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Showing papers on "Fluorenone published in 2000"


Journal ArticleDOI
TL;DR: The use of hexamethylphosphoric triamide (HMPA) as a stabilizing ligand allowed successful isolation of a series of structurally characterizable alkali metal and calcium ketyl complexes.
Abstract: The use of hexamethylphosphoric triamide (HMPA) as a stabilizing ligand allowed successful isolation of a series of structurally characterizable alkali metal and calcium ketyl complexes. Reaction of lithium and sodium with one equivalent of fluorenone and reaction of sodium with one equivalent of benzophenone in THF, followed by addition of two equivalents of HMPA, yielded the corresponding ketyl complexes 1, 2, and 11, respectively, as microketyl-bridged dimers. If one equivalent of HMPA was used in the reaction of sodium with fluorenone, a further aggregated complex, the mu3-ketyl-bridged tetramer 3, was isolated, whereas analogous reaction of benzophenone with sodium afforded the trimeric ketyl complex 13, rather than a simple benzophenone analogue of 3. In the reaction of potassium with fluorenone, the use of two equivalents of HMPA gave the tetramer 4, rather than a dimeric complex analogous to 1 or 2. Compared to the tetrameric sodium complex 3, there is an extra HMPA ligand that bridges two of the four K atoms in 4. When 0.5 equiv of HMPA was used in the above reaction, complex 5, a THF-bridged analogue of 4, was isolated. In the absence of HMPA, the reaction of sodium with an excess of fluorenone yielded the tetrameric ketyl complex 6, in which two of the four Na atoms are each terminally coordinated by a fluorenone ligand, and the other two Na atoms are coordinated by a THF ligand. Two bridging THF ligands are also observed in 6. Reaction of 1,2-bis(biphenyl-2,2'-diyl)ethane-1,2-diol (7) with two equivalents of LiN(SiMe3)2 or NaN(SiMe3)2 in the presence of four equivalents of HMPA easily afforded 1 or 2, respectively, via C-C bond cleavage of a 1,2-diolate intermediate. The reaction of calcium with two equivalents of fluorenone or benzophenone in the presence of HMPA gave the corresponding complexes that bear two independent ketyl ligands per metal ion. In the presence of 3 or four equivalents of HMPA, the fluorenone ketyl complex was isolated in a six-coordinate octahedral form (10), while the benzophenone ketyl complex was obtained as a five-coordinate trigonal bipyramid (13). The radical carbon atoms in both benzophenone ketyl and fluorenone ketyl complexes are still in an sp2-hybrid state. However, in contrast with the planar configuration of the whole fluorenone ketyl unit, the radical carbon atom in a benzophenone ketyl species is not coplanar with any of the phenyl groups; this explains why benzophenone ketyl is more reactive than fluorenone ketyl. Hydrolysis of 2 or 11 with 2N HCI yielded the corresponding pinacol-coupling product, while treatment of 2 or 11 with 2-propanol, followed by hydrolysis, gave the pairs fluorenone and fluorenol or benzophenone and benzhydrol, respectively. A possible mechanism for these reactions is proposed.

48 citations


Journal ArticleDOI
TL;DR: In this article, the azo-enol and hydrazone-quinone tautomeric forms of bisazone-based bisazo compounds have been investigated by means of the steady-state absorption and fluorescence spectroscopy and picosecond time-resolved absorption pump-probe spectrograph.
Abstract: Spectroscopic properties of a fluorenone-based bisazo compound in different organic solvents have been investigated by means of the steady-state absorption and fluorescence spectroscopy and picosecond time-resolved absorption pump-probe spectroscopy. The spectra of the molecules have been shown to be mainly determined by the excitations localized on individual chromophores - azo fragments. Spectra of the azo-enol and hydrazone-quinone tautomeric forms were distinguished. Excited states of the two forms were found to relax in different ways. The hydrazone-quinone form relaxes predominantly nonradiatively with the 400 ps time constant in α-chloronaphthalene, resulting in the fluorescence quantum yield of the order of 10−2. The azo-enol form relaxes via two competing ways, directly to the ground state with the time constant of the order of tens of picoseconds, or via the long-lived intermediate state.

