Investigation of propylene oxidation on multicomponent a Bi-and Mo-based oxide catalyst

It has been established that porpylene oxidation to acrolein on a multicomponent oxide catalyst containing Mo, Bi, Fe, Ni, Co, K, P and SiO₂ follows an alternating oxidation-reduction mechanism and involves the participation of lattice oxygen with the bond energy of about 280 kJ/mol.

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, Mo, Bi, Fe, Ni, Co, K, P SiO₂ 280 /.

     

Investigation of the effects of diethylene glycol on the hydration of C3S and C3A pastes

The effects of diethylene glycol on the hydration characteristics of tricalcium silicate and tricalcium aluminate pastes were studied. Diethylene glycol acts as a retarder in the hydration of C₃S, and as an accelerator in the hydration of C₃A. The amount of Ca(OH)₂ found in pastes of C₃S treated with diethylene glycol was lower, the induction period increased and the formation of hydrates was retarded. For C₃A pastes, hydration in the presence of diethylene glycol accelerated the formation of the hexagonal aluminate hydrates and promoted the conversion to the cubic form.

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Zusammenfassung Der Einfluss von Diethylenglykol auf die Hydratation von Tricalciumsilicat- (C₃S) und Tricalciumaluminat- (C₃A) -Pasten wurde untersucht. Diethylenglykol verzögert die Hydratation des C₃S und beschleunigt die des C₃A.In C₃S-Proben, die mit Diethylenglykol hydratisiert wurden, ist der Gehalt an Ca(OH)₂ geringer, die Induktionsperiode länger und die Bildung von Hydraten verzögert. In C₃A-Pasten wird in Gegenwart von Diethylenglykol die Bildung des hexagonalen Calciumaluminathydrats beschleunigt und seine Umwandlung in die kubische Form begünstigt.

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. , . , , , , , . .

     

Studies of vapor phase synthesis of pyridine bases on non-steady state catalysts

The reaction of NH₃ with R–CHO (R=CH₃, Ph) has been studied. Experimental data and parameters of the laboratory catalytic reactor are reported.

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NH₃ c R–CHO(R=CH₃, Ph). .

     

Comparative testing of the flammability of upholstery textiles

Flash ignition temperatures of upholstery textiles were measured with a modified derivatograph, and the TG, DTG, DTA and T curves were also recorded. The results obtained with the newly-developed system were compared with those of the ASTM D 1929 test procedure and with the simultaneously recorded thermal analysis curves.

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Zusammenfassung Der Flammpunkt von Upholstery-Textilien wurde mittels eines modifizierten Derivatographen gemessen. TG-, DTG-, DTA- und T-Kurven wurden registriert. Die mit diesem neuentwickelten System erhaltenen Ergebnisse wurden mit den nach dem ASTM D 1929 Testverfahren erhaltenen und mit den simultan registrierten thermoanalytischen Kurven verglichen.

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, -, -, - -. , ASTM 1929 .

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Paper presented at the World Conference on Thermal Analysis, Madeira (Portugal), 1986.     

Study of hydrogen adsorption on iridium catalysts

The influence of dispersity on hydrogen adsorption on Ir black and Ir/C catalysts has been studied. It is shown that supported iridium reduces the heat of hydrogen adsorption as compared to Ir black. With decreasing catalyst dispersity, the amount of weakly bound hydrogen increases, while its adsorption heat decreases on all Ir catalysts.

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Ir- Ir/C-. , Ir-. C , Ir-.

     

Change of selectivity of butadiene oxidation due to zeolitic support for phosphorus-vanadium catalyst

The effect of the OH groups of the zeolites HY, HZSM-5 and HZSM-11 on the selective behavior of the supported active component P–V–O (P/V=1) in the oxidation of butadiene is characterized in detail and discussed. It was shown that the change in the selectivity was caused by the interaction of the pure component with the protondonor centres of zeolite: on this type of catalysts with the supported active component only furan and not maleic anhydride is formed as a product.

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OH- HY, HZSM-5 HZSM-11 P–V–O (P/V=1) . , - : , .

