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1
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Iron porphyrins-catalysed oxidation of α-alkyl substituted mono and dimethoxylated benzyl alcohols

100%
Fabbri C., Aurisicchio C., Lanzalunga O.
Open Chemistry
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2008
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vol. 6
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issue 2
145-153
EN
The mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO5 as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane, two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species iron-oxo porphyrin radical cation and the substrate. [...]
2
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Oxidation of Distyryl Ketone by Quinaldinium Chlorochromate – A Kinetic Study

80%
Periyasamy S. K., Saravanakumar K.
World News of Natural Sciences
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2017
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vol. 13
113-121
EN
Oxidation of distyrylketone by quinaldinium chlorochromate [QnCC] in water and acetic acid medium has been studied under pseudo first order condition. The reaction shows unit order dependence each with respect to oxidant and hydrogen ion. The reaction with respect to substrate is found to be fractional order. The reaction rate decreases with increasing the concentration of Mn2+ ions. The reaction does not induce the polymerization of acrylonitrile. A possible mechanism has been proposed in the formation of cinnamic acid and Phenyl acetaldehyde.
3
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Electrochemical oxidation of methylthiomethyleneisoquinolinium chloride - the first water soluble alkylthiomethylene substituted ammonium salt

80%
Smarzewska S., Skrzypek S., Bachowska B., Bałczewski P., Ciesielski W.
Open Chemistry
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2011
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vol. 9
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issue 5
840-845
EN
Electrochemical oxidation of methylthiomethyleneisoquinolinium chloride (MTMIQ), the first alkylthiomethyl substituted ammonium salt, which is fully miscible with water has been investigated by voltammetric (SWV) method using glassy carbon electrode. On the electrode, MTMIQ undergoes oxidation at the potential near Ep = 0.07V (vs. Ag/AgCl/3 M KCl). The influence of the pH of buffers, amplitude, frequency, step potential on the received signal was studied. The best results were obtained with a citrate buffer at a pH of 5. The oxidation peak current used for MTMIQ voltammetric determination was in the range of 2–8×10−5 mol L−1, LOD = 3.7×10−6, LOQ = 1.2×10−5. The product of the oxidation was accumulated at the working electrode and was investigated by spectroscopic method. Mechanistic pathways of the oxidation have been proposed. [...]
4
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Kinetic investigation of oxidation of aromatic anils by magnesium monoperoxyphthalate in aqueous acidic medium

80%
Ramakrishnan V., Kulandaivelu K.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 3
55-60
EN
The kinetics of oxidation of aromatic anils to benzaldehyde and azobenzene by magnesium monoperoxyphthalate (MMPP) has been studied in aqueous acetic acid medium. The low dielectric constant of the medium facilitates the reactivity. It has been found that ionic strength of the reaction has no significant effect on rate. The added acrylonitrile has no effect on the reaction rate indicating the absence of free radical mechanism. The added Mn(II) decreases the rate of the reaction, which indicates the involvement of two-electron transfer. Highly negative ΔS# values indicate a structured transition state. The deviation of Hammett plot is noted and a non-linear concave downward curve is obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus σ is attributed to the transition state whereas the non-linear concave upward curve is observed for the substituents in the benzaldehyde moiety and a non-linear concacve upward curve is observed for the substituents in the combination of aniline and benzaldehyde moiety and a suitable mechanism is proposed
5
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The study of cyclooctene oxidation with molecular oxygen catalyzed by VSi2

80%
Makota O., Trach Y., Leboda R., Skubiszewska-Zięba J.
Open Chemistry
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2009
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vol. 7
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issue 4
731-738
EN
The catalytic effect of VSi2 on initial stages of the liquid-phase oxidation of cyclooctene by molecular oxygen was studied. The vanadium disilicide influences on the oxidation process in the presence of hydroperoxide. VSi2 takes part in a radical formation stage by catalysis of hydroperoxide decomposition reaction. The catalyst was investigated before and after reaction using FTIR spectroscopy. From the data obtained, the kinetic model of the catalytic oxidation process was proposed and the equation for the reaction rate was derived. The equation has described all observed dependences of reaction rate on the concentration of reactants and content of catalyst. [...]
6
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Aerobic oxidation of cumene catalysed by 4-alkyloxycarbonyl-N-hydroxyphthalimide

