- Time-delayed, two-color excimer laser photolysis of 1,8-bis(substituted-methyl)naphthalenes with group 16 atom leaving groups
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Time-delayed, two-color photolysis of 1,8-bis(phenoxymethyl)-(1a), 1,8-bis(phenylthiomethyl)-(1b), and 1,8-bis(phenylselenomethyl)-naphthalene (1c) was conducted by successive irradiation of XeCl (308 nm) and XeF (351 nm) excimer lasers. The yield of the two-photon product, acenaphthene 3, was strongly dependent on the delay time and showed two maxima at different delay times.
- Ouchi, Akihiko,Koga, Yoshinori
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- Laser-jet Photolysis of 1,8-Bis(substituted-methyl)naphthalenes: the Effect of Heteroatom Leaving Groups on the Two-photon C-C Bond Formation
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The formation of acenaphthene 4 by laser-jet photolysis of 1,8-bis(phenoxymethyl)- (1a), 1,8-bis(phenylthiomethyl)- (1b) and 1,8-bis(phenylselenomethyl)-naphthalene (1c) strongly depends on the hetroatom of the leaving group; the increasing order of naphthalene consumption was 1c ca. 1b > 1a, whereas that for the formation of 4 was 1c > 1a > 1b.
- Ouchi, Akihiko,Adam, Waldemar
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- Time-delayed, Two-color Excimer Laser Photolysis of 1,8-Bis(halomethyl)naphthalenes
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Time-delayed two-color photolysis of 1,8-bis(bromomethyl)-naphthalene and 1,8-bis(chloromethyl)naphthalene was conducted by successive irradiation of XeCl (308 nm) and XeF (351 nm) excimer lasers.Increase in the yield of the two-photon product, acenaphthene, strongly depended on the delay time of the two lasers and showed two maxima at the delay times of 0-30 ns and 0.2-0.5 μs.
- Ouchi, Akihiko,Yabe, Akira
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- Reactivity of the 5-hydroacenaphthylene anion towards electrophiles
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The dianion of acenaphthylene can be converted into the 5-hydroanion by protonation with one equivalent of methanol. Subsequent reaction with electrophiles such as allyl bromide and propargyl bromide occurs selectively at position 1, resulting in the formation of the novel 1-allylacenaphthene and 1-propargylacenaphthene. In addition to what was observed in the case of methyl iodide, the hitherto unknown 1,1-dialkylated acenaphthene derivatives are formed as minor products; probably the lower reactivity of the unsaturated bromides is responsible for this side reaction. From the products of the reactions with 3,3-dimethylallyl bromide and (bromomethyl)cyclopropane the mechanism was found to be SN2. Reaction of the hydroanion with benzyl bromide takes place at position 1 as well as at position 2a. The reactivity of carbon 2a towards the soft electrophile benzyl bromide is attributed to the high HOMO coefficient at this position.
- Van Loo, Marcia E.,Lugtenburg, Johan,Cornelisse, Jan
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- A laser-specific C-C bond formation of bichromophoric compounds
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The formation of acenaphthene from less photoreactive 1,8-bis(bromomethyl)naphthalene and 1,8-bis(chloromethyl)naphthalene by high-fluence KrF excimer laser irradiation was observed; the result contrasts with failed attempts using a low-pressure mercury lamp.
- Ouchi, Akihiko,Yabe, Akira
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- Highly efficient C - C bond formation in the two-photon chemistry of 1,8-bis(substituted-methyl)naphthalenes by direct excitation of photoactive leaving groups
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High efficiency in the two-photon intramolecular C - C bond formation to the two-photon product acenaphthene (4), obtained in a maximum yield of 72%, was achieved by direct activation of two separate leaving groups of 1,8-bis(phenoxymethyl)- (1a), 1,8-bis(phenylthiomethyl)- (1b), and 1,8-bis(phenylselenomethyl)-naphthalenes (1c) during KrF excimer laser (248 nm) and of 1,8-bis(4-benzoylphenoxymethyl)- (1d), 1,8-bis(3-benzoylphenoxymethyl)- (1e), and 1,8-bis(2-naphthoxymethyl)naphthalenes (1f) during XeF excimer laser (351 nm) photolyses.
- Ouchi, Akihiko,Yabe, Akira,Adam, Waldemar
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- A remarkable wavelength dependence on the laser-induced two-photon C-C bond formation
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Two-photon intramolecular C-C bond formation of 1,8-bis(bromomethyl)naphthalene and 1,8-bis(chloromethyl)naphthalene by high fluence excimer laser irradiations showed a considerable wavelength dependence on the conversion, the efficiency, and the yield of the product; the results are interpreted by the selective excitation of the substrates.
- Ouchi,Yabe
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- Two-photon chemistry of 1,8-bis(bromomethyl)naphthalene in the laser-jet: Generation of acenaphthene by intramolecular C - C bond formation
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Argon ion laser-induced photolysis of 1,8-bis(bromomethyl)naphthalene (1) in the laser-jet with benzophenone as sensitizer gave ca. 8% (61% conversion) of acenaphthene (4) through cyclization of the intermediary non-Kekule diradical 1,8-dimethylenenaphthalene; in this two-photon process the first photon (333-nm) consumes 1, whereas the second photon (351 and 364 nm) forms 2, both steps are sensitized by benzophenone.
