Low Degree Of Oxidation Research Articles

Hydrogenation of ethyl acetate on Re/?-Al2O3 catalyst

1. The possibility was shown of the activation of the 5% Re/γ-Al2O3 catalyst for the hydrogenation of ethyl acetate directly into ethanol under the experimental conditions (230°C, 30 atm, molar ratio H2;ethyl acetate=5). Thus, deposited rhenium(VII) is reduced to rhenium at lower degrees of oxidation. 2. In the range of conditions studied, the maximal conversion of ethyl acetate (EA) into ethanol is 49% (selectivity 83.5%), which is observed at 60 atm, 230°C, H2:EA=5, Vmax=0.7 h−1. Increase in the temperature and molar ratio, and also decrease in pressure leads to a decrease in the selectivity of hydrogenation of ethyl acetate into ethanol. 3. Byproducts of the hydrogenation of ethyl acetate — diethyl ether and hydrocarbons — are formed not only as the result of dehydration of ethanol on Y-Al2O3, but also directly from ethyl acetate (diethyl ether) and also by the hydrogenolysis of the G-O bond in ethanol on rhenium (hydrocarbons).

Graft copolymerization of methyl methacrylate (MMA) on hydrazine treated oxycellulose in limited aqueous system

AbstractGraft copolymerization of methyl methacrylate (MMA) on oxycellulose modified with hydrazine treatment was studied in a limited aqueous system using K2S2O2 as the initiator. Hydrazine modified oxycellulose prepared from oxycellulose corresponding to low degrees of oxidation (copper nos. 2–6) produced the best grafting effects. Grafting parameters under different sets of conditions were studied and compared and the mechanism of graft copolymerization discussed.

An experimental study of chemical remanent magnetizations of synthetic monodomain titanomaghemites with initial thermoremanent magnetizations

We have carried out a laboratory simulation of the chemical remanent magnetization (CRM) of titanomaghemites produced by seafloor oxidation of titanomagnetites carrying a primary thermoremanent magnetization (TRM). The starting material was well‐characterized synthetic monodomain titanomagnetite of composition Fe2.4Ti0.4Al0.2O4, dispersed in CaF2 and sealed in evacuated quartz capsules. First a TRM, JTRM, was induced in a field of either 50 or 100 μT Then the samples were removed from their capsules and oxidized by long heatings in air between 100 and 230°C, well below the Curie temperature of 270°C. Titanomaghemites with oxidation parameters of 0.32, 0.46, 0.62, 0.72, 0.91 and 0.97 resulted. For 0.15 ≤ z ≤, 0.72, single‐phase spinels were produced. Faint hematite X‐ray lines were observed only for the most oxidized samples. During oxidation, a field HCRM of either 50 or 100 μT was applied perpendicular to JTRM The resulting CRM, HCRM was parallel to JTRM and uninfluenced by HCRM throughout most of the single‐phase oxidation range (0.15 ≤ z ≤ 0.62), and remained directionally stable during alternating field (AF) demagnetization to 100 mT. For z ≥ 0.72, JCRM was increasingly deflected toward HCRM For z = 0.97, the deflection amounted to 23.5°, but AF cleaning revealed that JCRM consists of a harder component (coercivities > 35 mT) with deflection 14.5° and a softer component with deflection 38°. We conclude that low and medium degrees of oxidation (z ≲ 0.7) of single‐domain titanomagnetites should not change the original NRM directions of submarine basalts nor the pattern of magnetic stripes over the oceans.

