Calorimetric study of the BrO3?/Ce4+/cyclohexanone and BrO3?/Ce4+/cyclopentanone oscillating systems

The heat output (Q) during the induction period of a Belousov-Zhabotinskii oscillating reaction usually evolves at a constant rate /6/; we observe in the BrO ₃ ^– /Ce⁴⁺/Cyclohexanone system a sudden change in the slope of the function Q=f(t), which corresponds to the beginning of the quasistationary phase /3/.

---

(Q) - ; BrO ₃ ^– /Ce⁺⁴/ Q=f(t), .

     

Thermal study of some sulphosuccinates

The thermal properties of some sulphosuccinates and their intermediates were studied by using combined dynamic thermal analysis and mass spectrometry. The temperature ranges were similar in the two methods, and a scheme of thermal decomposition of the compounds investigated was suggested. In the first temperature range of thermal decomposition of the sulphosuccinate a-rupture of the molecular ion occurs. In the second temperature range, the fragmentation proceeds in two directions: either-rupture of the ethoxylated nonylphenol, or-rupture of the acid residue of the sulphosuccinates.

---

Zusammenfassung Mittels einer Kombination von dynamischer Thermoanalyse und Massenspektroskopie wurden die thermischen Eigenschaften einiger Sulfosukzinate und deren Zwischenprodukte untersucht. Im ersten Temperaturbereich der thermischen Zersetzung des Sulfosukzinates findet eine-Spaltung des Molekülions statt. Im zweiten Temperaturbereich tritt auch ein alternativer Fragmentierungsweg auf: eine-Spaltung des Säurerestes des Sulfosukzinates.

---

- . . - -. : - - .

     

Mechanism of RuIV-catalyzed oxidation of alkanes in aqueous solutions

The Ru^IV-catalyzed oxidation of alkanes in aqueous solutions includes activation of the oxidant Ox (Cr^VI, HNO₃, HClO₄, etc.) via Ox–Ru^IV complex formation and is accompanied by H atom abstraction from the alkane by the activated oxidant.

---

Ru^IV - Ox (Cr^IV, HNO₃, HClO₄ .) Ox–Ru^IV - .

     

Effect of hydrolysis catalyst and thermal treatment on titania synthesis via sol-gel

The effect of acidic and basic catalysts and of thermal treatment on the preparation of TiO₂ by the sol-gel method has been studied. The resultant solids were characterized by UV-Vis spectroscopy. A displacement of the band due to a fundamental transition to lower energies was observed when acid catalysts were used.

---

, TiO₂ - . . .

     

On the pattern of hydrogenolysis of hexane isomers over four Group VIIIB metals

The hydrogenolysis patterns of five hexane isomers have been compared over Rh, Pd, Ir and Pt. The selectivity of rupture of various C–C bond types is different for various metals. The fingerprint-like patterns are, as a rule, similar to those reported in the literature, their correlation with the position of the metal in the periodic system is pointed out.

---

5- Rh, Pd, Ir Pt. C–C , . .

     

Possibilities of applying the Piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

The Piloyan activation energiesE, as well as the initial exotherm temperaturesT _D, are determined for sixN-monoalkyl- and fiveN,N-dialkyl-2,4,6-trinitroanilines. By comparison withR _f-factors, orR _M-functions of paper chromatography, the molecular-structural dependences ofE andT _D are studied for these compounds. Relationships are also found between the termE · T _D ^–1 and theR _M-functions. The effects are discussed of the introduction of the 6-nitro group into the TV-substituted 2,4-dinitroanilines, and of the introduction of the 4-nitro group into the 2,6-dinitro analogues, upon the thermal stabilities of the resulting 2,4,6-trinitroanilines.

