A new Ba(OH)2 catalyst for synthesis of diacetone alcohol

The application of new Ba(OH)₂ catalysts for the preparation of diacetone alcohol is described. No loss of activity is observed when they are stored in a dessiccator over NaOH. The same yield as that described in the literature is obtained, but in a much shorter reaction time (9.5 h against 72–120 h)

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Ba(OH)₂ . NaOH . , , (9,5 72–120 ).

     

Reaction between the OH group of hydroxyproline and diisocyanate catalyzed by an organotin compound

We have studied the kinetics of the reaction of L-hydroxyproline with OCH(CH₂)₆NCO, catalyzed by organotin, avoiding side reactions by protecting the other active hydrogens of the aminoacid, and comparing it with the MeOH/n-BuNCO system.

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L-- -OCN(CH₂)₆NCO, , . . - .

     

Oscillation chemiluminescence in liquid phase oxidation of organic compounds

It is for the first time that distinct chemiluminescence oscillations have been observed in the liquid phase oxidation for the system: oxidative substrate — thermal initiator — photosensitizer — O₂. Oscillations and their parameters are dependent on the experimental conditions.

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: — — —O₂. .

     

Mössbauer studies of thermal decomposition of metal(III) hexacyanoferrates(II)

The thermal decomposition of metal(III) hexacyanoferrates(II) (Al, As, Sb, Bi) was studied up to 700° in air by employing Mössbauer, infrared spectroscopy and thermal analysis techniques. With the exception of the bismuth compound, the isomer shift of these hexacyanoferrates(II) increases on dehydration at 200°. Dehydration is complete at 200°, decomposition into the ferrite at 300°, and formation of-Fe₂O₃ from aluminium and bismuth hexacyanoferrates(II) and Fe₃O₄ from antimony and arsenic hexacyanoferrates(II) at 700°.

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Zusammenfassung Die thermische Zersetzung von Metall(III)ferrocyaniden (Al, As, Sb, Bi) wurde bis zu 700° in Luft unter Anwendung der Mössbauer und Infrarotspektroskopie, sowie thermoanalytischer Techniken untersucht. Die Isomerverschiebung dieser Ferrocyanide nimmt mit der Dehydratisierung bei 200° zu, mit Ausnahme des Wismuts. Die Dehydratisierung ist bei 200° abgeschlossen, die Zersetzung zum Ferrit bei 300° und die Bildung von-Fe₂O₃ aus Aluminium- und Wismutferrocyanid, von Fe₃O₄ aus Antimon- und Arsenferrocyanid bei 700°.

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Résumé On a étudié dans l'air jusqu'à 700°, la décomposition thermique des ferrocyanures de métaux trivalents (Al, As, Sb, Bi), par spectroscopies Mössbauer et infrarouge, ainsi que par les techniques d'analyse thermique. Le déplacement des isomères de ces ferrocyanures augmente lors de la déshydratation à 200°, à l'exception du bismuth. La déshydratation est complète à 200°, la décomposition en ferrite à 300°, la formation d'-Fe₂O₃ à partir des ferrocyanures d'aluminium et de bismuth ainsi que du Fe₃O₄ à partir des ferrocyanures de l'antimoine et de l'arsenic à 700°

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-, , — Al, As, Sb, Bi- 700° . , , 200°. 200°, 300° -Fe₂O₃. 700° Fe₃O₄.

     

Kinetics and mechanism of ruthenium(III) and ruthenium(III)-EDTA catalyzed oxidation of cyclohexanol by molecular oxygen

The kinetics of the oxidation of cyclohexanol by molecular O₂ catalyzed by Ru(III) and Ru(III)-EDTA complexes has been investigated by oxygen absorption method in the pH range 1.75–3.00 at 30°C (=0.1M KNO₃) in a 11 ethanol-water medium. In both cases the reaction was found to be first order with respect to substrate and catalyst concentration. The rate was found to decrease with the decrease of pH in case of Ru(III)-EDTA complex. Ethanol is not oxidized under the reaction conditions. A possible mechanism for the catalytic oxidation of cyclohexanol is proposed.

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O₂, Ru(III) Ru(III)-EDTA, pH 1,75–3,00 30°C (=0,1M KNO₃) - (11). . pH Ru(III)-EDTA. . .

     

Kinetics of bromate-cerium(III) reaction

The induction period and the fast, and slow rates of the bromate-cerium(III) reaction were examined. It was found that the duration of the induction period was inversely proportional to both the bromate and acid concentrations, and that the fast reaction rate was proportional to the square of bromate concentration.

