Showing papers on "Fluorene published in 1981"
TL;DR: Synchronous fluorescence and the room-temperature phosphorescence methods were used to determine selected polynuclar aromatic hydrocarbons in a coal liquid (solvent-refined coal) product without a preseparation step.
88 citations
TL;DR: An analysis of a XAD-2 resin extract of a particulate air sample collected at an industrial environment was conducted by use of two simple spectroscopic methods performed at ambient temperature, the synchronous luminescence and room-temperature phosphorescence techniques.
Abstract: An analysis of a XAD-2 resin extract of a particulate air sample collected at an industrial environment was conducted by use of two simple spectroscopic methods performed at ambient temperature, the synchronous luminescence and room-temperature phosphorescence techniques. Results of the analysis of 13 polynuclear aromatic compounds including anthracene, benzo(a)pyrene, benzo(e)pyrene, 2,3-benzofluorene, chrysene, 1,2,5,6-dibenzanthracene, dibenzthiophene, fluoranthene, fluorene, phenanthrene, perylene, pyrene, and tetracene were reported.
80 citations
TL;DR: In this paper, the Vilsmeier reaction was used to synthesize polycyclic hydrocarbons (PAH) using the tetraloll and the saturated alcohol, respectively.
Abstract: The Synthesis of three typical polycyclic hydrocarbons (PAH) has been described, wherein the Vilsmeier reaction plays a major role. Vilsmeier reaction of the tetraloll gives the dihydronaphthaldehyde 2 which on cyclodehydration gives the dihydroarene 3. Ita dehydrogenation affords 3-methoxybenz[a]anthracene (4). Vilsmeier reaction on the dimethoxydihydronaphthalene 5 gives the versatile dimethoxydihydronaphthaldehyde 6 which has been converted to the dimethoxybenzo[c]fluorene 7 by direct cyclodehydration and the fulvene 10 by cyclodehydration of allylic alcohol 8 derived from 6 followed by dehydrogenation. The saturated alcohol 12 corresponding to 8 undergoes cyclodehydration to give the dimethoxyhexahydrobenzo[c]phenanthrene (13). Some of the advantages of the Vilsmeier approach to PAH have been pointed out.
38 citations
34 citations
TL;DR: In this paper, the authors examined the process of adsorbing fluorene on fly ash in detail, and the significance of the results in terms both of atmospheric dispersal of polycyclic aromatic hydrocarbons and sampling these compounds for chemical analysis is discussed.
Abstract: Fluorene is representative of group of polycyclic aromatic hydrocarbons that have been shown to exhibit oxidation in the absence of light when adsorbed on fly ash. The present study examines this process for fluorene in detail. Fluorene has been adsorbed on several different fly ashes and other adsorbents including activated carbon, molecular sieves, alumina, silica gel, and Ambersorb XE-340. In addition, the rate of decomposition of fluorene vapour-adsorbed on one of the fly ashes has been studied, and the effect of the amount of fluorene adsorbed on the fly ash upon its nonphotochemical oxidation has been determined. The significance of the results in terms both of atmospheric dispersal of polycyclic aromatic hydrocarbons and of sampling these compounds for chemical analysis is discussed.
23 citations
TL;DR: In this article, mass spectra of 2-hydroxydiphenylmethane and its derivatives are characterized in the upper mass region by an abundant ion m/z 165.
Abstract: Mass spectra of 2-hydroxydiphenylmethane and its derivatives are characterized in the upper mass region by an abundant ion m/z 165. Metastable ion measurements reveal that this ion is formed from the molecular ion of the parent compound by elimination of H2O and hydrogen. A fluorenyl cation structure is proposed for this ion on the basis of identity of collision induced mass analyzed ion kinetic energy spectra of ion m/z 165 generated from 2-hydroxydiphenylmethane and from fluorene. Four different pathways of formation of a fluorenyl cation are discussed. The contribution of each of these to the genesis of fragment m/z 165 was monitored in a reversed geometry instrument by measuring the first fragmentation in the first field free region and the second fragmentation in the second field free region.
12 citations
TL;DR: In this article, magnetic susceptibility anisotropies for acenaphthene, fluorene, biphenyl, and porphin were derived from the quadrupolar line splittings in the 2H NMR spectra of the compounds in a field of 9.3 T.
11 citations
10 citations
TL;DR: In this paper, the authors defined values of retention volumes for zero surface coverage (Henry's constant) at different temperatures, retention indices and variations of the internal energy (differential heats of adsorption) of diphenyl and its alkyl derivatives, including terphenyls and diphenylethanes, on graphitized thermal carbon black (GTCB).
