- Cycloreversion Induced by Charge-Transfer Excitation of Electron Donor-Acceptor Complexes. Wavelength-Dependent Photochemistry of Dianthracene
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The electron donor-acceptor or EDA complexes of dianthracene (An2 is the ?-dimer of anthracene) and its derivatives with tetracyanoethylene show two unusually well-resolved charge-transfer (CT) bands.Specific irradiation of each of these absorption bands with monochromatic light at five selected wavelengths ranging from 405 to 577 nm leads to the clean cycloreversion of An2 to anthracene.The striking wavelength-dependent quantum efficiency for cycloreversion is analyzed in terms of two different CT ion pairs derived from the photoexcitation of the first and second absorption bands, which correspond to electron promotion from the HOMO and SHOMO (second highest occupied molecular orbital) of the dianthracene donor, respectively.Orbital correlations between dianthracene ?-dimer reveal that electron promotion from the SHOMO of dianthracene leads to an excited radical ion An2(+) which is more dissociative than that derived from the HOMO transition.
- Masnovi, J. M.,Kochi, J. K.
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- Process for the preparation of anthraquinone
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In einem Verfahren zur Herstellung von Anthrachinon in der flüssigen Phase durch katalytische Oxidation von Anthracen behandelt man Anthracen in einem Carbons?uremedium in Gegenwart eines organischen Metallsalzes und eines Aktivierungsmittels für das Metallsalz bei einer Temperatur von etwa 40 °C und mehr unter Einwirkung von Sauerstoff und Licht, anschlie?end mit Wasserstoffperoxid und isoliert das erhaltene Reaktionsprodukt aus dem Reaktionsgemisch, wobei Ausbeute und Reinheit des Anthrachinions deutlich gesteigert werden.
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- Process for the production of carboxylic acid esters of 9,10-dihydroxy anthracene
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In einem Verfahren zur Herstellung von 9,10-Dihydroxyanthracencarbons?ureester und dessen Abk?mmlingen durch katalytische Oxidation von Anthracen wird Anthracen in der flüssigen Phase in einem Carbons?uremedium in Gegenwart eines organischen Metallsalzes und eines Aktivierungsmittels für das Metallsalz bei einer Temperatur von etwa 40 °C und mehr unter Einwirkung von Sauerstoff und Licht behandelt, der Niederschlag abgetrennt, der flüssige Rest mit Veresterungsmitteln behandelt und der erhaltene Ester aus dem Reaktionsgemisch isoliert.
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- Manganese(III)-Mediated Formylation of Aromatic Compounds in the Presence of Malonic Acid
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The reaction of naphthlenes with malonic acid in the presence of manganese(III) acetate gives naphthalenecarbaldehydes and naphthalenecarboxylic acids.Similar reactions of anthracene, pyrene, and methoxybenzenes also yield formylated and carboxylated products.It was found that the formyl group introduced to the aromatic ring was not derived from carboxymethyl radical generated directly by the thermolysis of manganese(III) acetate, but from a dicarboxymethyl radical formed by the interaction of malonic acid and manganese(III) acetate.In addition, it was also found that the dicarboxymethyl radicals attacked the position of the highest electron density on the aromatic ring and that this formylation was effective when the ionization potential of the aromatic copound was lower than 7.8 eV.
- Nishino, Hiroshi,Tsunoda, Katsunori,Kurosawa, Kazu
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p. 545 - 550
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of Some Aromatic Hydrocarbons by Phenyl Iodosylacetate
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Oxidation of toluene, o-xylene, p-xylene, m-xylene, naphthalene and anthracene with phenyl iodosylacetate follows second order kinetics.The reactions are strongly dependent on the permitivity of the solvent medium.The activation parameters have been computed.Side chain acetoxylation is the major reaction in the case of toluene, o-xylene and p-xylene while nuclear acetoxylation has been encountered in the case m-xylene, naphthalene and anthracene.The mechanisms of side chain and nuclear acetoxylation are proposed, which satisfy the kinetic data obtained.
- Radhakrishnamurti, P. S.,Panda, H. P.,Pradhan, D. C.
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p. 297 - 300
(2007/10/02)
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- Palladium(II)-Catalysed Aromatic Coupling and Substitution: Reactions of Anthracene, Phenanthrene, Diphenyl Ether and Diphenylamine
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Anthracene when refluxed with Pd(OAc)2 in glacial HOAc affords 9,9'-bianthranyl (1) in poor yield along with traces of para-anthracene (2), the major product being anthraquinone.Addition of small amount of HClO4 in the above reaction totally suppresses the coupling reaction and gives anthraquinone as the exclusive product in much better yield.Treatment of anthracene with Pd(OAc)2 in the presence of Pb(OAc)4 affords 9-acetoxyanthracene (4), anthraquinone and dianthrone (5).The observed divergence in the product profile with anthracene in the above reactions from those with its lower homologues has been rationalised.Intramolekular Pd(II)-catalysed aryl-aryl coupling reactions of diphenyl ether and diphenylamine have also been studied.It is observed that while the former is almost unreactive towards Pd(OAc)2 in HOAc, the latter is converted into carbazole in fairly good yield under identical reaction condition.
- Majumder, P. L.,Joardar, M.
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p. 1191 - 1193
(2007/10/02)
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