     

A conductance study of the binding of benzo-15-crown-5 with alkali cations in acetonitrile

The decrease in the molar electrolytic conductance of Na⁺, K⁺, Rb⁺, and Cs⁺ tetraphenylborates, caused by the addition of benzo-15-crown-5 in acetonitrile at constant ionic strength, is analyzed according to a model involving 1:1 stoichiometry. The stability constant,K, and the limiting molar conductivity, _c , for each 1:1 complex are determined from the conductance measurements by using a nonlinear least squares curve fitting procedure. The stability sequence of the 1:1 complexes, as deduced from data at 288, 293, 298, 303, and 308 K, has the order Na⁺>K⁺>Rb⁺>Cs⁺. Values of H ⁰, S ⁰, and _c at 298 K are reported and their significance is discussed.     

A study of the1H NMR spectra of octaacetates of disaccharides

Summary 1. The¹H NMR spectra of octaacetates of disaccharides with different positions (11, 12, 13, 14, and 16) and configurations of the glycosidc bonds have been studied.2. The possibility has been shown of determining the position and configuration of the glycosidic bonds from¹H NMR spectra of disaccharide octaacetates.Institute of Biologically Active Substances, Far-Eastern Scientific Center, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 425–430, July–August, 1972.     

Metal bioaccumulation by the freshwater algaScenedesmus quadricauda

Bioaccumulation of six metals (Cu²⁺, Cu⁺, Mo⁶⁺, Mn²⁺, V⁵⁺, Ni²⁺) and their combinations by algaScenedesmus quadricauda was determined by using radio nuclide X-ray fluorescence (RXFA). The metals were added into the cultivation medium in concentrations corresponding with EC₅₀ value for each metal. The obtained results indicate that Ni²⁺, Cu²⁺ and Cu⁺ were accumulated in high amounts (20%, 17.5% and 15.19%) the Mo⁶⁺ ion (<0.2%) was accumulated in the lowest amount. For metal-metal interactions in accumulation of metal ions by algaS. quadricauda three types of answers were determined: inhibition (MoCu²⁺, Ni, Mn, V; VNi, Mn; MnNi, Cu²⁺, Cu⁺; Cu⁺Ni; Cu²⁺Ni; NiMn, V), enhancement (VCu⁺; Cu²⁺Mn;Cu⁺V, Mn; MnV; NiCu²⁺, Cu⁺) and neutral effect (VMo; Cu²⁺Mo; Cu⁺Mo; MuMo; NiMo).     

Kinetic parameters of thermal decomposition of nitritocuprates (II)

Kinetic parameters of thermal decomposition of compounds of the general formula M ₂ ^I M^II[Cu(NO₂)₆] (where M^I=K⁺, Rb⁺ or Cs⁺; and M^II=Ca²⁺, Sr²⁺, Ba²⁺ or Pb²⁺) and K₂Pb[X(NO₂)₆] (where X=Co²⁺, Ni²⁺, Zn²⁺) are determined from the corresponding thermal curves. The order of reaction (n) and the activation energy (E _a) are derived. The kinetic data is discussed in terms of the effects of outer sphere cations and the central ion on the activation energy.

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Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen des allgemeinen Typs M ₂ ^I M^II[Cu(NO₂)₆] (M¹=K⁺, Rb⁺ oder Cs⁺; M^II=Ca²⁺, Sr²⁺, Ba²⁺ oder Pb²⁺) bzw. K₂Pb[X(NO₂)₆] (X=Co²⁺, Ni²⁺, Zn²⁺) werden aus den entsprechenden thermischen Kurven bestimmt. Die Reaktionsordnung (n) und die Aktivierungsenergie (E _a) werden abgeleitet. Die kinetischen Parameter werden hinsichtlich der Effekte der Kationen in der Äu\eren SphÄre und des zentralen Ions auf die Aktivierungsenergie diskutiert.

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Résumé Les paramètres cinétiques de la décomposition thermique des composés de formule générale M ₂ ^I M^II[Cu(NO₂)₆] où M^I=K⁺, Rb⁺ ou Cs⁺ et M^II=Ca²⁺, Sr²⁺, Ba²⁺ ou Pb² + et K₂Pb[X(NO₂)₆] où X=Co²⁺, Ni²⁺, Zn²⁺ ont été déterminés à partir des courbes thermoanalytiques correspondantes. L'ordre de réaction (n) et l'énergie d'activation (E _a) ont été calculés. Les effets des cations de la sphère externe et ceux de l'ion central sur l'énergie d'activation sont discutés.

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M ₂ ^I M^II[Cu(NO₂)₆, ^I=⁺, Rb⁺ Cs⁺; ^II=C²⁺, Sr²⁺, ^{2+ 2+}, K₂Pb[X(NO₂)₆], X=²⁺ Ni²⁺; Zn²⁺. (n) (E _a ). .

