Investigations on the compatibility of milk fat fractions and lauric fats

The compatibility of a lauric fat with several milk fat fractions (MF) was investigated. The enthalpy of crystallization was measured by differential scanning calorimetry (DSC). These values were related to the corresponding values calculated for an Ideal Blend. The different compatibility of the milk fat fractions with the lauric fat could be shown by this method very clearly.

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Untersuchungen zur Mischbarkeit/Verträglichkeit von Milchfettfraktionen mit laurischen Fetten

Zusammenfassung Die Mischbarkeit/Verträglichkeit von Milchfettfraktionen mit einem laurischen Fett wurde differenzkalorimetrisch untersucht. Die Auswertung der Befunde bezieht sich auf die entsprechenden Rechnungswerte einer Idealen Mischung. Es wurde nachgewiesen, da sich diese Milchfette deutlich in ihrer Mischbarkeit unterscheiden.

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. $ . , $ - . $ .

     

Hydrogenation and hydrogenolysis of methylcyclohexane-1,4-dione on Pt and Pd catalysts

Relative hydrogenation reactivity of the two carbonyl groups of methylcyclohexane-1,4-dione can be estimated beside that of two related compounds, 2- and 3-methyl-cyclohexanones. The reaction is accompanied with hydrogenolysis on Pt and Pd. The less hindered 4-carbonyl group is selectively hydrogenolyzed.

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-1,4- , 2- 3-. Pt Pd. 4- .

     

n-Butane oxidation over a vanadium-phosphorus catalyst

The activity of vanadium-phosphorus oxide catalysts with respect to maleic anhydride formation in n-butane oxidation has been found to correlate with the concentration of V⁴⁺ ions in the catalysts. The steady catalytic activitv of the samples examined is achieved more rapidly upon prereduction.

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, - - . , .

     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

Four Hg(II) complexes, containing as ligands 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) or 6-amino-1-methyl-5-nitrosouracil (CH), have been synthesized and their thermal behaviour studied by TG and DSC techniques: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂· 2 H₂O, HgCl₂(BH)₂ · H₂O and HgC₂· 2 H₂O.The dehydration processes take place in only one step, with enthalpies in the range 40.2–60.0 kJ · mole^–1 H₂O.Pyrolytic processes start between 200 and 250°, in all cases the thermal stability of the corresponding pyrimidine derivative being lower than that of the free ligand. These processes finish between 600 and 750°, with no residue.

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Zusammenfassung Vier 6-Amino-5-nitrosouracil (AH), 6-Amino-3-methyl-nitrosouracil (BH) oder 6-Amino-1-methyl-5-nitrosouracil (CH) als Liganden enthaltende Hg(II)-Komplexe wurden synthetisiert: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂ · 2 H₂O, HgCl₂(BH)₂ · H₂O und HgC₂ · 2 H₂O. Die Dehydratisierungsprozesse verlaufen in nur einem Schritt mit Enthalpien im Bereich von 40.2–60.0 kJ pro mol H₂O. Pyrolitische Prozesse setzen zwischen 200 und 250° ein. In allen Fällen ist die thermische Stabilität der entsprechenden Pyrimidin-Derivate geringer als die der freien Liganden. Diese Prozesse sind zwischen 600 und 750° beendet, wobei kein Rückstand zurückbleibt.

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g₃l₆()₄, gl₂( )₂ · 2 ₂O, gl₂()₂ · ₂O, g₂ · 2 ₂, — 6- -5-, — 6--3- — 6---5- . , 40.2–60.0 · ^–1 ₂. 200 250° 600–750° - . , .

     

Nonempirical SQM FF calculation of vibrational spectra for the acetonitrile molecule coordinated to Lewis acids BF3 and BCl3

In terms of SQM FF methods, nonempirical quantumchemical calculations of vibrational spectra for acetonitrile molecule coordinated to Lewis acids BF₃ and BCl₃ were carried out. Scaling factors were obtained from the conditions to reproduce vibrational spectra of CH₃CN and CD₃CN molecules. Contribution of the increase in the power force constant and the kinetic effect of the NB bond to the shift of _CN and _CC under coordination has been determined.

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SQM FF BF₃ BCl₃. CH₃CN CD₃CN. NB _{CN CC} .

     

Thermoanalytical investigation of sodium acetate trihydrate for application as a latent heat thermal energy storage material

The thermal behaviour of sodium acetate trihydrate (NaAc · 3H₂O) was investigated by DTA, Q-TG and measurements of the solubility properties. The nucleation efficiency of Na₄P₂O₇ · 10H₂O for the crystallization of NaAc · 3H₂O melts is not stable over long periods. Stratification can be ascribed to the formation of anhydrous sodium acetate in the supercooled melts. Under static heat storage conditions, NaAc · 3H₂O and Na₄P₂O₇ · 10H₂O do not exhibit stable behaviour.

