Fluorenone

About: Fluorenone is a research topic. Over the lifetime, 1067 publications have been published within this topic receiving 17162 citations. The topic is also known as: Diphenylene ketone & 9-Oxofluorene.

High pressure studies of fluorenone emission in plastic media

Abstract: The energy and the quantum efficiency for fluorenone fluorescence in the crystalline state and in polymeric matrices was measured as a function of external pressure over the range 0–140 kbar. The application of high pressure induces changes in the quantum yield, which ranges from 0.001 at low pressure to a maximum of ∼0.1 at high pressure in hydrocarbon plastics. These results are interpreted as arising from the decrease in the energy of the lowest ππ excited singlet state relative to other relevant states as the external pressure is increased.

High heat polyethersulfone compositions

Abstract: High heat polyethersulfone compositions are provided which possess unexpectedly high glass transition temperatures. The polyethersulfone compositions comprise structural units derived from fluorenone bisphenols such as 9,9-bis(4-hydroxyphenyl)fluorene, and structural units derived from at least one biphenyl-bissulfone such as 4,4′-bis((4-chlorophenyl)sulfonyl)-1,1′-biphenyl. The novel polyethersulfone compositions may further comprise structural units derived from one or more biphenols such as 4,4′-biphenol, bisphenols such as BPA, or other electrophilic sulfone monomers, such as bis(4-chlorophenyl)sulfone. In one embodiment, the polyethersulfone composition of the present invention comprises structural groups derived exclusively from 9,9-bis(4-hydroxyphenyl)fluorene and 4,4′-bis((4-chlorophenyl)sulfonyl)-1,1′-biphenyl and exhibits a single glass transition of greater than 300° C.

Alkali N.M.R. experiments on the radical ion pairs of biphenyl and fluorenone

Abstract: Line widths in the 6Li, 7Li, 23Na, 39K, 85Rb, 87Rb and 133Cs N.M.R. spectra of solutions of the alkali salts of biphenyl and fluorenone are reported as a function of solvent and temperature. From a numerical analysis of the room temperature data the contribution of the various relaxation mechanisms to the line widths are established. It is shown that the results are consistent with the observed solvent and temperature dependence of the line widths. Values of the electron spin correlation time are obtained and a value of 1·6 ± 0·4 A is found for the ‘Van der Waals radius’ of the biphenyl anion. Line width expressions for the static and the dynamic ion pair model are presented. It is demonstrated that the static ion pair model applies to solutions of caesium biphenylide. Semi-empirical rules are presented concerning the importance of various relaxation mechanisms for the different alkali nuclei in the type of solution studied here.

Crystal polymorph of fluorene derivative and method for producing the same

Abstract: PROBLEM TO BE SOLVED: To provide a novel crystal polymorph of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene with maintaining a certain quality and excellent as a polymer raw material, and a method for producing the crystal polymorph SOLUTION: The novel crystal polymorph of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene is produced by preparing a crude purified product of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene by reacting fluorenone with 2-phenoxyethanol in the presence of an acid catalyst, subsequently dissolving the crude purified product in at least one solvent selected from a group consisting of aromatic hydrocarbon solvents, ketone solvents and ester solvents and initiating precipitation of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene at ≥50°C COPYRIGHT: (C)2008,JPO&INPIT

Electron spin resonance study of radicals photolytically generated from aromatic carbonyl compounds. Part III. Reduction of fluorenone and benzophenone in amines

Abstract: E.s.r. spectra of the 9-hydroxyfluorenyl radical, which is produced by the u.v. photolysis of fluorenone in tertiary amines, are presented and discussed. Tertiary amines appear to have a vital and unique role in the reduction process as the 9-hydroxyfluorenyl radical was not observed in photolysed solutions of fluorenone in other amines or in many non-amine solvents. Reduction probably occurs by electron transfer from the nitrogen atom to the excited carbonyl group to form the fluorenone radical anion which then rapidly abstracts a proton from the amine radical cation.Amines can effect markedly the e.s.r. spectra of hydroxy-substituted radicals. Results on the Ph2ĊOH radical in various amine solvents are presented and compared with results for the same radical in solvents in which the effects of solvation are likely to be minimal. Such solvents are cyclohexane and toluene. In the latter, the spectrum of the benzyl radical, PhĊH2, is clearly resolved in addition to that for the Ph2ĊOH radical. The observations can be explained in terms of solvation via hydrogen bonding between the hydroxy-group protons and the nitrogen atom of some amines. Triethylamine appears to be a particularly potent solvator and affects the coupling constants to the hydroxy-protons and, in the case of the 9-hydroxyfluorenyl radical, the ring proton coupling constants quite drastically.