- Adam, Waldemar,Ouchi, Akihiko
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- Two-photon laser-induced reaction of 1,8-bis(halomethyl)naphthalenes from different excited states and transient targeting of its intermediate by time-delayed, two-color photolysis and argon ion laser-jet photolysis techniques
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Two-photon chemistry of 1,8-bis(bromomethyl)naphthalene (1a) and 1,8-bis(chloromethyl)naphthalene (1b) was studied by (a) laser photolysis with use of XeCl (308 nm), KrF (248 nm), and ArF (193 nm) excimer lasers, (b) time-delayed, two-color photolysis with use of XeCl and XeF (351 nm) lasers, and (c) argon ion laser-jet (333, 351, and 364 nm) photolysis by both direct and benzophenone sensitization. The reaction proceeds through an intermediate monoradical 2, which is generated by a one-photon process, followed by additional photolysis to the two-photon product acenaphthene (4). On excitation of substrate 1 to its S1 state, monoradical 2 is formed directly from the S1 state and subsequently from the T1 state through intersystem crossing, alternatively on benzophenone sensitization. Upper excited states, namely S2 and S3, of 1 are proposed in the KrF and AsF excimer laser irradiation, generating intermediate 2 through fast fragmentation of the T(σ*) state. Transient targeting of intermediate 2 by time-delayed, two-color photolysis and argon ion laser-jet photolysis increases considerably the yield of the two-photon product 4.
- Ouchi, Akihiko,Koga, Yoshinori,Adam, Waldemar
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- Synthesis of Decorated Carbon Structures with Encapsulated Components by Low-Voltage Electric Discharge Treatment
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Abstract: Polycondensation of complexes of chloromethanes with triphenylphosphine by the action of low-voltage electric discharges in the liquid phase gives nanosized solid products. The elemental composition involving the generation of element distribution maps (scanning electron microscopy–energy dispersive X?ray spectroscopy mapping) and the component composition (by direct evolved gas analysis–mass spectrometry) of the solid products have been studied. The elemental and component compositions of the result-ing structures vary widely depending on the chlorine content in the substrate and on the amount of triphenylphosphine taken. Thermal desorption analysis revealed abnormal behavior of HCl and benzene present in the solid products. In thermal desorption spectra, these components appear at an uncharacteristically high temperature. The observed anomaly in the behavior of HCl is due to HCl binding into a complex of the solid anion HCI-2 with triphenyl(chloromethyl)phosphonium chloride, which requires a relatively high temperature (up to 800 K) to decompose. The abnormal behavior of benzene is associated with its encapsulated state in nanostructures. The appearance of benzene begins at 650 K and continues up to temperatures above 1300?K.
- Bodrikov, I. V.,Pryakhina, V. I.,Titov, D. Yu.,Titov, E. Yu.,Vorotyntsev, A. V.
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- Metallic Barium: A Versatile and Efficient Hydrogenation Catalyst
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Ba metal was activated by evaporation and cocondensation with heptane. This black powder is a highly active hydrogenation catalyst for the reduction of a variety of unactivated (non-conjugated) mono-, di- and tri-substituted alkenes, tetraphenylethylene, benzene, a number of polycyclic aromatic hydrocarbons, aldimines, ketimines and various pyridines. The performance of metallic Ba in hydrogenation catalysis tops that of the hitherto most active molecular group 2 metal catalysts. Depending on the substrate, two different catalytic cycles are proposed. A: a classical metal hydride cycle and B: the Ba metal cycle. The latter is proposed for substrates that are easily reduced by Ba0, that is, conjugated alkenes, alkynes, annulated rings, imines and pyridines. In addition, a mechanism in which Ba0 and BaH2 are both essential is discussed. DFT calculations on benzene hydrogenation with a simple model system (Ba/BaH2) confirm that the presence of metallic Ba has an accelerating effect.
- Stegner, Philipp,F?rber, Christian,Zenneck, Ulrich,Knüpfer, Christian,Eyselein, Jonathan,Wiesinger, Michael,Harder, Sjoerd
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supporting information
p. 4252 - 4258
(2020/12/22)
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- Visible light enables catalytic formation of weak chemical bonds with molecular hydrogen
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The synthesis of weak chemical bonds at or near thermodynamic potential is a fundamental challenge in chemistry, with applications ranging from catalysis to biology to energy science. Proton-coupled electron transfer using molecular hydrogen is an attractive strategy for synthesizing weak element–hydrogen bonds, but the intrinsic thermodynamics presents a challenge for reactivity. Here we describe the direct photocatalytic synthesis of extremely weak element–hydrogen bonds of metal amido and metal imido complexes, as well as organic compounds with bond dissociation free energies as low as 31 kcal mol?1. Key to this approach is the bifunctional behaviour of the chromophoric iridium hydride photocatalyst. Activation of molecular hydrogen occurs in the ground state and the resulting iridium hydride harvests visible light to enable spontaneous formation of weak chemical bonds near thermodynamic potential with no by-products. Photophysical and mechanistic studies corroborate radical-based reaction pathways and highlight the uniqueness of this photodriven approach in promoting new catalytic chemistry. [Figure not available: see fulltext.].
