Showing papers on "Fluorene published in 1985"

Occurrence of chlorinated polynuclear aromatic hydrocarbons in tap water

Abstract: Organic compounds in tap waters were extracted by a modified continuous liquid-liquid extractor and analyzed by computerized gas chromatography/mass spectrometry using a fused silica capillary column. The results indicate the presence of monochlorinated derivatives of naphthalene, dibenzofuran, fluorene, fluorenone, phenanthrene, and fluoranthene and dichlorinated derivatives of naphthalene, phenanthrene, and fluoranthene. The parent polynuclear aromatic hydrocarbons (PAHs) and their oxygenated derivatives such as fluorenone and anthraquinone were also found. It was demonstrated that chlorinated PAHs (Cl-PAHs) were really present in tap waters at 10/sup -1/-10/sup -2/ ng/L levels.

Evidence for the generation of aromatic cationic systems in the excited state. Photochemical solvolysis of fluoren-9-ol

Abstract: Photolysis of Fluoren-9-ol (1) in aqueous methanol solution results in efficient formation of 9-methoxyfluorene (2); the driving force for the photosolvolysis is believed to be the formation of an aromatic 4π cationic system in the excited-state.

Method for making 9,9-bis-(4-hydroxyphenyl)-fluorene

Abstract: A method for making 9,9-bis-(4-hydroxyphenyl)-fluorene by reacting fluorenone with phenol at a temperature from 20° to 100° C. in the presence of sulfuric acid of a concentration higher than 70 percent and of a mercaptan, and particularly beta-mercaptopropionic acid, as acidic condensing agents.

Fluorene Analogues of Biphenyls: Comparison of Mesogenic Behaviour

Abstract: A variety of 2, 7-disubstituted fluorenes has been synthesised including 2-alkyl-7-cyanofluorenes, 2-pentyl-7-fluorenyl esters and esters of 7-pentyl-2-fluorenecarboxylic acid. Transition temperatures have been determined and are compared with those of analogous biphenyl compounds: it is found that the melting points are higher and the nematic clearing points slightly lower than those of the biphenyl analogues. Suitable mixtures have been used to determine other physical properties. All of the fluorene esters prepared have a phenyl or cyclohexane ring incorporated in the structure to promote wide mesophase temperature ranges and higher melting points. Some of the esters also give smectic phases.

Bis(hydroxyphenyl)fluorene polyarylate polymers and alloys

Abstract: Polyarylate polymers derived from (A) mixtures of bis(hydroxyphenyl)fluorene compounds with anthracene bisphenols, and (B) a mixture of isophthalic and terephthalic acid. Also disclosed are polyarylate alloy compositions comprising a bis(hydroxyphenyl)fluorene polyarylate and a polymer resin selected from polybisphenol A carbonate and polystyrene.

Thermotropic polyketones: a new class of main-chain liquid crystalline polymers

Abstract: The first examples of thermotropic liquid crystalline (LC) polyketones have been synthesized by the Friedel-Crafts acylation of biphenyl, fluorene and terphenyl with α,ω-dicarboxylic acid alkanes in a phosphorous pentoxide/methanesulfonic acid (PMMA) condensing agent. Polyketones prepared from biphenyl and fluorene exhibit good solubility as well as low thermal transition temperatures due to the copolymeric nature of these polymers. Both molecular weight and the inherent copolymer composition appear to influence the mesophase behavior in these polymers. Optical polarization microscopy has revealed smectic textures for all the polyketones exhibiting LC behavior.

Ab initio and semiempirical calculations on adducts of guanine and the metabolites of different carcinogens

Abstract: From numerous experiments it is evident that carcinogens bind covalently to cellular macromolecules, particularly nucleic acids. Therefore, to understand carcinogenesis at a molecular level, it is necessary to study the electronic structure and stereochemistry of the carcinogen adducts with subunits of DNA and the effects of their binding on the local environment. We have investigated these properties for different adducts of guanine and guanosine and the ultimate of alkylating agents and polycyclic hydrocarbons. Ab initio Hartree—Fock SCF LCAO calculations have been performed for the methyl-guanine cations, with the methyl group being attached to the N7 and O - atoms of guanine, respectively. In these cases the changes in the electronic charge distribution at the atoms which are involved in hydrogen bonding in the Watson—Crick base pairs and to the atoms which participate in the depurination reaction, may determine the anomalous functioning of the chemically modified molecules. With the aid of the mutually consistent field method we have calculated the interaction energies between methyl-guanine and nucleotide bases in stacked as well as hydrogen bonded configurations. These numerical results are compared with those for the corresponding non-methylated systems. Strong steric hindrance on the other side seems to be decisive for those compounds which are formed between guanine and bulky metabolized aromatic hydrocarbons, like benzo(a)pyrene and 2- and 3-acetamido fluorene. For this latter group of adducts we have carried out CNDO/2- and MINDO/3-calculations to investigate the electronic charge distribution and stereochemistry, respectively. The reaction of the cancerous fluorene derivative with guanine in DNA is accompanied by a drastic change in the helical structure. The acetamido fluorene residue is inserted into the helix and at the same time the nucleotide base is displaced to the outside. To obtain at least a partial answer as to how this new configuration is stabilized, the stacking interaction energies between the carcinogen and the four different nucleotide bases cytosine, thymine, guanine and adenine, respectively, have been computed in the supermolecule approach on the semiempirical level.

