Mass-spectrometric detection of an unstable product in silver-methanol interaction

The low pressure interaction of methanol vapors with a silver catalyst was studied by mass spectrometry. An unstable product contributing to m/e-15 was detected in this reaction. While yield of formaldehyde increased with addition of oxygen, the unstable product showed towards oxygen a reversed, decreasing trend.

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- , m/e=15. , .

     

Palladium and platinum guanine complexes

Summary Reaction of [MCl₂(H₄Y)] or (H₆Y)[MCl₄] compounds (M = Pd or Pt; Y = EDTA, PDTA or CDTA) with guanine (Gu-H) in 0.5 M HCl yields new complexes MCl₂(Gu-H)(H₂O which have been characterized by elemental analyses in conjunction with electronic, i.r. and n.m.r. spectra. A dimeric structure with two bridging chloride ligands, including coordination of guanine through atom N(9), is proposed for both compounds.Abbreviations used in the paper EDTA 1,2-diaminoethane-N,N,N,N-tetraacetate - PDTA 1,2-diaminopropane-N,N,N,N-tetraacetate - CDTA trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetate - Gu-H guanine - 9-EtGu-H 9-ethylguanine     

Electrochemical behaviour of a series ofN,N′-1,2-Phenylenebis(salicylideneimin)ato transition metal complexes

Summary The electrochemistry of a series of nickel(II), copper(II), cobalt(II), manganese(II) and oxovanadium(IV) complexes with theN,N-1,2-phenylenebis(salicylideneimin)ate ligand has been studied in dimethyl sulfoxide solution. Kinetic and thermodynamic aspects of the electron-transfer processes are discussed, also with respect to those of the correspondingN,N-ethylenebis(salicylideneimin)ate and bis(salicylideneiminate-3-propyl)amine derivatives     

1,2-bis(2',6'-dimethyl-i',3'-dioxa-6'-aza-2'-silacyclooctyl-2')ethane and the corresponding ethylene and acetylene derivatives

Conclusions The reaction of 1,2-bis(methyldimethoxysilyl)ethane and the corresponding ethylene and acetylene derivatives with bis(2-hydroxyethyl)methylamine gives 1,2-bis(2,6-dimethyl-1,3-dioxa-6-aza-2-silacyclooctyl-2)ethane and the corresponding ethylene and acetylene derivatives. Analogously, 1,2-bis(vinyldimethoxysilyl)acetylene gave 1,2-bis(2-vinyl-6-methyl-1,3-dioxa-6-aza-2-silacyclooctyl-2)acetylene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1420–1421, June, 1988.     

Relative thermodynamic stabilities of isomeric 1,2-dialkoxyethenes

The relative thermodynamic stabilities of the geometrical isomers of a number of 1,2-dialkoxyethenes have been determined by chemical equilibration in the neat liquid and in 1,4-dioxane solution with mercuric acetate as catalyst. From the variation of the value of the equilibrium constant with temperature, the thermodynamic parameters G , H , and S of theE Z isomerization were evaluated. In all cases theZ isomer proved to be thermodynamically the more stable species, its favor increasing with the bulkiness of the alkoxy groups. The thermodynamic data obtained for theEZ isomerization of 1,2-dimethoxyethene differ significantly from those reported in the literature. An attempt to correlate the experimental thermodynamic data with MM2 calculations for the title compounds as well as for 1,2-dimethoxypropenes is presented.     

Esters of (1,2, 5-trimethyl-4-hydroxy-4-piperedyl)- and phenyl-(1,2, 5-trimethyl-4-hydroxy-4-piperidyl) acetic acids

The methyl ester of a new hydroxy acid of the piperidine series (-phenyl--(1,2, 5-trimethyl-4-hydroxy 4-piperidyl)acetic acid) has been prepared. Ethyl -(1,2, 5-trimethyl-4-hydroxy-4-piperidyl)acetate has been converted into the substituted pyridine, 1,1-diphenyl-2-(2-5-dimethyl-4-pyridyl)ethylene.     

Etude calorimetrique de l'absorption de l'hydrogene sulfure dans des solutions aqueuses d'ethanolamines

Résumé La chaleur dégagée par l'absorption du sulfure d'hydrogène dans des solutions aqueuses de monoéthanolamine (MEA), diéthanolamine (DEA) et triéthanolamine (TEA) est mesurée directement par calorimétrie.Les valeurs des enthalpies obtenues sont comparées à celles obtenues par d'autres auteurs par calcul à partir des résultats d'expériences de solubilité ainsi qu'aux enthalpies de protonation par HC1 à 25.