- Park, Yoonsu,Kim, Sangmin,Tian, Lei,Zhong, Hongyu,Scholes, Gregory D.,Chirik, Paul J.
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p. 969 - 976
(2021/07/25)
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- Proton donor effects on the reactivity of SmI2. Experimental and theoretical studies on methanol solvationvs. Aqueous solvation
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Proton donors are important components of many reactions mediated by samarium diiodide (SmI2). The addition of water to SmI2creates a reagent system that enables the reduction of challenging substrates through proton-coupled electron-transfer (PCET). Simple alcohols such as methanol are often used successfully in reductions with SmI2but often have reduced reactivity. The basis for the change in reactivity of SmI2-H2O and SmI2-MeOH is not apparent given the modest differences between water and methanol. A combination of Born-Oppenheimer molecular dynamics simulations and mechanistic experiments were performed to examine the differences between the reductants formedin situfor the SmI2-H2O and SmI2-MeOH systems. This work demonstrates that reduced coordination of MeOH to Sm(ii) results in a complex that reduces arenes through a sequential electron proton transfer at low concentrations and that this process is significantly slower than reduction by SmI2-H2O.
- Bartulovich, Caroline O.,Boekell, Nicholas G.,Flowers, Robert A.,León-Pimentel, César Iván,Ramírez-Solís, Alejandro,Saint-Martin, Humberto
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supporting information
p. 7897 - 7902
(2020/06/26)
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- Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
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Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
- Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
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supporting information
p. 166 - 176
(2020/01/02)
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- Birch-Type Photoreduction of Arenes and Heteroarenes by Sensitized Electron Transfer
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The direct reduction of arenes and heteroarenes by visible-light irradiation remains challenging, as the energy of a single photon is not sufficient for breaking aromatic stabilization. Shown herein is that the energy accumulation of two visible-light photons allows the dearomatization of arenes and heteroarenes. Mechanistic investigations confirm that the combination of energy-transfer and electron-transfer processes generates an arene radical anion, which is subsequently trapped by hydrogen-atom transfer and finally protonated to form the dearomatized product. The photoreduction converts planar aromatic feedstock compounds into molecular skeletons that are of use in organic synthesis.
- Chatterjee, Anamitra,K?nig, Burkhard
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supporting information
p. 14289 - 14294
(2019/08/30)
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- Mechanisms of Heptane Degradation and Product Formation in Microwave Discharge
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Abstract: A mechanism for the degradation of n-heptane and the formation of the products of its plasma-chemical transformation by microwave discharge treatment has been proposed. Chemical reactions resulting in reactive species, namely free radicals that form lower hydrocarbons and polyaromatic structures are presented. The product composition of the gas, liquid, and solid phases has been studied using gas chromatography–mass spectrometry analysis of the precipitate obtained by evaporation of the liquid phase after the treatment of n-heptane.
- Bobkova,Stokolos,Garifullin
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p. 336 - 340
(2019/08/15)
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- A Practical and Chemoselective Ammonia-Free Birch Reduction
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A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. A broad range of aromatic and heteroaromatic compounds is reduced with excellent yields.
- Lei, Peng,Ding, Yuxuan,Zhang, Xiaohe,Adijiang, Adila,Li, Hengzhao,Ling, Yun,An, Jie
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supporting information
p. 3439 - 3442
(2018/06/26)
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- Novel electronic salt system and method for reducing unsaturated hydrocarbon compound
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The invention discloses an electronic salt system and a method for reducing unsaturated hydrocarbon compounds by using the electronic salt system, belongs to the field of organic synthesis, and solvesthe problems such as complicated operation, harsh conditions, easy generation of complex over-reduction products of methods for reducing the unsaturated hydrocarbon compounds in the prior art. An electron salt may be synthesized by an alkali metal reagent, an ether and an alcohol, the ether can be a crown ether or a cryptand; and the method adopts the electronic salt system, the unsaturated hydrocarbon compounds is reduced by the electronic salt system in an organic solvent. The method for reducing the unsaturated hydrocarbon compounds is used for reducing the unsaturated hydrocarbon compounds.
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Paragraph 0081-0085
(2018/09/08)
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- Nanoporous metal oxides with tunable and nanocrystalline frameworks via conversion of metal-organic frameworks
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Nanoporous metal oxide materials are ubiquitous in the material sciences because of their numerous potential applications in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics, and drug delivery. While synthetic
- Kim, Tae Kyung,Lee, Kyung Joo,Cheon, Jae Yeong,Lee, Jae Hwa,Joo, Sang Hoon,Moon, Hoi Ri
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supporting information
p. 8940 - 8946
(2013/07/26)
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- Clay entrapped nickel nanoparticles as efficient and recyclable catalysts for hydrogenation of olefins
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Nickel nanoparticles are prepared in the interlamellar spaces of K10-Montmorillonite clay by chemical reduction at moderate temperatures. These clay entrapped nickel nanoparticles are characterized by UV-vis, powder XRD, EDX and HRTEM studies. The resultant ecofriendly supramolecular assembly with nickel content (2.84 wt %) has good catalytic efficiency in hydrogenation of alkenes and alkynes with hydrazine as a reducing agent in ethanol medium. Advantages of the present study include absence of an external hydrogen source, catalyst reusability and a green medium.
- Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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p. 1818 - 1823
(2008/09/18)
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- Vanadium(I) chloride and lithium vanadium(I) dihydride as selective epimetallating reagents for π- and σ-bonded organic substrates
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Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, whose efficient preparation, structural constitution and mode of reaction toward certain organic substrates have been described in a preceding article, are here evaluated in their reactions toward a wide variety of π- and σ-bonded organic substrates, namely carbonyl, imine, azo, alkene, 1,3-diene, nitrile π-bonds and C-X, C-O, C-N and N-N σ-bonds. Compared with the high reactivity of CrCl and LiCrH2 reagents in attacking both types of bonds, the VCl and LiVH2 reagents were much milder and selective in epimetallating π-bonds, often forming the 1:1 adduct of LiVH2 and π-bonded substrate as the major product. Finally, the vanadium reagents showed little tendency to cleave C-O, C-S and C-N bonds and a smaller scope in cleaving C-X bonds than their chromium counterparts. Because of their selectivity these vanadium reagents offer the following preparative promise: 1) smooth McMurry carbonyl coupling to their reductive dimers; 2) deoxygenation of epoxides; 3) selective aromatic C-X reduction; 4) high yields of epimetallated carbonyls or imines as intermediates to α-hydroxy and α-amino acids; 5) 1,4-reductions of 1,3-alkadienes; 6) reductive dimerization of nitriles to ketones; 7) 1,4 or 1,n-epimetallations leading to acyloins or indoles; and 8) reductive dimerizations of azines to produce unusual imidazole derivatives. In explaining the greater kinetic stability of the 1:1 LiVH2 adduct with carbonyl or imine substrates it is pointed out that such epimetallated adducts from LiVH2 would likely be diamagnetic, whereas such adducts from LiCrH2 have an unpaired electron on the Cr center and hence would rupture, so that the electron would be on the C center. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Eisch, John J.,Fregene, Paul O.
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scheme or table
p. 4482 - 4492
(2009/05/07)
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- Role of temperature and hydrochloric acid on the formation of chlorinated hydrocarbons and polycyclic aromatic hydrocarbons during combustion of paraffin powder, polymers, and newspaper
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Formation of chlorinated hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were determined using a laboratory-scale incinerator when combusting materials at different temperatures, different concentrations of hydrochloric acid (HCl), and when combusting various types of polymers/newspaper. Polychlorobenzenes (PCBz), polychlorophenols (PCPhs), polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and their toxic equivalency (TEQ) and PAHs were highlighted and reported. Our results imply maximum formation of chlorinated hydrocarbons at 400°C in the following order; PCBz≥PCPhs?PCDFs>PCDDs>TEQ on a parts-per-billion level. Similarly, a maximum concentration of chlorinated hydrocarbons was noticed with an HCl concentration at 1000 ppm with the presence of paraffin powder in the following order; PAHs>PCBz≥PCPhs?PCDFs>PCDDs>TEQ an a parts-per-billion level. PAHs were not measured at different temperatures. Elevated PAHs were noticed with different HCl concentrations and paraffin powder combustion (range: 27-32 μg/g). While, different polymers and newspaper combusted, nylon and acrylonitrile butadiene styrene (ABS) produced the maximum hydrogen cyanide (HCN) concentration, concentrations of PCDD/FS, dioxin-like polychlorinated biphenyls (DL-PCBs), and TEQ were in a decreasing order: polyvinylchloride (PVC)newspaperpolyethyleneterephthalate (PET) polyethylene (PE) polypropylene (PP) ABS = blank. Precursors of PCBs were in a decreasing order: PPnylonPEnewspaperABSPVCblankPET. Precursors of PCDD/Fs were in a decreasing order: newspaper PP= nylonPEABSPVC= blankPET. BTX formation was in a decreasing order; PEnylonnewspaperABSPP. PAHs formation were elevated with parts-per-million levels in the decreasing order of PPnylonPE newspaperblankABS PETPVC.
- Takasuga, Takumi,Umetsu, Norihito,Makino, Tetsuya,Tsubota, Katsuya,Sajwan, Kenneth S.,Kumar, Kurunthachalam Senthil
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- Estimating the limiting reducing power of SmI2/H 2O/amine and YbI2/H2O/amine by efficient reduction of unsaturated hydrocarbons
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The mixture of samarium diiodide, amine, and water (SmI2/H 2O/Et3N) is known to be a particularly powerful reductant, but until now the limiting reducing power has not been determined. A series of unsaturated hydrocarbons with varying half-wave reduction potentials (E 1/2 = -1.6 to -3.4 V, vs SCE) have been treated with SmI 2/H2O/Et3N and YbI2/H 2O/Et3N, respectively. All hydrocarbons with potentials of -2.8 V or more positive were readily reduced with SmI2/H 2O/Et3N, whereas all hydrocarbons with potentials of -2.3 V or more positive were readily reduced using YbI2/H 2O/Et3N. This defines limiting values of the chemical reducing power of SmI2/H2O/Et3N to -2.8 V and of YbI2/H2O/Et3N to -2.3 V vs SCE.
