Reduction of some D-homosteroids with an aromatic a ring by alkali metals under the conditions of the birch reaction. I

Summary In the Birch reduction of steroid compounds with a phenylbutadiene grouping, i.e., the ketal of 3-methoxy-^{1, 3, 5(10), 8, 14}-D-homoestrapentaen-17a-one (III), the corresponding ketone (IIIa), and 3-methoxy-^{1, 3, 5(10), 8, 14}-D-homoestrapentaen-17a-ol (VI), 1, 4 addition of the hydrogen takes place first, and is followed by reduction of the aromatic nucleus. In this way, 3-methoxy-^{1, 3, 5(10), 8(14)}-D-homoestratetraenone (XII), ^{4, 8(14)}-19-nor-D-homoandrostadienedione (VIII), and ^{4, 8(14)}-19-nor-D-homoandrostadien-17a-ol-3-one (IX) have been obtained.Khimiya prirodnykh soedinenii, Vol. 1, No. 1, pp. 7–15, 1965     

Marked differences between acetonitrile/water and methanol/water mobile phase systems on the thermodynamic behavior of benzodiazepines in reversed phase liquid chromatography

Summary Two different methods were used to determine the separation factor at different temperatures and the Gibbs-Helmholtz parameters ((H), (S)) of two adjacent benzodiazepines on a chromatogram were obtained from plots of ln versus 1/T. We first studied each factor (fraction of water in the ACN/water mixture and column temperatureT), which controls the retention mechanism, and then we examined the simultaneous variation of all these factors. The changes in (H) and (S) in relation to a volume fraction of water in an ACN/water mixture were examined. In the ACN/water system, (H) was fairly constant in the acetonitrile region of 0.52 and appears to be a roughly linear function of for 0.52. In this system (S) is approximately a parabolic function of with an optimum at 0.52. The retention mechanism of ten benzodiazepines was found to be significantly different in the methanol/water and ACN/water mixtures. The separation optimization of these ten benzodiazepines was then considered. A fraction of water of 0.43 in the ACN/water mixture and a column temperature of 44°C gave the most efficient separation conditions in the ACN/water mixture.     

Oxidation of [Co(en)2(SOCH2CO2)]+ by S2O82− and by IO4− in binary aqueous solvent mixtures at pressures up to 1.25 kbar

Second order rate constants and activation parameters H, S, and V have been measured for the oxidation of [Co(en)2(SOCH2CO2)]+ by S2O82– and by IO4– in highly aqueous H2O – t-BuOH mixtures. The changes in solvation on going from the initial to the transition state are discussed on the basis of the transfer functions Gto, Hto and Sto. Whereas Gt changes smoothly as the proportion of t-BuOH increases, the plots of Ht and TSt exhibit mirror behaviour and pass through extrema located around x2(t- BuOH)=0.038. Information on the role of solvation is complemented by the determination of activation volumes. These are discussed in terms of intrinsic and solvational contributions. It is proposed that changes in hydrophobic hydration are of principal importance in determining the response of H, S, and V to changes in solvent composition in H2O – t-BuOH mixtures.     

An investigation on the effects of additives during the thermochemical decomposition of phosphogypsum under isothermal conditions

A study was made of the isothermal kinetics of phosphogypsum in the presence of additives and in a reducing gaseous medium.

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Zusammenfassung Es wurden isotherme kinetische Untersuchungen an Phosphogips in Gegenwart von Zusätzen sowie m reduzierender Atmosphäre durchgeführt.

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- .

     

Chiroptical detection during liquid chromatography,part 5: On-line measurement of circular dichroism spectra Δε(λ) during stops of chromatographic flow

Summary A procedure is described which serves to measure circular dichrograms () on line during stops of flow in liquid chromatography. Since the concentration of substrate in the spectrometer cell during the stop is not known, the differential absorption coefficients are calculated from the experimental differential absorbances A by means of UV absorption (i. e. photomultiplier voltage) data. Verifications of the procedure are obtained by its application to three substrates (Table 1), the () spectra of which were known. The present on-line technique is compared with a corresponding off-line method.The N,N-dimethylthiobenzamides1 and2 as well as the 9,10-phenanthrenequinone7 consist of interconvertible enantiomers because their planar states are destabilized by steric overcrowding of groups. The unknown dichrograms () of1, 2 and7 are obtained (Figs. 2 and 4) and discussed with reference to the helicities of these molecules.In memory of the late Professor Dr. Dr. h. c. Günther Snatzke.     

Equilibrium oxidations of ferrocene and ruthenocene with iodine

Summary The thermodynamic characteristics (F, H, and S) of the formation of ferrocinium and ruthenocinium triand pentaiodides were measured.     

