Flavonoids of Ammothamnus lehmannii. Structure of lehmannin and of ammothamnidin

The new flavanon lehmannin (I) has been isolated from the roots ofAmmothamnus lehmannii Bunge. On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that compound (I) has the structure of 2,4,7-trihydroxy-8-(2-isopropenyl-5-methylhex-4-enyl)flavanone. The alkaline cleavage of lehmannin gave ammothamnidin (V). The structure proposed previously for the chalcone ammothamnidin has been corrected. It has been shown that it has the structure of 2,2-4,4-tetrahydroxy-3-(2-isopropenyl-5-methylhex-4- enyl)chalcone. A comparative study of the¹³C NMR spectra of a number of flavanones has revealed an empirical law permitting the prediction of the presence or absence of substituents (OH and OCH₃) at C-2 from the value of the chemical shift of the signal of the C-2 carbon atom.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. I. P. Pavlov Samarkand State Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–524, July–August, 1987.     

Symmetrische,gemischt substituierte Trisilylamine (RR′R″Si)3N

Zusammenfassung Gemischt substituierte Disilylamine (RRRSi)₂NH lassen sich von NaNH₂ zu reaktionsfähigen Natrium-bis-(silyl)-amiden metallieren, aus denen nach Umsetzung mit Organohalogensilanen und anschließender Alkoholyse der verbleibenden Si-Cl-Gruppen gemischt substituierte Trisilylamine (RRRSi)₃N mit R=(me), R, R=O(me); R,R=(me), R=O(et); R=(vi), R, R=O(me); R=(me), R=(vi), R=O(ⁱpr) dargestellt werden konnten.33. Mitt.:U. Wannagat, J. Pump undH. Bürger, Mh. Chem.94, 1013 (1963).Auszüge aus den DissertationenH. Bürger, TH Aachen 1962,P. Geymayer, TH Graz 1963, und der DiplomarbeitG. Torper, TH Graz 1962; vgl. auchU. Wannagat undH. Bürger, Angew. Chem.75, 95 (1963).     

Kinetics and mechanism of the hydrolysis of sodium carboxymethylcellulose (Na-CMC) by a cellulase complex

TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.

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Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex

Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

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Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] _w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]₀ weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M _s molecular mass of substrateS - K _s substrate constant (K _s , K _s , K _s ) - K _I inhibitor constant (K _I , K _I , K _I ) - K _m Michaelis-Menten constant - k ₊₁,k ₊₂ (k ₊₂ ,k ₊₂ ,k ₊₂ ) forward rate constants - k _–1 reverse rate constant - ₀ initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.     

Complex polarizability as used to analyze dielectric relaxation measurements

The effect of representing dielectric properties in terms of the complex polarizability ^c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.     

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.     

Alkylation of toluene with methanol over rare earth forms of Na?X, FAU and Na?Y, FAU

(La^ex, Na)-X, FAU, (Na, Y^ex)-X, FAU, (La^ex, Na)-Y, FAU and (Na, Y^ex)-Y, FAU have been shown to be active and selective catalysts for the alkylation of toluene with methanol. Na–X, FAU and Na–Y, FAU modified by La³⁺ have the highest activity but a very stable activity was reached only on Y³⁺ forms. (Na, RE^ex)-X FAU series prefer ortho-substitution while (Na, RE^ex)-Y, FAU para-substitution. Brönsted acid centers and their strength are responsible for substition.

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, (La^ex, Na)-X, FAU, (Na, Y^ex)-X, FAU, (La^ex, Na)-Y, FaU (Na, Y^ex)-Y, FAU . Na–X, FAU Na–Y, FAU, La³⁺, , , Y³⁺. (Na, RE^ex)-X, FAU -, (Na, RE^ex)-Y, FAU--. .

     

Mixed-ligand and binuclear complexes of oxovanadium(IV)

Summary Mixed ligand complexes of the type [VOLA]ClO₄ where L=5-bromosalicylaldehyde (L) or 5-nitrosalicylaldehyde (L) and A=2, 2-dipyridyl (A) or 1, 10-phenanthroline (A) have been prepared. Treatment of the mononuclear complexes, [VOLA]ClO₄, withp-phenylenediamine (ppd) orm-phenylenediamine (mpd) yielded homobinuclear [VOLA-NC₆H₄N-LAVO](ClO₄)₂, complexes, which were characterised by elemental analyses, spectra, magnetic susceptibility and molar conductance measurements.     