- Dahlen, Anders,Nilsson, Ake,Hilmersson, Goeran
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p. 1576 - 1580
(2007/10/03)
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- Synthesis of aromatic carboxylic acids by carbonylation of aryl halides in the presence of epoxide-modified cobalt carbonyls as catalysts
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A new procedure was developed for synthesis of aromatic and heteroaromatic acids and their derivatives (esters, salts) by carbonylation of the corresponding aryl halides. The acids are selectively formed in a high yield under very mild conditions. Highly active catalytic systems, base-containing alcoholic solutions of cobalt carbonyl modified with epoxides, were used to activate aryl halides. 2005 Pleiades Publishing, Inc.
- Boyarskii,Zhesko,Lanina
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p. 1844 - 1848
(2007/10/03)
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- Emission factors and importance of PCDD/Fs, PCBs, PCNs, PAHs and PM 10 from the domestic burning of coal and wood in the U.K.
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This paper presents emission factors (EFs) derived for a range of persistent organic pollutants (POPs) when coal and wood were subject to controlled burning experiments, designed to simulate domestic burning for space heating. A wide range of POPs were emitted, with emissions from coal being higher than those from wood. Highest EFs were obtained for particulate matter, PM10, (～ 10 g/kg fuel) and polycyclic aromatic hydrocarbons (～ 100 mg/ kg fuel for ΣPAHs). For chlorinated compounds, EFs were highest for polychlorinated biphenyls (PCBs), with polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) being less abundant. EFs were on the order of 1000 ng/kg fuel for ΣPCBs, 100s ng/ kg fuel for ΣPCNs and 100 ng/kg fuel for ΣPCDD/Fs. The study confirmed that mono- to trichlorinated dibenzofurans, Cl1,2,3DFs, were strong indicators of low temperature combustion processes, such as the domestic burning of coal and wood. It is concluded that numerous PCB and PCN congeners are routinely formed during the combustion of solid fuels. However, their combined emissions from the domestic burning of coal and wood would contribute only a few percent to annual U.K. emission estimates. Emissions of PAHs and PM 10 were major contributors to U.K. national emission inventories. Major emissions were found from the domestic burning for Cl1,2,3DFs, while the contribution of PCDD/F-ΣTEQ to total U.K. emissions was minor.
- Lee, Robert G. M.,Coleman, Peter,Jones, Joanne L.,Jones, Kevin C.,Lohmann, Rainer
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p. 1436 - 1447
(2007/10/03)
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- Experimental study on the removal of PAHs using in-duct activated carbon injection
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This paper presents the incineration tests of municipal solid waste (MSW) in a fluidized bed and the adsorption of activated carbon (AC) on polycyclic aromatic hydrocarbons (PAHs). An extraction and high performance liquid chromatography (HPLC) technique was used to analyze the concentrations of the 16 US EPA specified PAHs contained in raw MSW, flue gas, fly ash, and bottom ash. The aim of this work was to decide the influence of AC on the distribution of PAHs during the incineration of MSW. Experimental researches show that there were a few PAHs in MSW and bottom ash. With the increase of AC feeding rate, the concentrations of three- to six-ring PAHs in fly ash increased, and the concentration of two-ring PAH decreased. The total-PAHs in flue gas were dominated by three-, and four-ring PAHs, but a few two-, five-ring PAHs and no six-ring PAHs were found. PAHs could be removed effectively from flue gas by using in-duct AC injection and the removal efficiencies of PAHs were about 76-91%. In addition, the total toxic equivalent (TEQ) concentrations of PAH in raw MSW, bottom ash, fly ash, and flue gas were 1.24 mg TEQ kg-1, 0.25 mg TEQ kg-1, 6.89-9.67 mg TEQ kg-1, and 0.36-1.50 μg TEQ N m-3, respectively.
- Zhou, Hong-Cang,Zhong, Zhao-Ping,Jin, Bao-Sheng,Huang, Ya-Ji,Xiao, Rui
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p. 861 - 869
(2007/10/03)
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- Facile deoxygenation of dicarbonyl compounds using a samarium diiodide-additive system
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The reduction of α- and β-dicarbonyl compounds was investigated with samarium diiodide in the presence of additive. Diketones and ketocarboxylic acids were easily reduced at room temperature to give the mono-alcohols in good to excellent yield, and ketoester afforded the saturated ester as the major product in moderate yield. These reductions containing the reductive deoxygenation can be rapidly performed under the facile and mild conditions by this method.
