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  • 1980-1984  (916)
  • 1981  (916)
  • Inorganic Chemistry  (704)
  • Physical Chemistry  (123)
  • Gas chromatography  (89)
  • 101
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2754-2768 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Iron Complexes as Model Compounds for the Homogeneous Hydrogenation of Carbon MonoxideThe μ-dinitrogen complex {Fe(CO)2[P(OCH3)3]2N2 (2) is prepared. Its reaction with H2, CH2O and C2H4 leads to dihydrido-, formaldehyde-, and ethylene-dicarbonylbis(trimethylphosphite)-iron complexes (4,5, and 6, respectively). The structures of 2 and of the dicarbonyltris(trimethylphosphite)iron complex 3 were determined by X-ray analyses.
    Notes: Der μ-Distickstoffkomplex {Fe(CO)2[P(OCH3)3]2N2 (2) wird dargestellt und mit H2, CH2O und C2H4 zu Dihydrido-, Formaldehyd- und Ethylen-dicarbonylbis(trimethylphosphit)eisen-Komplexen 4,5 bzw. 6 umgesetzt. Die Strukturen von 2 und dem Dicarbonyltris(trimethylphosphit)-eisen-Komplex 3 wurden röntgenographisch bestimmt.
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  • 102
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2744-2753 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleophilic Addition of Triorganotin Anions to Carbon Disulfide. X-Ray Structure Determination of Methyl Triphenylstannanedithiocarboxylate(Triphenylstannyl)lithium is added as a nucleophile to carbon disulfide. Purple alkyl triphenyl stannanedithiocarboxylates 1a-d are obtained by alkylation of the primary CS2 adduct. By the same method methyl [tri(o- and p-tolyl)stannane]dithiocarboxylate (2a-b) are synthesized. The reaction of the methyl ester 1a with irradiated CpMn(CO)6 yields the n1-complexes CpMn(CO)2L (3a) and W(CO)5L (3b) (L = 1a), respectively. 1a crystallizes in a “orderly disordered” tetraphenyltin structure (tetragonal, p42cc, Z = 2) in which the planar (methylthio)-thiocarbonyl ligands are distributed statistically with a population factor of 0.25.
    Notes: (Triphenylstannyl)lithium läßt sich nucleophil an Kohlenstoffdisulfid addieren. Durch Alkylierung des primären CS2-Addukts erhält man die rotvioletten Alkyl-triphenylstannandithiocarboxylate 1a-d. Nach der gleichen Methode lassen sich Methyl-[tri(o-und p-tolyl)stannan]dithiocarboxylat (2a, b) darstellen. Bei der Umsetzung des Methylesters 1a mit photochemisch aktiviertem CpMn(CO)3 und W(CO)6 entstehen die n1-Komplexe CpMn(CO)2L (3a) und W(CO)5L (3b) (L = 1a). 1a kristallisiert in einer„ordentlich fehlgeordneten“ Tetraphenylzinn-Struktur (tetragonal, p42cc, Z = 2) in der die planaren (Methylthio)thiocarbonyl-Liganden mit dem Besetzungsfaktor 0.25 statistisch verteilt sind.
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  • 103
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2769-2785 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Peroxides, XIV. The Thermal Decomposition of Polycyclic tert-Butyl Bridgehead PeroxycarboxylatesEleven bridgehead peresters (1,2,5,-8,10,12,14,18,21) have been prepared for the first time and the products and the kinetics of their thermal decomposition were investigated. The correlations of all known thermolysis constants of bridgehead peresters with the steric substituent constants Sf, with the solvolysis constants of the corresponding bridgehead bromides, as well as with the change in strain enthalpy ΔHsp for hydride abstraction from the bridgehead, as calculated by the procedure of v. R. Schleyer, were analysed. The thermolysis constants of these peresters are mainly determined by the polar effect in the transition state of the perester fragmentation.
    Notes: Elf Brückenkopf-Peroxycarbonsäure-tert-butylester (1,2,5,-8,10,12,14,18,21) wurden erstmals dargestellt, und ihr thermischer Zerfall wurde präparativ und kinetisch studiert. 18O-Äquilibrierungsversuche und der Einfluß der Solvensviskosität auf die Zerfallskonstanten der Perester sind mit dem homolytischen Fragmentierungsmechanismus im Einklang. Es wurden die Korrelationen sämtlicher thermischer Zerfallskonstanten von Brückenkopf-Peroxycarbonsäure-tertbutylestern mit den sterischen Substituenten Sf mit den Solvolysekonstanten entsprechender Brückenkopf-Bromide und mit den nach v. R. Schleyer berechneten Werten der Änderung der Spannungsenthalpie ΔHsp bei der Hydridabspaltung vom Brückenkopf der Kohlenwasserstoffe analysiert. Die Thermolysekonstanten der Brückenkopf-Perester werden hauptsächlich durch den polaren Effekt im Übergangszustand der Peresterfragmentierung bestimmt.
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  • 104
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2786-2801 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoselective Synthesis of Alcohols, IX. Absolute configuration of StegobinoneDiastereoselective as well as enantioselective conversion of the boronate 4 into the homoallyl alcohol 5 served as basis for the synthesis of optically active stegobinone isomers. Material with the correct absolute configuration at C-2 was obtained starting from (3S)-3-hydroxy-2-methyl-butyrate 17. The CD spectrum of the isomer 20B corresponded to that of the natural product. Its Configuration was assigned as 2S, 3R, 7R and was substantiated by an X-ray structure determination of 7-epistegobinone (20A).
    Notes: Eine diastereo- und enantioselektive Synthese des Homoallylalkohols 5 aus dem Boronester 4 eröffnete den Zugang zu optisch aktiven Isomeren des Stegobinons. Stegobinon-Isomere mit der richtigen absoluten Konfiguration an C-2 wurden ausgehend von (3S)-3-Hydroxy-2-methylbuttersäureester 17 dargestellt. Das CD-Spektrum des Isomeren 20B entsprach dem des Naturstoffs. Daraus wurde die konfiguration zu 2S, 3R, 7R für das natürliche Stegobinon abgeleitet und durch eine Röntgenstrukturanalyse des 7-Epistegobinons (20A) erhärtet.
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  • 105
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2300-2308 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The He(I) Photoelectron Spectra of (CH3)2PSCH3, (CH3)2AsSCH3, (CH3)2AsSeCH3 and (CH3)2PSeCH31)The He(I) photoelectron (PE) spectra of (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) and (CH3)2PSeCH3 (4) have been recorded. The assignment of the first five bands is based on a comparison with the PE spectra of (CH3)3X, (CH3)2XX(CH3)2 (X = P, As) as well as of (CH3)2 and CH3YYCH3 (Y = S, Se). Additionally the measured ionization potentials have been compared with calculated orbital energies (CNDO, INDO, MNDO). The first two bands of the PE spectra of 1-4 are due to ionization events from linear combinations of the lone electron pairs.
    Notes: Die He(I)-Photoelektronen (PE)-Spektren von (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) und (CH3)2PsSeCH3 (4) wurden gemessen. Die Zuordnung der ersten fünf Banden erfolgte durch Vergleich mit den PE-Spektren der Verbindungen (CH3)3X, (CH3)2XX(CH3)2 (X = P, As), sowie (CH3)2Y und CH3YYCH3 (Y = S, Se). Außerdem wurden die gemessenen Ionisationspotentiale mit berechneten Orbitalenergien (CNDO, INDO, MNDO) verglichen. Die ersten beiden Banden in den PE-Spektren von 1-4 können Ionisierungen zugeordnet werden, bei denen das Elektron aus Linearkombinationen der einsamen Elektronenpaare stammt.
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  • 106
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transannular Interactions Between Acetylenes - Photoelectron Spectroscopic Investigations on 1,8-Diethynylnaphthalene and Cyclic Derivatives of 2,2′-DiethynylbiphenylThe He(I) photoelectron (PE) spectra of 1,8-diethynylnaphthalene (3), 2,2′-diethynylbiphenyl (6) and the cyclic derivatives of 6 (4 and 5) as well as 1-ethynyl-, 2-ethynyl-, 1,5-diethynyl-, 1-vinyl-, and 1,8-divinylnaphthalene have been recorded. The first bands in the PE spectra of these compounds can be assigned using correlation techniques and semiempirical MO calculations. In case of 3 the resonance integral for the transannular interaction has been found to be β = -0.48 eV. For 4 and 5 the evaluation of β was not possible due to the strong interaction between biphenyl and ethynyl units.
    Notes: Die He(I)-Photoelektronen (PE)-Spektren von 1,8-Diethinylnaphthalin (3), 2,2′-Diethinylbiphenyl (6), der cyclischen Derivate von 6 (4 und 5) sowie von 1-Ethinyl-, 2-Ethinyl-, 1,5-Diethinyl-, 1-Vinyl- und 1,8-Divinylnaphthalin wurden durch Korrelation bzw. semiempirische MO-Rechnungen interpretiert. Bei 3 wurde das Resonanzintegral β für die transannulare Wechselwirkung zu -0.48 eV ermittelt, bei 4,5 und 6 ist wegen der starken Wechselwirkung zwischen Biphenylteil und Acetyleneinheiten eine Ermittlung von β nicht möglich.
    Additional Material: 7 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 1752-1766 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal Rearrangements of 1-Allyloxy- and 1-Propargyloxy-λ5-phosphorin DerivativesThe thermal rearrangements of 1-allyloxy-λ5-phosphorin derivatives 1 affords - contrary to the formally similar Claisen rearrangement of allyl phenyl ethers - in the irreversible step an “anti-Woodward-Hoffmann” [3s5s] allyl shift to 4-allyl-1,4-dihydro-λ5-phosphorin derivatives 2. - The reaction is, as cross experiments prove, intramolecular and stereospecific according to 1st order law. It is accelerated by electron donating substituents in position 4 and by electron attracting substituent at the phosphorus, but is not much solvent-dependant. In a next step, again with allyl-inversion, a [3s3s] Cope rearrangement follows to give 2-allyl-1,2-dihydro-λ5-phosphorin derivatives 3. At somewhat higher temperature, by an intramolecular [4 + 2]-cycloaddition from 3j a tricyclus 4 is formed. Besides the experiments with deuterium marked compounds, the X-ray analysis of 4 proves the uniform stereochemic way of all these rearrangements. Steric and electronic influences on some analogous rearrangements are studied, the mechanism is discussed.
    Notes: Die thermische Umlagerung von 1-Allyloxy-λ5-phosphorin-Derivaten 1, führt im Gegensatz zu der formal ähnlichen Claisen-Umlagerung von Allylphenylethern im irreversiblen Primärschritt in einer“ anti-Woodward-Hoffmann”-[3s5s]-Allylwanderung zu 4-Allyl-1,4-dihydro-λ5-phosphorin-Derivaten 2. -Die Reaktion verläuft, wie Kreuzungsexperimente beweisen, intramolekular und stereospezifisch nach einer Reaktion 1. Ordnung. Sie wird durch elektronenabgebende Substituenten in R4 und elektronenanziehende substituenten am Phosphor gefördert, ist jedoch wenig löungsmittelabhängig. Ihr folgt in einem irreversiblen Schritt unter erneuter Allyl-Umkehr eine [3s3s]-Cope-Umlagerung zu 2-Allyl-1,2-dihydro-λ5-Phosphorin-Derivaten 3. Bei etwas höherer Temperatur gehen diese eine intramolekulare [4 + 2]-Cycloaddition zum Tricyclus 4 ein. Dessen Röntgenstrukturanalyse sowie die eindeutigen Deuterierungsergebnisse sprechen für einen stereochemisch einheitlichen verlauf der Umlagerungen. Sterische und elektronische Einflüsse auf einige analoge Umlagerungen werden untersucht, der Mechanismus wird diskutiert.