1H-NMR-spektroskopische Analyse von 2-Chlor-1.3.2-dioxarsolan

The¹H-NMR-spectral data of 2-chloro-1.3.2-dioxarsolane are presented and discussed. The protons of the methylene groups form in concentrated solutions by rapide chlorine exchange anAAAA spin system. In dilute solutions the protons form anAABB spin system, which is changed to anAAAA system by addition of chlorine ions.The vicinal H–C–C–H-coupling constants indicate a twist-envelope conformation.

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Mit 1 Abbildung     

Phthalocyaninartige Bor-Komplexe

Zusammenfassung Aus Halogenboranen und Organohalogenboranen (RBX ₂R=C₆H₅, Cl, Br;X=F, Cl, Br) sowie aus Organoboranen oder Thioboranen entstehen mit Phthalodinitril Triisoindolo-[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8,9a,9b]-hexaazaboraphenalene von denen die B–Cl- und B–F-Verbindungen näher charakterisiert werden.Dekaboran(14), Diboran(6) oder Boranaddukte von Stickstoffbasen liefern hingegen mit Phthalodinitril metallfreies Phthalocyanin.

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Triisoindolo[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8,9a,9b]-hexa-azaboraphenalene

Triisoindolo[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8, 9a,9b]-hexaazaboraphenalenes are obtained from the reactions of haloboranes and organohaloboranes (RBX ₂R=C₆H₅, Cl, Br;X=F, Cl, Br) as well as from organoboranes or thioboranes with phthalodinitrile. The B–Cl and B–F compound have been characterized by analyses, i.r.-, u.v.- and mass-spectrometry.Diborane(6), dekaborane(14) and amine-boranes, however, upon reaction with phthalodinitrile lead to high yields of metal free phthalocyanine.

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Herrn Prof. Dr.M. Pailer zum 60. Geburtstag gewidmet.     

Complexing equilibria and redox potentials of the Ag(II)/Ag(I) system in the presence of 2,2′:6′,2″-terpyridine in water

Summary The conditional protonation constants (=0.1) for 2,2:6,2-terpyridine, logK ₁=4.93, logK ₂=3.69, were determined by thepH-metric method. The compositions of complexes of Ag²⁺ and Ag⁺ ions with 2,2:6,2-terpyridine (tp) were studied and equilibria of the complex formation process were described. The values of conditional complex formation constants are as follows: for Ag(tp) ₂ ⁺ :log₀₁=5.79, log₀₂=9.68, for Ag(tp) ₂ ²⁺ :log₀₂=25.31, while the conditional constant of the Ag(tp)NO₃ precipitate formation is:K _SO=2.45·10⁴. Using coulometric and chronovoltamperometric measurements, the redox systems being formed in the complex solutions of Ag(II) and Ag(I) were determined and described including their formal potentials.

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Komplexibildungsgleichgewichte und Redoxpotentiale des Systems Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Wasser

Zusammenfassung Mit Hilfe derpH-metrischen Methode wurden die konditionalen Protonationskonstanten (=0.1) von 2,2:6,2-Terpyridin bestimmt: logK ₁=4.93, logK ₂=3.69. Es wurde auch die Zusammensetzung der Komplexe von Ag(II) und Ag(I) mit 2,2:6,2-Terpyridin(tp) bestimmt sowie die Gleichgewichte der komplexbildung beschrieben. Die Werte der Konditionalkomplexbildungskonstanten sind: für Ag(tp) ₂ ⁺ :log₀₁=5.79, log₀₂=9.68, für Ag(tp) ₂ ²⁺ :log₀₂=25.31 und für das Löslichkeitsprodukt Ag(tp)NO₃:K _SO ^–1 =4.08·10^–5. Die in Komplexlösungen von Ag(II) und Ag(I) vorliegenden Redoxsysteme wurden mittels cyclischer Voltametrie und Coulometrie untersucht und die Formalpotentialwerte dieser Systeme in Wasser bestimmt.