- Kamochi, Yasuko,Kudo, Tadahiro,Masuda, Toshinobu,Takadate, Akira
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p. 1017 - 1020
(2007/10/03)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Relationship between pressure fluctuations and generation of organic pollutants with different particle size distributions in a fluidized bed incinerator
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The hydrodynamic behaviors of fluidization perhaps significantly influence the uniformity of fluidization in fluidized bed incinerator. Good uniformity of fluidization expressed the air across uniformly through the bed and the particles being distributed well in the fluid stream. The aggregates, flocs and channels of particles do not happen during fluidization. The Good uniformity will maintain high heat and mass distribution to improve reaction efficiency. These parameters include the height of static bed, gas velocity, mixing and distribution of bed particle, which have rarely been studied in previous investigations. Consequently, this study examines how the hydrodynamic parameters affect the generation of organic pollutants (BTEXs and PAHs) during incineration. The statistical and power spectral analysis of the measured pressure fluctuation during incineration are used to elucidate the relationship between behaviors of fluidization and generation of pollutants during incineration. Experimental results show the organic concentration does not increase with uniformity of fluidization decreasing. The reason may be the explosion of the gas and the consequent thermal shock destroy the coalescent bubbles to form small bubbles again and enhance the efficiency of transfer of oxygen to increase combustion efficiency. Additionally, the mean amplitude and fluidized index of pressure fluctuation similarly vary with the concentration of organic pollutants. These two indices can be used to assess the efficiency of combustion. The four particle size distributions could be divided into two groups by statistical analysis. The Gaussian and narrow distributions belong to one group and the binary and flat the other. The organic concentration of the Gaussian and narrow distributions are lower than that of the other distributions. Consequently, the bed materials should maintain narrow or Gaussian distributions to maintain a good combustion efficiency during incineration.
- Lin, Chiou-Liang,Wey, Ming-Yen,Cheng, Han-Tsung
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p. 911 - 922
(2007/10/03)
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- Therapeutics for chemokine mediated diseases
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The invention provides therapeutic and biological uses of chemokine-receptor-binding compounds (including chemokine receptor ligands such as chemokine receptor agonists or antagonists), such as tricyclic phenanthrene derivatives, including uses in the treatment of disease states mediated by chemokines. The relevant chemokines may for example be monocyte chemoattractant protein-one (MCP-1) or interleukin-8 (IL-8), and the relevant chemokine receptors may for example be corresponding chemokine receptors (CCR-2, CCR-4, CXCR-1, and CXCR-2). In other aspects, the invention provides corresponding pharamaceutical compositions and therapeutic methods. In one aspect, for example, the invention provides for the use of phenanthrene-9,10-dione in the treatment of multiple sclerosis.
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- Preparation process of fluorenes
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A tetrahydrofluorene, which is represented by the following formula (I) wherein R1to R6each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or R1and R2are combined together to represent ═O, ═N or ═S, R7and R8each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group or a carboxyl group, is subjected to a hydrogen transfer reaction in the presence of a hydrogen acceptor and a catalyst, whereby a fluorene and a hydride of the hydrogen acceptor are formed at the same time.
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- Reduction of diaryl alkenes by hypophosphorous acid-iodine in acetic acid
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A mixture of 50% aqueous H3PO2 and I2 (in catalytic amount) in HOAc efficiently reduces aryl alkenes to the corresponding alkanes in high yield. Addition of acetic anhydride to the medium results in ring-acetylation (or N-acetylation in the case of amines). H3PO2 costs only one-fifth as much as hydriodic acid on a mole basis and one mole of H3PO2 produces four moles of HI, resulting in a 20-fold cost advantage for H3PO2/I2 over aqueous HI as a source of HI.
- Fry, Albert J.,Allukian, Myron,Williams, Allison D.
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p. 4411 - 4415
(2007/10/03)
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- Preparation process of fluorenes
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A tetrahydrofluorene, which is represented by the following formula (I) wherein R1 to R6 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or R1 and R2 are combined together to represent ═O, ═N or ═S, R7 and R8 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group or a carboxyl group, is subjected to a hydrogen transfer reaction in the presence of a hydrogen acceptor and a catalyst, whereby a fluorene and a hydride of the hydrogen acceptor are formed at the same time.
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- Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator
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Emissions data have been obtained from a waste propellant incinerator. The incinerator is a dual fixed hearth, controlled air incinerator equipped with acid gas and particulate scrubbing. Puffing has been evident in this waste propellant incinerator by spikes in the CO concentration. Transient puffs of organics may travel down the combustion chambers and lead to stack emissions. The major conclusions from this study are that (1) transient puffs are formed due to the semi-batch feed nature of the combustion process (causing a local oxygen deficiency) and high water content of the desensitized propellant; (2) in batch-fed combustors, puffs can contribute to most of the organic emissions (which are relatively low) measured with US EPA sampling and analytical methods; (3) it is estimated that batch-fed combustion contributes up to 7-18 times more emissions than steady-state combustion will generate; (4) by applying dispersion analyses to determine the amount of oxygen deficiency in the flame zone, the combustion zone concentration of CO during batch-fed operation could be as high as 160,000 ppm, compared to a measured peak stack concentration of 1200 ppm CO; and (5) an organic sample is collected and averaged over at least a 2-h period that smooths out the transient peaks of organics emissions during batch-fed operation. For emissions that are associated with long-term potential health impacts, this is an appropriate sampling method. However, if a compound has a short-term potential health impact, it may be important to measure the time-resolved emissions of the compound.