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  • 108
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 1767-1785 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tricyclo[4.1.0.02,7]hept-1(7)-ene as a Reactive Intermediate: Diels-Alder Trapping Reactions and Proof of ExistenceThe reaction of bulky lithium amides or potassium tert-butoxide with 1-chlorotricycloheptane 3a, generated tricyclo[4.1.0.02,7]hept-1(7)-ene (7) as a short-lived intermediate which could be trapped with reactive 1,3-dienes like anthracenes, furans and spiro[2.4]hepta-4,6-diene forming [4.1.1]- and [3.1.1.]propellanes. The existence of 7 as a free intermediate has been established by competition experiments.
    Notes: Die Einwirkung von sperrigen Lithiumamiden oder Kalium-tert-butylat auf das 1-Chlortricyclo-heptan 3a, erzeugte Tricyclo[4.1.0.0.2,7]hept-1(7)-en (7) als kurzlebige Zwischenstufe, die sich mit reaktiven 1,3-Dienen wie Anthracenen, Furanen und Spiro[2.4]hepta-4,6-dien unter Bildung von [4.1.1]- und [3.1.1]Propellanen abfangen ließ. Durch Konkurrenzexperimente wurde nachgewiesen, daß 7 als freies Teilchen auftritt.
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  • 109
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 1836-1844 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Applications of Phase Transfer Catalysis, VIII1) Synthesis and some Reactions of Tetrasubstituted 6,6-Dihalogenobicyclo[3.1.0]hex-3-en-2-onesThe reaction of tetrasubstituted cyclopentadienones 1 with dichlorocarbene or dibromocarbene gives specifically the 6,6-dihalogenobicyclo[3.1.0]hex-3-en-2-ones 2 and 3. Reductive ring opening of 2 or 3 with LiAlH4 cleanly yields the tetrasubstituted 3-halogenophenols 4 and 5. Reaction of 2 or 3 with methylmagnesium iodide leads to 2,4-cyclohexadien-1-ones 13 and to 1-halogeno-5-methylene-1,3-cyclohexadienes 14.
    Notes: Die Reaktion der tetrasubstituierten Cyclopentadienone 1 mit Dichlorcarben bzw. Dibromcarben führt spezifisch zu den 6,6-Dihalogenbicyclo[3.1.0]hex-3-en-2-onen 2 bzw. 3, deren reduktive Ringöffnung mit LiAlH4 einen einfachen Weg zu den tetrasubstituierten 3-Halogenphenolen 4 bzw. 5 darstellt. Umsetzung von 2 bzw. 3 mit Methylmagnesiumiodid ermöglicht einen neuen Zugang zu 2,4-Cyclohexadien-1-onen 13 und zu 1-Halogen-5-methylen-1,3-cyclohexadienen 14.
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  • 110
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2360-2364 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydridoiridium(III) Complexes with Terminal and Bridging Thio- and Selenocyanate1)The thio- and selenocyanato complexes (Ph3P)2(CO)(Cl)(H)IrX 1 (X = SCN) and 2 (X = SeCN) and 2 (X = SeCN) have been prepared from the corresponding tetrafluoroborato- and trifluoromethanesulfonato-compounds (X = BF4, CF3SO3). The SCN ligand in 1 is S-bonded. 2 was obtained as a mixture of linkage isomers. The reaction of 2 with the tetrafluoroborato-complex (Ph3P)2(CO)(Cl)(H)IrFBF3 gives the salt [(Ph3P)2(OC)(Cl)(H)Ir—SeCN—Ir(H)(Cl)(CO)(PPh3)2]+BF-4 which contains the selenocyanate-bridged cation as a mixture of stereoisomers.
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  • 111
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2365-2368 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chirale Butadiene, 91) Präparative Anreicherung enantiomerer 2,3,4,5-Tetrabrom-2,4-hexadiene durch Flüssigkeits-ChromatographieDie Enantiomeren des Diols 1 wurden durch Flüssigkeits-Chromatographie an Triacetylcellulose teilweise getrennt (Enantiomere Reinheiten P = 29% und 24%), während die Diether (+)- und (-)-2 mit P = 80% (Tab. 1) erhalten wurden. Ihre Schwellen der Teilrotation um die zentrale Einfachbindung wurden durch thermische Racemisierung gemessen und mit denen entsprechender Tetrachlordiene 3 und 4 verglichen (Tab. 3).
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  • 112
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3378-3384 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Trimethylsilyl-substituted 1,3-Dithietane 1,1,3,3-TetroxidesSubstitution reactions of 1,3-dithietane 1,1,3,3-tetroxide (1) (sulfene dimer) have been regarded as difficult. We now succeeded in the silylation of 1 by the reaction with trimethylsilyl nonafluorobutanesulfonate (2) in the presence of triethylamine yielding 2,4-bis(trimethylsilyl)-(3) and 2,2,4-tris(trimethylsilyl)-1,3-dithietane1,1,3,3-tetroxide (4) as well as - via a metallation - the four times silylated product, which has the structure 1-(tirmethylsiloxy)-2,4,4-tris(trimethylsilyl)-1,3-dithiet-1-ene 1,3,3,-trioxide (5b) and which can be considered as the first enol ether of a sulfone.
    Notes: Substitutionsreaktionen an 1,3-Dithietan-1,1,3,3-tetroxid (1) (Disulfen) galten bisher als schwierig. Es gelang nun die Silylierung von 1 mit Nonafluorbutansulfonsäure-trimethylsilylester (2) in Gegenwart von Triethylamin zu 2,4-Bis(trimethylsilyl)-(3) und 2,2,4-Tris(trimethylsilyl)1,3-dithietan-1,1,3,3-tetroxid (4) bzw. nach Metallierung zum vierfach silylierten Produkt, das als 1-(Trimethylsiloxy)-2,4,4-tris(trimethylsilyl)-1,3-dithiet-1-en-1,3,3-trioxid 5b) vorliegt und als erster Enolether eines Sulfons angesehen wurden kann.
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  • 113
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3385-3394 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Tetra(cyclopropyl)phosphonium cation and the Tri(cyclopropyl)phosphonium CyclopropylideTertiary phosphane can not be quaternized by cyclopropyl halides. The preparation of the three possible mixed cyclopropyl/methyl phosphonium salts [CH3)n(c-C3H5)4 - nP]+X- with n = a - 3 and of the corresponding ylides (CH3)n(c-C3H5)3 - nP = CH2 with n = 0 - 2 (1 - 3) is therefore only accomplished via the cyclopropylphosphanes or through formation o the cyclopropyl ring at the phosphonium center. Quaternization of tri(cyclopropyl)phosphane with 1,3-dibromopropane followed by treatment wih base thus also allows the synthesis of the tri(cyclopropyl)phosphonium cyclopropylide (5). With acids, 5 is converted into tetra(cyclopropyl)phosphonium salts. All three ylides 1 - 3 exist as methylides, and isomerization to cyclopropylides is not observed. 2 and 3 yield ethylphosphonium salts on reaction with methyl iodide. 5 is the only cyclopropylide bearing solely aliphatic substituents. Ist unusal NMR parameters indicate an equilibrium in which the CH protons are involved in a rapid scrambling process among the tautomers. The ylides 1 - 3 and 5 are colourless liquids, thermally stable up to 200°C, and of high chemical reactivity. Reduced reactivity is encountered in the tri(cyclopropyl)phosphonium benzylide (4).
    Notes: Tertiäre Phosphane sind mit Cyclopropylhalogeniden nicht quartärisierbar. Die Darstellung der drei Möglichen (Cyclopropyl/Methyl)Phosphoniumsalze [(CH3)n(c-C3H5)4-nP]+X- mit n = 1 - 3 und der korrespondierenden Ylide (CH3)n(c-C3H5)3-nP = PH2 mit n = 0 - 2 (1 - 3) gelingt daher nur über die Cyclopropylphosphane oder über den Aufbau des Cyclopropylrests am Phosphoniumzentrum. Quartärisierung mit 1,3-Dibrompropan und nachfolgende Cyclisierung mit Basen ermöglicht so auch erstmals die Darstellung von Tri(cyclopropyl)phosphonium-cyclopropylid (5) aus Tri(cyclopropyl)phospan. Mit Säuren entstehen aus 5 Tetra(cyclopropyl)phosphoniumsalze. Die Ylide 1 - 3 liegen alle als Methylide vor und eine Isomerisierung zum cyclopropylid wird nicht beobachtet. Mit Methyliodid entstehen aus 2 und 3 die Ethylphosphoniumsalze. - 5 ist das einzige rein aliphatisch substituierte Cyclopropylid. Seine ungewöhnlichen NMR-Parameter zeigen ein Tautomerengleichgewicht an, bei dem die CH-Protonen einem raschen Austausch unterworfen sind. Die vier Ylide 1 - 3 und 5 sind farblose, bis 200°C thermisch stabile Flüssigkeiten hoher Reaktivität. Nur im Tri(cyclopropyl)phosphonium-benzylid(4) ist die Reaktionsfähigkeit deutlich gemindert.
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  • 114
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3403-3411 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rasche thermische Öffnung und Schließung einer B-N-Bindung in 2-(Aminomethyl)benzolboronaten1)1H-, 11B- und 15N-NMR-Verschiebungen weisen darauf hin, daß die Titelverbindungen 1 - 6 (Tab. 1) eine intramolekulare B - N-Bindung ausbilden, die laut 1H- und 13C-NMR mit hoher Frequenz geöffnet (δ G c≠ = 40 bis 54 kJ/mol, Tab. 2) und wieder geschlossen wird.
    Notes: The Title compounds 1 to 6 (Table 1) are shown by 1H, 11B, and 15N NMR shifts to fom an intramolecular B - N bond which, according to 1N and 13C NMR, is frequently broken (δ G c≠ = 40 to 54 kJ/mol, Table 2) and re-formed.
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  • 115
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3395-3402 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2-Amino-3, 7-dihydro-7(β-D-ribofuranosyl)-4H-pyrrolo[2,3-d]pyrimidin-one - 7-Deazaguanosine - the Parent Compound of the Nucleoside Q2-Amino-3, 7-dihydro-7-(β-D-ribofuranosyl)-4H-pyrrolo[2,3-d]pyrimidin-4-one (1a), the parent compound o e rare nucleoside Q, has been synthesized using the pyrrolo [2,3d]pyrimidine derivative 3a11) which was available by phase transfer glycosylation. N-3 alkylation of 3a with chloromethyl isopropyl ether yields 3b, which reacted in a molten mixture of sodium hydride/acetamide to give 3c. Boron trichloride in methylene chloride removes the isopropoxymethyl as well as the benzyl groups at - 78°C simultaneously with formation of 4c. After ammonolysis of 4c 7-deazaguanosine &1par;la) was obtained. IN contrast to guanosine, la shows an anomalous weak Cotton effect implying an unusual flexibility of the nucleobase around the N-glycosylic bond.