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Absorption heats of hydrogen sulphide in aqueous solutions of monoethanolamine, diethanolamine and triethanolamine were determined by calorimetry. The measured enthalpies were compared to those calculated on the basis of solubility measurement and to the enthalpies of protonation of hydrogen chloride at 25.

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Zusammenfassung Die durch Absorption von Schwefelwasserstoff in wÄssrigen Lösungen von MonoÄthanolamin (MEA), DiÄthanolamin (DEA) und TriÄthanolamin (TEA) abgegebene WÄrme wurde unmittelbar durch Kalorimetrie gemessen. Die erhaltenen Enthalpiewerte wurden mit Versuchsergebnissen der Löslichkeit sowie der Protonierung durch HC1 bei 25 anderer Autoren verglichen.

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-, - . 25.

     

Synthesis and properties of a new family of cyclodextrin analogues

The chemical synthesis of a series of cyclic oligosaccharides built up from (14)-linked alternatingD– andl-pyranosidic units is described for the first time. Key intermediates employed were disaccharides representing minimal repeating units. These disaccharides (monomers) have been prepared in specifically modified forms so that they bear both glycosyl donor (cyanoethylidene group) and glycosyl acceptor (trityloxy group) functions. Polycondensation-cyclisation of these disaccharide monomers, catalysed by TrC1O₄ under normal conditions of dilution, has led to series of homologous cyclic oligosaccharides with an even number of sugar residues (6, 8, 10, 12,etc.) in each case. Cyclic hexa- and octa-saccharides, based onl-rhamnose andD-mannose as the alternating monosaccharides units, have been deprotected to produce analogues of - and -cyclodextrins (CDs) and the X-ray crystal structure of the cyclic octasaccharide has been determined.     

Z-,E-Isomer of 1,2:4,5-di-O-cyclohexylidene-β-d-erythro-hexo-2,3-diulopyranose oxime

The syntheses of 1,2:4,5-di-O-cyclohexylidene -fructopyranose and 1,2:4,5-di-O-cyclohyexylidene--d-erythro-2,3-diulopyranose were improved. A method for the separation of isomeric oxines of diulos was developed, and their structures were established by¹³C NMR spectroscopy, 3-Amino-3-deoxy-1,2:4,5-di-O-cyclohexylidene--d-psychopyranose was obtained.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 1003–1005, April. 1996.     

Über N-(α-Aminoacyl)-sulfonamide, 2. Mitt.

Zusammenfassung Es wird über die Synthese von N-(-Aminoacyl)-p-toluolsulfonamiden und N-(-Aminoacyl)-methansulfonamiden berichtet, deren Acylreste sich vonl-Tyrosin,d,l--Methyl-tyrosin undd,l-3,4-Dihydroxy-phenylalanin ableiten.

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The synthesis of N-(-aminoacyl)-p-toluenesulfonamides and N-(-aminoacyl)-methanesulfonamides containing the acyl groups ofl-tyrosine,d,l--methyltyrosine andd,l-3,4-dihydroxy-phenylalanine is described.

     

A flow-mixed reactor

A glass flow mixed reactor is described. In this reactor a stationary catalyst in the form of a plate 72 mm in diameter and 2 mm thick is placed on the bottom of the reactor. Determination of mass transfer at the upper surface of the plate showed that the whole surface of the catalyst was equally accessible to reacting gas mixtures.

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. 72 2 . , .

     

Hydrogenation of toluene over Pt and Pt?Cu alloys in NaY

The hydrogenation of toluene is performed over small Pt and Pt–Cu particles in a NaY zeolite. For toluene hydrogenation the T.O.N. of Pt and Pt alloyed with Cu are very different at room temperature but at high temperature (530 K) they are of the same order of magnitude.

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Pt Pt–Cu NaY. ( ) Pt Pt, , , , (530 K) .

     

Cooligomerization of 1,2-dienes with norbornadienes catalyzed by cobalt complexes

Conclusions Under the action of low-valency cobalt complexes [2 + 2 + 2] cycloaddition of allene, cyclopropylallene, phenylallene, and 1,2-cyclononadiene to norbornadiene and spirocyclo-[2.2.l]hepta-2,5-diene-7,1-cyclopropane takes place with the formation of derivatives of tetracyclo[4.3.0.0^2,4. 1.0^3,7] nonane in high yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1346–1356, June, 1988.     