Binding of calcium ions to 2,3-dicarboxy derivatives of starch and amylose

A series of 2,3-dicarboxy derivatives of oxidation degree DO(d.c.) 0.13 to 0.90 was prepared by a two-stage oxidation of corn starch and amylose. The activity coefficient γCa2+ of calcium counterions was estimated in solutions of calcium salts of these carboxy derivatives in a 3.00 mmol (COOCa0.5)l-1 concentration by a metallchromic indicator (tetramethylmurexide) method. A loss of electrostatic free enthalpy, Δ(Gel/N)KCa, due to the exchange of Ca2+ → 2K+ cations was determined by potentiometric titrations of the investigated polyacids and pectinic acids of various linear charge density of the macromolecule employing potassium and calcium hydroxides. 2,3-Dicarboxy derivatives of starch and amylose show a considerably strong binding of calcium ions even at low oxidation degree of the starting polysaccharides in contrast to solutions of the corresponding pectinates and carboxymethyl derivatives of cellulose and amylose. The strong bond of calcium ions to 2,3-dicarboxy derivatives of starch and amylose is ascribed to a favourable spatial arrangement of two neighbouring carboxyl groups at C(2) and C(3) of the oxidized D-glucose units due to a flexibility of the macromolecule chain at sites of the pyrane ring cleavage.

Photograft Copolymerization of Methyl Methacrylate, Acrylonitrile, and Acrylamide on Oxycellulose Using Potassium Persulfate as the Initiator in Limited Aqueous Systems

Abstract Graft copolymerization of methyl methacrylate (MMA), acrylonitrile (AN), and acrylamide (AA) on cellulose of low degrees of oxidation (effected through periodate treatment) was studied under photoactivation with visible light in limited aqueous systems. The degree of oxidation of the cellulose sample given in terms of copper number was between 0.25 (for the native cellulose) and 46. Increasing degree of oxidation initially produced higher overall % conversion or rate of polymerization. Overall grafting effects, i.e., % grafting and grafting efficiency, were also generally higher in oxycellulose than in unmodified cellulose. Effects of variations of time of polymerization, initiator content, and monomer content on overall grafting were also studied, and related data for the three monomer systems have been presented and compared. Percent grafting as high as 300–500% and grafting efficiency of the order of 80–95% were easily obtained.

Catalyst based on nickel and molybdenum of a high specific surface

Reduction of mixed oxides NiO-MoO3 of varying composition by hydrogen in the temperature range 653-773 K was studied as well as several physico-chemical parameters of the reduction products - methanation catalysts.Initial oxides contain - depending on their composition - a varying concentration of nickel molybdate as a free phase. The reduction of molybdenum oxide is catalytically influenced by nickel reduced and takes place, depending on its actual concentration, to the lower oxidation degrees eventually to the metallic molybdenum. On the other hand, the molybdenum present stabilizes nickel microcrystallites during the reduction by hydrogen. Resulting active catalytic systems exhibit a high specific surface. The rate, degree, and apparent activation energy of the reduction are markedly dependent on the initial sample composition. The reduction kinetics can be qualitatively described by an equation of the zone model of solid phase decomposition.

ESR study on photodecomposition mechanism of oxidized poly(vinyl alcohol)

AbstractPhotolysis behavior of oxidized poly(vinyl alcohol) (PVA) in which carbonyl groups were introduced by oxidation with sodium hypochlorite and periodic acid was investigated by using ESR spectrometry. Increased formation of PVA radicals was observed in the sample with low degree of oxidation, which showed an emphasized formation of triplet component radical. On the other hand, the formation of radicals tended to be depressed in the highly oxidized sample, and a singlet component was dominant in the ESR spectrum. By examining infrared and ultraviolet spectra of the oxidized sample, the sample was found to contain two structures, a saturated ketone group and an α,β‐unsaturated group; the latter structure was intensified with increasing degree of oxidation. Based on ESR studies of the photoirradiated acetone and mesityl oxide, the models of saturated and α,β‐unsaturated ketone structures in the oxidized PVA, respectively a photodecomposition mechanism of oxidized PVA was proposed.

