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  • Chemistry  (12)
  • 1-Hydroxy-2-vinylinden-3-ones  (1)
  • Conformational energy  (1)
  • 1
    ISSN: 1434-4475
    Keywords: 2-Alkylidene-1,3-indandiones ; Autoxidation ; 1-Hydroxy-2-vinylinden-3-ones ; Photoenolisation ; 2-Vinyl-1,3-indandion-2-yl radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title compound,1, slowly decomposes in solution by autodixation, especially in daylight. The chemism of this photoinduced autoxidation has been investigated. Upon irradiation1 passes to the brick red isolable dienol2. The quantum yield is 0.3 at 313 nm in methanol. In solution an equilibrium is set up within several minutes between2 and the colorless deconjugated3. Unpolar or moderately polar solvents shift the equilibrium completely to3, whereas in highly polar solvents2 and3 coexist. In the dark the equilibrium1⇄2 (ca. 50∶1 in methanol) is established very slowly.3 upon irradiation reacts further to dimer8. 2 instantaneously reacts with oxygen. With high oxygen concentrations, hydroperoxide9 is formed, with lower ones dehydrodimer10, inter alia.9 and10 may further form12, 14, and15. These reactions, together with ESR spectroscopy, point to a central role of the free radical13 both in the autoxidation and in the reaction10→14. Basic catalysis sets up an equilibrium between1 and its dimer,17. The photoreaction1→2 has been investigated by sensitizing and quenching experiments.
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  • 2
    ISSN: 1434-4475
    Keywords: Conformational energy ; Cyclohexanes, 2,x-dialkyl-1-dicyanomethylene ; Malononitriles, dialkylcyclohexylidene ; 1H-N M R
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Knoevenagel condensation of malononitrile withcis- andtrans-2,5-dimethylcyclohexanone (1 c and1 t, respectively) leads to2 c and2 t, respectively, and withtrans-1-decalone to4 t. The equilibria2 c⇌2 t and4 c⇌4 t have been determined as well as, by means of 270-MHz-1H-NMR, the conformations of these four compounds. The dicyanomethylene group is found to induce axial positions of neighbouring alkyl residues on the cyclohexane ring (or when this is impossible, as in the case of4 t, the twist form of the cyclohexane ring). This results in a strong predominance of thecis isomers in the equilibria2 c⇌2 t and4 c⇌4 t whereas thetrans isomers strongly predominate in the equilibria among the starting ketones. This situation allows the optional preparation of2 c or2 t, and of4 c or4 t, from the more stable starting ketone (or ketone mixture). The free conformational energy of the distorted twist form of4 t amounts to 17 kJ/mol.
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Lewis Acids, 341. Thermal [4π + 2π]-Cycloaddition of Enol Ethers to 1,1-Dicarbonyl Substituted EthenesEnol ethers such as ethyl vinyl ether and 1,1-dimethoxyethene (3f) react thermally, in some instances below 0°C, with cyclic 2-alkylidene-1,3-dicarbonyl compounds such as 1 and 2 to give [4π + 2π]-cycloadducts 4 and 5, respectively (cyclic enol acetals and enol orthoesters), and with 1,1-dicyanoethenes 6 to give [2π + 2π]-cycloadducts 7. On passing from toluene to acetonitrile as the solvent, rates of formation of 4bf from 1b and 3f increase about tenfold and those of 7b from 6b and 3f about sixfold. A discussion of these rates, including rates of related reactions, the relative Lewis acid strengths of 1b and 6b, and the behaviour of 1b/3f towards methanol leads to the conclusion that the degree of concert of the formation of 4bf is below 6.5 kJ · mol-1. - The configurations and conformations of adducts 4 and 5 are discussed.
    Notes: Enolether wie Ethylvinylether und 1,1-Dimethoxyethen (3f) bilden mit exocyclisch 1,1-dicarbonylsubstituierten Ethenen wie 1 und 2 z.T. schon unterhalb von 0°C thermisch die [4π + 2π]-Addukte 4 bzw. 5 (cyclische Enolacetale und Enolorthoester) und mit den 1,1-Dicyanethenen 6 die [2π + 2π]-Addukte 7. Die Bildungsgeschwindigkeit von 4bf aus 1b und 3f steigt auf etwa das Zehnfache und die von 7b aus 6b und 3f auf etwa das Sechsfache beim Übergang von Toluol auf Acetonitril als Lösungsmittel. Eine Diskussion dieser Bildungsgeschwindigkeiten unter Einbeziehung verwandter Reaktionsgeschwindigkeiten sowie der relativen Lewis-Säurestärken von 1b und 6b und des Verhaltens des Systems 1b/3f gegenüber Methanol führt zum Schluß, daß der energetische Konzertiertheitsgrad der Bildung von 4bf unter 6.5 kJ · mol-1 liegt. Die Konfigurationen und Konformationen der Addukte 4 und 5 werden diskutiert.
    Additional Material: 3 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1683-1688 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und intramolekulare Charge-Transfer(TICT)-Fluoreszenz von 8,8π-Bi-naphtho[1,2,3,4-def]chrysenylBei der Belichtung von Naphtho[1,2,3,4-def]chrysen (3) in Chlorbenzol entsteht ein neues symmetrisches Biaryl, 8,8′-Bi-naphtho[1,2,3,4-def]chrysenyl (4). Fluoreszenzuntersuchungen an 4 ergaben, daß die Emission aus einem TICT-Zustand erfolgt.