---

Zusammenfassung Die AktivierungsenergienE nach Piloyan und die Anfangswerte der ExothermenT _D der sechsN-monoalkyl- und fünfN,N-Dialkyl-2,4,6-trinitroaniline wurden bestimmt. Unter Berücksichtigung des Vergleichs mitR _f-Faktoren oderR _M-Funktionen der Papierchromatographie wurden die molekularstrukturellen AbhÄngigkeiten der WerteE undT _D dieser Verbindungen untersucht. ZusammenhÄnge wurden auch zwischen dem AusdruckE · Tw _D ^–1 und denR _M-Funktionen gefunden. Der Einfluss der Einführung der 6-Nitrogruppe in dieN-substituierten 2,4-Dinitroaniline, sowie der Einfluss der Einführung der 4-Nitrogruppe in 2,6-Nitroanaloge auf die ThermostabilitÄt der resultierenden 2,4,6-Trinitroaniline werden erörtert.

---

Résumé On a déterminé les énergies d'activation par la méthode de Piloyan ainsi que les températures initialesT _D de l'effet exothermique de sixN-monoalcoyl- et cinqN,N-dialcoyl-2,4,6-trinitroanilines. En se référant aux facteursR _F ou aux valeurs des fonctionsR _M en Chromatographie sur papier, on a étudié la dépendance entre les valeurs deE et deT _D sur les caractéristiques moléculaires-structurales de ces composés.On a également trouvé des rapports entre le termeE · T _D ^–1 et les fonctionsR _M. On discute l'influence de l'introduction du groupe 6-nitro dans les 2,4-dinitroanilinesN-substituées ainsi que l'influence de l'introduction du groupe 4-nitro dans les 2,6-dinitro analogues sur la stabilité thermique des 2,4,6-trinitroanilines qui en résultent.

---

N-- N,N--2,4,6- E , T _D. R _f,- R _M — , - E T _D. E.T _D ^–1 R _M-. 6N- 2,4- 4 2,6- 2,4,6- .

---

---

The authors would like to thank Mrs. Anna Colláková for careful DTA measurements, and Dr. Ladislav Smolka for help in the treatment of the measured results with the Wang 600 computer.     

The electronic structure of molecules by a many-body approach

The vertical valence ionization potentials of cyclopropane, ethylene oxide and ethylene imine are calculated by a many-body Green's function method. For C₃H₆ the ordering of the ionization potentials is 2e(), 1e(), 2a₁(), 1a₂(), 1e(). The assignment of the 2a₁ and the 1a₂ ionization potentials which has been controversial is thus clarified. The ordering is in agreement with the result obtained via Koopmans' theorem. For ethylene oxide and ethylene imine Koopmans' theorem fails in predicting the correct order of ionic states. For C₂H₄O the ordering of the ionization potentials is 2b ₁(), 4a ₁, 1a ₂(), 2b ₂,3a ₁, 1b ₁(), 1b ₂, 2a ₁ and for C₂H₅N 6a, 5a, 3a, 2a, 4a, 3a, 1a, 2a. The agreement of the computed ionization potentials with the experimental values is very satisfactory.     

Hreels studies of Hads effect on NO adsorption on Pt(111)

HREELS studies of NO molecular adsorption on clean and hydrogen covered Pt(111) have revealed that a reversible transition between bridge (₁) and on-top (₂) states of NO_ads is realized in the (NO+H₂)/Pt(111) system. In the presence of H_ads the adsorption of NO in the ₁ state is inhibited and the main state of NO_ads is ₂. Upon heating the layer (₂-NO_ads+H_ads) hydrogen desorption is accompanied by on-top to bridge state conversion.

---

NO Pt(III). , (NO+H₂)/Pt(III) (₁) (₂) NO. H NO ₁ , , ₂ NO. (₂-NO+H) NO .

     

Reaction of triphenyl phosphite ozonide with thioacetals

Kinetic regularities in the reaction of triphenyl phosphite ozonide with several thioacetals in CH₂Cl₂ solution at –15°C have been studied. The consumption rate of ozonides is described by the kinetic equation W=k₀[(C₆H₅O)₃P·O₃]+k₁[(C₆H₅O)₃P·O₃][R₁R₂C(SR₃)₂] Rate constants k₀ and k₁ for the thioacetals: (CH₃H₇S)₂CH₂, (C₆H₅S)₂CH₂, (C₆H₅CH₂S)₂CH, (n=C₁₂H₂₅–S)₂CH₂, (C₃H₇S)₂C(H)CH₃, (C₃H₇S)₂C(H)C₆H₅, (C₃H₇S)₂C(CH₃)C₆H₅ and (C₃H₇S)₂C(H)C₁₀H₉, increases with increasing the electron-donating power of subtituents R_i.