     

Influence of substituents on rate constants for recombination of secondary and primary peroxy radicals

A linear correlation has been found between the logarithm of rate constants (2k_t) for the recombination of secondary peroxy radicals (ROO) and the constants of substituents, R:1g 2k_t=(6.84±0.03)+(2.60±0.10) . Rate constant for the recombination of primary peroxy radicals proves to be independent of the substituent nature: 1g 2k_t=8.5±0.4.

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(2k_t) (ROO) R: 1g 2k_t=(6,84±0,03)+(2,60±0,10) . , 1g 2k_t=8,5±0,4.

     

Thermal decomposition of Cu(I) phosphine complexes

The thermal decomposition of Cu(I) phosphine complexes of the general types (CuXPPh₃)₄, [CuX(PPh₃)₂] and [CuX(PPh₃)₃] was investigated.The thermal decomposition of (CuXPPh₃)₄, where X denotes Cl^–, Br^–, I^–, NO ₃ ^– and PPh₃=P(C₆H₅)₃, occurs with formation of a phosphine oxide intermediate. For the remaining complexes this intermediate was not proved in the thermal decomposition.

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Zusammenfassung Die thermische Zersetzung der Cu(I)-Phosphinkomplexe vom allgemeinen Typ (CuXPPh₃)₄ und [CuX(PPh₃)₂], wie auch [CuX(PPh₃)₃] wurde untersucht. Die thermische Zersetzung von (CuXPPh₃)₄, wobei X=Cl^–, Br^–, I^– und NO ₃ ^– bedeutet und PPh₃=P(C₆H₅)₃, verläuft unter Bildung eines Phosphinoxid Zwischenproduktes, bei den übrigen Komplexen konnte dieses im Laufe der thermischen Zersetzung nicht nachgewiesen werden.

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Résumé On a étudié la décomposition thermique des complexes phosphine-Cu(I) de formule générale (CuXPPh₃)₄, [CuX(PPh₃)₂], [CuX(PPh₃)₃]. La décomposition thermique de (CuXPPh₃)₄, où X désigne Cl^–, Br^–, I^– et NO ₃ ^– , et PPh₃=P(C₆H₅)₃, s'effectue avec formation d'un oxyde de phosphine intermédiaire; avec les autres complexes, cet intermédiaire n'a pas été mis en évidence au cours de la décomposition thermique.

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(CuXPPb₃)₄ [CuX(PPh₃)₂] [CuX(PPh₃)₃]. (CuXPPh₃)₄, X=Cl^–, Br^–, I^–, NO ₃ ^– , PPh₃=(₆₅)₃ . .

     

ESR studies of the generation of adsorbed oxygen radicals under irradiation of CaO in the range of surface absorption

Anion-radicals of oxygen O ₂ ^– and complexes of molecular oxygen with hole centers [X·O₂] (g₁=2.002, g₂=2.009, g ₃ ¹ =2–015, g ₃ ² =2.016) and [Y·O₂] (g=2.004, g=2.012) have been found to form under CaO irradiation in the range of surface absorption (h4 eV). ESR spectra of X and Y centers have not been observed. They are suggested to be anion-radicals O _st ^– in various coordinations: (O _3C ^– )_st and (O _4C ^– )_st, respectively.

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- O ₂ ^– [XO₂] (g₁=2.002, g₂=2.009, g ₃ ¹ =2.015, g ₃ ² =2.016) (g=2.004, g=2.012) CaO (h4 ). X Y . , - O _st ^– , : (O _3C ^– )_st (O _4C ^– )_st, .

     

The effect of outer sphere cations on the thermal stability of nitritocuprates(II)

Thermal analyses by Derivatograph were made for salts of the general formula M ₂ ^I M^II[Cu(NO₂)₆] where M^I=K⁺, Rb⁺ or Cs⁺; and M^II=Ca²⁺, Sr²⁺, Ba²⁺ or Pb²⁺. From the results and the chemical and diffractometric analysis of sinters of chosen salts, the mechanism of thermal decomposition was established. Some conclusions concerning the effects of outer sphere cations on the thermal stabilities of these salts are also drawn.