Zur Berechnung der freien Mischungsenthalpie und der Aktivitätskoeffizienten beschränkt mischbarer Systeme aus der Löslichkeitskurve

Zusammenfassung Die in dieser Arbeit vorgeschlagene Methode gestattet, die Änderungen der freien Zusatzenthalpie mit der Konzentration bei der kritischen Lösungstemperatur auf Grund der Löslichkeitskurve beschränkt mischbarer Systeme innerhalb des Konzentrationsbereiches der Mischungslücke zu berechnen, soferne Daten für die Zusatzentropie S _z und für die Zusatzwerte zu den Molwärmen C _p,z bekannt sind. Durch numerische Integration von erhält man die Werte für die freie Zusatzenthalpie G _z bei der kritischen Lösungstemperatur.Die Methode wird zur Berechnung von G _z der Systeme n-Pentan-Aceton und Nickel-Gold herangezogen. An diesen Beispielen wird der Einfluß der näherungsweisen Vernachlässigung von S _z und C _p,z untersucht.Bei dem System n-Pentan-Aceton stimmen die nach dieser Methode erhaltenen Werte mit den aus Dampfdruckmessungen gewonnenen innerhalb der Fehlergrenzen vollkommen überein. Die Vernachlässigung von S _z bzw. C _p,z führt hier lediglich zu einem Fehler von weniger als 2%.Die für das System Nickel-Gold erhaltenen G _z-Werte sind niedriger als die vonSeigle, Cohen undAverbach auf Grund elektromotorischer Kräfte berechneten. Die Vernachlässigung von S _z und C _p,z bedingt hier einen Fehler von etwa 10%.Mit 7 Abbildungen     

TPD studies of hydrogen adsorption on group VIII metals

Hydrogen desorption proceeds in several temperature regions and differs by its order of magnitude and activation energy. Differential curves of adsorbed hydrogen distribution with respect to the desorption activation energy, dN/dE (E), show a considerable inhomogeneity of adsorbed atomic species and the energetic homogeneity of molecular species.

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. dN/dE (E) .

     

Peculiarities of propylene metathesis over catalysts prepared by anchoring of Mo(V) oxalate to γ-Al2O3

Propylene metathesis over catalysts prepared by coordination of Mo(V) oxalate to -Al₂O₃ has been studied.

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, (V) -Al₂O₃.

     

Synthesis of 3β-fluoro derivatives of 7-dehydrocholesterol and of ergosterol

It has been established that the fluorination of 3-hydroxy-^5,7-steroids, unlike that of 3-hydroxy-⁵-steroids, does not lead to the formation of 3-fluoro derivatives. The reaction products are 3,5-cyclo-^6,8(14) compounds. Consequently, to obtain the 3-fluoro derivatives of provitamins D — 7-dehydrocholesterol and ergosterol — the 5,7-diene system was first protected by the formation of a cyclo-adduct with 4-phenyl-1,2,4-triazoline-3,5-dione after which the adduct was fluorinated with morpholinosulfur trifluoride to the 3-fluoro adduct, and then the 5,7-double bonds were regenerated by treating the adduct with a solution of sodium methanolate in methanol.A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 102–107, January–February, 1985.     

Heterogeneous-homogeneous decomposition of HNO3

In contrast to ZSM zeolites impregnated with V⁵⁺ salts, catalysts prepared by adding V³⁺ salts during zeolite synthesis exhibited (even when transformed into cristobalite by oxidative activation) higher selectivity to furane in the oxidation of butadiene. Non-oxidative activation preserved the zeolitic structure and increased both the total activity and the selectivity to furane.

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ZSM, V⁵⁺, V³⁺ ( ) . , , .

     

Synthesis ofΔ 1, 3, 5 (10)-estratriene -4,17β-diol

Conclusions A simple route for the synthesis of ^1,3,5(10)-estratriene-4.17-diol starting from the accessible ⁴-estren-17-ol was realized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, p. 655, March, 1972.     

Thermal curve interpretation by spectral resolution into the basic set of rectangular pulse curves

A new numerical method for the determination of thermokinetics is proposed. This is based on the spectral resolution of a thermal curve into the basic set of unit rectangular pulse curves orthogonalized by Löwdin's transformation. A numerical example shows that the present method can be successfully applied to experimental curves.

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Zusammenfassung Eine neue numerische Methode zur Bestimmung von Thermokinetika wird vorgeschlagen. Sie beruht auf der spektralen Auflösung einer thermischen Kurve in die Grundfolge von Einheiten rechteckiger Pulskurven, welche durch eine Löwdins Transformation orthogonalisiert worden sind. Ein numerisches Beispiel zeigt, dass diese Methode bei experimentellen Kurven mit Erfolg eingesetzt werden kann.

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ë- . , .

