Permanganate oxidations in strongly basic solutions

In strongly basic solutions the permanganate ion oxidation of C₁ and C₂ alcohols, aldehydes and acids obeys a second-order kinetic law of the type rate=k_o [S]_o [MnO ₄ ^– ], where S is the substrate. The rate constant k for both alcohols and aldeydes is proportional to the OH^– ion concentration. This behavior is interpreted in terms of a deprotonation equilibrium followed by rate-determining hydride ion transfer to MnO ₄ ^– .

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, C₁ C₂ W=k_o [S]_o [MnO ₄ ^– , S — . OH^–. MnO ₄ ^– , .

     

Adsorption kinetics of nonionic surfactants using the drop volume method

The kinetic results obtained for the nonionic surfactantsn-octyl,n-decyl, andn-dodecyl dimethyl andn-octyl, andn-decyl diethyl phosphine oxide show purely diffusion controlled adsorption. The drop volume technique applied in a static and dynamic version proves to be useful to measure the adsorption kinetics in the form of surface tensions in function of time. Comparisons of the results obtained from both the static and the dynamic measuring procedure confirm the validity of a theory applied to interpret the kinetic data.Nomenclature a Langmuir parameter - c ₀ surfactant bulk concentration - D diffusion coefficient - surface concentration - ₀ equilibrium surface concentration - ¯ (t)/ ₀ reduced surface concentration - maximum value of - R gas law constant - surface tension - ₀ surface tension of pure water - t time - T absolute temperature     

Cyclohexane photooxygenation by air oxygen in CH2Cl2 in the presence of chromium oxocomplex-iodosylbenzene system

Cyclohexane is oxidized by air oxygen in CH₂Cl₂ solution to yield cyclohexanol, cyclohexanone and cyclohexyl chloride when irradiated by light (>310 nm) in the presence of (Bu₄N)₂CrO₄ or (Bu₃SnO)₂CrO₂. The addition of PhIO greatly accelerates the reaction and increases the yield of products. The reaction mixture contains neither cyclohexanol nor cyclohexanone when the photoreaction in the presence of the Cr(VI)–PhIO system is carried out in argon atmosphere. Hence neither iodosylbenzene nor oxochromium compounds can be oxygen atom donors in alkane oxygenation. The accelerating effect of iodosylbenzene may be due to the enhanced oxidizing power of photo-excited oxochromium species when coordinated to iodosylbenzene.

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CH₂Cl₂ , , (>310 ) (Bu₄N)₂CrO₄ (Bu₃SnO)₂CrO₂. PhIO . Cr(VI)–PhIO , , . , ( ) . .

     

Adsorption kinetics measurements of some nonionic surfactants

Dynamic surface tension values of aqueous surfactant solutions were measured by using the ring and plate method. The mean diffusion coefficients calculated on the basis of the purely diffusion controlled adsorption model vary between 2 · 10^–6 to 7 · 10^–6 cm²/s for all surfactants studied:n-alkanols,n-alkanoic acids, dimethyl and diethyln-alkyl phosphine oxides. That means the surfactants investigated adsorb with a purely diffusion controlled adsorption mechanism and no barriers excist to hinder sorption processes.Nomenclature c ₀ surfactant bulk concentration - D diffusion coefficient - surface concentration - ₀ equilibrium surface concentration - ¯ (t)/ ₀ reduced surface concentration - maximum surface concentration - K ₀/c₀ - surface tension - t time - Dt/K ² reduced time - a _L coefficient of the Langmuir isotherm     

Thermal analysis of heterocyclic thione donor complexes. Part 1

The thermal decomposition of the Co(II) complexes of 1-methylimidazoline-2(3H)-thione (MImt), general formula Co(MImt)₂X₂ (X=Cl, Br & I), have been studied in air and argon by means of TG and DTG as well as in nitrogen by DTA. Quantitative DTA has been used to derive reaction enthalpies (H _R) from the melting and decomposition endotherms in nitrogen. Decomposition processes have been proposed for the complexes in air and in inert atmospheres. A mean coordinate bond dissociation energy (¯D) has been estimated for the Co-MImt bond in Co(MImt)₂Cl₂.Reaction end products in air have been identified by X-ray powder diffraction.