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(III). , , .

     

Kinetics and mechanism of TI(III) oxidation of cellobiose in acidic medium

TI(III) oxidation of cellobiose in the presence of H₂SO₄ in aqueous acetic acid is first order in each reactant and is acid catalyzed. TI(OAc) ₂ ⁺ is the active species. Products identified are gluconic acid and glucose. A mechanism consistent with the temperature, solvent, acidity and salt effects is been proposed.

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TI(III) H₂SO₄ . TI(OAc) ₂ ⁺ . . , , , .

     

Cerium(III) ion catalysis in the oxalic acid-bromate reaction: Anomalous kinetic behavior of oxalic acid

The kinetics of cerium(III) ion catalyzed Br(V) oxidation of oxalic acid in the presence of HClO₄/H₂SO₄ and mercury(II)-a bromide removing ion, exhibits second order each in [br(V)] and [acid], 0.4 and zero order in [Ce(III)]. However, the kinetic behavior of oxalic acid is anomalous with –0.7, zero and 1.4 order. The chemistry underlying the phenomena is discussed.

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Br(V), Ce(III), HClO₄/H₂SO₄ (II), , [Br(V)], [], 0,4 [Ce(III)]. , , .. –0,7, 0 1,4. , .

     

Micellar effect of sodium dodecyl sulfate on the reactions between iron(II) and p-benzoquinone, and iron(III) and hydroquinone

The micellar effet of sodium dodecyl sulfate (SDS) on the initial stages of the reaction between (1) Fe(II) and p-benzoquinone, and (2) Fe(III) and hydroquinone have been investigated. In the former case acceleration was observed, the rate-[surfactant] profile showing a maximum. SDS has an inhibitory effect on the latter reaction. Kinetic analysis has been carried out using Berezin's approach.

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() 1) Fe(II) 2) Fe(III) . - . . , .

     

Testing thermal stabilities of base oils and their additives via high-temperature infrared spectroscopy

The thermal stabilities of base oils and their additives could be examined by employing an infrared spectroscopic technique. As the heat temperature was increased, changes in absorption were recorded at different wavelengths characteristic of the chemical groups. These changes were observed to occur slowly at first, but then turn to become more marked at specific temperatures. The magnitudes of these changes and temperatures were taken as indications of the thermal stabilities of the samples. The thermal stability was found to decrease in the following sequence: aromatics > naphthenes > hetero compounds > substituted aromatic rings > paraffins.

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Zusammenfassung Ziel der Arbeit ist die Untersuchung der thermischen Stabilität von Ölen und deren Additiven bei Temperaturen bis zu 250 °C. Die angewandte Technik beruht auf der Verfolgung der bei verschiedenen Temperaturen eintretenden Veränderungen der Infrarotspektren der getesteten Proben. Die Probe wird in eine spezielle, auf unterschiedliche Temperaturen aufheizbare IR-Zelle eingefüllt. Die Zelle wird zunächst direkt auf 80 °C aufgeheizt, danach wird in Abständen von 10 °C je ein Spektrum aufgenommen, bis eine Temperatur von 250 °C erreicht ist. Die Referenzzelle wird ebenfalls mit der zu untersuchenden Probe gefüllt, jedoch nicht aufgeheizt. Bemerkenswerte und sich klar unterscheidende Veränderungen in der Intensität von einigen, charakteristischen Gruppen chemischer Verbindungen zuzuordnenden Banden wurden beobachtet. Diese Veränderungen gehen zunächst langsam vor sich, werden dann aber bei spezifischen Temperaturen sehr schnell. Das Ausmaß dieser Veränderungen und die spezifischen Temperaturen unterscheiden sich für die verschiedenen Gruppen chemischer Verbindungen. Die thermische Stabilität nimmt in der Reihenfolge Aromaten >Naphthene> Heteroverbindungen > substituierte Aromaten > Paraffine ab. Ein Antioxidant-Additiv des Zinkdialkyldithiophosphat-Typs wurde ebenfalls getestet und bewertet.

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250°. , . . 80°, 10° 250°. , . , , . , . , , . > > > > . , .

     

Oxidation of 2,6-xylenol by Co(III) chelates in toluene

A simple reaction scheme and kinetic data are presented for the oxidation of 2,6-xylenol by Co(III) chelates in toluene.

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2,6- Co(III) .