- Hart, John R.
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p. 559 - 569
(2007/10/03)
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- Reactivity of the 5-hydroacenaphthylene anion towards electrophiles, 2. - Single electron transfer vs. S(N)2 reaction
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Reaction of the 5-hydroacenaphthylene anion with benzyl halides proceeds at carbon atom 1 as well as at carbon atom 2a, in the latter case creating a quaternary centre. The hardness-softness of the electrophiles was shown to play only a minor role in determining the regioselectivity of the reaction of the hydroanion with several benzyl and alkyl halides: the leaving group hardly affects the ratio of 1- and 2a-substituted products. This indicates that the alkylation might proceed by an electron transfer (SET) instead of an S(N)2 mechanism. Further evidence for SET was obtained by the use of free radical and electron scavengers. The substitution products 1-benzyl- acenaphthene and 2a-benzyl-2a,5-dihydroacenaphthylene could be isolated and purified.
- Van Loo, Marcia E.,Lugtenburg, Johan,Cornelisse, Jan
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p. 713 - 721
(2007/10/03)
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- Investigation of polycyclic aromatic hydrocarbons in fly ash from fluidized bed combustion systems
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A laboratory scale fluidized bed reactor and a bench scale 0.1 MW(th) fluidized bed combustor were used to study the effect of operating conditions on the formation of Polycyclic Aromatic Hydrocarbons (PAHs) in fly ash from fluidized bed combustion systems. A high volatile bituminous coal was chosen to investigate PAH emissions during the entire pyrolysis to oxygen-rich combustion process. During the experiments, the fluidized bed reactor was operated at temperatures between 700°C and 900°C, while the excess air ratio was varied from 0 to 1.3. An extraction and GC/MS analysis of PAHs was used in this study. Approximately 40 different PAHs were identified during the tests, of which only a few are specified by the U.S. EPA. The experimental results indicate the majority of the PAHs in the solid phase (bed and fly ash) are derived from the breakdown reactions during the processes of combustion and/or pyrolysis in a Fluidized Bed Combustion (FBC) system, although FBC systems have an efficient solid-gas mixing process and relatively long residence time. The total amount of PAHs in the fly ash was much higher than that in the raw coal and in the gas phase. Three-and four- ring aromatic compounds were the major PAHs from pyrolysis conditions, while naphthalene (two-rings) is the dominant compound in bed ash collected from oxygen-rich combustion conditions. Only naphthalene was detected in the bed ash in the FBC system. High-speed secondary air (air staging) injected into the freeboard of the FBC system is an effective method for minimizing PAH emissions, along with the other benefits including minimizing NO(x) and SO(x) emissions. A laboratory scale fluidized bed reactor and a bench scale 0.1 MWth fluidized bed combustor were used to study the effect of operating conditions on the formation of Polycyclic Aromatic Hydrocarbons (PAHs) in fly ash from fluidized bed combustion systems. A high volatile bituminous coal was chosen to investigate PAH emissions during the entire pyrolysis to oxygen-rich combustion process. During the experiments, the fluidized bed reactor was operated at temperatures between 700°C and 900°C, while the excess air ratio was varied from 0 to 1.3. An extraction and GC/MS analysis of PAHs was used in this study. Approximately 40 different PAHs were identified during the tests, of which only a few are specified by the U.S. EPA. The experimental results indicate the majority of the PAHs in the solid phase (bed and fly ash) are derived from the breakdown reactions during the processes of combustion and/or pyrolysis in a Fluidized Bed Combustion (FBC) system, although FBC systems have an efficient solid-gas mixing process and relatively long residence time. The total amount of PAHs in the fly ash was much higher than that in the raw coal and in the gas phase. Three-and four-ring aromatic compounds were the major PAHs from pyrolysis conditions, while naphthalene (two-rings) is the dominant compound in bed ash collected from oxygen-rich combustion conditions. Only naphthalene was detected in the bed ash in the FBC system. High-speed secondary air (air staging) injected into the freeboard of the FBC system is an effective method for minimizing PAH emissions, along with the other benefits including minimizing NOx and SOx emissions.
- Liu, Kunlei,Xie, Wei,Zhao, Zheng-Bao,Pan, Wei-Ping,Riley, John T.