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Zusammenfassung Die thermische Zersetzung von Kobaltkomplexen des 1-Methylimidazolin-2(3H)-thions (IMmt) der allgemeinen Formel Co(MImt)₂X₂ (X=Cl, Br, J) wurde in Luft und Argon mittels TG und DTG und in Stickstoff mittels DTA untersucht. Reaktionsenthalpien (H_r) wurden durch quantitative DTA aus den in Stickstoffatmosphäre erhaltenen endothermen Schmelz- und Zersetzungspeaks erhalten. Es wurden Mechanismen für die Zersetzungsprozesse der Komplexe in Luft und inerter Atmosphäre vorgeschlagen. Die mittelere Dissoziationsenergie (¯D) der koordinativen Bindung Co—MImt in Co(MImt)₂Cl₂ wurde bestimmt.In Luft erhaltene Reaktionsendprodukte wurden durch Röntgenpulverdiffraktometrie identifiziert.

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1- -2()- () ()₂₂, X=l, I, , . (H _R) . . - ()₂l₂. , , - .

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The author is grateful to Mr. J. R. Creighton, Newcastle upon Tyne Polytechnic, for technical assistance with this work and to Dr. F. Buttler, Teesside Polytechnic for mass spectral data and helpful discussion.     

Phase-fixed double-group 3-Γ symbols. V. 3-Γ symbols and coupling coefficients for all the octahedral double group-subgroup hierarchies

For all the subgroup hierarchies descending from the octahedral double group O ^*, we have obtained sets of 3- symbols and discuss here their properties. We have entirely real sets of 3- symbols for the tetrahedral and tetragonal hierarchies as well as for O ^* C ₃ ^* . For the latter hierarchy and the tetragonal ones, formalisms almost as powerful as the classical one for the rotation group may be established. We also discuss results obtained for cases with strict adaption to D ₃ ^* where it is now known that non-real 3- symbols are unavoidable.The 3- symbols are phase-fixed by the specification of basis functions (or, equivalently, subduction coefficients) generating them.The significance of the concept of associated representations of O* is discussed. The problems raised by the two multiplicity triples UT₁U and UT₂U in O* are given particular attention.     

On the theory of adsorption kinetics of ionic surfactants at fluid interfaces

The kinetic equation to describe the adsorption process of ionic surfactants (derived in part 1) will be solved numerically. The results show the effect of parameters such as ion valencyz, thickness of theDL x ^–1, and surfactant parameters_eq,K, andK _ads on the adsorption process. The results can be used to decide whether the model can explain experimental data on charged surfactant molecules or not.Nomenclature c concentration - c_e bulk concentration in equilibrium - C =c/c _e dimensionless concentration - D diffusion coefficient - e proton charge - F Faraday's constant - f ₀ =e/kTdimensionless potential - k Bolzmann's constant - K _ads rate constant of adsorption - K _des rate constant of desorption - K(f ₀) coefficient of electrostatic deceleration - K = _eq /c _e Henry's constant - R gas law constant - t time - T absolute temperature - z electrovalence - ₀ adsorption of ions - _eq equilibrium value of _o - = ₀/ _eq dimensionless adsorption - , constants - dielectric constants - x Debye-Hückel reciprocal distance - =Dt/K ² dimensionless time - electric potential     

On the application of quantitative models of diffusion-controlled adsorption kinetics at fluid interfaces

The model of diffusion-controlled adsorption kinetics can be solved by different mathematical procedures. For the most important case of a Langmuir isotherm, useful solutions are summarized and extended and the ranges of application are given. New approximations are presented which can be applied to most experiments in practice.Nomenclature a _i coefficients of the collocation solution - a _L Langmuir parameter - a interaction parameter of the Frumkin isotherm - _n coefficients of a power series - c surfactant bulk concentration - c ₀ equilibrium bulk concentration - D diffusion coefficient - surface concentration - ₀ equilibrium surface concentration - _t8 maximum surface concentration - ( _x ) Gamma function - t time - dimensionless time Dedicated to the 60th birthday of G. Kretzschmar.     