80%
Kasperczyk K., Orlińska B., Zawadiak J.
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issue 11
1176-1182
EN
4-Hexyloxycarbonyl-, 4-dodecyloxycarbonyl- and 4-hexadecyloxycarbonyl-N-hydroxyphthalimides were synthesised using trimellitic anhydride chloride as the starting material. The obtained lipophilic derivatives of N-hydroxyphthalimide were applied as catalysts of the cumene oxidation reaction with oxygen performed in polar acetonitrile, in non-polar tert-butylbenzene and in the absence of a solvent. The courses of reactions catalysed by N-hydroxyphthalimide and its derivatives were compared.
7
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Effect of oxidation of nitride coatings on corrosion properties of Ti-6Al-4V alloy in 0.9% NaCl at 40°C

70%
Pohrelyuk I., Tkachuk O., Proskurnyak R.
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issue 2
260-265
EN
The corrosion properties of Ti-6Al-4V alloy with oxidized thermodiffusion nitride coatings were investigated in isotonic 0.9% solution of NaCl at temperature of 40°C. It was shown that modification of nitride coatings by oxygen leads to a deterioration of the protective properties of nitrided surface of Ti-6Al-4V alloy. The protective properties of the alloy with nitride coatings modified by oxygen are determined by the composition of formed surface oxynitride film.
8
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Oxidation of α-methylstyrene on an MCM-22 encapsulated (R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) catalyst

70%
Bogár K.
Open Chemistry
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2005
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vol. 3
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issue 1
63-71
EN
(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism proposed by Annis and Jacobsen.
9
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Studies of the soluble part of oxidised coals

70%
Pietrzak R., Kozłowski M., Wachowska H., Yperman J.
Open Chemistry
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2004
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vol. 2
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issue 2
278-289
EN
Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO3 contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.
10
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Experimental and theoretical studies on the photodegradation of 2-ethylhexyl 4-methoxycinnamate in the presence of reactive oxygen and chlorine species

70%
Gackowska A., Przybyłek M., Studziński W., Gaca J.
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issue 5
612-623
EN
2-Ethylhexyl 4-methoxycinnamate (EHMC) is one of the most commonly used sunscreen ingredient. In this study we investigated photodegradation of EHMC in the presence of such common oxidizing and chlorinating systems as H2O2, H2O2/HCl, H2O2/UV, and H2O2/HCl/UV. Reaction products were detected by gas chromatography with a mass spectrometric detector (GC-MS). As a result of experimental studies chloro-substituted 4-methoxycinnamic acid (4-MCA), 4-methoxybenzaldehyde (4-MBA) and 4-methoxyphenol (4-MP) were identified. Experimental studies were enriched with DFT and MP2 calculations. We found that reactions of 4-MCA, 4-MBA and 4-MP with Cl2 and HOCl were in all cases thermodynamically favorable. However, reactivity indices provide a better explanation of the formation of particular chloroorganic compounds. Generally, those isomeric forms of mono- and dichlorinated compounds which exhibits the highest hardness were identified. Nucleophilicity of the chloroorganic compounds precursors were examined by means of the Fukui function.
11
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Preparation and characterization of high specific surface area Mn3O4 from electrolytic manganese residue