Abstract: This paper defines values of retention volumes for zero surface coverage (Henry's constant) at different temperatures, retention indices and variations of the internal energy (differential heats of adsorption) of diphenyl and its alkyl derivatives, terphenyls, diphenylmethane, triphenylmethane, diphenylethanes and fluorene on graphitized thermal carbon black (GTCB). Adsorption on GTCB takes place in accordance with the geometry of these molecules, the strongest adsorption being observed for para-terphenyl with least inhibited internal rotation of the molecule, while the weakest adsorption occurs for 2,6,2′,6′-tetramethyldiphenyl with the most inhibited internal rotation of the molecules. The flat molecules of fluorene are adsorbed on GTCB more readily than the nonflat molecules of diphenylmethane.
8 citations
TL;DR: The structures of spiro[cyclopropane-1,9′-[9H]fluorene] (1) and 2,2- dichlorospiro(1, 9′]-9H) fluorene [2] have been determined by conventional single-crystal X-ray diffraction techniques.
Abstract: The structures of spiro[cyclopropane-1,9′-[9H]fluorene] (1) and 2,2- dichlorospiro[cyclopropane-1,9′-[9H]fluorene] (2) have been determined by conventional single-crystal X-ray diffraction techniques. Compound 1 crystallizes with 32 molecules in the unit cell in space group C212v–Iba 2 of the orthorhombic system in a cell of dimensions a = 42.228(23), b = 27.318(17) and c = 7.664(8) A. Compound 2 crystallizes with four molecules in the unit cell in space group C52h–P21/c of the monoclinic system in a cell of dimensions a = 8.451(3), b = 8.960(3), c = 15.882(5) A and β = 97.31(1)°. The structures of 1 and 2 have been refined by full-matrix least-squares techniques to conventional R indices of 0.055 and 0.049, respectively. Relative to the bridgehead position, the cyclopropane ring in 1 contains a short distal bond of average value 1.496(9)A and lengthened vicinal bonds averaging 1.531(11)A. This geometry agrees qualitatively with a simple molecular orbital model for charge transfer from cyclopropane to an aromatic π-system held in the bisected conformation. The cyclopropane ring in compound 2 contains C–C bond lengths of 1.537(3), 1.517(3) and 1.475(3) A. These values cannot be explained by summing the expected changes induced by the aromatic and halogen substituents.
8 citations
TL;DR: In this article, the electrochemical reductions of fluorenone hydrazone (Fl=NNH2) and benzophenone analogs were studied at platinum cathodes in DMF−0.1 M(n-Bu)4NClO4 in the absence and presence of an added proton donor.
TL;DR: Using time dependent phosphorescence and triplet-triplet absorption studies, the kinetics of the lowest excited triplet state of deuterated acridine has been studied up to room temperature in the hosts fluorene-d8h2, flourene-d10 and dibenzofurane as discussed by the authors.
TL;DR: The solvolytic reaction of several 9-(ortho-substituted benzyl)fluorene-9-trimethylammonium salts in ethanol at 57.3 °C has been found to give both the substitution and elimination products as discussed by the authors.
Abstract: The solvolytic reaction of several 9-(ortho-substituted benzyl)fluorene-9-trimethylammonium salts in ethanol at 57.3 °C has been found to give both the substitution and elimination products. The ob...
TL;DR: In this article, the conjugative properties of cyclopropanes were studied using the Corey method, which is suited for the preparation of modest (1 − 5 g) amounts of cyclops in one step.
TL;DR: In this article, the rotamers of 9-(2-formyl-l-naphthyl)fluorene and 9-(α-hydroxybenzyl)-1-mixture of 9-2-hydroxymethyl-1-nophthyl]fluorenes were investigated and the results suggest that steric hindrance to the approach of a base to a proton in E2 elimination is the cause of poor reactivities of the aldehyde and the benzylic alcohol.
Abstract: Rotational isomers (sp and ap) of 9-(2-formyl-l-naphthyl)fluorene were isolated. ΔH\eweq and ΔS\eweq for rotation (sp → ap) were 24.0 kcal mol−1 and −7.9 e. u., respectively. Oxidation of the sp form afforded the corresponding carboxylic acid smoothly, whereas the ap form reacted very slowly to give a lactone. Oxidations of 9-(2-hydroxymethyl-1-naphthyl)fluorene and 9-[2-(α-hydroxybenzyl)-1-naphthyl]fluorene showed that the relative reactivities of the rotamers of the former were almost the same, while those of the latter differed to a great extent. The results suggest that the steric hindrance to the approach of a base to a proton in E2 elimination is the cause of poor reactivities of the ap forms of the aldehyde and the benzylic alcohol.