    Notes: Upon irradiation of naphtho[1,2,3,4-def]chrysene (3) in chlorobenzene a symmetric biaryl, 8,8′-bi-naphtho[1,2,3,4-def]chrysenyl (4), is formed. Fluorescence studies of 4 reveal that the emission originates from a TICT state.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1647-1650 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermische und photochemische Reaktionen von Naphtho [1,2,34-def]chrysen mit 4-Phenyl-1,2,4-triazolin-3,5-dionDie thermischen und photochemischen Reaktionen von Naphtho [1,2,3,4-def]chrysen (1) mit 4-Phenyl-1,2,4-triazolin-3,5-dion (2) werden verglichen. In der thermischen Reaktion führt elektrophiler Angriff von 2 an 1 zum Substitutionsprodukt 4, welches z. T. zu 5 und 6 weiter umgesetzt wird. Unter Lichteinwirkung findet vorzugsweise [4π + 2π]-Cycloaddition von 2 an 1 unter nachfolgender Dehydrierung zu 6 statt; 6 wird durch das Licht zu einem komplexen Gemisch zersetzt, aus dem 10 isoliert werden kann. 5 existiert in zwei atropisomeren Formen. Die Struktur einer dieser Formen, 5b, wurde durch Kristallstrukturanalyse bestimmt.
    Notes: The thermal and photochemical reactions between naphtho-[1,2,3,4-def]chrysene (1) and 4-phenyl-1,2,4-triazoline-3,5-dione (2) have been compared. In the thermal reaction, 2 electrophilically attacks 1 to give substitution product 4 which in part is further transformed into 5 and 6. In the light-induced reaction, 2 predominantly undergoes [4π + 2π] cycloaddition to 1 with subsequent loss of hydrogen to yield 6 which then photodecomposes to give a complex mixture containing 10. 5 exists in two atropisomeric forms. The structure of one form, 5b, was determined by X-ray crystallography.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3521-3527 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemical Intramolecular Acylation of Polycyclic Aromatic o-Dicarboxylic AnhydridesThe light-induced Diels-Alder addition of maleic anhydride to naphtho[1,2,3,4-def]chrysene (1) yields the same dicarboxylic anhydrides 2 and 4 as the thermal Diels-Alder addition. 4 is further isomerized by light to give the fluorenone carboxylic acid 6, as was revealed by isolation of compounds 7 and 8 after decarboxylation of the mixture 2 + 4. Analogously, 12 is formed by irradiation of the dicarboxylic anhydride 10; decarboxylation of 12 yields 13 and 14. The simpler systems 15 and 17 did not undergo an analogous light-induced Isomerization. Photophysical examination of 4, 10, 15, and 17 gave no clue to the reasons for this difference in behaviour.
    Notes: Die lichtinduzierte Diels-Alder-Addition von Maleinsäureanhydrid an Naphtho[1,2,3,4-def]chrysen (1) führt zu den gleichen Dicarbonsäureanhydriden 2 + 4, wie die thermische Diels-Alder-Addition. 4 wird lichtinduziert zu der Fluorenoncarbonsäure 6 isomerisiert, wie durch Isolierung der Verbindungen 7 und 8 nach Decarboxylierung des Gemisches 2 + 4 nachgewiesen werden konnte. Analog entsteht aus dem Dicarbonsäureanhydrid 10 bei Belichtung 12, dessen Decarboxylierung 13 und 14 liefert. In den einfacheren Systemen 15 und 17 bleibt die analoge lichtinduzierte Isomerisierung aus. Die photophysikalische Untersuchung von 4, 10, 15 und 17 lieferte keinen Hinweis auf die Ursache dieses Unterschiedes.
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  • 7
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Under the influence of aluminium chloride plus tin tetrachloride in boiling benzene (contrary to the solvent-free system) 1-(1-phenanthryl)pyrene (2) does not form the expected product 1 of a dehydrogenating cyclisation of 2 (Scholl reaction). Instead, complete rearrangement of 2 to isomeric biaryls occurs. Besides biaryls 3 and 4, isolated products include fluoranthenes 5-7 derived from unphenylated 3 by dehydrogenating cyclisations and phenylations.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 83 (1971), S. 410-410 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 84 (1972), S. 547-549 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 3293-3301 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Lewis Acids, 331) The Photochemistry of Cyclic Acylals of Alkylidene-, Alkenylidene-, and Benzylidenemalonic AcidsThe photochemistry of the title compounds 1 resembles that of α,β-unsaturated esters. Observed reactions include deconjugation (→ 2), β, δ-cyclopropane ring closure(→ 4), and [2 + 2]-cycloaddition (→ 5, 7, 8) as well as ene-type addition to olefins (→ 9). Reaction mechanism and preparative aspects are discussed.
    Notes: Die Photochemie der Titelverbindungen 1 entspricht der von α,β-ungesättigten Estern: Dekonjugation zu 2, β,δ-Cyclopropanbildung (→ 4) und [2 + 2]-Cycloaddition (→ 5, 7, 8) sowie substituierende Addition an Olefine (→ 9) Reaktionsmechanismus und präparative Aspekte werden diskutiert.
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