     

Interaction between metal and support: Effects of support acidity on adspecies of co over Ru

Supported Ru/X catalysts (X: SiO₂, Al₂O₃, SiO₂·Al₂O₃, HY) have been investigated by IR and TPR (temperature programmed reduction). Due to interaction between Ru and Lewis or Brönsted sites of the support, the Ru sites become electron-deficient. Stronger acidity of the support makes the Ru sites more electron-deficient, and as a result, adspecies of Ru⁺ (CO)₄ or Ru⁺(CO)₂ can occur more easily.

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Ru/X (X:SiO₂, Al₂O₃, SiO₂·Al₂O₃, HY) - . Ru . , Ru⁺(CO)₄ Ru⁺(CO)₂.

     

Synthesis of dihydro-10H-pyrano[3′,4′: 5,6]pyrido[3,2:4″,5″]-thieno[3″,2″-d][3,1]oxazines and pyrimidines

Convenient methods have been developed for synthesizing dihydro-10H-pyrano[3,4:5,6]-pyrido[3,2:4,5]thieno[3,2-d][3,1]-oxazines and -pyrimidines. Optimum conditions have been established for the chlorodeoxygenation of condensed thieno-pyrimidin-4-ones.A. L. Mndzhoyan Institute of Fine Organic Chemistry, Armenian Academy of Sciences, Yerevan, 375014. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 250–253, February, 1995. Original article submitted November 15, 1994.     

Synthetic studies in the field of the curare alkaloids

By oxidation and the identification of the oxidation products, it has been shown that the -[4-(2-alkoxy-5-alkoxycarbonylmethylphenoxy)-3-methoxyphenyl] ethylamides of 4-benzyloxyphenylacetic acid obtained previously and differing in their physicochemical properties are based on the same skeleton and differ only in their spatial configuration, since on Bischler-Napieralski cyclization they give isomeric dihydroisoquinoline compounds. The structure of the latter was established by oxidation to the isomeric acids 2,2-dimethoxy-3,4,5-tricarboxy(diphenyl ether) and 2,2-dimethoxy-4,5,5-tricarboxy-(diphenyl ether); the latter is identical with the compound obtained by the degradation of the methyl ester of natural tubocurarine. 1-(4Benzyloxybenzyl)-6-methoxy-7-(2-methoxy-5-methoxycarbonyl methylphenoxy)-N-methyl-1,2,3,4-tetrahydroisoquinoline and a compound isomeric with it have also been synthesized, and the former has been shown to be identical with a substance obtained by independent synthesis from the 4-benzyl ether of N-methylcoclaurine. During the synthesis of the latter it was shown that cyclization takes place unambiguously without the formation of isomeric compounds.For part XIII, see [2].     

Molecular structure of 4,5;7,8-(4′,4″-dimethyl-6′,6″-di-tert-butyl)dibenzo-6h-2-diethylamino-2-thiono-1,3,2-dioxaphosphocine

Conclusions X-ray structure analysis shows that for 4,5;7,8(4,4 -dimethyl-6,6-di-tert-butyl)-dibenzo-6H-2-diethylamino-2-thiono-1,3,2-dioxaphosphocine, the boat-chair conformation of C_s symmetry with an equatorial diethylamino group occurs in the crystal.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 74–77, January, 1989.     

IR spectra of oxygen adsorbed on SnO2

IR spectra of oxygen adsorbed on SnO₂ with and without lattice defects have been studied. At low temperatures oxygen is adsorbed on defect SnO₂ in two forms of O ₂ ^– . This supports the earlier results obtained by ESR. The low-temperature forms of adsorbed oxygen (unrevealed in ESR spectra) were detected on defectless SnO₂. High-temperature forms of adsorbed oxygen appear in the IR-spectra as bands due to vibrations of the cation-oxygen bond.

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- SnO₂. , O ₂ ^– , . SnO₂ .

     

Excess heat of mixing of binary mixtures of pyridine withn-alkanes at 313.15 K

The molar excess enthalpies of binary mixtures of pyridine with C₆–C₉ n-alkanes have been measured at 313.15 K in the entire composition range. The measuredH ^E values were compared with those calculated by means of the Prigogine-Flory-Patterson theory and by the ERAS method.