---

CH₂Cl₂ –15°C. : W=k₀[(C₆H₅O)₃P·O₃]+k₁[(C₆H₅O)₃P·O₃][R₁R₂C(SR₃)₂] k₀ k₁ (C₃H₇S)₂CH₂, (C₆H₅S)₂CH₂, (C₆H₅CH₂S)₂CH₂, (n-C₁₂H₂₅S)₂CH₂, (C₃H₇S)₂C(H)CH₃, (C₃H₇S)₂C(H)C₆H₅, (C₃H₇S)₂C(CH₃)C₆H₅, (C₃H₇S)₂C(H)C₁₀H₉. .

     

Acid-base properties of supported vanadium oxide catalyst

Reduction of V₂O₅/Al₂O₃ and V₂O₅/silica-alumina produced Lewis acid sites which could strongly adsorb CO (heat of adsorption: 90 kJ/mol). Such strong acid sites were not formed in the cases of V₂O₅/SiO₂ and V₂O₅/MgO. V₂O₅ loaded on Al₂O₃ interacted with the basic sites of alumina but not with the acidic sites, while the V₂O₅ on silica-alumina interacted with the acidic sites of the silica-alumina and decreased its acidity.

---

V₂O₅/Al₂O₃ V₂O₅/SiO₂–Al₂O₃ , CO ( 90 /). V₂O₅/SiO₂ V₂O₅/MgO . V₂O₅, Al₂O₃, , , V₂O₅ SiO₂–Al₂O₃ - .

     

Ab initio investigation of the electron structure in bis-Cu+ acetylene and vinylidene complexes

[Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺ and [Cu(-C₂H₂) (-CCH₂]⁺ complexes have been studied by the ab initio double-zeta basis set method. It has been established that all calculated compounds are stable to decomposition into two C₂H₂ molecules and Cu⁺ cation and into one C₂H₂ molecules and the respective monocomplex. Calculation results suggest the possibility of intramolecular acetylene-vinylidene rearrangement in the coordination sphere of Cu⁺.

---

ab initio : [Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺, [Cu(-C₂H₂) (-CCH₂)]⁺. C₂H₂ Cu⁺ C₂H₂ . - Cu⁺.

     

Molecular orbitals and the virial theorem

It is shown that for H₂ ⁺ and H₂ an atomic orbital exponent chosen from the condition = - E _obs. gives calculated total energies which are insignificantly different from those obtained using a obtained through a variational treatment. A scheme is proposed in which the atomic orbital exponents of -electron molecular orbitals are taken to be a function of the orbital energies, such that these molecular orbitals qualitatively satisfy the virial theorem.

---

Zesummenfassung Es wird gezeigt, daß für H₂ ⁺ und H₂ ein Atomorbital-Exponent , der entsprechend der Bedingung = - E _obs. gewählt wurde, zu Gesamtenergien führt, die nur unwesentlich von jenen abweichen, die man nach der Variations-Methode erhält. Es wird ein Verfahren vorgeschlagen, in welchem der Exponent der Atomorbitale eines -Elektronensystems als Funktion der Orbitalenergien angesetzt wird, so daß diese Orbitale dem Virial Theorem qualitativ genügen.

---

Resume On montre que l'exposant que l'on choisit pour les orbitales atomiques de H₂ ⁺ et H₂ en se servant de la condition = - E _obs. diffère d'une façon insignifiante de celui calculé par la méthode variationelle. On propose un procédé dans lequel les exposants des orbitales atomiques de systèmes n sont fonction de l'énergie des orbitales moléculaires de manière que le théorème du viriel est qualitativement satisfait.

