Temperature dependence of the volumetric properties of binary mixtures containing oxaalkane +n-heptane

Excess molar volumes of mixtures of n-heptane + 2,5-dioxahexane and n-heptane + 2,5,8-trioxanonane were determined from density measurentents at 5, 15, 25 and 35°C. These results allowed the following mixing quantities to be reported in all range of concentrations: , (v ^E /T) _P and (h ^E /P) _T , at 25°C. The obtained values were then compared with the calculated values by using the Flory theory and the Nitta-Chao theory of liquid mixtures. The results are discussed in terms of order or disorder creation.     

Photoluminescence Spectra and Crystallization of θ-Al2O3 and α-Al2O3 from AlOOH-Fe(NO3)3 Gels

Diphasic boehmite derived unseeded and seeded (by either -Al₂O₃, -Fe₂O₃, or Fe(NO₃)₃) alumina gel planar monoliths were examined by DTA, XRD and photoluminescence spectroscopy. Luminescence spectra enable sensitive monitoring of the - and -Al₂O₃ crystallization in heat-treated gels due to Cr³⁺ impurity traces. Fe(NO₃)₃ unlike other seeds effectively influences crystallization of both - and -Al₂O₃. The present results are interpreted as prevailing solution or Fe³⁺ ion effect on the crystallization process.     

Studies on the non-isothermal kinetics of the thermal decomposition of [Cu(NBOCTB)][Cu(NO3)4]· H2O

The thermal decomposition process of the complex [Cu(NBOCTB)][Cu(NO₃)₄] H₂O has been studied by TG and DTG technique, and possible intermediates of the thermal decomposition have also been conjectured from the TG and DTG curves. The results suggest that the decomposition of the complex involves five steps: The non-isothermal kinetics of steps 1, 2 and 3 have been studied by means of the Achar and Coats-Redfern method based on TG and DTG curves. Step 1 is a Coring and Growth mechanism (n= 1), its kinetic equation may be expressed as: d/dt=Ae^–E/RT(1–). Steps 2 and 3 are both two order chemical reaction mechanisms, their kinetic equations can be expressed as: d/dt=Ae^–E/RT(1–)².This project was supported by the National Natural Science Youth Fundation of China.     

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.     

Polarographic determination of the protonation rate constants of pyridine and some of its homologs as affected by water

Summary The heights of the catalytic waves in nonbuffer solutions (0.5 M KC1) at 25° have been used to find the rate constants for protonation by water, using the following compounds: Pyridine (5.5 liter/M-sec),-picoline (10.1),-picoline (8.0),-p+icoline (12.5), and ,-lutidine (26). A discussion is given of the effect of steric factors on the protonation rate of these compounds.     

Energy shift of vanadium Kα X-rays accompanying EC decay in51Cr-labeled compounds

The VK X-rays induced by the electron capture decay of⁵¹Cr-labeled compounds and the fluorescent X-rays of the vanadium compounds have been measured with a Bragg spectrometer. The evident chemical shifts of the K₁ and K₂ lines were observed for the oxidation state both by electron capture and photoionization. The differences of the K peak energy (K₁ and K₂ peaks) with the modes of the excitation were also obtained. The K peaks of⁵¹Cr shift to lower energy by ca. 0.5 eV than those of vanadium at the same oxidation state. This is because the probability of the electron shake up (and shake off) during the electron capture decay is extremely small, as compared to photoionization.     

Polyhydroxysteroids from the Far-Eastern starfishCtenodiscus crispatus

Four new polyhydroxysteroids, 5-cholesta-3,5,6,15,16,25,26-heptaol, 24-ethyl-5-cholesta-3,5,6,15,28,29-heptaol-29-sulfate, (22E)-24-methyl-5-cholest-22-ene-3,5,6,15,25,26-hexaol-26-sulfate, 24-propyl-5-cholesta-3,5,6,8,15,28,29-heptaol, and the known 5-cholesta-3,5,6,15,16,26-hexaol, have been isolated from the starfishCtenodiscus crispatus.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1825, October, 1994.     

Correlated one-center wavefunctions for two-electron molecules

A one-center self-consistent field (SCF) wavefunction for two electrons, built from a m-term molecular orbital, is multiplied by the correlation factor 1 + r ₁₂. All integrals required for a variational treatment are obtained from previous papers in this series. Application to the ground state of equilateral triangular H ₃ ⁺ shows that the energy improvement due to the correlation factor and the optimized value of increase as m increases. Joshi's [4] SCF-functions were used. For m = 9 our best energy is –1.3037 a.u. for = 0.189, compared with Joshi's energy of –1.28028 a.u., at R _HH= 1.607 a.u.

