Showing papers on "Fluorenone published in 1994"

ortho and remote metalation – cross coupling strategies. Total synthesis of the naturally occurring fluorenone dengibsinin and the azafluoranthene alkaloid imeluteine

Abstract: The total synthesis of the naturally occurring fluorenone, dengibsinin (7a), and the azafluoranthene alkaloid, imeluteine (30e), is described. Using combined ortho metalation – cross coupling seque...

Solvent-dependent radiationless transitions in fluorenone: A probe for hydrogen bonding interactions in the cyclodextrin cavity

Abstract: Fluorescence lifetimes fluorescence quantum yields and triplet yields were measured for fluorenone in various hydroxylic and non-hydroxylic solvents, and inβ-cyclodextrin complexes. The rate of singlet-triplet intersystem crossing, which decreases with increasing polarity, was found to be a good indicator of nonspecific solvent-solute interactions, while the rate of direct internal conversion from the singlet excited state was correlated with hydrogen bonding. The fast internal conversion of singlet excited fluorenone/β-cyclodextrin complexes shows that the probe molecule, while embedded within the cyclodextrin cavity, still remains hydrogen bonded.

Method of preparing a fluorene derivative and the method of purifying thereof

Abstract: A fluorene derivative of high purity is produced by reacting fluorenone with phenoxyethanol in the presence of a sulfuric acid-thiol catalyst system, dissolving the reaction mixture in a lower aliphatic alcohol and adding water to the resulting solution for precipitation of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene [fluorene derivative]. A fluorene derivative of still higher purity is obtained by recrystallization from a lower aliphatic alcohol. In accordance with this invention, a fluorene derivative can be produced advantageously on a commercial scale without incurring any appreciable loss of fluorenone, in good yield, with high efficiency and in a reduced production time.

Fluorenone derivatives, process for preparing the same and central or peripheral nerve degeneration repair and protective agent

Abstract: The present invention provides novel fluorenone derivatives represented by formula (A) (wherein Ra-Rg are defined in the specification), and a method for repairing and protecting central or peripheral nerve degeneration comprising use of a fluorenone derivative represented by formula (1) (wherein R1, R2, p and q are as defined in the specification) as an active component.

Production of fluorenone and oxidation catalyst used therein

Abstract: PURPOSE:To permit the efficient production of fluorenone of high purity from fluorene with no formation of by-products using a specific amine derivative as an oxidation catalyst economically in a shortened time. CONSTITUTION:To 2.5 to 30wt.% fluorene solution, is added 35 to 50wt.% of alkali aqueous solution and a catalyst aqueous solution. Then, oxygen is introduced into the mixture in an amount of 1.0 to 1.5 mole per mole of the fluorene. As the oxidation catalyst, is used an aqueous solution of 30 to 70wt.% concentration of one or more amine derivatives of the formula I (R is H, lower alkyl; R is lower alkyl; a is 1 to 2; X is SO4 , CH3SO4 where when X is SO4 , a=2; when X is CH3SO4 , a=1), particularly N,N-dimethylaniline is preferred). The catalyst is obtained, for example, by mixing N,N-dimethylaniline with dimethyl sulfate, stirring the mixture at room temperature, admixing water thereto, dripping IN sodium hydroxide until the pH reaches 7, filtering off the precipitate and adding water to the filtrate.

Process for the preparation of bisphenols

Abstract: A process for the preparation of bishydroxy aromatic compounds, such as 9,9-bis(4-hydroxyphenyl)fluorene, involving contacting a ketone, such as fluorenone, with phenol or substituted phenol in the presence of a mercaptan cocatalyst and a solid superacid catalyst of Hammett acid strength H0 greater than -13.0. Solid superacid catalysts include the sulfates, sulfated oxides, sulfated oxyhydroxides, and sulfated oxysilicates of aluminum, tin, and the Group IVA metals, such as zirconium. Other solid superacid catalysts include mixed metal oxides, such as tungsten-zirconium oxides. Isolated yields of 9,9-bis(4-hydroxyphenyl)fluorene are high.