    Notes: 2-Amino-3 7,dihydro-7(β-D-ribofuranosyl)4H-pyrrolo[2,3-d]pyrimidin-4-on (1a), die Stammverbindung des seltenen Nucleosids Q, wurde aus dem durch Phasentransferglycosylierung erhaltenen Pyrrolo [2,3-d]pyrimidin-Derivat 3a11) dargestellt. N-3-Alkylierung von 3a durch Chlormethyl-isopropyl-ether führt zu 3b und Austausch der 2-Methylthiogruppe in einer NaH/Acetamid-Schmelze zum geschützten 7-Desazaguanosin 3c. Bortrichlorid im Methylenchlorid entfernt bei - 78°C sowohl den Isopropoxymethylrest als auch die Benzylschutzgruppen unter Bildung von 4c. Nach dessen Ammonolyse erhält man 7-Desazaguanosin (1a), das im Gegensatz zu Guanosin einen anomal schwachen Cotton-Effekt zeigt, der auf starke konformative Beweglichkeit der Nucleobase an der N-glycosylischen Bindung hinweist.
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  • 116
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    Keywords: Chemistry ; Inorganic Chemistry
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    Topics: Chemistry and Pharmacology
    Notes: Heterocyclic β-Enamino Esters, 27 synthesis of Heterocondensed 6H-1,3-Oxazin-6-ones from N-Acylenamino Esters in the system Triphenylphosphane/Hexachloroethane/TriethylamineA simple ring closure reaction of N-acylenamino esters (1b, e,2,3a-f,7) in the system triphenyl-phosphane/hexachloroethane/triethylamine is described proceeding with high yields. Under chlorinating 3-ester cleavage heterocondensed 6H-1,3-oxazin-6-ones 4a -f, 5, 6b, e, 8, 9 are formed (UV, IR, NMR, MS).
    Additional Material: 3 Tab.
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  • 117
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3197-3208 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: anti-[4+4]-Dicyclopentadiene.The synthesis of anti-tricyclo[4.2.1.12,5]deca-3,7-diene(2) starting from the [4+6]-cycloadduct 4a derived from cyclopentadiene and tropon is described. Compound 2 decomposes at 200°C yielding a Mixture of cyclopentadiene (12), endo-[2+4]-dicyclopentadiene (13), anti-cis-[2+2]-dicyclopentadiene (14) and the cyclopentenyl-cyclopentadienes 15 and 16. The formation of a common diradical intermediate 11 in the decomposition of 2, 13 and 14 has been sought by means of the kinetic analyses of these reactions.
    Notes: Die Synthese des anti-tricyclo[4.2.1.12,5] deca-3,7-diens (2) aus dem [4+6]-Cycloaddukt 4a von Cyclopentadien und Tropon wird beschrieben. Bei Temperaturen um 200°C zerfällt 2 in ein Gemisch aus Cyclopentadien (12), endo-[2+4]-Dicyclopentadien (14) sowie den Cyclopentenyl-cyclopentadienen 15 und 16. Aufgrund der kinetischen Analyse dieser Reaktion sowie der Kinetik der Thermolysen von 13 und 14 wird geprüft, ob bei diesen Reaktionen ein gemeinsames Diradikal 11 durchlaufen wird.
    Additional Material: 10 Tab.
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  • 118
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3209-3219 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbene Complexes, CXVII1) [(Arylseleno)(diethylamino)carbene]pentacarbonylchromium(0)Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [CO)5CrCNEt2]BF4, (1) reacts with lithium arylselenolate, LiSeR, (3) [R = 4-C6H4CF3 (a), 4-C6H4Br (b) 4-C6H4F (c), C6H5 (d), 4-C6H4CH3 (e), 4-C6H4OCH3 (f), 1-C10H7 (g)] with addition of the selenolate anion to the carbyne carbon atom to give [(arylseleno)(diethylamino)carbene]pentacarbonylchromium(0), (CO)5Cr[C(SeR)NEt2], (4a - g). The complexes 4 were characterized by elemental analyses, spectroscopic data and in the case fo 4d additionally by an X-ray analysis. On heating in solution, 4a - g rearrange with CO-elimination and C,Cr-migration of SeR to the corresponding trans-(arylseleno)tetracarbonyl(diethylaminocarbyne)chromium complexes, trans-RSe(CO)4-CrCNEt2, (5a - g).
    Notes: Pentacarbonyl(diethylaminocarbin)chrom-tetrafluoroborat, [(CO)5CrCNEt2]BF4, (1) reagiert mit Lithium -arylselenolat, LiSeR, (3) [R = 4-C6H4CF3 (a), 4-C6H4Br (b) 4-C6H4 (c), C6H5 (d), 4-C6H4CH3 (e), 4-C6H4OCH3 (f), 1-C10H7 (g)] unter Addition des Selenolat-Anions an das Carbinkohlenstoffatom und Bildung von [Arylseleno)(diethylamino)carben]pentacarbonylchrom(0), (CO)5Cr[C(SeR)NEt2], (4a-g). Die Komplexe 4 wurden elementaranalytisch, spektroskopisch sowie im Fall von 4d zusätzlich durch eine Röntgenstrukturanalyse gesichert. Beim Erwärmen in Lösung lagern sich 4a-g unter CO-Abspaltung und C, Cr-Wanderung von SeR zu den entsprechenden trans-(Arylseleno)tetracarbonyl(diethylaminocarbin)chrom-Komplexen, trans-RSe(CO)4(CrCNEt2, (5a-g) um.
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  • 119
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3233-3241 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units for Oligosaccharides, XXXIII1) Synthesis of β-Glycosidically Linked Disaccharides of L-RhamnoseThe 2,3,4-tri-O-benzyl-α-L-rhamnopyranosyl bromide (4) is a reactive halogenose which in the presence of a silver silicate catalyst reacts with saccharides containing a reactive hydroxyl group to dive a β-glycosidically linked disaccharide with good selectivity. The three β(1 → 4) and β(1 → 3) linked disaccharides of L-rhamnose 6, 17, and 27 were made in this way with either L-rhamnose or D-galactose as hydroxyl group component. Subsequent deprotection gave the free disaccharides 8, 19 and 31 respectively.
    Notes: Das 2,34-Tri-O-benzyl-α-L-rhamnopyranosylbromid (4) ist eine reaktive Halogenose, die sich bei Gegenwart eines Silbersilicatkatalysators mit Sacchariden, die eine reaktive Hydroxylgruppe enthalten in guter Selektivität zu β-glycosidisch verknüpften Disacchariden umsetzen läßt. Die β(1 → 4)- und β(1 → 3)-verknüpften Disaccharide der L-Rhamnose 6, 17 und 27 mit L-Rhamnose und D-Galactose als Hydroxylkomponenten wurden auf diesem Wege dargestellt. Durch Entblockierung wurden die freien Disaccharide 8, 19 und 31 erhalten.
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  • 120
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3462-3466 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical Calculations of the CO - CO Repulsion Potential in Dinuclear Carbonyl ComplexesThe van der waals repulsion between CO molecules has been obtained by means of quantum mechanical ab initio calculations. The results show in a quantitative way how this interaction between parallel CO ligands on neighbouring metals counteracts bonding forces of single or double bonds between metal atoms.
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  • 121
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3467-3470 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Synthesis of Some Imino Pentafluorosulfanyl DerivativesFrom the reaction of SF5NSCl2 and Ag2O in nitromethane SF5NSO (1) is isolated. The also obtained 2 is probably formed form 1. In the presence of CsF 1 and Cl2 will give SF5NSOCIF (4)
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  • 122
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    Berichte der deutschen chemischen Gesellschaft 114 (1981) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 123
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3471-3484 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: β,β-Diacyl-enamines and -enoles, 9: Synthesis of Aminomethylene Derivatives of Open-Chain Active Methylene CompoundsThe reaction of a combination of primary or secondary aromatic or aliphatic amines with orthocarboxylic esters upon a variety of open-chain CH2-acidic molecules gives N-substituted aminoalkylidene derivatives. The method is highly recommended for methylene compounds activated by cyano, nitro, or phenylsulfonyl groups, whereas low yields are obtained, when highly enolized active methylene compounds are used. CH2-Acidic carboxylic acids give salts 10a-g.
    Notes: Die Reaktion primärer und sekundärer aromatischer oder aliphatischer Amine mit Orthocarbonsäureestern und offenkettigen CH2-aciden Verbindungen liefert N-substituierten Aminoalkylidenderivate; die Ausbeuten variieren stark mit der Natur der aktivierenden Gruppen. Die Methode kann für solche CH2-acide Moleküle empfohlen werden, welche durch eine nichtenolisierbare Gruppe (CN, NO2 oder PhSO2) aktiviert sind, während niedrige Ausbeute oder keine Umsetzung zu erwarten ist, wenn stark enolisierte methylenaktive Verbindungen eingesetzt werden. CH2-Acide Carbonsäuren liefern die Salze 10a-g.
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  • 124
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3499-3504 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphonium Hydrogendichlorides, II: Three Crystal Structures in ComparisonBy means of crystal structure analysis the compounds [(4-CH3OC6H4)(CH3)PCl2][ClHCl] (1), [(4-CH3OC6H4)PCl3][ClHCl] (2), and [(4-C2H5OC6H4)PCl3][ClHCl] (3) are confirmed as phosphonium hydrogendichlorides and the number of existing geometric parameters of hydrogen bonding between Cl atoms in crystals is substantially increased. The symmetric hydrogendichloride anions who the shortest distances Cl…Cl (312.1 pm in 2) and the largest distance of this kind (328.8 pm also in 2) is observed in the anion with the shortest Cl-H bond.
    Notes: Durch Kristallstrukturanalyse werden die Verbindungen [(4-CH3OC6H4)(CH3)PCl2][ClHCl] (1), [(4-CH3OC6H4)PCl3][ClHCl] (2) und [(4-C2H5OC6H4)PCl3][ClHCl] (3) als Phosphonium-hydrogendichloride bestätigt und die vorhandenen geometrischen Daten zur Wasserstoffbrückenbindung zwischen Cl-Atomen in Kristallen deutlich vermehrt. Die symmetrischen Hydrogendichlorid-Anionen zeigen die kürzesten Abstände Cl…Cl (312.1 pm in 2), und der längste Abstand dieser Art (328.8 pm ebenfalls in 2) wird beim Anion mit der kürzesten Bindung Cl—H beobachtet.