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Zusammenfassung Eine Ein-Zentrum-Wellenfunktion für zwei Elektronen vom SCF-Typ wird mit dem Korrelationsfaktor 1 + r ₁₂ multipliziert. Alle Integrale, die für eine Variationsrechnung benötigt werden, können aus früheren Ergebnissen hergeleitet werden. Eine Anwendung auf den Grundzustand von H ₃ ⁺ mit der Struktur des gleichseitigen Dreieckes zeigt, daß sowohl die Energieverbesserung als auch die optimalen Werte von mit m zunehmen, wobei m die Zahl der Terme in dem MO darstellt. Joshis [4] SCF-Funktionen bilden die Grundlage. Für m = 9 erhielten wir die Energie –1,3037 a.E. und = 0,189. Joshis Energie war –1,28028 a.E. (R _HH = 1,607 a.E.).

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Résumé Une fonction d'onde SCF monocentrique pour deux électrons, construite à partir d'une orbitale moléculaire à m termes, est multipliée par le facteur de corrélation 1+ r ₁₂. Toutes les intégrales nécessaires pour un traitement variationnel sont obtenues à partir des articles précédents de cette série. L'application à l'état fondamental de H ₃ ⁺ (triangle équilatéral) montre que l'amélioration de l'énergie dûe au facteur de corrélation ainsi que la valeur optimale de augmente lorsque m augmente. On a utilisé les fonctions SCF de Joshi [4]. Pour m = 9, notre meilleure énergie est – 1,3037 u. a., pour = 0,189, alors que Joshi obtient –1,28028 u. a. à R _HH = 0,928 u. a.

     

Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

Reaktionen mit phosphororganischen Verbindungen, 24. Mitt.: Zur Umsetzung von α-Acyl-α-alkyl-methylentriphenylphosphoranen mit Acetylazid

Zusammenfassung -Acyl--alkyl-methylentriphenylphosphorane, (C₆H₅)₃P=CC(OR₁)(R₂), setzen sich mit Acetylazid zu 4-R₁-5-R₂-N-Acetyl-1,2,3-triazolen um. R₁ kann auch Doppelbindungen enthalten oder Äthoxyl sein. Dieselben Triazolverbindungen erhält man auch, wenn man die genannten -Oxophosphorylene zuerst mit Acetylchlorid, und anschließend mit NaN₃ umsetzt. Nur im Falle des Phosphorylens1g liefert die zuletzt genannte Führung der Reaktion ein anderes Produkt, die -Azidovinylcarbonylverbindung2g. Aus dem Phosphorylen1h entsteht auf beiden Reaktionswegen der -Azidoacrylester2d.

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Reactions with phosphoroorganic compounds, XXIV: Reaction of -acyl--alkyl-methylene-triphenyl-phosphoranes with acetyl azide

-Acyl--alkylmethylenetriphenylphosphoranes (C₆H₅)₃P=C(COR₁)(R₂) react with acetyl azide to give 4-R₁-5-R₂-N-acetyl-1,2,3-triazoles, where R₁ is an unsaturated lower alkyl or an ethoxy group. The same reaction products are formed by acylation and subsequent treatment with sodium azide. Only in the case of the phosphoroylene1g the two-step modification of the reaction leads to the -azidovinylcarbonyl compound2g. The -azidoacrylester2d, however, is formed from the phosphoroylene1h in either way.

     

Tertiary amines and quaternary salts derived from alpha-substituted stilbenes and heterocyclic nitrogen bases

N-bromosuccinimide and -methylstilbenes, p-methyl--chlorostilbene, and p-methyltolan give bromomethyl derivatives, which react with piperidine to give tertiary amines. The latter and methyl iodide give quaternary salts.With pyridine, -picoline, and quinoline, the p-bromomethyl-d-chlorostilbenes synthesized give quaternary bromides which are readily soluble in water and converted into perchlorates by KClO₄.     

Formation of Supramolecular Polymers Constructed by Cyclodextrins with Cinnamamide

-Cyclodextrin having cinnamamide at 6- or 3-positions (6-CiNH--CD, 3-CiNH--CD) and -cyclodextrin with cinnamamide on 6-position (6-CiNH--CD) have been prepared. Supramolecular structures were formed in the solid state or aqueous solutions and characterized by measurements of NMR and vapor pressure osmometry (VPO). The results indicate that 6-CiNH--CD formed insoluble supramolecular polymers in the solid state, while 6-CiNH--CD and 3-CiNH--CD formed supramolecular complexes in aqueous solutions. 6-CiNH--CD was found to form a dimer in an aqueous solution. 3-CiNH--CD formed intermolecular complexes to give supramolecular polymers. The differences of the position of guest part on cyclodextrins caused to give a variety of supramolecular structures in aqueous solutions.     