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Zusammenfassung Das thermische Verhalten von Natriumacetat-trihydrat (NaAc · 3H₂O) wurde durch DTA, Q-TG und Löslichkeitsmessungen untersucht. Der Keimbildungseffekt von Na₄P₂O₇ · 10H₂O gegenüber NaAc · 3H₂O ist über längere Zeit nicht stabil. Die Schichtbildung kann zurückgeführt werden auf die Bildung von wasserfreiem NaAc in unterkühlten Schmelzen. Unter statischen Bedingungen der Wärmespeicherung zeigen NaAc·₃H₂O und Na₄P₂O₇ · 10H₂O kein stabiles Verhalten.

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, Q- . Na4P2O7 · 102, . . .

     

Infrared spectra of nitric oxide adsorbed on photoreduced V/SiO2 catalyst

Studies of the IR spectra of surface species produced via NO adsorption on selectively photoreduced V/SiO₂ catalysts indicate that at low coverages NO is adsorbed on V³⁺ ions to form strongly bonded mononitrosyl species V³⁺...... NO. With increasing NO coverage, V³⁺ is oxidized to V⁴⁺, which is accompanied by the appearance of gaseous N₂O and weak adsorption of NO on V⁴⁺.

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- , NO V/SiO₂ . , V³⁺ NO V³⁺... NO. V³⁺ V⁴⁺, N₂O NO V⁴⁺.

     

Coumarin composition of Seseli grandivittatum

Summary From the roots ofSeseli grandivittatum, together with -sitosterol and (–)-3R-decursinol, found in nature for the first time, and its angelate, we have isolated two new compounds which we have called grandivittin and grandivittinol.On the basis of IR, PMR, and mass spectra and chemical transformations, the structure of 3-senecioyloxy-3,4-dihydro-3R-xanthyletin is proposed for grandivittin, and 7-hydroxy-6-(3-hydroxy-2-senecioyloxyisopentyl) coumarin for grandivittinol.Leningrad Sanitary-Hygienic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 640–646, September–October, 1977.     

SCF Xα DW nuclear magnetic screening tensor calculations

Conclusions Calculations have been performed on the nuclear magnetic screening tensors for molecules via perturbation theory and the X DW method, and a comparison is made with results from other methods. Although the absolute errors in the for the molecules are appreciable, the relative errors in determining the NR chemical shifts are much less (see for example, the shift for CO relative to CH₄), which is a hopeful factor leading one to expect that X DW can be widely used in analyzing NMR spectra. At the same time, X DW can closely reproduces the anisotropy, which is particularly important for compounds such as V₂O₅ or its derivatives, which show very large anisotropy in the magnetic screening tensors.Catalysis Institute, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 5, pp. 32–36, September–October, 1988.     

Triterpene glycosides and their genins fromThalictrum foetidum. V. Structure of cyclofoetoside B

A new glycoside (cyclofoetoside B) (I) has been isolated from the epigeal part of the plantThalictrum foetidum L. (Ranunculaceae). On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that cyclofoetoside B is 24S-cycloartane-3, 16, 24, 25, 29-pentaol 3-O--L-arabinopyranoside 16-O-[O--L-rhamnopyranoside-(1 6)--D-glucopyranoside], C₄₇-H₈₀O₁₇, mp 194–197°C (methanol); [] _D ²⁴ +15.7 ± 2° (c 0.88; pyridine). The enzymatic hydrolysis of (I) has yielded cyclofoetigenin B (III), 24S-cycloartane-3,16,24,25,29-pentaol 16-O--D-glucopyranoside, (IV), C₃₆H₆₂O₁₀, mp 223–225°C (acetone), [] _D ²⁴ +37 ± 2° (c 0.97; methanol) and 24S-cycloartane-3,16,24,25,29-pentaol 16-O-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranoside, C₄₂H₇₂O₁₄, mp 229–231°C (methanol), [] _D ³⁰ +41 ± 2° (c 0.7; methanol). Details of the IR and¹H and¹³C NMR spectra of the compounds are given.Irkutsk Institute of Organic Chemistry, Academy of Sciences of the USSR. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Trashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 341–345, May–June, 1986.     

On the calculation of activation energies using a modified Kissinger method

Augis and Bennett (J. Thermal Anal. 13 (1978) 283.) [6] recently proposed a modified Kissinger method for determining the activation energy of a transformation. It is shown that the proposed method was, in fact, based upon a modification to the equation for the rate of reaction under non-isothermal conditions. The apparent discrepancy between the proposed method and the original Kissinger method is therefore resolved. The modified rate equation appears to have, at best, only a limited application. However, if the equation should be appropriate for a particular transformation, it is demonstrated that Augis and Bennett's method would be the correct method for determining the activation energy.