     

Relativistic perturbation theory of molecular structure

Summary The recently developed relativistic double perturbation theory is extended to handle relativistic changes of molecular structure more easily. This is achieved by simple coordinate scalings. Accurate higher order mixed perturbation energies for H ₂ ⁺ are calculated. The relativistic changes of bond energy,DE, of bond length,R _e , and especially of force constant,k, and of anharmonicity,a, are large, up to 100%·(Z/c)². The dominant contributions tok anda are due to the indirect change of the nonrelativistick anda connected with the relativistic change of bond length. Accordingly the relativistic changes obey Badger's and Gordy's rules (–RDEk).Dedicated to Prof. Klaus Ruedenberg in appreciation of his fundamental contributions to both formal theory and physical explanations in quantum chemistry     

Kinetics and mechanism of oxidation of methanol by acid bromate

The kinetics of oxidation of methanol by bromate ion in hydrochloric acid medium has been investigated. A mechanism consistent with the experimental observations is suggested.

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. , .

     

Thermodynamics of 15-Crown-5 Complexation with Ag+ and Pb2+ Ions

Heats and constants of 15-crown-5 (R) complexation with silver and lead ions at 298, 308, and 318 K are determined using direct calorimetry. Thermodynamic parameters (G°, H°, S°, and C _p°) of formation of AgR⁺ and PbR²⁺ complexes at various temperatures are calculated. The effects of the properties of the cations and crown ethers on the thermodynamic parameters of complexation are discussed.     

Far infrared spectra (500–50 cm−1) of the 2,2′-bipyridine complexes of palladium and platinum halides

Summary The far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts ( >10 cm^–1) in internal ligand modes, intermediate shifts between 2 and 9 cm^–1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC _2v synanetry [two (M–N) and two (M–X) bands] are observed. Previous ambiguities in the assignment of the (M–N) bands have been resolved by the isotopic labelling technique employed in this study.     

The Influence of Dimerization of Water-Soluble Metalloporphyrins as Photosensitizers on the Efficiency of Generation of Singlet Oxygen

Quantum yields () for the generation of singlet oxygen sensitized by Pd(II) complexes of water-soluble porphyrins: meso-tetrakis(4-N-methylpyridyl)porphine [PdTMPyP]⁴⁺ ( = 0.9), meso-tetrakis(4-N,N,N-trimethylaminophenyl)porphine [PdTTMAPP]⁴⁺ ( = 0.8), meso-tetrakis(4-carboxyphenyl)porphine [PdTCPP]^4– ( = 0.7), and meso-tetrakis(4-sulfonatophenyl)porphine [PdTSPP]^4– ( = 0.5) were determined using a chemical method. It was found that the dimerization and aggregation of metalloporphyrins greatly influence the value. The quantum yields evaluated for the formation of singlet oxygen sensitized by metalloporphyrin monomeric and dimeric forms are _{, M} 0.9 and _{, D} 0.2, respectively, and do not depend on the porphyrin nature.     

Kinetics of dehydration and thermal decomposition of Sr(NO3)2.4H2O and its deuterated analogue with a view to obtaining SrO

The kinetics and mechanism of thermal dehydration of Sr(NO₃)₂.4H₂O and its deuterated analogue were studied by means of DTA, TG and DSC. The temperatures, enthalpies and weight losses of phase transitions were measured. The dehydration occurs in a stepwise manner, and the composition of the intermediate depends on the rate of thermal decomposition. The kinetic parameters (E ^* andZ) for the two steps of dehydration at a heating rate of 5 deg min^–1 were calculated. A correlation was found between the dispersity of the end-product of the thermal decomposition (SrO) and the conditions of its preparation.

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Zusammenfassung Kinetik und Mechanismus der thermischen Entwässerung von Sr(NO₃)₂.4H₂O und der deuterierten Verbindung Sr(NO₃)₂.4D₂O wurden mittels TG-DTA und DSC untersucht. Temperaturen, Enthalpien und Gewichtsverluste der Phasenumwandlungen wurden gemessen. Der Prozess verläuft stufenweise, die Zusammensetzung des Zwischenprodukts hängt von der Zersetzungsgeschwindigkeit ab. Die kinetischen ParameterE ^* undZ der beiden Entwässerungsstufen bei einer Aufheizgeschwindigkeit von 5 Grad min^–1 wurden berechnet. Zwischen der Dispersität des Endproduktes SrO und seinen Bildungsbedingungen wurde eine Korrelation gefunden.

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, . . , . , 5 /, E Z. .

     

Dielectric properties of mixtures of acetylene tetrachloride with toluene and acetone

Relative permittivities are reported for binary liquid mixtures of acetylene tetrachloride (ATC) with toluene and acetone at 35°C. Measurements of refractive indices have also been made for the mixtures. The values of the quantity , the deviations of the relative permittivities of these mixtures from ideality, have been calculated. The negative values of obtained for ATC+ toluene mixtures may be explained as being due to a decrease in the degree of alignment of the molecular dipoles with changing composition of the mixture, whereas the positive values of obtained for ATC+acetone mixtures are attributed to the formation of molecular complex between acetone and CHCl₂CHCl₂. The values of the Kirkwood correlation parameter g for both sets of mixtures have been calculated using the relative permittivity data.