28 citations


Patent
25 Jan 2000
TL;DR: In this article, a 9, 9 bis(an alkyl-substituted-4-hydroxyphenyl)fluorene is obtained by reacting 1 pt.mol 9-fluorenone with 4-8 pts.C.% based on a reaction solvent (e.g., methanol).
Abstract: PROBLEM TO BE SOLVED: To obtain the subject new compound useful as a raw material of a highly heat resistant and highly transparent polyester resin, polyether resin, polyimide resin and epoxy resin and as a raw material of an optical material having a large refractive index and transparency, or the like. SOLUTION: This 9, 9 bis(an alkyl-substituted-4-hydroxyphenyl)fluorene is a compound of formula I [R1 is H or methyl; R2 is a 2-4C alkyl, 5C or 6C cycloalkyl or the like; (n) is 1, 2], e.g. 9,9-bis(4-hydroxy-3-isopropylphenyl) fluorene. The compound of formula I is obtained by reacting 1 pt.mol 9- fluorenone with preferably 4-8 pts.mol alkylphenols of formula II (e.g.; o- isopropylphnol) in the presence of an acid catalyst (e.g.; hydrogen chloride gas or a conc. hydrogen chloride), by preferably simultaneously using an alkylmercaptane, and preferably using a reaction solvent (e.g.; methanol) at 20-80 deg.C. The alkylmercaptane is used 3-20 mol.% based on the 9-fluorenone.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a benzophenone-and fluorenone-based β2-adrenergic receptor (β2AR) photoaffinity ligand was developed to directly probe the catechol binding region.
Abstract: To develop molecules capable of directly probing the catechol binding region of the β2-adrenergic receptor (β2AR), novel benzophenone- and fluorenone-based β2AR antagonists were prepared as potential photoaffinity probes. While the benzophenone-containing ligands bound with relatively modest affinity, one of the fluorenone-based compounds, 4-(2-hydroxy-3-isopropylaminopropoxy)-7-amino-6-iodofluorenone (iodoaminoflisopolol, IAmF), showed very high affinity for the β2AR, inhibiting [125I]ICYP binding with an apparent Ki of approximately 1 × 10-9 M. In comparison to the benzophenone ligands, the fluorenone ligands have one additional carbon−carbon bond that creates a planar unsaturated ring system and leads to a large increase in receptor binding affinity. Unlike previous β2AR photoaffinity ligands, an attractive and unique feature of the fluorenone derivative IAmF is that the large planar unsaturated ring (believed to correspond to the catechol end of other β2AR ligands) serves as both the binding pharmacop...

14 citations


Journal ArticleDOI
TL;DR: The enantioselective reduction of substituted fluorenones by aluminium lithium hydride in the presence of different chiral amino alcohols has been investigated in this article, where the best conditions found were also assayed with a multi-substituted fluorenone achieving the corresponding fluorenol compound with high enantiomeric excess.
Abstract: The enantioselective reduction of substituted fluorenones by aluminium lithium hydride in the presence of different chiral amino alcohols has been investigated. The best conditions found were also assayed with a multi-substituted fluorenone achieving the corresponding fluorenol compound with high enantiomeric excess. Shorter reaction times with high conversion yields were found when compared with borane reductions.

6 citations


Journal ArticleDOI
TL;DR: In this article, the enantioselective reduction of 1-bromofluorenone by borane in the presence of different chiral amino alcohols has been studied.
Abstract: The enantioselective reduction of 1-bromofluorenone by borane in the presence of different chiral amino alcohols has been studied. The alcohol obtained has the ( S ) or ( R ) configuration depending on the nature of the substitution of the amino alcohol. The experimentally determined absolute configuration can be explained when a four-center cyclic transition state consisting of the oxazaborolidine and fluorenone compound is considered.

4 citations



Patent
20 Sep 2000
TL;DR: In this paper, a process for preparing fluorenone includes preparing catalyst, preparing industrial fluoresnone and refining, which includes impregnation while stirring, homogenizing, baking and calcining.
Abstract: A process for preparing fluorenone includes preparing catalyst, preparing industrial fluorenone and refining. Said step for preparing catalyst includes impregnation while stirring, homogenizing, baking and calcining. For the refining step, the aqueous solution of alkali-metal hydroxide is used to remove impurities. Said catalyst has efficient and stable catalytic action and long service life up to 3-4 years.

3 citations


Patent
04 Jul 2000
TL;DR: In this paper, a biphenyl-2-carboxylic acid was obtained from an inexpensive starting substance by an industrially advantageous reaction operation, where fluorenone being an oxidation product of fluorene was reacted with potassium hydroxide or sodium hydroxides in a dispersed state in an organic solvent except an alcohol and a ketone under heating.
Abstract: PROBLEM TO BE SOLVED: To obtain a biphenyl-2-carboxylic acid from an inexpensive starting substance by an industrially advantageous reaction operation. SOLUTION: Fluorenone being an oxidation product of fluorene is reacted with potassium hydroxide or sodium hydroxide in a dispersed state in an organic solvent except an alcohol and a ketone under heating, and the reaction product is recovered by precipitation with an acid to give a biphenyl-2-carboxylic acid having >=99% purity in a short reaction time in a quantitative yield.

1 citations


Patent
05 Jul 2000
TL;DR: In this article, an anti-reflective coating composition is disclosed which comprises one of the aforementioned polymers and at least one light absorbing compound selected from Anthracene, fluorenone, fluorenol, xanthone, quinazarin, fluorescein, and the derivatives of anthracene and fluoresnone.
Abstract: A polymer suitable for use as an anti-reflective coating of a semiconductor device is a polyhydroxystyrene, a poly(styrene-acrylate), or a novolac polymer, which polymers are substituted with the diazonaphthoquinonesulfonyl group shown below: An anti-reflective coating composition is disclosed which comprises one of the aforementioned polymers and at least one light absorbing compound selected from anthracene, fluorenone, fluorenol, xanthone, quinazarin, fluorescein, and the derivatives of anthracene and fluorenone. Process for preparing the diazonaphthoquinonesulfonyl substituted polymers and the coating composition are also described.