The partitioning of alkanediols into SDS and DTAB micelles from NMR-PRE experiments

The p-values of a number of ,-alkanediols, 1,2-alkanediols, and 1,5-hexanediol and 2,5-hexanediol between D₂O and the micellar phases of anionic sodium dodecylsulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) have been determined using the using a NMR paramagnetic relaxation enhancement experiment (NMR-PRE). From the p-values, mole-fraction based partition coefficients and Gibbs energies of transfer for the alkanediols from the bulk D₂O phase to the micellar phase have been calculated. Differences in the partition coefficients of the ,-alkanediols and the 1,2-alkanediols are discussed in terms of the smaller Gibbs transfer energy per CH₂ group for ,-alkanediols. For the 1,5- and the 2,5-hexanediols, the p-values are substantially smaller than for the other hexanediols in both SDS and DTAB micelles. All of these results are consistent with the location of the two hydroxyl groups on the carbon backbone making a substantial contribution to the thermodynamics of transfer of solubilizates.     

Catalytic ammoxidation of coal

Ammoxidation of coal on oxide catalyts has shown the possibility of hydrocyanic acid formation at sufficiently low temperatures.

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. .

     

Improved synthesis of 6-deoxy-1,2-O-isopropylidene-β-L-talofuranose and 6-deoxy-1,2-O-isopropylidene-β-L-idofuranose

Summary The key step in the preparation of 6-deoxy-1,2-O-isopropylidene--L-talofuranose (7) and 6-deoxy-1,2-O-isopropylidene--L-idofuranose (13) is the selective exchange of the 6-O-mesyl rest of 3-O-acetyl-5,6-O-dimesyl-1,2-O-isopropylidene--D-allofuranose (4) and 3-O-acetyl-5,6-O-dimesyl-1,2-O-isopropylidene--D-glucofuranose (10) by acetate group (potassium acetate/18-crown-6).

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Ein neuartiger und präparativ nützlicher Zugang zu 6-Desoxy-1,2-O-isopropyliden--L-talofuranose und 6-Desoxy-1,2-O-isopropyliden--L-idofuranose

Zusammenfassung Schlüsselschritt bei der Herstellung von 6-Desoxy-1,2-O-isopropyliden--L-talofuranose (7) und 6-Desoxy-1,2-O-isopropyliden--L-idofuranose (13) ist der selektive Austausch der primären Mesyl-Gruppe in 3-O-Acetyl-5,6-O-dimesyl-1,2-O-isopropyliden--D-allofuranose (4) und 3-O-Acetyl-5,6-O-dimesyl-1,2-O-isopropyliden--D-glucofuranose (10) durch den Acetat-Rest in Gegenwart von Kaliumacetat/Kronen-Ether.

     

Kinetics of the acid catalyzed hydrolysis of hydroxamic acids

The acid catalyzed hydrolysis of some alkylhydroxamic acids has been studied spectrophotometrically in perchloric, hydrochloric and sulfuric acids. Plots of the first order rate constant, k_obs against H⁺ show maxima, which are caused by protonation of the substrate. The mechanism of hydrolysis is found to be similar to that of amides. The variation of reaction rate with acid concentration can be described by a two-parameter equation.

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, , , . k_obs [H⁺] , . . .

     

Preparation and characterization of Mg(II)-, Ca(II) and Cd(II) complexes of 1,2-ethanediol and water

Mixed ligand complexes of different compositions were prepared with water, sulfate ion and 1,2-ethanediol as ligand. IR spectra and the thermoanalytical curves of the complexes were recorded. Oxygen atoms bound by one or two coordinate bonds to the metal ion, or by hydrogen-bonds in the crystal, were observed. As for the water molecule, 1,2-ethanediol molecules of crystal and monohydrate type were found, depending on the type of binding of the oxygen atoms.This revised version was published online in November 2005 with corrections to the Cover Date.     

Electrochemical synthesis of halogen derivatives of bis(1,2-dicarbollyl)cobalt(III)

A convenient electrochemical method for the synthesis of 8,8-dihalogen derivatives of bis(1,2-dicarbollyl)cobalt(III) anion [8,8X₂-3,3-Co(1,2-C₂B₉H₁₀)]^– (X = Cl, Br, I) was developed. The method includes the electrolysis of a solution of alkaline metal halide and tetramethylammonium salt of bis(1,2-dicarbollyl)cobalt(III) in methanol at 50 °C in a one-compartment electrochemical cell with a nickel cathode and platinum anode.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2448–2451, November, 2004.