Triterpene Glycosides and Their Genins from Tragacantha stipulosa. Structure of Cyclostipuloside C

A new cycloartane glycoside of the cyclostipuloside C series, 3-O--D-xylopyranoside-6,16-di-O--D-glucopyranoside-20S-24R-epoxycycloartan-3,6,16,25-tetraol is isolated from aerial organs of Tragacantha stipulosa Boriss.     

Thermal and some other properties of the complexes crystallizing from the system Ni(II)-en-[Ni(CN)4]2−-H2O

Seven complex compounds exhibiting the compositions Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) and-Ni(en)₂Ni(CN)₄ (VII) were prepared from the system Ni-en-[Ni(CN)₄]^2–-H₂O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.

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Zusammenfassung Aus einem System Ni-en-[Ni(CN)₄]^2–-H₂O wurden sieben Komplexe der Formeln Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) und-Ni(en)₂Ni(CN)₄ (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

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Ni- -[No(N)]² -₂ Ni(en)₃Ni(CN)₄ · ₂ (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄-2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2,5H₂O (VI) -Ni(en)₂Ni(CN)₄ (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .

     

Reforming type Pt/Al2O3 catalyst prepared from [(CH3)3PtX]4 complexes by thermal decomposition

Pt/Al₂O₃ catalysts with good reforming activity were prepared from [(CH₃)₃PtX]₄ (X=Cl, Br, I) complexes and tested in pulse and continuous-flow reactors in n-hexane dehydrocyclization. It has been demonstrated that [(CH₃)₃PtX]₄ complexes are excellent precursors of supported platinum catalysts.

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Pt/Al₂O₃ [(CH₃)₃ PtX]₄ (X=Cl, Br, I) -. , [(CH₃)₃PtX]₄ .

     

Non quasi-stationary state pyrolysis. Induction period of neopentane pyrolysis

The principle of an apparatus using an isothermal continuous flow stirred tank reactor to study homogeneous gas phase reactions at space times of the order of 1 sec is given. With this apparatus, the induction period of neopentane pyrolysis (as an example) has been clearly shown.

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, , 1 . , , .

     

Non-catalyzed oscillation reaction in the aniline-KBrO3?H2SO4 system. II. Reaction products and their oscillating behavior

By means of thin-layer and gas chromatography the reaction products have been determined in the oscillation system of aniline, KBrO₃ and H₂SO₄. These products include: 2-bromoaniline, 4-bromoaniline, 2,4-dibromoaniline, 2,4,6-tribromoaniline, 1,4-benzoquinone, 2-bromo-1,4-benzoquinone, 2,6-dibromo-1,4-benzoquinone and a brominated oxidation product. The brominated aniline derivatives do not exhibit an oscillating behavior, and the addition of these substances to an oscillating mixture damps the course of other oscillations.

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, KBrO₃ H₂SO₄. : 2-, 4-, 2,4-, 2,4,6-, 1,4-, 2--1,4-, 2,6--1,4- . , , , .

     

AlPO4 as catalyst in organic reactions. IV. Transesterification of methyl methacrylate

Coke deposition on monometallic Pt, Re, Ir, Ge and Sn catalysts supported on -Al₂O₃, and its influence on activity and selectivity over methylcyclopentene reforming was studied. As a result the effect can be interpreted in terms of metal-support interactions that modify the overall catalytic deactivation rates.

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Pt, Re, Ir, Ge Sn, -Al₂O₃ . , .

