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  • 11
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 87. Suche nach alternativen Wegen zum Tetra-tert-butyltetrahedran; Synthese sterisch überladener Verbindungen (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 153-160 
    Details
    ISSN: 0947-3440
    Keywords: Valence isomerization ; Diazoketons ; Cycloadditions ; Steric hindrance ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 87. - Search for Alternative Routes to Tetra-tert-butyltetrahedrane; Synthesis of Sterically Overcrowded MoleculesKetene 3 can be isomerized to triclopentanone 2 by treatment with silica gel. Thus, the yield of tetrahedrane 5, which is formed upon irradiation of 2, has been improved. On the other hand, diazoketone 10 cannot be used as a precursor for 2. This failure is due to steric hindrance. For the same reason cyclobutadiene 4 is a very poor candidate for Diels-Alder cycloadditions.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950121
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  • 12
    Electronic Resource
    Electronic Resource
    Notiz zu Einer Arbeit von R. M. Lagidse und A. D. Petrow Über die Alkylierung von Benzol mit Butindiol-(1.4)-Diacetat (1957)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 90 (1957), S. 2949-2950 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19570901235
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  • 13
    Electronic Resource
    Electronic Resource
    Hetero-π-Systeme, 7. Silabenzol (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2337-2350 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hetero-π-Systems, 7. SilabenzeneFlash pyrolysis of silacyclohexadiene derivatives 5k, 5m, and 7b yields silabenzene (1), which can be isolated in an argon matrix at 10 K. 1 exhibits characteristic IR and UV spectra. By photoexcitation a mutual interconversion between silabenzene (1) and dewarsilabenzene (2) can be achieved.
    Notes: Durch Kurzzeitpyrolyse der drei Silacyclohexadien-Derivate 5k, 5m und 7b läßt sich Silabenzol (1) erzeugen und in einer Argonmatrix bei 10 K isolieren. 1 zeichnet sich durch charakteristische IR- und UV-Spektren aus. Mittels photochemischer Anregung ist eine gegenseitige Umwandlung zwischen Silabenzol (1) und Dewarsilabenzol (2) zu erreichen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170707
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  • 14
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 50. Ungewöhnliche Dimerisierung von Tri-tert-bytylcyclobutadien (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 409-412 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 50. Unusual Dimerization of Tri-tert-butylcyclobutadieneThe dimerization of tri-tert-butylcyclobutadiene (2) does not lead to syn-dimer 4 but  -  as shown by a X-ray structure determination  -  via a two-step process to the unexpected anti-configurated dimer 5.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180141
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  • 15
    Electronic Resource
    Electronic Resource
    Methoxy- and Aminoisocyanate (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 745-748 
    Details
    ISSN: 0009-2940
    Keywords: Flash Pyrolysis ; Matrix IR spectroscopy ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methoxy- und AminoisocyanatMethoxyisocyanat (1) kann durch Photolyse von Azidoameisensäure-methylester (3) oder Pyrolyse von N-Methoxycarbonyl-O-methylhydroxylamin (4) dargestellt werden. Aminoisocyanat (2) ist auf ähnliche Weise durch Photolyse von Carbamoylazid (12) und Pyrolyse von Carbazinsäure-methylester (13) oder 3,4-Diaminofurazan (14) zugänglich. Die IR-Spektren von 1 und 2, aufgenommen in einer Argon-Matrix bei 10 K, werden diskutiert.
    Notes: Methoxyisocyanate (1) can be prepared by photolysis of methyl azidoformate (3) or pyrolysis of N-methoxycarbonyl-O-methyl-hydroxylamine (4). Aminoisocyanate (2) is similarly formed on photolysis of carbamoyl azide (12) and pyrolysis of either methyl carbazate (13) or 3,4-diaminofurazan (14). The infrared spectra of 1 and 2 in an argon matrix at 10 K have been measured, and some of their properties are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220423
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  • 16
    Electronic Resource
    Electronic Resource
    Hetero-π-Systeme, 17: Aminosilylen (Aminosilandiyl) (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2403-2405 
    Details
    ISSN: 0009-2940
    Keywords: Hydrogen capture ; Matrix isolation ; Photochemistry ; Aminosilylene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hetero π-Systems, 17.  -  Aminosilylen (Aminosilanediyl)Aminosilylene can be prepared by 254-nm photolysis of silyl azide isolated in an argon matrix at 12 K. Subsequent irradiation with wavelengths 〉 300 nm yields silaisonitrile (3) and molecular hydrogen. This reaction may be reversed with 254-nm light.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891221231
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  • 17
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl-substituierter Cyclobutadiene und Tetrahedrane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 191-200 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Valence isomerization ; „Corset effect“ ; limits of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 79[1].  -  Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and TetrahedranesThe cyclobutadienes 2b, d as well as the corresponding tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13C—NMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butyltetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of tetrahedrane 3d with LiAlH4 in boiling THF leads to tetrahedrane 3e, which is much less stable than all previously known tetrahedrane derivatives.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270127
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  • 18
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 38: Tetra-tert-butyltetrahedran (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3965-3987 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 38: Tetra-tert-butyltetrahedraneThe first synthesis of a tetrahedrane stabilized by sterically demanding substituents is described. Tetrahedrane 37 originates from irradiation of tetra-tert-butylcyclopentadienone (26), which can be prepared starting from the already known cyclopentadienone 5. It forms colourless stable crystals. At 135°C tetrahedrane 37 valenceisomerizes to the corresponding cyclobutadiene 36. This reaction can be reversed photochemically.