Triterpene glycosides of Astragalus and their genins. XX. Cycloorbigenin from Astragalus orbiculatus

A new genin — cycloorbigenin (I), C₃₀H₄₈O₅, mp 217–219°C, [] _D ²⁰ +28.3° (c 1.19; ethanol) has been obtained from a glycoside isolated from the epigeal parts of the plantAstragalus orbiculatus (Leguminosae), and on the basis of chemical transformation and spectral characteristics its structure has been established as 16,23:16,24-diepoxy-23(R),24(S)cycloartane-3,7,25-triol. The acetylation of (I) with acetic anhydride in pyridine yielded its diacetate (II), C₃₄H₅₂O₇, mp 148–150°C, [] _D ²⁰ +32.6° (c 0.92; methanol) and its triacetate (III), C₃₆H₅₄O₈, mp 137–139°C, [] _D ²⁰ +75° (c 0.4; methanol). The Jones oxidation of (I) led to a diketone (IV), C₃₀H₄₄O₅, mp 155–158°C, [] _D ²⁰ -73° (c 0.63; methanol). Details of the PMR, IR, and mass spectra are given for all the compounds.Institute of The Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 455–460, July–August, 1986.     

Synthesis and base hydrolysis kinetics of the nitrile complexes [Co(tetren)NCR]3+ (R=Me,Ph and p-MeOC6 H4) and the synthesis and kinetics of formation of the tetrazolato complexes [Co(tetren)N4R]2+ (R=Me and Ph; tetren=1,11-diamino-3,6,9-triazaundecane) by reaction with azide ion

The N-bonded nitrile complexes -[Co(tetren)NCR]³⁺ (R=Me, Ph, p-MeOC₆ H₄) have been prepared by the reaction of -[Co(tetren)OH₂]³⁺ with the corresponding nitrile. The kinetics of base hydrolysis have been studied by pH-stat methods. The reactions involve an SN₁CB displacement of the nitrile to give the hydroxopentamine; nucleophilic attack at the nitrile carbon to give the corresponding carboxamido complex does not occur. NaN₃ reacts with the nitrile complexes in slightly acidic solution (pH ca. 5.7) to give the tetrazolato complexes [Co(tetren)N₄ R]²⁺ (R=Me, Ph) which have been characterised. The reaction of azide ion with -[Co(tetren)NCMe]³⁺ has been studied kinetically. The reaction is biphasic involving the initial rapid formation of the N₁-bonded (5-methyltetrazolato) pentaminecobalt(III) complex with k=2×10^–2dm³ mol^–1s^–1 at 25°C followed by the slow isomerisation to the N₂-bonded complex with k=3.5×10^–5s^–1 at pH 5.7.     

Some sources of defects in α-HgI2, the room temperature γ-ray detector

In the course of a systematic optimization of the materials properties of -HgI₂ crystals for room temperature - and X-ray detectors, we have investigated possible sources of defects and discuss briefly the possibility to supress them. Due to the particular structure of -HgI₂, large amount of impurities, particularly hydrocarbons, can be absorbed invan der Waals layers and lattice channels. Purification by sublimation does not work due to the affinity of hydrocarbons to iodine and their easy re-absorption in the sublimate. Lattice filtering of the large concentration of hydrocarbons contained even in suprapure iodine has been performed using the close spaced lattice of CuI. Oxidation of hydrocarbons by reaction of oxygen with HgI₂ is another possibility for their removal.Mass spectrometric investigations of a molecular beam of -HgI₂ has solved the long disputed problem of the existence of nonstoichiometry: both excess of Hg or excess of I are possible. The removal of nonstoichiometry can be achieved by suitable thermal treatment only in the case of pure crystals. In the presence of hydrocarbons, the non-stoichiometric defects are fixed showing the predominant importance of hydrocarbons for -HgI₂.Investigation of the evaporation of -HgI₂ with mass spectrometry at low temperatures (150>T>40 °C) shows a strong change of the enthalpy of evalporation at 67 °C whereas DSC does not show any peak at this temperature. It seems probable that this is due to a surface reconstruction which influences the evaporation but not the thermal bulk lattice effects which are detected by DSC.Dedicated to Prof. Dr.K. L. Komarek at the occasion his 60th birthday.     