     

NMR studies of the interaction between tris-acetylacetonates of Fe(III), Cr(III) and diethyldichloride of Sn (IV)

Paramagnetic relaxation rate of CH₂ protons has been found to be higher than that of CH₃ protons of SnEt₂Cl₂ in the presence of tris-acetylacetonate of Cr(III) in chloroform at 298 K, which supports the specific interactions between these compounds. The revealed ligand exchange between Cr(AA)₃, Fe(AA)₃ and SnEt₂Cl₂ takes place with the equilibrium shifted to the side of initial reactants.

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, -CH₂ CH₃- SnEt₂Cl₂ - Cr(III) 298 K, . Cr(AA)₃, Fe(AA)₃ SnEt₂Cl₂, .

     

Kinetics of reduction of tris(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionato)ruthenium(III) in methanol

Reduction of tris(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionato) ruthenium(III) in methanol solution containing potassium hydroxide has been studied kinetically. The results suggest outer-sphere complex formation between ruthenium(III) species and methoxide anion.

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(4,4,4--1-(2-)--1,3)(III) . , -.

     

Synthesis and structure of (pyridine) bis(acetylacetonato) (1-methyl-1-phenylethylperoxo) cobalt (III)

Synthesis and structure of (pyridine) bis(acetylacetonato) (1-methyl-1-phenylethylperoxo) cobalt(III) complex are described.

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() () (III).

     

Thorough study of bromide control in bromate oscillators, III. Simulation by the oregonator model of the behavior of reacting BZ systems perrturber by mercury (II) ions

The behavior of the bromate-maloni acid-cerium (III) oscillator in the presence of mercury (II)-a bromide-removing ion-can be simulated by the Oregonator model if the dynamics of bromocomplex-formation and dissociation reactions is taken into account.

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- - (III) (II)- - , .

     

Kinetics of decomposition of hydrogen peroxide on Fe(III)?Al(III) hydroxide-oxide systems

The kinetics of decomposition of hydrogen peroxide have been studied on mixed Fe(III)–Al(III) hydroxide and oxide catalysts. While iron hydroxide possesses considerable catalytic activity, aluminium hydroxide has very little activity. The rate of decomposition on mixed hydroxides increases with increasing concentration of aluminium hydroxide up to about 1.5 mol% and decreases thereafter. The mixed oxides possess negligible activity compared to the corresponding hydroxides. The energy of activation, as calculated from the Arrhenius equation, is 10.1 kcal/mol for sample S4, containing 1.52 mol% of alumina. The rate of decomposition of S4 increases with increasing pH up to 6.8 and decreases thereafter. The rate is first order in all these cases. A suitable mechanism is suggested.

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Fe(III)–Al(III). , . , 1,5 , . . , , 10,1 / S4, 1,52 . S4 pH 6,8, . . .

     

Effect of the medium in hexacyanoferrate (III)-iodide and peroxodisulfate-iodide reaction

The kinetics of the two reactions hexacyanoferrate (III)-iodide and peroxodisulfate-iodide in several isodielectric water-cosolvent mixtures have been studied. The results can be rationalized as a consequence of the cosolventwater interaction.

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(III) -. -.

     

Kinetics and mechanism of oxidation of quinol by alkaline hexacyanoferrate(III)

The reaction between quinol and alkaline hexacyanoferrate(III) at constant ionic strength gives p-benzoquinone. The rate of the reaction was first order in the concentrations of substrate, oxidant and alkali. The slow step of the reaction involves the formation of the p-benzosemiquinone radical, which was detected by esr spectroscopy as a five-line spectrum with peak intensity ratios of 14641.

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(III) -. , . - , , 14641.

     

Formation and thermal decomposition of silicon oxynitride compounds. Part III

The formation of a previously unknown compound with stoichiometry Li₆SiN₂O₂ was found during studies on the reactivity of Li₂SiN₂ with Li₂O, of SiO₂ with Li₃N and of Li₃SiNO₂ with Li₃N.

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Zusammenfassung Die Bildung einer bisher unbekannten Verbindung der Stöchiometrie Li₆SiN₂O₂ wurde bei Untersuchungen der Reaktivität von Li₂SiN₂ mit LiO, von SiO₂ mit Li₃N und von Li₃SiNO₂ mit Li₃N beobachtet.

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Li₆SiN₂O₂ Li₂SiN₂ , , Li₃SiNO₂ .

     

Catalytic activity of transition metal silicides in hydrogen oxidation

The catalytic activity of transition metal silicides in H₂ oxidation is much higher compared to metal-like carbides, which can be due to the lower electronegativity of silicon compared to carbon.

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, , .