Elemental fractionations among enstatite chondrites

Neutron activation data on 14 elements in eight enstatite-chondrite falls are reported. These and literature data on an additional 28 elements show that intragroup elemental fractionations generally fall into one of three basic patterns: 1. (1) siderophilic- and chalcophilic-element abundances are about 1.5 times greater in E4-5 than in E6 chondrites; 2. (2) non-volatile lithophile-element abundances in E4-5 chondrites are generally about 1.0–1.2 times those in E6 chondrites; 3. (3) highly volatile elements are higher in E4-5 chondrites than in E6 chondrites by factors of 6–50. In addition, abundances (relative to Si) of most refractory and volatile elements are lower (by factors of 0.5–0.9) in E4 chondrites than in C1 chondrites. Because of the compositional hiatus often observed between E4-5 and E6 chondrites, there exists the distinct possibility that they are separate groups which were stored in different parent bodies. However, because of their close similarity in oxidation state, it seems likely that they originated at the same nebular location, far removed from the formation locations of the other, much more oxidized groups of chondrites. The E-group fractionation patterns can be plausibly explained in terms of four fractionation processes: 1. (1) loss of oxidizing agents (i.e. H 2O) and refractory materials from starting materials of solar composition: 2. (2) partial loss of moderately volatile elements, perhaps as a result of gradual loss of nebular gas during condensation; 3. (3) more efficient agglomeration of metal particles than silicate particles; and 4. (4) increase of nebular temperatures during agglomeration-accretion resulting in the loss of volatile-rich late condensates from E6 chondrites. The low degree of oxidation of enstatite chondrite materials is best understood in terms of a fractionated nebula. At a pressure of 10 −4 atm the Si content of E4 metal can be produced at 1350°K if the H 2O H 2 ratio is 5 times lower than that in unfractionated solar-system material. A nebula-wide fractionation process involving radial transport of refractories and H 2O is indicated, and a suitable model in which the nebula-wide mixing of the gas phase continues during condensation is proposed.

Infrared spectra of coal macerals separated from Bulgarian lignites

The infrared spectra of the macerals resinite, humoresinite, textinite, ulminite, semifusinite and fusinite, separated from Bulgarian lignites, are discussed. Quantitative increment analysis is used. It has been established that the contents of the functional groups in the liptinite and huminite maceral groups are different, but the aromaticities are quite similar. The spectral characters and complexity are due to the different amount of lignincellulose tissue and resinite which entirely or partially fills the cell lumens of the wood. The infrared spectra of the inertinite maceral group have a simple pattern. In the semifusinite the absorption bands recorded are attributed to the low degree of oxidation and the large resinite content, respectively. The strong absorption of the fusinite is influenced by the higher content of condensed aromatic and hydroaromatic ring structures. The investigations indicate that the fusinite was formed during thermal destruction of the wood tissue, which proceeded at a high speed.

Stimulation of β-(l → 6)-glucanase production by oxidized pustulan

A strain of Penicillium lilacinum, isolated from soil, produced pustulanase, β-(1 → 3)-glucanase, (EC. 3.2.1.6) and cellulase (EC.3.2.1.4) when cultivated on a medium containing pustulan as the sole source of carbon. If pustulan was replaced by ketopustulan, the production of pustulanase was stimulated about 10-fold although the amount of stimulation was dependent on the degree of oxidation of pustulan. β-(1 → 3)-Glucanase production was stimulated slightly by ketopustulan; however, the degree of oxidation did not affect significantly the yield of this enzyme. Cellulase production was either unaffected by the oxidized polymer, or at higher degrees of oxidation, decreased. Tween 80 stimulated the production of the three enzymes in media containing ketopustulan with a low degree of oxidation but was inhibitory to pustulanase and cellulase production in media containing ketopustulan with a high degree of oxidation. A combination of gel filtration and isoelectric focusing revealed that each enzyme activity was attributable to at least two proteins.

New data on písekite

Písekite is a metamict mineral from the group of niobates, tantalates and titanates, with the general formula ABO 4 where A=RE, As, Ca, Fe, U and B = Nb, Ti, Ta, and where Nb ⪢ (Ti + Ta); RE ≥ As; ΣY > ΣCe. The cores of písekite crystals have a low degree of inner oxidation and recrystallize in a hydrothermal environment at 3000 atm when heated to 600°C and also in air or N 2 at atmospheric pressure if heated to temperatures of 600–700 °C, forming a monoclinic phase with a unit cell approaching that of monazite. At higher temperatures, this phase disintegrates into several phases. It is believed that the monoclinic structural arrangement corresponds to the structure of písekite before its metamict alteration. The rims of písekite crystals with a high degree of inner oxidation, if heated in air or in an inert atmosphere (600–1200 °C) yield, upon recrystallizing, a mixture of phases with a prevailing trigonal phase probably consisting of the oxide UNb 2O 8 and a cubic phase of the pyrochlore type.