TL;DR: In this article, the polarization directions for the excited states of β-cyclodextrin (β-CyD) complexes with fluorene, carbazole, dibenzofuran, and Dibenzothiophene were investigated.
TL;DR: In this paper, the rotamers of 9-(2-hydroxy-1-naphthyl)fluorene, 9-( 2-hydroxyl 4,6-dimethylphenyl) fluororene and their methyl ethers have been prepared.
Abstract: 9-(2-Hydroxy-1-naphthyl)fluorene, 9-(2-hydroxy-4,6-dimethylphenyl)fluorene, and their methyl ethers have been prepared. They give stable rotamers, sp and ap, at room temperature, ap forms of the hy...
TL;DR: The addition of dibenzo-18crown-6 has been found to influence the rate of decay of the fluorene and 9-methyl-fluorene radical anions.
Abstract: The addition of dibenzo-18-crown-6 has been found to influence the rate of decay of the fluorene and 9-methyl-fluorene radical anions. The influence is most significant when Li+ is the counterion and the second-order kinetics observed with this counterion in the absence of the crown ether have been found to be prevented by its addition.
TL;DR: In this paper, thin crystalline films of the strong electron acceptors tetracyano-p - quinodimethane, quinode-dimethyl-quinone (QuD-QuD), quinD-dimethane (QuEQ), tracyanoethylene, chloranil, bromanil, fluorene and anthraquinone were formed on the ( ab ) plane of anthracene single crystals by condensation from the vapour phase.
TL;DR: In this article, it was shown that potassium superoxide can initiale autoxidations of fluorene, diphenylmethane, and distyryl methane.
Abstract: Potassium superoxide was found to initiale autoxidations of fluorene, diphenylmethane, and distyrylmethane. In each case the oxidation results in the formation of ketones as primary products. Kinet...
TL;DR: In this paper, it was shown by infrared that lead in the soluble compounds is incorporated into chelate compounds, while the insoluble products contain polymeric salts of the metal, and it was also shown that lead was incorporated into the chelate compound.
Abstract: Soluble and insoluble products differing in their metal content have been prepared by thermal degradation of tetraphenyl lead in polyphenolphthalein terephthalate, poly-9,9-bis(hydroxyphenyl)fluorene terephthalate and poly-(2,5)-4,4-diphenylene phthalide-1,3,4-oxadiazole. It is shown by infrared that lead in the soluble compounds is incorporated into chelate compounds, while the insoluble products contain polymeric salts of the metal.
TL;DR: In this article, the structural aspects of the acridine molecules as guests in the fluorene crystal were investigated by the method of atom-atom potential energy functions, and it was shown that in either case only a relatively small distance prevails between the nitrogen atom of a guest molecule and a hydrogen atom of the methylene group in adjacent host molecules, thus facilitating the hydrogen atom transfer process.
Patent•
04 Feb 1981
TL;DR: In this article, basic ethers of 7-oxo-7H-benzo(c) fluorene have been shown to evidence a pronounced antineoplastic and immunosuppressive effect in mammals suffering from leukemia.
Abstract: Basic ethers of 7-oxo-7H-benzo(c) fluorene have been shown to evidence a pronounced antineoplastic and immunosuppressive effect in mammals suffering from leukemia. The technique for preparing the described ethers and the addition salts thereof with pharmaceutically acceptable organic and inorganic acids involves the aminoalkylation of 5-hydroxy-7-oxo-7H-benzo(c) fluorene and its corresponding nuclear substituted derivatives on the hydroxylic oxygen atom.
TL;DR: In this article, the authors investigated the triplet state radical pair in fluorene single crystals doped with anthracene and showed that the resulting three-state radical pair can be investigated by EPR.
Abstract: Light absorption in fluorene single crystals doped with anthracene induces a photoreaction. One hydrogen atom from a fluorene host gets transferred to an anthracene guest molecule over a distance of several angstroms. The resulting triplet state radical pair is investigated by EPR. Fine‐ and hyperfine structure analyses are given. The photoprocess is similar to that found earlier in fluorene crystals doped with acridine or phenazine. Where the nitrogen lone pair orbitals of acridine or phenazine were suitable acceptors for the transferred hydrogen atoms with anthracene, the hydrogen has to enter a tetrahedral sp3 configuration at the guest molecule. Somewhat higher crystal temperatures are required for comparable intensity EPR‐lines of the photoproduct.