     

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + + 23.5 H₂OThe data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

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Zusammenfassung Die thermische Zersetzung von Hydrazin-monoperchlorat (HP-1) im geschmolzenen Zustand wurde unter Einsatz der Differentialthermoanalyse, der thermogravimetrischen Analyse, der manometrischen Methode mit konstrantem Volumen und der Maßenspektrometrie untersucht. Die Stöchiometrie der Reaktion kann durch folgender Gleichung dargestellt werden: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 20₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂ODie Angaben zeigen, dass der Mechanismus, in welchen ein assoziierter Komplex mit inbegriffen ist, im Temperaturenbereich von 140° bis 190° C unverändert bleibt. Folglich setzen Verunreinigungen, die mit dem Hydrazinoder dem Perchlorat-Ion assozüerte Komplexe zu bilden imstande sind, die Empfindlichkeit der thermischen Zersetzung von HP-1 herab, wobei das Ausmaß der Herabsetzung von der Grösse, der Ladung und der Konzentration der Verunreinigung abhängt.

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Résumé La décomposition thermique en milieu fondu du monoperchlorate d'hydrazinium (HP-1) a été étudiée par analyse thermique différentielle, thermogravimétrie, manométrie à volume constant et spectromètrie de masse. La réaction peut être représentée par l'équation suivante: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂OLes données semblent indiquer que le mécanisme mettant en jeu un complexe associé reste inaltéré dans l'intervalle de températures allant de 140 à 190°. Par conséquent, les impuretés qui pourraient former des complexes associés avec les ions hydrazinium ou perchlorate désensibilisent la décomposition thermique de HP-1, le taux de désensibilisation étant déterminé par la taille, la charge et la concentration de l'impureté.

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(-1), , , - -. : 20 N₂H₅ClO₄ 13 NH₄ClO₄ + 3.5 l₂ + 2 ₂ + 13 N₂ + 0.5 N₂O + 0.5 ₂ + 23.5 ₂ , , - , 140° 190°. , , - , -1, , .

     

Phase-fixed double-group 3-Γ symbols. II. General features of double groups and their 3-Γ symbols

Following a general exposition of the theory of 3- symbols [1], we now focus on the particular features encountered when dealing with double groups of (proper as well as improper) point groups.The paper starts with a brief outline of the definition of double groups adopted in the present work. After this, some properties of double group 3- symbols are discussed which are independent of the way the 3- symbols have been constructed. The main part of the paper then deals with the actual generation of 3- symbols for the non-commutative double groups.In the approach described, the 3- symbols become determined in part by adaption of the standard matrix irreps to subgroup hierarchies and then completely, phases included, by the specification of standard basis functions (or, equivalently, standard subduction coefficients).     

Thermal behaviour of transition metal complexes of dithiocarbazic esters. II

A thermal study (simultaneous TG and DTA measurements) was carried out on the dithiocarbazic ester complexes M[N³CH₂R₁N²C¹(S)SCH₃]₂, where M=Ni, Pt; R₁=C₆H₅. The following disproportionation reaction occurs in the solid state: II is formed through deprotonation of the CH₂ group bound to N³, whereas III is formed through protonation of N³.The influence of inductive and/or steric effects on the mechanism of this reaction is discussed, taking into account the electrochemical and X-ray data on the complexes Pt[NRNC(S)SR']₂ with differentR substituents: R=H, Ph, CH₂Ph, CH₂C₅H₁₁, CH(CH₃)₂, C(CH₃)₃; R=CH₃, CH₂Ph.These results accord with the behaviour of the same complexes in solution.

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Zusammenfassung Dithiokarbamidsäureesterkomplexe M[N³CH₂R₁N²C¹(S)SCH₃]₂ mit M=Ni, Pt und R₁=C₆H₅ wurden thermisch untersucht. Im festen Zustand spielt sich folgende Disproportionierungsreaktion ab: II wird durch Deprotonierung der an N³ gebundenen CH₂ Gruppe und III durch Protonierung des Atoms N² gebildet. Unter Zuhilfenahme der elektrochemischen und Röntgendaten der Komplexe Pt[NRNC(S)SR']₂ mit verschiedenen Substituenten R: R=H, Ph, CH₂Ph, CH₂C₅H₁₁, CH(CH₃)₂, C(CH₃)₃ und R=CH₃ bzw. CH₂Ph wurde der Einfluß von induktiven und/or sterischen Effekten auf den Reaktionsmechanismus diskutiert. Diese Ergebnisse stehen in Übereinstimmung mit dem Verhalten der Komplexe in Lösung.