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  • 125
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3485-3498 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphonium Hydrogendichlorides, I Preparation and Properties of Phosphonium HydrogendichloridesPhosphonium hydrogendichlorides of general formula [RR′PCl2]+ [ClHCl]- (1) and [RPCl3]+ [ClHCl]- (5) as well as of the bifunctional type [P(R)Cl2—R′ — P(R)Cl2]2+ 2[ClHCl]- (6) are obtained by differnt methods as well crystallized compounds, which are extremely sensitive toward moisture. Their structures are confirmed by spectroscopic methods and conductivity measurements. - It is shown that the stability of the phosphonium ion is increased by the +M-effect of R, thus favouring the formation of [ClHCl]-. Some reactions of 1 and 5 are described. On loosing HCl, they give the corresponding Phosphoranes RR′PCl3 (3) and RPCl4 (4). This reaction is reversible. By reaction with HBr, 1 and 5 are converted into the bromophosphoranes RR′PBr3 (8) and RPBr4 (9), while phosphonium hydrogendibromides [P(R)Br2—R′—P(R)Br2]2+ 2[BrHBR]- (7) are obtained from 6.
    Notes: Phosphonium-hydrogendichloride der Zusammensetzung [RR′PCl2]+ [ClHCl]- (1) und [RPCl3]+ [ClHCl]- (5) bzw. des bifunktionellen Typs [P(R)Cl2—R′ — P(R)Cl2]2+ 2[ClHCl]- (6) erhält man als extrem hydrolyseempfindliche, gut kristallisierende Stoffe nach verschiedenen Methoden. Ihre Konstitution wird durch spektroskopische Untersuchungen und Leitfähigkeitsmessungen sichergestellt. - Es wird gezeigt, daß der +M-Effekt von R die Stabilität des Phosphonium-Ions erhöht und dadurch die Bildung von [ClHCl]- begünstigt. Einige Reaktionen von 1 und 5 werden beschrieben. So erhält man aus ihnen durch HCl-Entzug die entsprechenden Phosphorane RR′PCl3 (3) und RPCl4 (4). Diese Reaktion ist reversibel. Die Umsetzung mit HBr führt bei 1 und 5 zu den Bromphosphoranen RR′PBr3 (8) und RPBr4 (9), bei 6 hingegen zu Phosphonium-hydrogendibromiden [P(R)Br2—R′ — P(R)Br2]2+ 2[BrHBr]- (7).
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  • 126
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3505-3517 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Generation and Evidence of the Silaethene Me2Si=C(SiMe3)2: Thermolysis of (Me3Si)2(Me2XSi)CLi (X e. g. Hal, OR, SR)Thermal decomposition of Me2Xsi—CLi(SiMe3)2 (1,LiX) in deithyl ether at - 102 to 10°C leads under intramolecular LiX-elimination (X = Hal, TosO, Ph2POn, PhS) to 1,3-disilacyclobutane [Me2Si—C(SiMe3)2]2. (2). The reactive intermediate product is the silaethene Me2Si=C(SiMe3)2 (1) the intermediate formation of which has been established by the determination of reaction rates and order and also through chemical means by trapping 1 with 2, 3-dimethyl-1,3-butadiene. In the last case a [2 + 4]-cycloadduct as well as an ene-reaction product is formed. The speed of intramolecular LiX-elimination from 1,LiX decreases in the order: 1, LiOTos 〉 1,LiCL 〉 1,LiBr 〉 1,Lil 〉 1,Ph2PO4Li 〉 1,LiSPh ≍ 1,LiF 〉 1,Ph2PO2Li.
    Notes: Der thermische Zerfall von Me2XSi—CLi(SiMe3)2 (1,LiX) führt in Diethylether bei -102 bis 10°C unter intramolekularer LiX-Eliminierung (X = Hal, TosO, Ph2POn, PhS) zum 1,3-Disilacyclobutan [Me2Si—C(SiMe3)2]2 (2). Reaktives Zwischenprodukt ist das Silaethen Me2Si=C(SiMe3)2 (1), dessen intermediäre Bildung auf kinetischem Wege durch Bestimmung von Reaktionsordnung und -geschwindigkeit der Eliminierungsreaktion sowie auf chemischem Wege durch Abfangen von 1 mit 2,3-Dimethyl-1,3-butadien wahrscheinlich gemacht werden konnte. In letzterem Falle entsteht ein [2 + 4]-Cycloaddukt sowie ein En-Reaktionsprodukt. Die Geschwindigkeit der intramolekularen LiX-Eliminierung aus 1, LiX nimmt in der Richtung 1,LiOTos 〉 1,LiCL 〉 1,LiBr 〉 1,Lil 〉 1,Ph2PO4Li 〉 1,LiSPh ≍ 1,LiF 〉 1,Ph2PO2Li ab.
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3916-3921 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 34: Attempts to Synthesize DimethyltetrahedraneIrradiation of dimethyltricyclo[2.1.0.02,5]pentanone (2) and 4,6-dimethyl-α-pyrone (6) in solution leads to products which are derivatives of 1,3-dimethylcyclobutadiene (1). However, in an argon matrix photochemical excitation of 2 results in the formation of methylenecyclobutene 12 which is in a photoequilibrium with vinylallene 11. Under analogous conditions pyrone 6 yields photostable 1,3-dimethylcyclobutadiene (1) via the bicyclic form 9. It is possible that dimethyltetrahedrane (14) is an intermediate in the decarbonylation of 2 into 11 ⇌ 12.
    Notes: Bestrahlung von Dimethyltricyclo[2.1.0.02,5]pentanon (2) und 4,6-Dimethyl-α-pyron (6) in Lösung führt zu Produkten, die sich von 1,3-Dimethylcyclobutadien (1) ableiten. In einer Argon-Matrix dagegen entsteht aus 2 bei photochemischer Anregung das mit dem Methylencyclobuten 12 in einem Photogleichgewicht stehende Vinylallen 11. Unter analogen Bedingungen liefert Pyron 6 über die bicyclische Form 9 photostabiles Cyclobutadien 1. Es ist möglich, daß bei der Decarbonylierung von 2 in 11 ⇌ 12 Dimethyltetrahedran (14) als Zwischenprodukt auftritt.
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    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 33: Attempts to Synthesize DiphenyltetrahedraneCarbene 7, formed on photochemical or thermal excitation of (2,3-diphenyl-2-cyclopropen-1-yl)-diazomethane (6i), splits mostly into two acetylenes 8 und 9 instead of undergoing an intramolecular cycloaddition. Photolysis of the Masamune ketone 16 depending on the reaction conditions gives either p-terphenyl or a mixture of the two cyclooctatetraenes 18 und 19. The intermediate formation of tetrahedrane 10 would fit into the mechanistic picture of this fragmentation.
    Notes: Das bei photochemischer oder thermischer Anregung von (2,3-Diphenyl-2-cyclopropen-1-yl)diazomethan (6i) entstehende Carben 7 geht anstatt einer intramolekularen Cycloaddition bevorzugt eine Fragmentierung in die beiden Acetylene 8 und 9 ein. Bei Belichtung des Masamune- ketons 16 kann abhängig von den Reaktionsbedingungen entweder p-Terphenyl oder ein Gemisch der beiden Cyclooctatetraene 18 und 19 isoliert werden. Die intermediäre Ausbildung des Tetrahedrans 10 fügt sich gut in das mechanistische Bild ein.
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3959-3964 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 37: Further Attempts on Matrix Isolation of TetramethyltetrahedraneIrradiation of diketone 4 or cyclobutenedicarboxylic anhydride 6 in an argon matrix leads to tetramethylcyclopentadienone (5). On the contrary, the valence isomeric anhydride 7 gives cyclobutadiene 3 via lactone 8 which also can be prepared directly from α-pyrone 10. Tetramethyltetrahedrane (2) cannot be detected.
    Notes: Belichtung von Diketon 4 oder Cyclobutendicarbonsäureanhydrid 6 in einer Argonmatrix führt zu Tetramethylcyclopentadienon (5). Im Gegensatz dazu liefert das zu 6 valenzisomere Anhydrid 7 über das bicyclische Lacton 8, welches auch direkt aus dem α-Pyron 10 zugänglich ist, das Cyclobutadien 3. Tetramethyltetrahedran (2) ist nicht nachweisbar.
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2632-2639 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical Ions, 47. Note on the Structural Change during the One-Electron Oxidation of Bis(dimethylamino) DisulfideOn one-electron oxidation, (H3C)2N—S—S—N(CH3)2 considerably changes its structure: where as the neutral molecule according to the ionization band pattern of the PE spectrum displays N and S lone pairs perpendicular to each other, as ESR spectroscopic comparison suggests a planarized skeleton for the radical cation. INDO closed and open shell total energy hypersurfaces for the model compounds H2N—S—S—NH2 and support the discussion of the spectra.
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  • 131
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    Topics: Chemistry and Pharmacology
    Notes: Metal Alkyl and Aryl Compounds, XXVII. Preparation and Crystal structure of Bis(phenylethynyl)bis(N, N, N′,N′-tetramethylethylenediamine)magnesium, Mg(C≡CPh)2(tmeda)2The title compound has been prepared from bis(phenylethynyl)magnesium and N, N, N′,N′-tetramethylethylenediamine (tmeda) and investigated by X-ray diffraction methods (orthorhombic space group Cmcm, Z = 4, 696 (reflections, R = 0.049). It represents a first example of an organomagnesium compound with octahedral coordination of the central atom. The phenylethynyl ligands are in trans position.
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2644-2648 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Properties of B(OTeF5)3, Cs[B(OTeF5)4], and B(OTeF5)3·CH3CNInteraction of BCl3 with HOTeF5 affords B(OTeF5)3 (1) in quantitative yield. This compound reacts with CsOTeF5 to give Cs[B(OTeF5)4] (2) and with acetonitrile to form the adduct B(OTeF5)3·CH3CN (3). Thermolysis of 1 above 130°C leads to TeOF4 which cannot be isolated, but dimerizes to 4 and polymerizes to F5Te[OTeF4]nOTeF5.
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2649-2652 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Arginine Containing Peptides by Means of the Condensing Reagent Tris(dimethylamino)phosphane/Hexachloroethane/1-HydroxybenzotriazoleThe combination of the title reagents is well suited for building up protected oligopeptides contatining arginine.
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  • 134
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2653-2657 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XVI1) Five-Membered Tungsten-, Iron-, and Nickel-Containing MetallacycloalkanesThe metallacyclopentanes, (3a-c) [m = 1-3: LnM = h5-C5H5Ni (3a), h5-C5H5Fe (3b), h5-C5H5W (3c)] are obtained by reductive cycloelimination of the complexes Ln(OC)m-1M(X)PPh2[CH2]3Cl (2a-c) with sodium amalgam. 3b is also formed from h5-C5H5-(OC)2FeBr (1b) and PPh2[CH2]3MgCl. 3a,b insert SO2 into their M—C σ bond to give the cyclic S-sulfinates (4a,b).
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  • 135
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2947-2955 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Ethyl lyxo Purine Nucleoside CarboxamidesMethyl-2,3-O-isopropylidene lyxuronate (1a) was transformed into 1 α-chloro-1-desoxy-N-ethyl-2,3-O-isopropylidene lyxuronamide (2d). Direct molten state condensation of 2d with silylated 6-chloro- and 2,6-dichloropurine (4a, b) yields mainly N-ethyl-N-9-purinyl nucleoside carboxamides with α and β-configuration (5a, b and 6a, b). The structure of these compounds was established from 1H- and 13C-NMR data.
