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  • 1
    Electronic Resource
    Electronic Resource
    Synthesen von α-Bromisothiocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1948-1955 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of α-BromoisothiocyanatesSecondary isothiocyanates (1j-q) and primary isothiocyanates R—CH2 - NCS with an activating group R (1f, g) react with N-bromosuccinimide (NBS) to form α-bromoisothiocyanates 2 in high yields. The not activated primary isothiocyanate 1c slowly forms the stable α,α-dibromoisothiocyanate 10. In the presence of β-hydrogens some of the α-bromoisothiocyanates 2 eliminate HBr spontaneously, and secondary products may be formed. The α-bromination of isothiocyanates is a radical reaction following a Goldfinger mechanism.
    Notes: Sekundäre Isothiocyanate (1j-q) und primäre Isothiocyanate R-CH2 - NCS mit einer aktivierenden Gruppe R (1f, g) lassen sich mit N-Bromsuccinimid (NBS) in hohen Ausbeuten zu den α-Bromisothiocyanaten 2 bromieren. Das nicht aktivierte Isothiocyanat 1c reagiert langsam zum stabilen α,α-Dibromisothiocyanat 10. Bei Anwesenheit von β-Wasserstoffatomen spalten die α-Bromisothiocyanate 2 zum Teil spontan HBr ab, und es entstehen Folgeprodukte. Die α-Bromierung der Isothiocyanate erfolgt radikalisch nach einem Goldfinger-Mechanismus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120605
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  • 2
    Electronic Resource
    Electronic Resource
    Reaktionen von α-Bromisothiocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1956-1972 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of α-Bromoisothiocyanatesα-Bromoisothiocyanates 11.2) with a hydrogen in β-position eliminate HBr to form vinyl isothiocyanates (products 2, 3, 5). Water hydrolyzes 1 to carbonyl compounds (7a). Hard nucleophiles attack 1 at the α-C-atom with substitution of bromine (products 8-12), but soft nucleophiles add to the C-atom of the isothiocyanato group (products 14, 19). Compounds 1 react with bifunctional nucleophiles to heterocycles (e. g. products 16, 21). The chemical properties of the classes of compounds, part of which are new, e. g. the geminal diisothiocyanates 12, are examined. The alkylidene thiourea 14f shows hindered rotation around the amide-CS—N bond (ΔG≠394 = 82.8 kJmol-1) and around the C=N double bond (ΔG≠244 = 52.9 kJmol-1).
    Notes: α-Bromisothiocyanate 1 mit einem β-Wasserstoff spalten HBr zu Vinylisothiocyanaten ab (Produkte 2, 3, 5). Wasser hydrolysiert 1 zu Carbonylverbindungen (7a). Harte Nucleophile greifen 1 am α-C-Atom unter Substitution des Broms an (Produkte 8-12), weiche Nucleophile lagern sich dagegen an das C-Atom der Isothiocyanatgruppe an (Produkte 14, 19). Verbindungen 1 reagieren mit bifunktionellen Nucleophilen zu Heterocyclen (z. B. Produkte 16, 21). Die chemischen Eigenschaften der z. T. neuen Verbindungsklassen, z. B. der geminalen Diisothiocyanate 12, werden untersucht. Der Alkylidenthioharnstoff 14f zeigt behinderte Rotation um die Amid Cs—N-Bindung (ΔG≠394 = 82.8 kJmol-1) und um die C=N-Doppelbindung (ΔG≠244 = 52.9 kJmol-1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120606
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  • 3
    Electronic Resource
    Electronic Resource
    Darstellung von Vinylisothiocyanaten durch Schwefel-Eliminierung aus Δ3-1,3-Thiazolin-2-thionen (1978)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 3750-3753 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Vinyl Isothiocyanates by Sulfur Elimination from Δ3-1,3-Thiazoline-2-thionesThe Δ3-thiazoline-2-thiones 1a, b eliminate sulfur thermally, photolytically, or with trimethyl phosphite to give the vinyl isothiocyanates 2a, b. Compound 2a forms a thiosemicarbazone 3a which cyclizes thermally to 4. This easily splits off the isopropyl group to give the triazolinethione 5. The vinyl isothiocyanate 2b rearranges thermally or photochemically to the isoquinoline-1-thione 7 which itself is photolabile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19781111122
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  • 4
    Electronic Resource
    Electronic Resource
    α-Bromierung von 2-Adamantylisothiocyanat und Folgereaktionen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1102-1109 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Bromination of 2-Adamantyl Isothiocyanate and Subsequent ReactionsOn irradiation of 2-adamantyl isothiocyanate (6) in the presence of N-bromosuccinimide 2-bromo-2-adamantyl isothiocyanate (5) is formed, which reacts with nucleophiles with substitution of bromine or addition to the isothiocyanato group with subsequent or simultaneous elimination of HBr. With thiophenol compound 10 is formed, with amines one gets unsaturated thioureas. e. g. 11 and 12, with hydrazines or hydroxylamines heterocycles, e. g. 14, 17, 18, and with NaN3 the heterocycle 19, which easily decomposes to the cyanoimide 20 when heated. Compound 5 reacts with NH4SCN to the geminal diisothiocyanate 15, which adds amines only to one isothiocyanate group with elimination of HSCN giving, for instance, 12 + 16.
    Notes: 2-Adamantylisothiocyanat (6) reagiert mit N-Bromsuccinimid photochemisch zum 2-Brom-2-adamantylisothiocyanat (5), welches sich mit Nucleophilen unter Substitution des Broms oder unter Addition an die Isothiocyanat-Gruppe mit anschließender oder gleichzeitiger Eliminierung von HBr umsetzt. Mit Thiophenol erhält man 10, mit Aminen ungesättigte Thioharnstoffe der Art 11 und 12, mit Hydrazinen oder Hydroxylaminen Heterocyclen, z. B. 14, 17, 18, und mit NaN3 den Heterocyclus 19, der thermisch leicht zum Cyanimid 20 zerfällt. Mit NH4SCN reagiert 5 zum geminalen Diisothiocyanat 15, welches mit Aminen unter Addition an eine NCS-Gruppe und Eliminierung von HSCN, z. B. zu 12 + 16 reagiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120406
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