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M[N³CH₂R₁N²C¹(S)SCH₃]₂, M= Ni, Pt,R ₁=C₆H₅. : II CH₂ , N³, III N². () , Pt[NRNC(S)SR]₂, R= , aR= . .

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We thank prof. A. La Ginestra for many helpful discussions on the various aspects of this work.     

Glass transition and crystallization effects demonstrated by thermal analysis of liquid-quenched ternary glasses Te80Ge20−xA x V (AV=Sb,Bi)

In DSC studies of liquid-quenched ternary chalcogenide glasses Te₈₀Ge_20–xA _x ^V (A^V=Sb, Bi), the characteristic temperatures (glass transition and crystallization temperatures) were determined. Changes in the thermal stabilities of these glasses, depending on the element A (Sb, Bi) from group V of the periodic table and on its content in the alloy were evaluated. Moreover, the effect of changes in the glass composition on the glass formation ability expressed by the parameter K_g1 was determined.

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Zusammenfassung In DSC-Untersuchungen abgeschreckter ternärer Chalkogenidgläser des Typs Te₈₀Ge_20–xA _x ^v (A^x=Sb, Bi) wurden die charakteristischen Temperaturen (die GlasÜbergangs- und Kristallisationstemperaturen) bestimmt. Die Änderungen der Thermostabilität dieser Gläser wurden in Abhängigkeit von dem Element A (=Sb, Bi) aus der V Gruppe der Periodensystems und von seinem Gehalt in der Legierung ausgewertet. Ausserdem wurde der Einfluß der Änderungen in der Glaszusammensetzung auf die Glasbildungsfähigkeit, ausgedrückt durch den Parameter K_g1, bestimmt.

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Résumé On a déterminé par analyse calorimétrique différentielle (DSC) les températures caractéristiques (températures de transition vitreuse et de cristallisation), des verres ternaires à chalcogénures formés par trempe à partir du liquide, du type Te₈₀Ge_20–xA _x ^v (A^v=Sb, Bi). On a évalué la variation de la stabilité thermique de ces verres en fonction de l'élément A (=Sb, Bi) du Vème groupe du tableau périodique et de sa teneur dans l'alliage. De plus, on a déterminé l'effet des variations de la composition du verre sur la capacité de formation du verre qui s'exprime par le paramètreK _g1.

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Te₈₀Ge_20–xA _x ^v (A^v=Sb, Bi), , . A(=Sb,Bi) . , K _gl, .

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Research supported by the U. S. National Science Foundation under Grant No. GF 421 76     

Selective catalytic hydrogenation of double bonds in unsaturated furan ketones

In the hydrogenation of unsaturated furan ketones in solvents at atmospheric pressure and room temperature the Raney Pd–Al catalyst is highly active and selective towards the hydrogenation of double bonds. The only reaction products are the respective saturated ketones.

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, Pd–Al . . .

     

High activity of MgO catalyst prepared from magnesium oxalate for the hydrogenation of butadiene

High activity of magnesium oxide prepared by thermal decomposition of magnesium oxalate for the hydrogenation of 1,3-butadiene has been examined by XPS and IR, together with the isomerization of 1-butene. XPS spectra of MgO differed from those of two other MgO catalysts. With Ar etching, the binding energies of Mg2p and 01s shift, which is related to the surface basicity. Both basic and acidic sites are responsible for hydrogenation, but isomerization proceeds only on basic sites.

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, 1,3- 1-, . MgO ; Ar 2p 1s Mg, . , , , - .