Triplet State Processes in Aqueous Colloidal Dispersions of Polycyclic Aromatic Hydrocarbons at Room Temperature

Abstract: A unique and facile means of producing room-temperature phosphorescence (RTP) from colloidal or microcrystalline suspensions of aromatic molecules in aqueous media is reported. Unlike previously reported RTP techniques, colloidal RTP is insensitive to quenching by dissolved oxygen. Delayed fluorescence was observed from several nonphosphorescent species. Potential uses of the technique are for the determination of the solubility of highly insoluble compounds and the ability to distinguish between suspended and dissolved matter.

Friedel–Crafts polymerization of fluorene with methylene chloride, methoxyacetyl chloride, and chloromethyl methyl ether†

Abstract: The polymerization of fluorene with various chloromethylating reagents (methylene chloride, methoxyacetyl chloride, and chloromethyl methyl ether) in the presence of aluminum chloride was studied. The products that were obtained were insoluble, infusible, colored powders which contain a low concentration of aromatic radicals. Each of the polymers is composed predominantly of fluorene nuclei bridged at the 2 and 7 positions by methylene groups. In addition, the materials possess varying amounts of crosslinked and ring-fused moieties. Based on physical and spectral properties and reaction stoichiometry, the fluorene/methylene chloride polymer is the most highly crosslinked of the three. The fluorene/methoxyacetyl chloride and fluorene/chloromethyl methyl ether polymers are similar to each other in most respects.

Synthesis of Some New Fluorene Esters with Mesomorphic Behavior

Abstract: A number of 2-fluorenyl 4′-alkylbenzoates and 4′-alkoxybenzoates have been synthesized to study the effects of the central ester linkage on their mesomorphic behavior. These compounds typically show nematic (N) and the uniaxial smectic phases. Many isomeric fluorene esters with reversed ester linkage were also prepared, but no major differences were observed. The presence of a lateral substituent in the phenyl ring decreases the nematic-isotropic (N-I) temperature by about 28°C. Replacement of phenylene by trans-cyclohexylene has the unusual effect of increasing the N-I transition temperature by about 21°C. The presence of a nitro group at position (7) of the fluorene ring increases N-I temperature by about 66°C and stabilizes the SA.

Preparation of fluorenone

Abstract: PURPOSE:To improve the yield stably with a long catalyst life, by using a specific catalyst containing vanadium oxide and titanium oxide as main components, in preparing the titled compound useful as a raw material for agricultural chemicals, medicines and functional high polymers, etc. through vapor-phase catalytic oxidation of fluorene. CONSTITUTION:Fluorene is catalytically oxidized in the vapor phase with a molecular oxygen-containing gas, using a catalyst mainly containing vanadium oxide and titanium oxide and optionally containing at least one alkali metal compound, preferably in amounts of 100pts.wt. titanium oxide (calculated as TiO2), within 1-100pts.wt., particularly 1-50pts.wt. range vanadium oxide (calculated as V2O5) and within 0.05-15pts.wt. range alkali metal compound (calculated as each oxide), to obtain the titled compound. Preferred reaction conditions are 330-450 deg.C reaction temperature, 800-8,000hr space velocity and 10- 100g/Nm -flowing gas concentration of the fluorene.

Liquid crystal properties of certain 4-alkoxy-N-(fluoren-2-ylmethylene)- and -(2-naphthylmethylene)-anilines

Abstract: The liquid crystal transition temperatures of 124-alkoxy-N-(fluoren-2-ylmethylene)anilines are reported. Differences in liquid crystal thermal stability between pairs of related series of azomethines of fluorene 9-oxofluorene, 9,10-dihydrophenanthrene, and biphenyl are compared. Only one member of the 4: alkoxy-N-(2-naphthylmethylene)anilines shows liquid crystal behaviour.

Stabilized organic compound composition

Abstract: PURPOSE:A stabilized organic compound composition causing no oxidation deterioration even if it is exposed to high-temperature atmosphere, obtained by blending an organic compound with a light stabilizer and a specific fluorene compound CONSTITUTION:(A) 100ptswt organic compound (eg, PE, PPE, PVC, polyacrylate, PVA, etc) is blended with (B) 0001-10ptswt light stabilizer (eg, 2-hydroxy-4-methoxybenzophenone, etc), and (C) 0001-10ptswt compound shown by the formula [R is H, (substituted) alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, halogen, or carboxyl; R1-R8 are H, (substituted) alkyl, cycloalkyl, aryl, aralkyl, hydroxyl, halogen, etc], to give the desired composition

13C- und 1H-NMR-spektroskopische Untersuchungen an 2,9-substituierten Fluorenen

Abstract: 13C- and 1H-NMR-spectroscopical Investigations of 2,9-substituted Fluorenes The 13C- and 1H-chemical shifts for a series of 9-substituted fluorenes and 9-substituted 2-nitrofluorenes, where the substituents are various azarenium ions, have been determined, shift data for several other fluorenyl compounds are also presented. The exact assignments of the 13C-signals are possible by comparison of calculated shifts from 13C-data with experimental 1H-values. The substituent effects are discussed in terms of transmissions of electronic interactions. The substituent chemical shifts (SCS) for selective positions of the fluorene system give a linear correlation with the substituent constants σI, F, respectively. An increment model for the calculation of the empirical 13C-chemical shifts of N-(2-nitrofluorene-9-yl)azareniumions 3b–6b are presented.