Reactions of partially oxidised hemoglobins solution. III

A sheep oxyhemoglobin of the B type was partially oxidised by ferricyanide and subjected to ion-exchange chromatography on CM-Sephadex. A fraction, F, was isolated containing hemoglobin derivatives in which two iron atoms were in the ferric state. A comparison of the reactions of F with those of solutions prepared either by randomly oxidising oxyhemoglobin, R, or by prior admixture of methemoglobin with oxyhemoglobin, PA, showed that: 1. 1. In dilute buffers at pH 6.1, the reactions of F or oxyhemoglobin with CO were not distinguishable. 2. 2. In dilute buffer at pH 7.0, the initial rate constants for the reaction of CO with deoxygeneted solutions of R increased with the degree of oxidation when measured at 30°: these changes were associated with an increase in activation energy. The corresponding reaction of F showed kinetic properties characteristic of R when compared at the same overall composition. When solutions of hemoglobin and methemoglobin were mixed at the same time that reaction with CO was initiated the resulting reaction was typical of hemoglobin but when deoxygenated solutions of PA were prepared in advance their properties were identical with solutions of R of the same composition. 3. 3. In dilute buffer at pH 5.1 or in solutions of 2 M NaCl at pH 7, the reaction of CO with deoxygenated solutions of R was less dependent on the degree of oxidation. In these conditions, the properties of F were characteristic of highly oxidised samples of R, whereas, when PA was prepared in solutions of high ionic strength, its properties resembled those of R with lower degrees of oxidation.

Heat treatment in drawing of titanium wire

1. Wire of titanium grade VTl-D can be annealed in ordinary air furnaces, in chloride (salt) baths and by resistance heating. The best results are obtained in salt baths. 2. The correct annealing temperature in electric (air) furnaces is 650–750° C with a 2–3 minute holding time. The thinner the section of the wire, the lower should be the temperature and the shorter the annealing time. 3. For annealing in salt baths, the best schedule is 680–720°C/0. 5–2 minutes. Annealing in fused chlorides ensures almost instant heating and a low degree of surface oxidation.

The influence of hydrogen-ion concentration on the decomposition of soil Organic matter by hydrogen peroxide (With two text-figures.)

The decomposition of the organic matter of the soil by means of hydrogen peroxide is shown to be a function of the hydrogen-ion concentration of the soil, alkaline soils permitting of a very low degree of oxidation, while with acid soils up to 90 per cent, of the organic matter is destroyed.The results obtained with a range of soils suggest that a portion of the organic matter is oxidised irrespective of the soil reaction, while the oxidation of the remainder is a definite function of the hydrogen-ion concentration, the relation being expressed by the equationThe proportion of the organic matter oxidised further appears to be a definite function of the clay content of the soil. Alkaline soils containing free manganese dioxide also show small losses.

SUGGESTIONS ON THE DIETETIC TREATMENT OF GOUT.

The great Fothergill and Garrod taught us that uric acid was the causative factor in gout; that it was formed by the metabolism of nitrogenous waste; that it represents a lower degree of oxidation than urea; that uric acid and its salts, being insoluble, are much less easily eliminated, and hence they accumulate in the system; that it is in the liver the splitting up of peptones into glycogen and waste, azotized substance takes place, and its insufficiency causes the diminished oxidation that produces uric acid instead of urea. Haig, in his masterly treatise on uric acid, accepts this theory. This tracing of gout to an excess of nitrogenous ingesta results in the exclusion of this important group of alimentary principles from this class of patients. This origin of uric acid, as the exclusive one, can not be maintained today, for we know that much, if not all, of this