Preparation and Spectroscopic Properties of Spirocyclic 1-Methyl-2,4,4,6-tetraaryl-1,4-dihydropyridines

Abstract: 1,5-Diones Ib - Ie were converted to spirocyclic 1,4-dihydropyridines IIb - IIe by treatment with methanolic methylamine. The starting diketones Ib - Ie were obtained from corresponding acetophenones 4-X-C 6 H 4 COMe and fluorenone with sodium amide except of If where only ketone III and 1,4-dione IV were isolated. Molecular spectra (UV-VIS, NMR, IR and MS) of compounds Ib - Ie , IIa - IIe , III , and IV were assigned and interpreted.

Extrinsic Photocarrier Generation at Fluorenone Bisazo Pigment/α-Phenylstilbene Derivative Interface

Abstract: We have investigated the molecular interface between an azo pigment and an α-phenylstilbene derivative where photocarriers are extrinsically produced from a microscopic viewpoint. From the measurement of the azo-pigment photoluminescence quenching by the α-phenylstilbene derivative, only the molecules that contact with the azo-pigment particles are known to promote generation of the photocarriers. The electron-transfer reaction at the interface for photocarrier generation is proven to occur adiabatically.

Synthesis and characterizatoin of polymers having fluorenone derivatives

Abstract: Summary form only given. It is well known that fluorenone derivatives have good electron transport ability due to low LUMO. However, low molecular weight compounds have poor mechanical properties and they easily crystallize and decrease the electron transport ability. We have prepared a new polymer having fluorenone units on the side chain- poly(4-vinylbenzyl 9-dicyanomethylenefluorene-4-carboxylate) and measured electrical porperties. The momomer was prepared from 9-dicyanomethylenefluorene-4-carboxylic acid and p-chloromethyl styene, and was polymerized by conventional radical polymerization in solution. Polymer was obtained with 61% yield and as a yellow powder. The polymer was soluble in organic solvent such as THF, chloroform and methylchloride. The number average molecular weight was determined to be 8,200 by GPC using a calibration curve of standard polystylene. The structures of the resulting polymer were confirmed by /sup 1/H-, /sup 13/C-NMR and IR spectra. Polymer in THF solution showed a UV absorption maximum(/spl lambda/max) at 351.25nm. The polymer film showed two reversible redox potentials at -0.51V,-1.04V(oxidation) and -0.62V,-1.15V(reduction). Further detailed studies will be presented at the poster session.

Fluorenone and Benzophenone 1,4‐Dihydropyridine Derivatives with Cardiodepressant Activity.

Abstract: A series of fluorenone and benzophenone 1,4-dihydropyridine derivatives were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties.

ortho and Remote Metalation-Cross Coupling Strategies. Total Synthesis of the Naturally Occurring Fluorenone Dengibsinin and the Azafluoranthene Alkaloid Imeluteine.

Abstract: The total synthesis of the naturally occurring fluorenone, dengibsinin (7a), and the azafluoranthene alkaloid, imeluteine (30e), is described. Using combined ortho metalation – cross coupling seque...

Solvent-Dependent Transitions in Fluorenone: A Probe for Hydrogen Bonding Interactions in the Cyclodextrin Cavity

Abstract: Fluorescence lifetimes, fluorescence quantum yields and triplet yields were measured for fluorenone in various hydroxylic and non-hydroxylic solvents, and in/3-cyclodextrin complexes. The rate of singlet-triplet intersystem crossing, which decreases with increasing polarity, was found to be a good indicator of nonspecific solvent-solute interactions, while the rate of direct internal conversion from the singlet excited state was correlated with hydrogen bonding. The fast internal conversion of singlet excited fluorenone/p-cyclodextrin complexes shows that the probe molecule, while embedded within the cyclodextrin cavity, still remains hydrogen bonded.