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Zusammenfassung Von Augis und Bennett (J. Thermal Anal.13, (1978) 283) wurde eine modifizierte Kissinger-Methode zur Bestimmung der Aktivierungsenergie einer Umwandlung vorgeschlagen. Es wird gezeigt, dass die vorgeschlagene Methode tatsächlich in einer Modifizierung der Gleichung für die Reaktionsgeschwindigkeit unter nicht-isothermen Bedingungen ihren Ursprung hat. Die scheinbare Diskrepanz zwischen der vorgeschlagenen Methode und der ursprünglichen Kissinger-Methode wird dadurch behoben. Die modifizierte Geschwindigkeitsgleichung hat bestenfalls nur eine begrenzte Anwendung. Jedoch, bei Eignung dieser Gleichung für eine bestimmte Umwandlung zeigt sich, dass die Methode von Augis und Bennett die richtige Methode zur Bestimmung der Aktivierungsenergie sein kann.

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(J. Thermal Anal. 13 (1978) 283.) - . , , , . , . , , , . , , .

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The author is indebted to the Senate of the University of Queensland for the award of a University Research Fellowship; and to Professor R. R. Stephens for providing laboratory facilities.     

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) . , - : , .

     

Effect of the reduction of Sn?Sb oxide catalyst on its activity

The decreased total activity and increased selectivity of an Sn–Sb catalyst in isobutylene partial oxidation are due to its decreasing activity in deep oxidation caused by surface reduction and the blocking of its centers responsible for deep oxidation.

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, - , , , , .

     

Hydrogenation of 4-tert-butylphenol over supported catalysts in different solvents

It has been established that in hydrogenation of 4-tert-butylphenol over Rh/-Al₂O₃ in isopropanol the addition of CH₃COOH increases the yield of 4-tert-butylcyclohexanol.

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, CH₃COOH -4- 4- Rh/-Al₂O₃ .

     

Electronic influence of water adsorbed on ZnO in H2 and Co oxidation

In this paper we calculate the effect of surface OH/OH^– on the simultaneous adsorption of H₂ and O₂ on ZnO. A quantitative comparison between H₂ and CO oxidation rates shows that the two mechanisms are similar for the same water recovery on ZnO.

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OH/OH^– H₂ O₂ ZnO. H₂ CO , ZnO.

     

Synthesis and thermal decomposition of double dimethylammonium sulphate hexahydrates of aluminium and chromium

Double sulphates of trivalent aluminium and chromium with dimethylammonium, with general formula (CH₃NH₂M(SO_{4 2}·6H₂O, were synthesized and studied by means of thermogravimetry and differential thermal analysis over the range 20–600 °C under dynamic conditions in a flow of dry nitrogen or air, and with the methods of chemical analysis. An X-ray powder diffraction study of the above compound was also undertaken. It is assumed that dimethylammonium aluminium sulphate hexahydrate and dimethylammonium chromium sulphate hexahydrate are isostructural. The mechanism of thermal decomposition of these double salts is also suggested.

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Zusammenfassung Verbindungen der Formel (CH₃)₂NH₂M(SO₄)₂·6H₂O mit M=Al(III) oder Cr(III) wurden synthetisiert und mittels TG und DTA im Intervall 20–600 °C unter dynamischen Bedingungen in bewegtem trockenen Stickstoff-oder Luftstrom sowie mittels chemischer Analyse untersucht. Auf Grund einer ebenfalls durchgeführten röntgenografischen Pulvermethode wurde festgestellt, daß Dimethylammonium-aluminiumsulfat-hexahydrat sowie Dimethylammoniumchromsulfat-hexahydrat isostrukturell sind. Ein Mechanismus für die thermische Zersetzung dieser Doppelsalze wird ebenfalls vorgeschlagen.

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(CH₃)₂NH₂M(SO₄)₂· 6H₂O, 20–600° . , . .

     

Vibrational excitation effects on silane reactivity in its reaction with bromine atoms

A rate increase of SiH₃Br formation in SiH₄ photobromination under irradiation by a cw CO₂ laser is reported. At low SiH₄ pressures (1–2 Pa) the radiation effect is shown to be isotope-selective.

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SiH₃Br CO₂ SiH₄. , SiH₄ (1–2 ) .

     

Reactivity of chemisorbed hydrogen species on Pt towards acetylene

In the presence of both molecular and atomic hydrogen on catalyst surface, C₂H₂ is hydrogenated directly to C₂H₆. In the presence of atomic hydrogen only, the reaction can also have another route to form C₂H₄.

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, C₂H₂ C₂H₆, , C₂H₄.

     

On the deactivation of Fe2O3?MoO3/SiO2 catalysts in the oxidation of methanol to formaldehyde

The deactivation behavior of Fe₂O₃–MoO₃/SiO₂ catalysts with different Fe₂O₃+MoO₃ content in the oxidation of methanol to formaldehyde is investigated. A simplified reaction-deactivation kinetic model is presented and used to compare and discuss the different behaviors.

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Fe₂O₃–MoO₃/SiO₂ Fe₂O₃+MoO₃ . : -.