    Notes: Aus 2,3-O-Isopropylidenlyxuronsäure-methylester (1a) wurde was 1 α-Chlor-1-desoxy-N-ethyl-2,3-O-isopropylidenlyxuronamid (2d) hergestellt. Schmelzkondensation mit silyliertem 6-Chlor- und 2,6-Dichlorpurin (4a, b) lieferte im wesentlichen die N-9-verknüpften α- und β-konfigurierten N-Ethyl-lyxo-purinnucleosidcarboxamide 5a, b und 6a, b. Die Struktur der erhaltenen Nucleoside wurde 1H- und 13C-NMR-spektroskopisch gesichert.
    Additional Material: 4 Tab.
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  • 136
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2956-2970 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Acetyl Transition Metal Complexes with Phosphorus Ylides - a Further Example of Halide/Metalate AnalogyThe reaction of the acetyl metal complexes LnM—C(O)CH3 [LnM = C5H5(CO)2Fe, C5H5(CO)3Mo, C5H5(CO)2[P(CH3)3]Mo] with the phosphorus ylides (CH3)3P=CH2, C2H5(CH3)2P=CH2, (C2H5)3P=CHCH3 and (C4H9)3P=CH2 in the ratio 1:2 yields the corresponding acetyl-substituted ylides R3P=CR′C(O)CH3 3a-d (R = CH3, C2H5, n-C4H9; R′ = H, CH3) and phosphonium metalates [R4P][MLn]4a-d, 6a, b via heterolysis of the Fe—C-σ-bond and transylidation. With CH3C(O)Cl an analogous way of reaction is observed, which however can be repeated to give the diacetyl ylides R3P=C(COCH3)2 8a, b (R = Ch3, n-C4H9). The new compounds are characterized by spectroscopic methods (NMR, IR) and further reactions.
    Notes: Die Umsetzung der Acetyl-Metallkomplexe LnM—C(O)CH3 [LnM = C5H5(CO)2Fe, C5H5(CO)3Mo, C5H5(CO)2[P(CH3)3]Mo] mit den Phosphor-Yliden (CH3)3P=CH2, C2H5(CH3)2P=CH2, (C2H5)3P=CHCH3 und (C4H9)3P=CH2 im Verhältnis 1 : 2 liefert unter Heterolyse der Fe—C-σ-Bindung und Umylidierung die entsprechenden Acetyl-Ylide R3P=CR′C(O)CH3 3a-d (R = CH3, C2H5, n-C4H9; R′ = H, CH3) und Phosphonium-metallate [R4P][MLn] 4a-d, 6a, b. Mit CH3C(O)Cl wird ein analoger Reaktionsverlauf nachgewiesen, der sich aber wiederholen und zu Diacetyl-Yliden R3P=C(COCH3)2 8a, b (R = CH3, n-C4H9) führen kann. Die neuen Verbindungen werden spektroskopisch (NMR, IR) und durch Folgereaktionen charakterisiert.
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  • 137
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2971-2978 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Reactions of Cationic Chlorobis(phosphane)platinum(II) Complexes[(R3P)2Pt(Cl)H2O]+BF-4 (1) and (R3P)2Pt(Cl)OSO2CF3 (2) have been prepared by abstraction of chloride from cis-(R3P)2PtCl2 using tetrafluoroboric acid or trifluoromethanesulfonic acid, respectively. The protons of the aqua ligand in 1 form hydrogen bridges to the BF-4 anion. The acidic complexes 1 and 2 are useful starting materials for new platinum(II) complexes. HCO-3 neutralizes 1 to form the carbonato complex (Et3P)2PtO2CO (5). The heterogenous reaction of 2a with glycinate gives the cationic chelate complex (6). The coordinated water of 1 is easily substituted by other ligands, e. g. phosphanes. The chloro-bridged complexes [(R3P)2PtCl2Pt(PR3)2]2+ are formed by treatment of 1 or 2 with ethers.
    Notes: [(R3P)2Pt(Cl)H2O]+BF-4 (1) und (R3P)2Pt(Cl)OSO2CF3 (2) (R = Et, n-Bu, Ph; 2 PR3 = Ph2PCH2CH2PPh2) werden durch Chlorid-Abstraktion aus cis-(R3P)2PtCl2 mit Tetrafluoroborsäure bzw. Trifluormethansulfonsäure erhalten. Die Protonen des Aqua-Liganden von 1 bilden Wasserstoffbrücken zum BF-4-Anion aus. Die sauren Komplexe 1 und 2 lassen sich zur gezielten Synthese neuer Platin(II)-Komplexe nutzen. In heterogener Reaktion entsteht aus 2a mit Glycinat der kationische Chelatkomplex (6). Hydrogencarbonat neutralisiert 1 unter Bildung des Carbonatokomplexes (Et3P)2PtO2CO (5). Das koordinierte H2O in 1 läßt sich leicht durch andere Liganden, z. B. Phosphane, ersetzen. 1 und 2 bilden in Ethern die Chloro-verbrückten Dikationen [R3P)2PtCl2Pt(PR3)2]2+.
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  • 138
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3056-3062 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal-Boron Compounds, 13. Synthesis and Reactivity of some (Trimethylstannyl)boranes2)The preparation of some amino(trimethylstannyl)boranes and their chemical properties are described. With Me3SnLi (Me = CH3) as a reagent only the synthesis of Me3SnB(NR2)2 (1a, b), Me3SnBCl(NR2) (2a, b), and (Me3Sn)2BNR2 (3b) was achieved. The stannylboranes Me3SnB(NR2)2 show astonishing thermal stability. Their Sn—B bonds are broken by hydrogen, the halogens, and chalcogens as well as by alcohols. HCl cleaves the B—N bond.
    Notes: Die Darstellung einiger Amino(trimethylstannyl)borane und deren chemische Eigenschaften werden beschrieben. Mit Me3SnBCl(NR2) (1a, b) und Me3SnBCl(NR2) )2a, b) (Me3Sn)2BNR2 (3b). Die Stannylborane Me3SnB(NR2)2 sind thermisch erstaunlich stabil. Ihre Sn—B-Bindungen werden von Wasserstoff, den Halogenen, Chalcogenen und Alkoholen gespalten, während HCl die B—N-Bindung öffnet.
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  • 139
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3019-3023 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radicals by Oxidation of λ3-Phosphorin DerivativesThe first ESR spectra, which are observed when 2,4,6-trisubstituted λ3-phosphorins 1a-c are oxidized electrolytically or with dichlorodicyanoquinone (DDQ) in dichloromethane or tetracyanoethene (TCNE) in 1,2-dimethoxyethane, are not - as formerly supposed - those of λ3-phosphorin cation radicals 2a-c. They are secondary radicals of the λ4-phosphorin-type 3 which are produced from the very short living radicals 2 by addition of water from the solvent. Oxidation of 1c in dichloromethane/methanol with DDQ affords the 2,4,6-tri-tert-butyl-1-methoxy-λ4-phosphorin radical 3′c. Further oxidation of the radicals 3 produces the very stable radicals 7a-c, once again by addition of water and deprotonation. Their ESR spectra are very similar to those of the „neutral radicals“, described in the precedent paper, which are formed by the electrolytic oxidation of 1,1-dimethoxy-λ5-phosphorins in dichloromethane in the presence of lithium bromide or by oxidation with lead tetrabenzoate and which are the methyl esters of 7.
    Notes: Die ersten ESR-Spektren, die man bei der elektrolytischen Oxidation von 2,4,6-trisubstituierten λ3-Phosphorinen 1a-c, der Oxidation mit Dichlordicyanchinon (DDQ) in Dichlormethan oder der mit Tetracyanethen (TCNE) in 1,2-Dimethoxyethan beobachtet, sind nicht, wie früher angenommen, die der λ3-Phosphorin-Kationradikale 2a-c. Es sind die von Folgeradikalen vom λ4-Phosphorintyp 3, die aus den sehr kurzlebigen Radikalen 2 durch Addition von Wasser aus dem Lösungsmittel entstehen. Methanolzusatz zum Dichlormethan bei der Oxidation von 1c mit DDQ führt zum 2,4,6-Tri-tert-butyl-1-methoxy-λ4-phosphorin-Radikal 3′c. Bei weiterer Oxidation der Radikale 3 entstehen unter erneuter Addition von Wasser und Deprotonierung die sehr beständigen Radikale 7a-c. Ihre ESR-Spektren unterscheiden sich nur wenig von denen der in der vorstehenden Mitteilung beschriebenen „Neutralradikale“, die bei der elektrolytischen Oxidation aus 1,1-Dimethoxy-λ5-phosphorinen in Dichlormethan bei Anwesenheit von Lithiumbromid oder der Oxidation mit Bleitetrabenzoat entstehen und die den Methylestern von 7 entsprechen.
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  • 140
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3044-3055 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, 120. Tetraorganyldiboranes(4): Preparation and Stabilitytert-Butylation of B2(OCH3)4 by LiC(CH3)3 proceeds via [(CH3)3C](CH3O)B—B(OCH3)[C(CH3)3] (1) to give tri-tert-butylmethoxydiborane(4) (2). Tetraalkylation of B2(OCH3)4 is achieved by isopropyllithium; no reaction intermediates were found in this case. Al(C2H5)3 reacts with B2(OCH3)4 to give B2(C2H5)4 which is stable only below - 30°C. On the other hand the CH3O group in 2 is replacable by CH3, and the CH3O groups in 1 by ethyl groups. Thus, product control by steric factors is evident. - The thermal stability of tetraorganyldiboranes(4) is controlled by the steric screening of the boron atoms: tetraisopropyldiborane(4) decomposes slowly at room temperature, tetraethyldiborane(4) rapidly at - 20°C.
    Notes: Die tert-Butylierung von B2(OCH3)4 mit LiC(CH3)3 führt über die Stufe [(CH3)3C](CH3O)B—B-(OCH3)[C(CH3)3] (1) zu Tri-tert-butylmethoxydiboran(4) (2). Die Tetraalkylierung von B2(OCH3)4 gelingt mit Isopropyllithium; Isopropylmethoxydiboran(4)-Zwischenstufen sind nicht faßbar. Al(C2H5)3 reagiert mit B2(OCH3)4 zu dem nur unterhalb von - 30°C stabilen B2(C2H5)4. Die CH3O-Gruppe in 2 ist gegen eine CH3-Gruppe ersetzbar, die CH3O-Gruppen von 1 gegen Ethylgruppen. Produktkontrolle erfolgt somit durch sterische Effekte. - Die thermische Stabilität der Tetraorganyldiborane(4) wird von der sterischen Abschirmung der Boratome gesteuert: Tetraisopropyldiboran(4) zersetzt sich langsam bei Raumtemperatur, Tetraethyldiboran(4) rasch bei - 20°C.