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Zusammenfassung Es wurden thermische Analysen mit einem Derivatographen für die Salze der allgemeinen Formel M₂ ^IM^II [Cu(NO₂)₆] durchgeführt [M^I=K⁺, Rb⁺, Cs⁺; M^II=Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺]. Aus den Ergebnissen dieser sowie der chemischen und diffraktometrischen Analysen der Sinterprodukte der jeweiligen Salze wurde der Mechanismus ihrer chemischen Zersetzung ermittelt. Einige Folgerungen bezüglich der Wirkung von Kationen der äusseren Sphäre auf die thermische Stabilität konnten ebenfalls gemacht werden.

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Résumé Le mécanisme de la décomposition thermique des sels de formule générale M₂ ^IM^II [Cu(NO₂)₆] où M^I=K⁺, Rb⁺, Cs⁺ et M^II=Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺ a été établi à partir des données thermiques obtenues à l'aide d'un Derivatograph, ainsi que par des analyses thermiques et diffractométriques sur les produits frittés. L'effet des cations de la couche externe sur la stabilité thermique de ces sels est discuté.

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M ₂ ^I M^II[Cu(NO₂)₆], M^I=K⁺, Rb⁺, Cs⁺; M^II=Ca²⁺, Sr²⁺, Ba²⁺, b²⁺. , , . , .

     

Competitive uptake of Cs+, Ba2+, and Zn2+ ions from binary aqueous mixtures by zeolite-13X

The preferential exchange uptake of the cations Cs⁺, Ba²⁺ and Zn²⁺ from pure solutions by zeolite-13X follows the order Q [Cs⁺]>Q [Ba²⁺]>Q [Zn²⁺], while in case of binary mixtures the order is Q [Ba²⁺(Zn²⁺)]>Q [Ba²⁺(Cs⁺)]>Q [Cs⁺(Zn²⁺)]>Q [Cs⁺(Ba²⁺)]>Q [Zn²⁺(Cs⁺)]>Q [Zn²⁺(Ba²⁺)]. Ba²⁺ uptake from mixtures shows the least suppression effect.

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Cs⁺, Ba⁺² Zn⁺² -13 Q[Cs⁺]>Q[Ba⁺²]>Q[Zn⁺²] Q[Ba⁺²(mix Zn⁺²)]>Q[Ba⁺²(mix Cs⁺)]>Q[Cs⁺(mix Zn⁺²)]>Q[Cs⁺(mix Ba⁺²)]>Q[Zn⁺²(mix Cs⁺)]>Q[Zn⁺²(mix Ba⁺²)]. Ba⁺² .

     

Determination of the activation energy of tuneling recombination for radiation-induced defects in CaO

Tunneling recombination between surface Fs_s ⁺- and bulk V^–-centers has been studied by ESR technique over the temperature range of 77–240 K. The activation energy has been measured.

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F_s ⁺- V^–- 77–240 .

     

Kinetics and mechanism of chlorination of p-aminobenzoic acid by chloramine-B

The chlorination of p-aminobenzoic acid (PABA) by chloramine-B (CAB) in HCl medium at 303 K indicates simultaneous catalysis by H⁺ and Cl^–. The reaction is first order in [CAB] and [HCl], but fractional order in [PABA]. The observed solvent isotope effect is 1.52. A suitable mechanism is proposed.

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- (PABA) -B (CAB) HCl 303 H⁺ Cl^–. [PABA]. 1,52. .

     

Influence of substituents on rate constants for recombination of tertiary peroxy radicals

A linear correlation between the logarithm of rate constant (2k_t) for recombination of tertiary peroxy radicals (ROO)^* and ^* constants of substituents R was found to be 1g 2k_t=lg 2k _t ^° . The calculated values are 1g 2k _t ^° =4.59±0.08 and ^*=5.56±0.35.

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I (2k_t) (ROO) R: 1g 2k_t=lg 2k _t ^° . , 1g 1g 2k _t ^° =4,59±0,08 =5,56±0,35

     

Kinetics of the homogeneous oxidation of hydrogen by platinum(II) and platinum(IV) chloro complexes in aqueous solution

The kinetics of the homogeneous oxidation of hydrogen in the Pt(II)–Pt(IV)–Cl^––H₂O system has been studied for the first time in conditions permitting to avoid the formation of Pt-black. It is shown that platinum (II) [Pt(II)Cl_i(H₂O)_4-i, where i=1, 2, 2], is active in the reaction, whereas the PtCl ₄ ^2– complex and platinum(IV) do not react with hydrogen.

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, Pt-, H₂ Pt^II–Pt^IV–Cl^––H₂O. (II) (Pt^IICl_i(H₂O)_4-i, i=1, 2, 3); PtCl ₄ ^2– (IV) .