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Zusammenfassung Die molaren Überschußenthalpien binärer Mischungen von Pyridin mit C₆–C₉ n-Alkanen wurden bei 313,15 K im ganzen Zusammensetzungsbereich gemessen. Die gemessenenH ^E Werte wurden mit denen verglichen, die mit Hilfe von Prigogine-Flory-Patterson Theorie und nach der ERAS-Methode berechnet wurden.

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313,5 n- (₆-₉) ce . -- (ERAS).

     

Synthesis,crystal structure and reaction of differentially ring-substituted titanocene dichlorides

Summary A new class of differentially ring-substituted titanocene dichlorides of the type CpCpTiCl₂ has been prepared by reacting CpM (M=Li, K; Cp=RC₅H₄) with CpTiCl₃ (Cp=MeOCH₂CH₂C₅H₄). The crystal structure of Cp(PhCEt₂C₅H₄)TiCl₂, the first example, has been determined by x-ray diffraction and refined to a final R factor of 0.0532 for 2304 reflections. The crystal belongs to the monoclinic space group C _2h ⁵ –P2₁/c with unit cell parameters:a 10.205(6),b 13.003(5),c 17.591(9) Å, 101.91(4)°, V=2284 ų, Z=4 and Dc=1.32 g/cm^–3. Replacement of one neomenthyl in bis(neomenthyl-cyclopentadienyl)titanium dichloride by one MeOCH₂CH₂ — raises the e.e. value from 5.8% to 11.2% in the catalytic asymmetric hydrogenation of 2-phenyl-1-butene.     

Characteristic of the Ag(II)/Ag(I) system in the presence of 2,2′:6′,2″-terpyridine in acetonitrile

Summary Composition of complexes of Ag(II) and Ag(I) ions with 2,2:6,2-terpyridine (tp) have been established. It has been found that the Ag⁺ ion forms only one complex Ag(tp)⁺ withtp in acetonitrile; its conditional formation constant: ₀₁=6.6·10⁴ has been determined by the potentiometric method. Equilibria and redox systems formed in solutions due to the complexation of Ag⁺ and Ag²⁺ and oxidation of Ag(II) complexes are described. Their formal potentials have been found by coulometric and voltamperometric examinations. The presence of the Ag(tp) ₂ ³⁺ ion in the anodic oxidized solutions of the complexes Ag(tp)(NO₃)₂ and Ag(tp)₂(NO₃)₂ has been proved. Properties of the system Ag(II)/Ag(I) in the presence of terpyridine in water and in acetonitrile have been compared.

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Charakteristik der Systeme Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Acetonitril

Zusammenfassung Die Zusammensetzung der Komplexe von Ag(I)- und Ag(II)-Ionen mit 2,2:6,2-Terpyridin (tp) wurde bestimmt. Das Ag⁺-Ion bildet mittp in Acetonitril nur einen Komplex-Ag(tp)⁺. Seine Konditionalbildungskonstante ₀₁=6.6·10⁴ wurde mit Hilfe der potentiometrischen Methode bestimmt. Es wurden die Gleichgewichte und Redoxsysteme als Resultat der Komplexbildung von Ag(II)- und Ag(I)-Ionen und der Ag(II)-Komplexoxidation charakterisiert und die Formalpotentiale mittels Voltametrie und Coulometrie bestimmt. Die Gegenwart der Ag(tp) ₂ ³⁺ -Ionen wurde in anodisch oxydierten Lösungen der Komplexe Ag(tp)(NO₃)₂ und Ag(tp)₂(NO₃)₂ nachgewiesen. Die Eigenschaften des Systems Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Wasser und in Acetonitril wurden verglichen.

     

Reaction of substituted iron phthalocyanines with dioxygen in acidic medium

The reaction of acidic form of the substituted icon phthalocyanine complex (3-PhS- 5-Bu^t)⁴pcFe (pcFe) with dioxygen in o-dichlorobenzene in the presence of dichloroacetic acid (HX) was investigated. The oxidation of HpcFeX gives the corresponding radical cation, which was confirmed by the stoichiometry of reduction of the product formed in this reaction with a two-electron reducing agent. The kinetic equation obtained on the basis of dependences of the oxidation rate on the HpcFeX, HX, and O₂ concentrations are consistent with the reaction mechanism that implies the formation of a HpcFeX complex with O₂ and its transformation to give a radical cation under the action of HX.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1592–1597, August, 2004.