     

Synthesis of γ-Fe2O3 by thermal decomposition of FeC4H4O6·2.5H2O

Iron(II) tartrate two and a half hydrate (FeC₄H₄O₆·2.5H₂O) was prepared and its thermal dehydration and decomposition were studied with a simultaneous thermal analyser (TG/DTA/DTG) under atmospheres of static air, dynamic dry nitrogen and dynamic air. This study was supplemented with the two-probe d.c. electrical conductivity technique under the same atmospheres. Under all the above atmospheres, the thermal dehydration was found to be a two-step process. However, the thermal decomposition process was quite complicated, involving the formation of various metastable intermediates, including-Fe₂O₃. The final product of decomposition under all atmosphere was-Fe₂O₃.Studies on the physical properties of-Fe₂O₃ were also undertaken.

---

Zusammenfassung Es wurde Eisen(II)-tartrathydrat (FeC₄H₄O₆ · 2,5H₂O) hergestellt und seine thermische Dehydratation bzw. Zersetzung in statischer Luftatmosphäre bzw. im Stickstoff- und Luftstrom mittels eines Simultanthermoanalysators (TG/DTA/DTG) untersucht, ergänzt durch Untersuchungen nach dem Gleichstromleitfähigkeitsverfahren in den gleichen Atmosphären. Die thermische Dehydratation wurde in jedem Falle als zweistufig befunden. Der thermische Zersetzungsprozeß ist jedoch wegen der Bildung verschiedener metastabiler Zwischenprodukte, z. B.-Fe₂O₃, recht kompliziert. Das Endprodukt der Zersetzung war in allen Fällen-Fe₂O₃. Weiterhin wurden die physikalischen Eigenschaften von-Fe₂O₃ untersucht.

---

, FeC₄H₄O₆ · 2,5₂. . , . , y-Fe₂O₃. -Fe₂O₃. -Fe₂O₃.

---

---

Now deceased.

---

Financial assistance for this work was given by Grants-in-aid (Defence Ministry), Govt. of India. One of the authors (A.V.R.) is grateful to the Head, Dept. of Chemistry, Sardar Patel University, for his interest and encouragement.     

Studies on double malonates. III. Thermal decomposition of sodium lanthanide malonates,Na5Ln(C3H2O4)4.7.5H2O,where Ln=Gd,Tb or Ho

The double malonates of gadolinium, terbium and holmium with sodium, of the type Na₅Ln(C₃H₂O₄)₄.7.5H₂O, have been studied by means of thermal analysis. A mechanism of thermal dehydration and decomposition has been proposed on the basis of the results obtained.

---

Zusammenfassung Doppelmalonate von Gadolinium, Terbium und Holmium mit Natrium des Typs Na₅Ln(C₃H₂O₄)₄.7,5 H₂O wurden mittels thermischer Analyse untersucht. Für die thermische Dehydratisierung und Zersetzung wird ein auf den erhaltenen Ergebnissen basierender Mechanismus vorgeschlagen.

---

, Na₅Ln(C₃H₂O₄)₄.7.5H₂O. .

---

---

Part II. Communicated     

Interaction of PM12?nVnO40?(3+n) (M=Mo, W) heteropoly complexes with nitrogen oxide

In aqueous solution, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) hetero-polyanions provide a much faster oxidation of NO than mononuclear VO ₂ ⁺ ions, yielding HNO₂, NO ₃ ^– and reduced HPA.

---

, PM_12–nV_nO₄₀ ^–(3+n) (M=Mo,W) , VO ₂ ⁺ , NO HNO₂ NO ₃ ^– .

     

Heat evolution during hydration of Ca4(Al6O12)(SO4)

The hydration of the sulphatealuminate phase Ca₄(Al₆O₁₂)(SO₄) at room temperature was observed by means of differential calorimetry and quantitative X-ray diffraction phase analysis in situ. The results were used to evaluate the kinetics of the hydration process and to explain the causes of the exothermic effects: an initial surface reaction, the formation of a highly dispersed system, and the crystallization of monosulphate, Ca₄(Al₂O₆)(SO₄) · 12H₂O, and gibbsite, Al(OH)₃. The experiments showed an increase in efficiency of hydration with a higher mass ratio of water to solid phase (from 143.8 kJ/mol) atw/s=1 to 170.0 kJ/mol atw/s=10).

