Showing papers on "Fluorenone published in 1990"

Synthese von Reinst-Rubicen und Rubicen-Derivaten

Abstract: Synthesis of Highly Pure Rubicene and Rubicene Derivatives A simple one-step synthesis of highly pure rubicene (2) from fluorenone (1) and magnesium with 24% yield is described and compared with other preparation procedures. Mono- and disubstituted rubicene derivatives are prepared by electrophilic aromatic substitution.

Polymerization photoinitiated by carbonyl compounds. IX. Methyl methacrylate polymerization photoinitiated by anthraquinone in presence of triethylamine

Abstract: The photoinitiation efficiency of the fluorenone/triethylamine (TEA) system in the polymerization of methylmethacrylate (MMA) has been evaluated as a function of the monomer concentration, the amine concentration, and the polarity of the reaction medium. The polymerization proceeds readily in low polarity media (benzene/monomer), but it is negligible in more polar solvents (acetonitrile/monomer). The polymerization rate increases with the amine concentration up to 0.01 M TEA. Further increase in amine concentration produces a decrease in the polymerization rate. A similar behavior was observed for the fluorenone photoreduction yield and the yield of fluorenone derived radicals. All these processes are considered to involve the excited triplet, while quenching of the excited singlet by the amine decreases the rate of these processes. However, the decrease in photoinitiation efficiency observed at high amine concentration is larger than that expected from the singlet quenching extent, as estimated from the effect of the amine on the fluorescence yield under the same experimental conditions. This discrepancy indicates that other process(es) must contribute to the protection afforded by high amine concentrations. Quenching of the charge transfer intermediate by the amine is postulated as a competitive process that could explain the above mentioned effects. © 1994 John Wiley & Sons, Inc.

Liquid Crystalline Derivatives Containing Fluorene and Fluorenone Structures

Abstract: The authors have synthesized liquid crystalline materials containing fluorene, fluorenone and biphenyl structures. Among these materials, comparison have been made for 1) Thermal stabilities for sm...

Synthesis of 2,7-Fluorenone Bisglycidyl Ether and related compounds as potential cytostatics

Abstract: The syntheses of fluorenone derivatives having one to three glycidyl groups and related compounds are reported. Their activity against experimental tumors in vitro in relation to the molecular structure is discussed.

Studies on 1,3‐indandione: Synthesis of Fluorenones and Indeno(2,1‐c)pyridazine

Abstract: 1,1-Dicyanomethylene-3-indanone (2) reacted with cinnamonitriles 1a-c to afford fluorenone derivatives 6a-c. Compounds 6a-c were also obtained when treating 2 with 1d-f. The coupling of 2 with aromatic diazonium chlorides resulted in the formation of the hydrazones 8a-c. 8a readily cyclized to indeno[2,1-c]pyridazine (9a) in acidic medium. The action of 1d-f on enaminone 3 was also studied.

Production of bis 4-hydroxyphenyl)fluorenes

Abstract: PURPOSE: To obtain the subject compound at a low cost by condensing fluorenone with phenols in the presence of a catalyst, mixing the obtained reaction mixture with a lower aliphatic alcohol without separating unreacted phenols from the system and adding water to the obtained homogeneous solution to effect the crystallization of the subject compound. CONSTITUTION: A reaction mixture containing bis(4-hydroxyphenyl)fluorene (objective compound) and unreacted phenols is produced by condensing fluorenone with phenols in the presence of a catalyst. The reaction mixture is mixed with a lower aliphatic alcohol (preferably methanol, ethanol or 2- propanol) without separating the above unreacted raw material or after separating a part of the raw material and leaving at least a part of the material in the reaction mixture. Water is added to the obtained homogeneous solution to crystallize the objective compound useful as a raw material for polyesters, epoxy resins, etc. The compound can be produced in high purity and yield with simple procedures. COPYRIGHT: (C)1992,JPO&Japio

Photochemistry and photopolymerization activity of novel perester derivatives of fluorenone: a conventional and laser flash photolysis study

Abstract: The photochemistry of three novel t-butylperester derivatives of fluorenone was examined and compared with unsubstituted fluorenone and a mono-t-butylperester of benzophenone using both conventional microsecond and nanosecond laser flash photolysis. On conventional microsecond flash photolysis in 2-propanol, all four fluorenone compounds gave transient absorption in the region 300–400 nm due to a ketyl radical formed from the abstraction of a hydrogen atom from the solvent by the upper excited triplet n—π* state of the fluorenone chromophore. This assignment was confirmed by a pH-dependent study on the transient absorption spectra. The nitro-t-butylperester derivative of fluorenone gave additional absorption above 400 nm due to species associated with the nitro group. No evidence for benzoyloxy radical formation could be found in non-hydrogen-atom-donating solvents with microsecond flash photolysis which is associated with homolysis of the perester groups. On nanosecond laser flash photolysis of the fluorenone compounds at 355 nm excitation in acetonitrile and hexa-fluorobenzene, transient absorptions were observed in the region 320–640 nm due to the corresponding triplet states. All the t-butylperester derivatives showed residual absorbances at longer time delays which were tentatively assigned to the corresponding benzoyloxy radicals produced by homolysis of the perester groups. In contrast, the mono-t-butylperester of benzophenone, included for comparison only, showed very weak transient absorption in the region 320–640 nm compared with that of the strong triplet of benzophenone under the same excitation conditions. The triplet absorptions and lifetimes of the fluorenone compounds were correlated with their photopolymerization activities in bulk methylmethacrylate monomer. In oxygenated solutions, the triplet absorptions of fluorenone and benzophenone were effectively quenched; however, long-lived transient growths were observed for all the t-butylperester derivatives. The intensities of these novel transient absorptions appear to correlate with the total number of t-butylperester groups in the fluorenone molecule and tentative assignments are discussed.

Synthesis of 2,7-Fluorenone Bisglycidyl Ether and Related Compounds as Potential Cytostatics.

Abstract: The syntheses of fluorenone derivatives having one to three glycidyl groups and related compounds are reported. Their activity against experimental tumors in vitro in relation to the molecular structure is discussed.