 28000 daltons.

Features of the solid-phase oxidation of oriented polyethylene

A study has been made of the low-temperature initiated oxidation and auto-oxidation of isotropic and oriented PE films. It was found that qualitatively orientational drawing has the same effect on the kinetics of PE oxidation as that previously observed with orientational drawing of isotatic PP. Far from temperatures loading to rapid relaxation drawing results in a lower hydroperoxide yield, and in a slightly lower value of k 2 k 6 , and lowers the rate of scission of stretched load-bearing macromolecules.