---

Zusammenfassung Die Hydration der Sulfat-aluminat-Phase Ca₄(Al₆O₁₂)(SO₄) bei Zimmertemperatur wurde mittels Differentialkalorimetrie und quantitativer in-situ-Röntgenbeugungs-Phasenanalyse verfolgt. Ein vergleich der Ergebnisse erlaubte die Kinetik des Hydratationsprozesses abzuschätzen und die Ursache der exothermen Effekte zu klären: Anfängliche Oberflächenreaktion, Bildung eines hochdispersen Systems, Kristallisation von Monosulfathydrat Ca₄(Al₂O₆)SO₄·12H₂O und Hydrargillit Al(OH)₃. Die Versuche zeigten eine Zunahme der Hydratationseffektivität mit steigendem Verhältnis Wasser: Feststoff (w/s) von 143,8 kJ mol^–1 beiw/s=1 auf 170,0 kJ mol^–1 beiw/s=10.

---

in situ ₄(l₆)(S₄). , , ₄(l₂₆)(S₄) · 122 l()₃. : 143,8 ^–1 1 170,0 · ^–1 10.

     

Systematics of bonding in non-icosahedral carbon clusters

General formulas are presented for the vertex numbers, , of pentagon+hexagon polyhedra of icosahedral, tetrahedral or dihedral symmetries. Criteria for uniqueness of representation, isomer counts and grouping of pentagons are established. All polyhedra with 256 vertices or less and belonging to T, D ₅, D₆or their supergroups are listed. With the addition of C₃ to the dihedral and higher groups, at least one pentagon+hexagon cluster is found for all even 20 except for = 22 which is unrealisable in any symmetry, and = 46 (for which a C₃ polyhedron exists). Carbon clusters with closed electronic shells are shown to be generated by a geometrical leapfrog procedure: for all = 60+6k (where k is zero or greater than one) at least one closed shell structure is predicted. In dihedral symmetry closed shells also exist for some other values of . Separation of the 12 pentagonal faces is not sufficient to ensure a closed electronic shell but appears to be a necessary condition in dihedral or tetrahedral symmetry.     

Formation of N-butane in the pyrolysis of ethylene [1]

Yields of n-C₄H₁₀ have been measured from the flow pyrolysis of C₂H₄ at 897 (±7) K. From 77 to 720 Torr the order of n-C₄H₁₀ formation was found to be 2.0±0.3 The rate constant for the reaction, was estimated to be 2.4(±0.6)×10^–4l mol^–1s^–1.

---

-C₄H₁₀ C₂H₄ 897 (±7) . -C₄H₁₀ 77 720 2.0±0.3. 2C₂H₄C₂H₃+C₂H₅ 2,4 (±0,6)×10^{–4 –1–1}.

     

Infrared spectroscopy of hydrogen bond and substituent effects in electron donor molecules

The frequency shift, , of the O—H stretching mode in the IR spectra of the H-complexes of phenol with electron donor molecules BX_i (B is the n- or -donor center and X_i are substituents; a total of eight series), the change in the Gibbs free energy, G, due to H-complexation, and the parameter (a measure of the ability of BX_i molecules to donate an electron pair; two series) are determined by both the electrostatic interaction and charge transfer in the formation of H-complex. The , G, and values depend not only on the inductive and resonance effects, but also the polarizability of substituents characterized by the parameters.     

Proton-magnetic-resonance spectra of some organoethoxysilanes

The PMR spectra of 33 organoethoxysilanes have been investigated. Comparison of the chemical shifts of C₂H₅O and CH₃ groups attached to the silicon atom with the values of the remaining substituents at the central silicon atom gives reason to suppose that the contribution of each atom in p– interaction decreases with increased number of ethoxy groups at the silicon atom, while the over-all effect of increased electron density at the silicon heteroatom arising from this interaction increases. The Taft constants for several substituents are calculated.