70%
Peng T., Xu L., Chen H.
Open Chemistry
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2010
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vol. 8
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issue 5
1059-1068
EN
Mn3O4 powders have been produced from Electrolytic Manganese Residue (EMR). After leaching of EMR in sulfuric acid, MnSO4 solution containing various ions was obtained. Purifying the solution obtained and then adding aqueous alkali to the purified MnSO4 solution, Mn(OH)2 was prepared. Two methods were employed to produce Mn3O4. One way was oxidation of Mn(OH)2 in aqueous phase under atmosphere pressure to obtain Mn3O4. The other way was roasting Mn(OH)2 precursors in the range of 500°C to 700°C. The prepared samples were investigated by using several techniques including X-ray powder diffraction (XRD), Fourier Transformation Infra-Red (FTIR) spectra, and Brunauer-Emmett-Teller (BET) specific surface area instrument. Particle distribution and magnetic measurements were carried out on laser particle size analyzer, vibrating sample magnetometer (VSM). Through XRD, FTIR and determination of total Mn content (TMC), the products prepared were confirmed to be a single phase Mn3O4. BET specific surface areas can reach to 32 m2 g−1. The results indicated that products synthesized by aqueous solution oxidation method had higher specific surface areas and smaller particle size than those prepared by means of roasting. However the products prepared using the above two methods showed no obvious differences in magnetic property. [...]
12
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RuO4-mediated oxidation of N-benzylated tertiary amines. 3. Behavior of 1,4-dibenzylpiperazine and its oxygenated derivatives

70%
Petride H., Drăghici C., Florea C., Petride A.
Open Chemistry
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2006
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vol. 4
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issue 4
674-694
EN
1,4-Dibenzylpiperazine (1),-2-piperazinone (7),-2,6-piperazinedione (9), and 1-benzoyl-4-benzylpiperazine (30) were oxidized by RuO4 (generated in situ) by attack at their endocyclic and exocyclic (i.e., benzylic) aminic N-α-C-H bonds to afford various oxygenated derivatives, including acyclic diformamides, benzaldehyde, and benzoic acid. The reaction outcome was complicated by (i) the hydrolysis of diformamides, occurred during the work-up, and (ii) the reaction of benzaldehyde with the hydrolysis-derived amines giving imidazolidines and/or Schiff bases. Benzoic acid resulted from benzaldehyde only. Compounds 7, 30, and 1-benzylpiperazine, but not 9, were transiently formed during the oxidation of 1. In the same reaction conditions, 1,4-dibenzyl-2,3-(or 2,5)-piperazinedione, 1,4-dibenzyl-2,3,6-piperazinetrione, 4-benzyol-1-benzyl-2-piperazinone, and 1,4-dibenzoylpiperazine were inert. The proposed oxidation mechanism involves the formation of endocyclic and exocyclic iminium cations, as well as of cyclic enamines. The latter intermediates probably result by base-induced deprotonation of the iminium cations, provided an N +−β-proton is available. In the case of 1, the cations were trapped with NaCN as the corresponding α-aminonitriles. The statistically corrected regioselectivity (endocyclic/exocyclic) of the RuO4-induced oxidation reaction of 1, 7, and 30 was 1.2–1.3.
13
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Effect of Magnet Scrap Size on the Extraction Behavior of Heavy Rare Earth Elements by Liquid Metal Extraction

61%
Nam S.-W., Rasheed M. Z., Park S.-M., Lee S.-H., Kim D.-H., Kim T.-S., Nam S.-W., Rasheed M. Z., Park S.-M., Lee S.-H., Kim D.-H., Kim T.-S.
Archives of Metallurgy and Materials
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2020
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vol. 65
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issue 4
14
Content available remote

A new oxidation process. Transformation of gem-bishydroperoxides into esters

61%
Terent’ev A., Platonov M., Kutkin A.
Open Chemistry
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2006
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vol. 4
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issue 2
207-215
EN
A new oxidation process has been found where α,ω-dicarboxylic acid esters and ω-hydroxycarboxylic acid esters are formed on heating gem-bishydroperoxides in alcohol in the presence of BF3·Et2O. By addition of H2O2 to this reaction α,ω-dicarboxylic acid esters are formed almost selectively.
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