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  • 141
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3024-3043 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, 119. Synthesis and Structure of Tris[bis(organylthio)boryl]aminesNMR data of Tris[bis(organylthio)boryl]amines, N[B(SR)2]3, prepared by two different routes, indicate chemically equivalent RS groups in solution. The rather weak screening at boron and nitrogen agrees with the competition of three boron atoms for the lone pair of electrons at nitrogen, e.g. weak BN-π-bonding. - The equivalence of the RS groups is lost in the solid state. One(RS)2B group in each of the compounds 1-4 is strongly twisted against the B3N plane, and following the series 1, 2, 4, and 3 the other two orient themselves more and more coplanarily to this plane. Accordingly, a relatively long BN bond (147-148 pm) is observed besides two shorter BN bonds (143-145 pm) in each of these compounds. This is experimental evidence for the dependence of the B—N distance from π-bond order and its angular dependence. In addition, the structures of the 1,3,2-dithiaborolan, the 1,3,2-benzodithiaborol, and the 1,3,2-dithiaborolene ring systems have been ascertained. Only the latter two posses planar rings. - Mass spectrometric fragmentation of the tris[bis(organylthio)boryl]amines proceeds with preferential retention of BN bonding. For instance, the molecular ion of 2 breaks apart by three successive eliminations of ethylene with formation of the radical cation of NB3S6+ (12), derived from a hitherto unknown tricyclic system.
    Notes: Tris[bis(organylthio)boryl]amine, N[B(SR)2]3, nach zwei verschiedenen Verfahren dargestellt, besitzen in Lösung nach NMR-Untersuchungen chemisch äquivalente RS-Gruppen. Die gefundene geringe Abschirmung des Bors und Stickstoffs steht in Übereinstimmung mit der Konkurrenz von drei Boratomen um das freie Elektronenpaar am Stickstoff, d. h. schwacher BN-π-Bindung. - Im festen Zustand der Verbindungen 1-4 ist dagegen jeweils eine der drei (RS)2B-Gruppen stark gegen die B3N-Ebene verdrillt, und in der Reihe 1, 2, 4 und 3 zunehmend stellen sich die beiden anderen koplanar zu dieser Ebene ein. Dementsprechend beobachtet man eine relativ lange (147-148 pm) neben zwei kürzeren BN-Bindungen (143-145 pm). Dies ist ein experimenteller Beleg für die Abhängigkeit des B—N-Abstands von der π-Bindungsordnung zwischen B und N und ihrer Winkelabhängigkeit. Zugleich wurde die Struktur des 1,3,2-Dithiaborolan-, des 1,3,2-Benzodithiaborol- und des 1,3,2-Dithiaborolen-Ringes ermittelt. Nur die beiden letztgenannten Heterocyclen besitzen ein planares Ringgerüst. Die massenspektrometrische Fragmentierung der Tris[bis(organylthio)boryl]amine verläuft bevorzugt unter Erhaltung der BN-Bindungen. Dabei zerfällt das Molekül-Ion von 2 vor allem unter sukzessiver Abspaltung von 3 mol Ethylen und Bildung des Radikal-Kations NB3S6+ (12), das sich von einem bisher unbekannten Tricyclus ableitet.
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  • 142
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3102-3114 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units for Oligosaccharides, XXX. New Efficient β-Glycoside Synthesis of Mannose Glycosides Syntheses of Mannose Containing OligosaccharidesA new method was developed for the stereo selective synthesis of oligosaccharides containing a β-linked mannose-unit which were hitherto not available by direct synthesis. The glycoside synthesis is promoted by a silversilicate-catalyst which was precipitated on aluminium oxide. The trisaccharides 20 and 31 (see german summary) and the tetrasaccharide 33 were synthesized, demonstrating the advantages offered by block synthesis.
    Notes: Es wird eine neue Methode zur selektiven Synthese von Oligosacchariden mit β-verknüpfter Mannose-Einheit entwickelt, für deren direkte Gewinnung es bisher kein Verfahren gab. Als Katalysator dient ein auf Al2O3 niedergeschlagenes Silbersilicat. Es werden die Trisaccharide β-D-Man-(1→4)α-D-Gal-(1→4)-L-Rha (20) und sowie das Tetrasaccharid 33 synthetisiert. Hierbei werden die Vorteile der Blocksynthese demonstriert.
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  • 143
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    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3063-3069 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Cyclic Carbodiphosphorane and an Open-chain Reference CompoundThe cyclic carbodiphosphorane 8 is prepared from bis(diphenylphosphino)methane (1) and 1,3-dibromopropane, via a diphosphonium salt 6 and a semiquaternary salt 7, through transylidation with salt-free trimethyl methylene phosphorane. The structure is established by 1H-, 13C-, 31P-NMR and mass spectrometry, as well as by X-ray diffraction. Reprotonation with anhydrous HCl regenerates the diphosphonium salt 6. With tetrahydrofuran-borane, 8 is converted into a 1:1-borane complex 9, with the BH3 acceptor attached to the double-ylide carbon bridge. Methylation with CH3I occurs in the same position (10). 1:1-complexes (11, 12) are also formed with dimethylzink and -cadmium. The products are probably dimeric and show a rapid CH3-exchange in solution. - The already known open-chain analogue CH3(C6H5)2P=C=P(C6H5)2CH3 (4) resembles 8 in many respects, including the molecular structure. In the coordination interaction with metals a metalation in the CH3-groups in strongly favoured, however, as it is again shown in the nickel complex 5.
    Notes: Aus Bis(diphenylphosphino)methan (1) und 1,3-Dibrompropan wird über ein Diphosphoniumsalz 6 und ein Semiquartärsalz 7 durch Umylidierung mit salzfreiem Trimethylmethylenphosphoran das cyclische Carbodiphosphoran 8 dargestellt. Der Strukturbeweis gelingt über 1H-, 13C-, 31P-NMR-und Massenspektrum sowie durch eine Röntgenbeugungsanalyse. Durch wasserfreien Chlorwasserstoff wird das Diphosphoniumsalz 6 zurückgebildet. Mit Tetrahydrofuran-Boran wird ein 1:1-Komplex 9 erhalten, der den BH3-Akzeptor am Doppelylid-Brückenkohlenstoffatom gebunden hat. In gleicher Position erfolgt die Methylierung mit Methyliodid (10). Mit Dimethylzink und -cadmium entstehen 1:1-Komplexe (11, 12) vermutlich dimerer Struktur, die in Lösung raschen CH3-Austausch zeigen. - Das schon bekannte offenkettige Analogon CH3(C6H5)2P=C=P(C6H5)2CH3 (4) gleicht in vielen Eigenschaften, einschließlich seiner Molekülstruktur, dem Heterocyclus 8 Bei der Komplexbildung mit Metallen erfolgt hier jedoch bevorzugt Eintritt in die CH3-Gruppen. Der Nickelkomplex 5 ist dafür ein charakteristisches Beispiel.
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  • 144
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    Chromatographia 14 (1981), S. 576-578 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Tortuosity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the obstructive factor γ and velocity was restudied. The dependence of the obstructive factor on velocity was verified. The effects of diffusion coefficient and particle-to-column diameter ratio on the obstructive factor-velocity relationship were investigated. The results are consistent with Hawkes' hypothesis that values of γ at low velocities are averages over tightly packed and loosely packed domains while at high velocities they are weighted in favour of the loosely packed domains where there is more flow.
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  • 145
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    Chromatographia 14 (1981), S. 648-652 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas-liquid adsorption ; Bulk solution ; Mixed stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the blending of some retention effects can make the resolution of complex mixtures on short classical columns as effective as on capillary columns.
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  • 146
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    Chromatographia 14 (1981), S. 699-703 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Aromatic hydrocarbons ; Water analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities of using headspace analysis of aromatic hydrocarbon traces in aqueous solutions with changing values of the partition coefficients are discussed. A variant of headspace analysis of the simplest aromatic hydrocarbon in natural and waste water is described. It involves two-step gaseous extraction of a sample in vessels of varying volume before and after the equilibrium phase is replaced with a pure gas (air or nitrogen). This method permits to analyse 5–50 ml water samples with benzene and toluene contents varying from the ppb to the ppm range within an error not exceeding 155. The analysis time is about 1.5 h. The presence of non-volatile organic or mineral substances does not influence the determination. This method is unsuitable to heterogeneous systems (aqueous oil emulsions): before carrying out the analysis for the hydrocarbon content these systems have to be homogenized first.
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  • 147
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open tubular (capillary) columns ; Glass columns ; Fused-silica columns ; Column testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Column characteristics affecting the chromatographic behavior of glass and siliceous glass (“fused silica”) capillary columns include the dimensional uniformity of the column, the physical and chemical characteristics of the column wall and the characteristics of the liquid phase. In the case of the coated column the uniformity and thickness of the liquid phase film are the most important criteria affecting column reproducibility. The paper discusses these factors and their influence on column performance.
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  • 148
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    Chromatographia 14 (1981), S. 203-211 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Quantitative analysis ; Copper oxide converter ; Inorganic gas analysis ; Determination of fluorine and oxygen ; Hydrocarbon analysis ; Wine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A review of past activities concerning selected industrial analytical problems is given. This includes the following question: preparation of pure gas mixtures to be used for calibration, catalytic conversion of ester and pyridin samples to carbon dioxide and a one-point calibration method using peak heights, both for quantitative analysis, analysis of gas mixtures containing fluorine and inorganic fluorine compounds and the determination of the oxygen and fluorine content of the sample, separation and identification of hydrocarbons in shale oil and petroleum fraction samples, and analysis of wine.
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  • 149
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    Chromatographia 14 (1981), S. 143-147 
    ISSN: 1612-1112
    Keywords: Capillary columns ; Gas chromatography ; Retention index ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention index of twenty different homologous series of esters have been determined experimentally on polar (Carbowax 1540) and non-polar (squalane) columns. General equations to calculate retention index have been established by statistical methods. The influence of the length and inductive effect of acid and alcohol chains and the relative position of the carboxylic group are discussed.
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  • 150
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    Chromatographia 14 (1981), S. 285-288 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Porous layer open tubular columns ; Kaolin as support ; Column performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PLOT columns have been prepared with kaolin as the liquid phase support. These columns show good efficiency with different stationary phases and good thermal stability with polar phases. The performance of columns is shown by the separation of various mixtures such as fatty acids, phenols and anilines which are of analytical importance.
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  • 151
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    Chromatographia 14 (1981), S. 39-40 
    ISSN: 1612-1112
    Keywords: Xylidine isomers ; Heteroaromatic liquid phases ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Nicotinic acid and 1H-benzotriazole appreciably resolved all the xylidine (dimethylaniline) isomers, while benzimidazole, nicotinamide and phthalimide can also separate all the isomers except 2,4- and 2,3-xylidines. The analyses were carried out on supports which were not treated with an alkali.
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  • 152
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    Chromatographia 14 (1981), S. 345-350 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica capillaries ; Glass capillaries ; Mixed gum phases ; Polarity and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mixed phases of Superox 20M and OV-1 can be coated homogeneously on the untreated wall of fused silica capillary columns. Excellent columns with regard to efficiency, inertness and thermal stability can be obtained. (CE〉95% and MAOT≥250°). The polarity and selectivity were ascertained with Rohrschneider-Reynolds probes and a capillary polarity test mixture. The analysis of an essential oil mixture illustrates the possibilities of mixed phases in practical capillary GC.