Phase and chemical transformations of lanthanum and iron alloys in a nitrogen-hydrogen medium

The behavior of La_xFe_1–x alloys in a nitrogen-hydrogen medium at 293–723 K and a pressure of up to 1.5 × 10⁷ Pa was studied. The alloys decompose to give LaH_2.9 and -Fe at 293 K, LaN, LaH_2.4, and -Fe at 623 K, and LaN and -Fe at 723 K. Ammonia was detected in the gas phase at 623–723 K.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1241–1243.Original Russian Text Copyright © 2004 by Shilkin.This revised version was published online in April 2005 with a corrected cover date.     

Reactions of polyhalopyridines. 8. Reactions of polychlorotrifluoromethyl-pyridines with sodium N,N-dimethyldithiocarbamate. Structure of the 8-trifluoromethylbis-1,3-dithiolo-[4,5-b:4′,5′-e]-pyridine-2,6-dione molecule

The reaction of the isomeric tetrachloro--, -, and -trifluoromethylpyridines and of 3,4,5-trichloro-2-trifluoromethylpyridine with sodium N,N-dimethyldithiocarbamate dihydrate has been studied. In the case of the -, and -isomers an intramolecular cyclization with the formation of 1,3-dithiol-2-one derivatives occurs and the remaining compounds give only products of mono- or disubstitution of chlorine atoms by a dithiocarbamate fragment at positions 4 or 6 of the pyridine ring. The structure of the compounds synthesized was proved using¹³C NMR and X-ray crystallographic analysis.See [6] for part 7.Institute of Chemical Physics, Chernogolovka, Russian Academy of Sciences, Chernogolovka 142432. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1278–1284, September, 1994. Original article submitted June 25, 1994.     

Thermodynamics of Binding of α:-Cyclodextrin to Straight-Chain Alkyl Derivatives in Aqueous Solution

Apparent standard Gibbs energy, enthalpy, entropy, and heatcapacity data of the interactions of -cyclodextrin (CD) to some n-carboxylatesH(CH₂)_nCOO^- (n = 4–6), are determined by isothermal titration microcalorimetryat different temperatures in phosphate buffer, pH 9.0, assuming a 1 : 1 model indilute solution. Modelling of contributions of the thermodynamic properties of the solutionindicates that CD undergoes conformational change upon binding to homologousseries of n-carboxylates, n-alcohols, ,-alkane dicarboxylates and ,-alkane diols.     

Triterpene glycosides of alfalfa. III. Medicoside I

On the basis of chemical transformations and with the aid of physicochemical results, the structure of glycoside I isolated from the roots of the plantMedicago sativa has been established as hederagin 3-O-[O--L-arabinopyranosyl-(1 2)--D-glucopyranosyl-(1 2)--L-arabinopyranoside] 28-O--D-glucopyranoside. Compound (I), C₅₂H₈₄O₂₂, mp 210–212°C, [] _D ²¹ +38.4° (c 1.48; methanol). Acid hydrolysis of (I) led to hederogenin (II) — C₃₀H₄₈O₄, mp 326–330°C, [] _D ²³ +84.2° (c 0.19; pyridine. The Hakomorimethylation of glycoside (I) yielded the permethylate (IV) — C₆₅H₁₁O₂₂ [] _D ²³ +41.6° (c 1.79; methanol). The GLC analysis of the products of the methanolysis of compound (IV) showed the presence of 3,4,6-tri-O-methyl-D-glucopyranose, 2,3,4,6-tetra-O-methyl-D-glucopyranose, 3,4-di-O-methyl-L-O-arabinopyranose, and 2,3,4-tri-o-methyl-L-arabinopyranose. The alkaline hydrolysis of glycoside I gave compound (III) with mp 230–233°C, [] _D ²¹ +35.2° (c 0.21; methanol), which was identified as medicoside C. Details of the PMR spectrum are given for compound (IV) and of the IR spectrum for compound (I).Institute of the Chemistry of Plant Substances of the Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 607–610, September–October, 1986.     

Excess enthalpies of aqueous solutions of small peptides at 25°C

Heats of dilution of aqueous solutions of the following di-and tripeptides were determined at 25°C over a wide concentration range: -alanyl-glycine, -alanyl--alanine, DL--alanyl-glycine, glycyl-DL--alanine, L--alanyl-L-alanine, DL--alanyl-DL--alanine, DL--alanyl-DL-valine, DL--alanyl--alanine, glycyl--aminobutyric acid, glycyl-L-leucine and DL--alanyl-glycylglycine. The excess enthalpies H^ex and partial molar relative enthalpies L₂ were calculated and enthalpy coefficients of intermolecular interaction were analysed using the additivity principle of Savage and Wood. The concentration dependence of the enthalpic characteristics of peptide-peptide interactions is discussed based on of their hydrophobicity and hydrophilicity. The three-stage model of peptide association is described using enthalpic coefficients of intermolecular interactions.