    Notes: Es wird über die erste Synthese eines durch sterisch anspruchsvolle Substituenten stabilisierten Tetrahedrans berichtet. Das Tetra-tert-butyl-Derivat 37 entsteht bei der Belichtung von Tetra-tert-butylcyclopentadienon (26), welches seinerseits aus dem bereits bekannten Cyclopentadienon 5 aufgebaut werden kann. Das Tetrahedran 37 bildet farblose beständige Kristalle und geht bei 135°C in das entsprechende Cyclobutadien 36 über. Diese Valenzisomerisierung ist photochemisch umkehrbar.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141218
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  • 19
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 36: Versuche zur Darstellung von Tetramethyltetrahedran aus alicyclischen Vorstufen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3935-3958 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 36: Attempts to Synthesize Tetramethyltetrahedrane from Alicyclic PrecursorsSynthesis as well as the thermal and photochemical behaviour of compounds with ring skeletons 1 and 3 are described. Whereas the former are accessible by standard procedures the approach to the bicyclobutane derivatives is based on the isomerization of diester 1b into valence isomer 3b which can be achieved in good yield by SiO2, or Al2O3. There are only minor differences in the cleavage of the pairs 1/3 provoked by heating or photochemical excitation. This is even true for irradiations in argon at 10 K. Under those conditions anhydrides la and 3a form the same charge transfer complex 28a between tetramethylcyclobutadiene and phthalic anhydride. A direct detection of tetramethyltetrahedrane using these means is not possible.
    Notes: Synthese sowie thermisches und photochemisches Verhalten von Verbindungen mit den Ringgerüsten 1 bzw. 3 werden beschrieben. Während erstere nach Standardverfahren zugänglich sind, fußt der präparative Zugang der Bicyclobutan-Derivate auf der mit SiO2 oder Al2O3 in guter Ausbeute erreichbaren Isomerisierung von Diester 1b zum Valenzisomeren 3b. Bei der durch Erhitzen oder Photoanregung bewirkten Spaltung unterscheiden sich die Paare 1/3 nur geringfügig. Dies gilt selbst für Bestrahlungen in Argon bei 10 K. Unter diesen Bedingungen liefern die Anhydride la und 3a den gleichen Charge-transfer-Komplex 28a zwischen Tetramethylcyclobutadien und Phthalsäureanhydrid. Ein direkter Nachweis von Tetramethyltetrahedran gelingt auf diese Weise nicht.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141216
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  • 20
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 35: Versuche zur Darstellung von Tetramethyltetrahedran aus heterocyclischen Vorstufen (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3922-3934 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 35: Attempts to Synthesize Tetramethyltetrahedrane from Heterocyclic PrecursorsBy comparison of the photochemical behaviour of heterocycles 1 and 3 under matrix conditions it should be possible to prove the existence of tetramethyltetrahedrane (5). Whereas irradiation of 1 leads to the charge-transfer complex 32, the same is not true for 3 in spite of the fact that after warm-up the products, namely dimer 31 of tetramethylcyclobutadiene (4) and tetramethyl-pyridazine (2), are identical in both series. Intermediate formation of tetramethyltetrahedrane is one but not the only way for mechanistic interpretation of the experimental findings.
    Notes: Durch Vergleich des photochemischen Verhaltens der Heterocyclen 1 und 3 unter Matrixbedingungen wird versucht, die Existenz von Tetramethyltetrahedran (5) zu beweisen. Während Belichtung von 1 glatt zum Charge-transfer-Komplex 32 führt, gilt dies für 3 nicht, obwohl nach dem Auftauen die Produkte, nämlich Dimeres 31 von Tetramethylcyclobutadien (4) und Tetramethyl-pyridazin (2), dieselben sind. Intermediäres Auftreten von Tetramethyltetrahedran ist ein, aber nicht der einzige, Weg zur mechanistischen Deutung der experimentellen Befunde.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811141215
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