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  • 153
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Fused silica ; Contact angle ; Wettability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the systematic characterization of glass and the newly introduced fused silica and quartz capillary columns from surface wettability measurements. Common gas chromatographic stationary phases were used in capillary-rise measurements at temperatures up to 300°C. By construction of Zisman plots and using the Cassie equation, the relative surface concentrations of wettable and non-wettable groups were determined. By application of the Fowkes equation, the dispersion force component of the surface energy was investigated. The influence of various surface treatments such as leaching, silylation, and polymeric film formation are discussed. Wettability measurements were also used to evaluate the thermostability of various treated surfaces and to compare the surface properties of glass, quartz, and fused silica. The wettability of the surfaces with selected stationary phases as a function of temperature is also discussed.
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  • 154
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polycyclic aromatic hydrocarbons ; Retention index ; Average molecular polarizabilities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A significant correlation has been found between the retention indices of polycyclic aromatic hydrocarbons on non-polar stationary phases and the average molecular polarizabilities of the molecules separated on these phases. Equations have been derived for the determination of the average molecular polarizabilities, directly from the retention indices.
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  • 155
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    Chromatographia 14 (1981), S. 69-72 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polynuclear aromatic hydrocarbons ; Retention index ; Vapour pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention index of a planar polynuclear aromatic hydrocarbon on the GC phases OV-101, SE-52, and OV-17 is strictly related only to the boiling point, and less closely to the relative molecular mass. The very approximates relation with connectivity index ins only a consequence of the latter. On a nematic lqiuid crystal phase, a variation of activity coefficient, expressed in terms of a shape factor, also influences the retention of PAH.
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  • 156
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    Chromatographia 14 (1981), S. 269-276 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Detector performance ; Trace analysis ; Catalytic conversion ; Multidimensional gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Relationships are derived describing how the detection limit of a chromatographic system depends on the minimum detectable limit of the detector and the chromatographic parameters such as column length, efficiency, carrier gas flow rate and the capacity factor. Performance data of detectors developed in the last 25 years at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences are given and a few selected application examples are listed. These include trace analysis by preconcentration and by direct analysis and the utilization of multidimensional gas chromatography with two columns, two detectors, a 12-port valve, and a catalytic conversion reactor.
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  • 157
    ISSN: 1612-1112
    Keywords: Gas chromatography ; C1−C5 Hydrocarbons ; Dimethyl ether
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical GC method was developed which uses a single packed column consisting of three packings in series prepared with the following liquid phases: dimethyl sulfolane, propylene carbonate, and silver nitrate. This system provides satisfactory resolution of mixtures of C1−C5 hydrocarbons and dimethyl ether obtained when converting methanol to gasoline. Due to the high capacity of the column it is possible to inject larger sample amounts permitting trace analysis.
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  • 158
    ISSN: 1612-1112
    Keywords: Phthalides ; Umbelliferae ; Liquid-solid chromatography ; Gas chromatography ; Ligustilide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid-solid chromatographic pre-fractionation of naturally occurring phthalides has been developed. The LSC was carried out on a column of silica applying a 1–50% gradient elution of diethyl ether (containing 2% methanol) in pentane. The enrichment in the fractions led to better possibilities for a gas chromatographic separation and isolation allowing further studies by spectroscopic methods. Ligustilide may easily isomerize during GC as a result of ageing of the column.
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  • 159
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    Chromatographia 14 (1981), S. 601-602 
    ISSN: 1612-1112
    Keywords: Ethanolamines ; Ethylene glycols ; Direct separation ; Gas chromatography ; Short glass capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An effective and rapid GC separation of ethanolamines, even in the presence of ethylene glycols, using short glass capillary columns is developed. No preliminary derivatisation of the sample is necessary. The separation is completed in 6 minutes.
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  • 160
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    Chromatographia 14 (1981), S. 507-509 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace ; Phenol ; Urine ; Enzymatic hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method has been developed for the determination of phenol in urine in which the phenol conjugates are hydrolysed enzymatically and the liberated phenol is analysed by headspace chromatography. The results compare favourably with those obtained by the method of van Haaften and Sie in which acid hydrolysis is carried out in a heated GC precolumn. The enzymatic hydrolysis headspace technique appears to be very reliable and does not suffer from the disadvantages of precolumn acid hydrolysis.
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  • 161
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    Chromatographia 14 (1981), S. 421-424 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid sulfur ; McReynolds' constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The McReynolds' constants for liquid sulfur as a stationary phase in gas-liquid chromatography (GLC) are presented. A simple graphical method of pattern analysis is used to indicate the uniqueness of the sulfur column as compared with other stationary liquid phases characterized by McReynolds. The limitations of using a single factor (as polarity) for the basis for the selection of GLC columns is discussed.
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  • 162
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Kováts retention indices ; Propellants ; Solvents ; Aerosol packs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A gas chromatographic method is described by which a nearly complete separation of all commonly used propellants and solvents and their identification and determination can be achieved in one step. The separation is by simple adsorption chromatography on columns packed with Porapak-T with a temperature program 100–180°C at 10°C/min. Kováts' retention indices have been calculated for isothermal conditions at 150°C respectively 100°C for the propellants, at 180°C for the solvents. An exact identification of the propellants and solvents by means of the Kováts' indices is practicable even in complex mixtures.
    Notes: Zusammenfassung Es wird eine gas-chromatographische Methode angegeben, welche eine fast vollständige Auftrennung aller handelsüblichen Aerosol-Treibgase und Lösungsmittel und ihre Identifizierung und Bestimmung in einem Schritt gestatet. Die Trennung erfolgt durch reine Adsorptions-Chromatographie and Porapak T-Säulen bei 100–180°C mit einer Temperaturate von 10°C/min. Zur Bestimmung der Retentionsindices nach Kovats wurden die Treibgase isotherm bei 150°C bzw. 100°C, die Lösungsmittel bei 180°C aufgetrennt. Anhand der Kovats-Indices ist eine eindeutige Identifizierung der Treibgase und Lösungsmittel selbst in vielfältigen Gemischen möglich.
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  • 163
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    Journal of High Resolution Chromatography 4 (1981), S. 11-16 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; SCOT column ; Coating, liquid phase ; Single-step coating ; Phenols ; Phenolic acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A single-step coating method for the preparation of glass capillary SCOT columns is described. It is reproducible and less time-consuming than the well-known two-step coating procedures. Other methods attempted are discussed briefly. Both the flame ionization and electron capture detectors could be used in conjunction with temperature programming. The separations achieved with an “activity mixture”, phenols and phenolic acids, illustrate the resolution obtained. The columns are suitable for quantitative determinations and a comparison is made with a conventional packed column.
    Additional Material: 6 Ill.
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  • 164
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    Journal of High Resolution Chromatography 4 (1981), S. 151-155 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; XAD-2 resin ; Fungicide residues, determination in wine and grape juice ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fungicides Bupirimate, Fenarimol, and Vinclozolin were sprayed on Vines. The fruits were harvested 8 and 21 days after the final application and processed to juice and wine. The fungicide residues were determined by filtration of the samples throug XAD-2 after pH adjustment, elution with methylene chloride, and glass capillary gas chromatography with SE-30 as stationary phase. Residue values of the three compounds were reported before and after fermentation. The precision of the analytical method was established by spiking portuguese white wine and spanish grape juice with the three fungicides and Triadimefon. The recoveries were in the range 80%-100%, except for Vinclozolin.
    Additional Material: 3 Ill.
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  • 165
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    Journal of High Resolution Chromatography 4 (1981), S. 183-183 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; End-sealing technique for static coating ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 166
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    Journal of High Resolution Chromatography 4 (1981), S. 215-217 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Direct method for flavor evaluation ; Aromatic herbs analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple, quick method is described for GC head space evaluation of herbs and drugs. The proposed procedure consists of milling a weighed sample of a certain herb in a glass device like a Braun MXK coffee grinder, modified in such a way that a special gas-tight valve allows the direct sampling of the vapors. Glass capillary columns are used to analyze the head space volatiles. Some preliminary applications of the method are given.
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  • 167
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    Journal of High Resolution Chromatography 4 (1981), S. 232-232 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Static coating ; Sealing method ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 168
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    Journal of High Resolution Chromatography 4 (1981), S. 38-39 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Fused silica capillary column ; Activity ; Hydroxylated surfaces ; Dehydroxylated surfaces ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 169
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    Journal of High Resolution Chromatography 4 (1981), S. 346-347 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; WCOT-glass capillary ; Organophosphorus insecticides ; Pesticides ; Metabolites ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article considers the separation of 23 organophosphorus insecticides to which two metabolites have been added. The high resolution of the column permits detection of the Z and E isomers of three of these insecticides.
    Additional Material: 1 Ill.
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  • 170
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    Journal of High Resolution Chromatography 4 (1981), S. 393-397 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica ; Simultaneous detection ; Splitting capillary effluent ; Detection limit of 1 ppm Archlor 1254 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A state-of-the-art gas chromatographic system for automatic simultaneous detection of halogenated and normal hydrocarbons has been developed, which consists of a standard Hewlett-Packard 5880 with a fused silica capillary column, whose effluent is split between the standard flame ionization detector and a Tracor Hall electroconductivity detector. The system provedes excellent capillary chromatography results and high sensitivity for halogenated compounds (a detection limit of 1 ppm Archlor 1254 in fuel oil). Reliability has been provides in the daily analysis of complex environmental samples.Emergency response cleanup and the containment of hazardous chemical spills and chemical dump sites forces one to deal with samples that are very complex. The contain large numbers of naturally occurring organic compounds and varying types of organic pollutants. Capillary chromatographic techniques of gas chromatographic and gas chromatographic/mass spectrometric analyses are necessary to achieve the resolution required for the analysis of these samples.
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  • 171
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    Journal of High Resolution Chromatography 4 (1981), S. 523-524 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Split injection ; Injection time influence ; PAH ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 172
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    Journal of High Resolution Chromatography 4 (1981), S. 533-534 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; End-sealing method for static coating ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 173
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    Journal of High Resolution Chromatography 4 (1981), S. 580-581 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Coal gasification tar ; Boiling point distribution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 174
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    Journal of High Resolution Chromatography 4 (1981), S. 647-648 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Direct injection of silicone fluids method of choice for determining trace organic contaminants ; ≥ 1 ppm toluene determined ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 175
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    Journal of High Resolution Chromatography 4 (1981), S. 79-80 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Glass capillary columns ; Barium carbonate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 176
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    Journal of High Resolution Chromatography 4 (1981), S. 86-89 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Packed columns ; Multidimensional switching, MDSS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multidimensional switching system with two packed columns has been used for the analysis of volatiles. Use of a high-boiling solvent and the backflush mode permitted total resolution of the mixture discussed in a short analysis time.
    Additional Material: 4 Ill.
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  • 177
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    Journal of High Resolution Chromatography 4 (1981), S. 102-108 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Series-coupled columns with different stationary phases ; Independent temperature control of columns ; Constant mass flow rate ; Retention time expressions ; Theory ; Selectivity control ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique of controlling chromatographic selectivity by the adjustment of column temperatures in systems of series-coupled columns is investigated by means of a general model incorporating the effects of temperature and mobile phase compressibility. In a previous article the performance of series-coupled columns was investigated under conditions of constant overall pressure drop. The present paper, on the other hand, considers systems in which a constant mass flow rate is maintained at all temperatures. The expressions derived for the effective partition coefficient and the retention time are compared with those of the previous paper. The numerical results for two-column systems exhibit the same major trends as those for constant pressure drop. It is shown that the effective partition coefficient is slightly dependent on the mass flow rate.
    Additional Material: 12 Ill.
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  • 178
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    Journal of High Resolution Chromatography 4 (1981), S. 164-168 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Simultaneous detection with effluent splitter ; Element-specific detection ; Petroleum residues ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two glass capillary gas chromatographic systems were equipped with inert effluent splitters which allowed simultaneous data acquisition using nonspecific and element-specific detectors. Simultaneous detection was achieved using the nonspecific flame ionization detector (FID) and the Hall® electrolytic conductivity detector (HECD) operated in either the sulfur-or the nitrogen-specific mode. Typical application of the simultaneous detection system as applied to analysis of petroleum residues is briefly described. The Hall electrolytic conductivity detector can be made element specific for halogen-, sulfur-, or nitrogen-containing compounds. Simultaneous detection enhances the information yield from a single sample injection and proves to be a powerful complementary technique when used with computerized gas chromatography/mass spectrometry.
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  • 179
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    Journal of High Resolution Chromatography 4 (1981), S. 186-187 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Effluent splitter, preparation of ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 180
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    Journal of High Resolution Chromatography 4 (1981), S. 218-223 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Column preparation ; “Split” vs. “on-column” injection ; Amino acid analysis, quantitative 10 ng level ; Average relative standard deviation 1% ; Fish muscle protein analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A carefully Standardized technique is described for the preparation of glass capillary columns which can be used successfully for routine quantitative amino acid analysis. Comparison is made between two different modes of sample injection. Preliminary quantitative results from “split” injection and “on-column” injection techniques are evaluated statistically and it is concluded that the “on-column” system is a prerequisite for quantitative amino acid analysis by glass capillary gas chromatography. An analysis of fish muscle protein hydrolyzate illustrates an application of this technique and results are compared with those from a packed column analysis.
    Additional Material: 4 Ill.
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  • 181
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    Journal of High Resolution Chromatography 4 (1981), S. 437-443 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Gas chromatographic profiles ; n-Butylboronates ; Alkyl-oximes ; Primary prostaglandins ; 6-Keto prostaglandin F1α ; Thromboxane B2 ; Isomers of prostaglandin F1α ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work describes the use of glass capillary columns (GCC) in the rapid concurrent analysis of primary prostaglandins (PGs) (e. g. PGE2, PGE2, PGF2α) and other functionally significant metabolites of arachidonic acid (AA) such as TXB2 and 6-keto PGF1α. The use of a new multistep mixed derivatization approach that generates the methyl esters of n-butylboronate, pentafluorobenzyloxime, trimethylsilyl ether derivatives of these compounds remarkably simplifies the GC profiling of the three main pathways of AA metabolism (PGs, thromboxane, and prostacyclin). Furthermore, isomeric species giving very similar or identical mass spectral patterns can be easily identified by their relative retention times on high efficiency capillary columns.
    Additional Material: 6 Ill.
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  • 182
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    Journal of High Resolution Chromatography 4 (1981), S. 495-499 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary column, fused silica ; Mass spectrometry ; Interface, direct coupling ; On-column injection ; Aflatoxin B1 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel fused silica capillary GC/MS direct coupling is described which ensures quantitative transfer of sample from the point of injection to the ion source of a mass spectrometer without contacting any surfaces other than the column wall. This device permits GC analysis of highly labile substances. Aflatoxin B1, previously considered unassayable by GC, can now be determined by GC/MS.
    Additional Material: 8 Ill.
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  • 183
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    Journal of High Resolution Chromatography 4 (1981), S. 333-336 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Rapid analysis ; On-line analysis ; Low molecular weight hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rapid analysis is important for on-line chromatography. Gaseous or vaporized samples have been injected via heated gas sampling valves of less than 500 μl dead volume. The critical sampling and split problems could be solved by temperature programming. The general analysis described could be successfully used inter alia in scouting reactions.
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  • 184
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    Journal of High Resolution Chromatography 4 (1981), S. 409-410 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Micro-HPLC ; Capillary columns, preparation ; Optical monitor ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 185
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    Journal of High Resolution Chromatography 4 (1981), S. 549-552 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary column ; Optically active stationary phase ; Amino acids, enantiomeric derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An enantiomeric mixture of amino acids is derivatized to give the respective N(O)-perfluoroacyl alkyl esters which can be resolved directly by gas chromatography on a Chirasil-Val capillary column. The retention times, resolution numbers, and elution order are reported.
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  • 186
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    Journal of High Resolution Chromatography 4 (1981), S. 578-579 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Crosslinked silicones ; Peroxide-initiated vulcanization ; Trifluoropylsilicone ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 187
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 583-584 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; 10% CuCl in stationary phase greatly improves resolution of high-boiling olefins (up to 190°C) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 188
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 641-643 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary column ; On-column injection ; Discrimination ; Criteria given for precise sampling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 189
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica ; Split injection ; Splitless injection ; Polynuclear aromatic hydrocarbons, quantitation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 190
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 553-556 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Carbohydrate enantiomer separation ; New chiral stationary phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New chiral polymers have been prepared by conversion of cyano groups of polysiloxanes XE-60 and OV-225 into carboxylic groups and subsequent coupling to give the respective S-valine-R-α-phenyl-ethyl amide. In contrast to the corresponding stationary phases with S-α-phenylethyl amide groups, which have been used for the resoultion of trifluoroacetylated hexose derivatives, the new phase show high enantioselectivity for pentose and 6-deoxyhexose derivatives.
    Additional Material: 2 Ill.
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  • 191
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 603-611 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica ; Gas chromatograph/mass spectrometer/data system ; Dynamic headspace analysis ; Focused cryogenic trapping ; Pyrolysis ; Polymers ; Adhesives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Focused cryogenic trapping has been used to maximize the high resolution capabilities of fused silica capillary columns during dynamic headspace and pyrolytic polymer analyses. Mass spectrometric detection with data system recording/processing provide sensitive, selective, and rapid results. The techniques described herein demonstrate the power of both dynamic headspace and pyrolytic analyses for troubleshooting applications with complex industrial polymer products.
    Additional Material: 11 Ill.
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  • 192
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 188-190 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Helium ionization detector (HID) ; Vinyl chloride ; Sulfur gases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 193
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 203-208 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary column ; Split injection, vaporizing ; Glass wool as evaporation aid in split injector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been reported that glass wool packed tightly into the glass liner of a vaporizing injector used in the splitting mode considerably reduces the standard deviation of the results obtained, because of improved evaporation of the sample prior to reaching the split point at the capillary column entrance. This finding could not be reproduced on using the same sample composition as reported in the literature, i.e. methanol/2-ethyl-1-hexanol (1:1).The standard deviations obtained were between 3 and 10% (depending on the conditions selected) and were not influenced significantly by the introduction of glass wool.The peak area ratio (methanol/2-ethyl-1-hexanol) was found to depend on a number of parameters, such as: injector temperature; glass liner internal diameter; syringe handling technique; the relative position of the syringe needle exit and capillary column entrance; the sample volume injected; and the packing of the glass liner. Generally, the area ratio deviated further from the correct one (determined by cold on-column sampling) when the glass liner was packed with glass wool.On the basis of the results, it is speculated that either a complete evaporation of the sample should be achieved (which appears to be impossible under the conditions we used) or, alternatively, the sample should be given the least possible opportunity to evaporate, thus allowing it to enter the column in the form of droplets. The results were worse in terms of precision and accuracy the greater the partition of sample components between the liquid (droplet) and vapor phase. It is concluded that the use of evaporation aids such as glass wool cannot be generally recommended.
    Additional Material: 5 Tab.
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  • 194
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 411-412 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica ; Chemical bonding - cross-linking ; Apolar columns ; Preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 195
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 49-53 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Glass capillary ; Routine analysis of C1-C6 carboxylic acids ; Animal wastes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The C1 -C6 fatty acids present in various types of heterogeneous animal wastes were isolated by steam distillation and determined as benzyl esters by high resolution gas chromatography. Glass capillary columns, deactivated with barium carbonate and coated with UCON HB 5100, allowed the analysis of benzyl formate, acetate, propionate, isobutyrate, butyrate, isovalerate, valerate, and caproate in less than 20 minutes. Recovery tests, performed on more than 50 different samples, indicated a benzylation yield and an overall efficiency higher than 99%, with a standard deviation of 2.6% (C5) to 6.0% (C1). The absolute detection limit ranged from 0.3 picomole (caproic acid) to 1.0 picomole (formic acid).
    Additional Material: 3 Ill.
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  • 196
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 323-327 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Deactivation by colloidal aqueous silica plus BTPPC plus Carbowax 1000 ; Use for adsorption-sensitive solutes fails with basic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillary columns have been prepared without acidic additive in the stationary phase, from which free organic acids elute as sharp and symmetrical peaks. The required surface in the borosilicate glass capillary was generated by a combination of leaching with aqueous HCl and deposition of colloidal silica particles; it can be coated with stationary phases have a broad range of polarity. Aqueous samples containing free organic acids can also be analyzed in such columns in an isothermal mode.
    Additional Material: 6 Ill.
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  • 197
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 317-322 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Series-coupled columns with different stationary phases ; Independent temperature control of columns ; Constant mass flow and constant pressure drop ; Temperature dependence of viscosity coefficient ; Retention time expressions ; Theory ; Selectivity control ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A previously established model of a system of series-coupled columns, incorporating the effects of temperature and mobile phase compressibility, is generalized to take the temperature dependence of the mobile phase viscosity coefficient into account. Expressions are reported for the linear flow velocity, the effective partition coefficient, and the retention time for both the case of constant mass flow rate and that of constant overall pressure drop. Numerical results indicate that the temperature dependence of the viscosity coefficient affects the retention time and pressure drop while the effective mass distribution coefficient remains essentially unchanged.
    Additional Material: 4 Ill.
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  • 198
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 344-345 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass/fused silica ; Gas phase deactivation reaction ; Readily adjustable thickness of silicon layers for deactivation ; Wettability for any known stationary phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 199
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 385-392 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Theory of band broadening ; Regression methods in column evaluation abt concept ; Possible aid in assessing coating efficiency ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the approach to the developement of a practical procedure for the evaluation of band broadening properties of gas capillary columns, the expression for the variance of a solute band is cast in a dimensionless form. This expression supplies the basis for a valid bench mark for column evaluation. Experimental results demonstrate the applicability of the method.
    Additional Material: 7 Ill.
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  • 200
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 406-408 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary ; Effluent splitter, fused silica ; Efficient ; Inert ; Minimum dead volume ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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