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p. 2273 - 2279
(2007/10/03)
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- Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
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A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
- Fullana,Font,Conesa,Blasco
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p. 2092 - 2099
(2007/10/03)
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- Fine particle and gaseous emission rates from residential wood combustion
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Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning-communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter(a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and se mivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8- C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and forts were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography. Residential wood combustion emissions were analyzed to determine emission rates and to develop chemical emissions profiles that represent the appliances and woods typically used in wood-burning communities. Over 350 elements, inorganic compounds, and organic compounds were quantified. A range of 4-9 g/kg dry fuel of particulate matter (a dilution stack sampler equipped with a 2.5-μm particle selective cyclone. Emissions were diluted 20-70 times, cooled to ambient temperature, and allowed 80 s for condensation prior to collection. Wood type, wood moisture, burn rate, and fuel load were varied for different experiments. Fine particle and semivolatile organic compounds were collected on filter/PUF/XAD/PUF cartridges. Inorganic samples and mass were collected on Teflon and quartz filters. Volatile organic carbon compounds were trapped with Tenax (C8-C20), canister (C2-C12), and 2,4-dinitrophenylhydrazine impregnated cartridges (carbonyl compounds). Analysis of particle and semivolatile organic species was conducted by gas chromatography/mass spectrometry. Teflon filters were analyzed for mass by gravimetry, trace elements were analyzed by X-ray fluorescence, and ammonium was analyzed by automated colorimetry. Quartz filters were analyzed for organic and elemental carbon by thermal/optical reflectance, and ions were analyzed by ion chromatography. Select quartz filters were analyzed by accelerator mass spectrometry for carbon-12 and carbon-14 abundance. Canister and Tenax samples were analyzed by gas chromatography with a flame ionization detector, and carbonyl compounds were analyzed by high-performance liquid chromatography.
- Mcdonald, Jacob D.,Zielinska, Barbara,Fujita, Eric M.,Sagebiel, John C.,Chow, Judith C.,Watson, John G.
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p. 2080 - 2091
(2007/10/03)
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- Perylene derivatives formation in reaction of 3-bromobenzanthrone and 4-bromonaphthalic acid derivatives with a reduction system NiCl2 - 2,2′bipyridyl (or 1,10-phenathroline) - Zn
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The reaction of 3-bromobenzanthrone and 4-bromonaphthalic acid derivatives with a reduction system NiCl2-2,2′bipyridyl (or 1,10-phenathroline)-Zn gives rise to compounds containing perylene fragment. Under similar conditions was established a possibility to transform substituted 1,1′-binaphthyls into the corresponding perylene derivatives.
- Adonin,Ryabinin,Starichenko
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p. 861 - 865
(2007/10/03)
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- Fine particulate matter (PM) and organic speciation of fireplace emissions
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This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an ongoing project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory- built fireplaces. RWC wood smoke particles 10 μm (PM10) consist primarily of a mixture of organic compounds that have condensed into droplets; therefore, the size distribution and total mass are influenced by temperature of the sample during its collection. During the series 1 tests (15 tests), the dilution tunnel used to cool and dilute the stack gases gave an average mixed gas temperature of 47.3 °C and an average dilution ratio of 4.3. Averages for the PM2.5 (particles 2.5 μm) and PM10 fractions were 74 and 84%, respectively. For the series 2 tests, the dilution tunnel was modified, reducing the average mixed gas temperatures to 33.8 °C and increasing the average dilution ratio to 11.0 in tests completed to date. PM2.5 and PM10 fractions were 83 and 91%, respectively. Since typical winter time mixed gas temperatures would usually be less than 10 °C, these size fraction results (even from the series 2 tests) probably represent the lower bound; the PM10 and PM2.5 size fractions might be higher at typical winter temperatures. The particles collected on the first stage (cutpoint ? 11.7 μm) were light gray and appeared to include inorganic ash. Particles collected on the remainder of the stages were black and appeared to be condensed organics because there was noticeable lateral bleeding of the collected materials into the filter substrate. Total particulate emission rates ranged from 10.3 to 58.4 g/h; corresponding emission factors ranged from 3.3 to 14.9 g/kg of dry wood burned. A wide range of Environmental Protection Agency (EPA) Method 8270 semivolatile organic compounds were found in the emissions; of the 17 target compounds quantified, major constituents are phenol, 2-methylphenol, 4- methylphenol, 2,4-dimethylphenol, and naphthalene. An account is given on fireplace particle size and organic speciation data gathered to date in an ongoing project. Total particulate matter emission rates and the results of analyses for semivolatile organics in the emissions are discussed.
- Purvis, Carol R.,Mccrillis, Robert C.,Kariher, Peter H.
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p. 1653 - 1658
(2007/10/03)
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- Reaction of substituted 5-bromoacenaphthenes with the catalytic reduction system NiCl2-2,2'-bipyridyl (or 1,10-phenanthroline)-Zn
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Transformations of substituted 5-bromoacenaphthenes under the action of a catalytic reduction system NiCl2-2,2'-bipyridyl (or 1,10-phenanthrolyne)-Zn in DMF and DMA was studied. Two types of transformation are shown to be characteristic for the studied compounds: reductive coupling with formation of the corresponding 5,5'-biacenaphthenyl and halogen elimination with hydrogen replacing the halogen. Yields of the coupling products and that of dehalogenation are found to depend substantially on the nature of the substituents in the nanhfhalene ring.
- Adonin,Ryabinin,Starichenko
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p. 913 - 915
(2007/10/03)
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- Combustion of high calorific value waste material: Organic atmospheric pollution
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Waste tire combustion in an atmospheric fluidized-bed (AFB) reactor (7 cm i.d., 76 cm height) has been performed in a laboratory plant with the aim of studying the polycyclic aromatic hydrocarbon (PAH) emissions as a function of combustion temperature. The main aim has been to compare these organic emissions with the ones obtained when coal is burned at the same combustion conditions. PAH emissions have been analyzed in solids collected in two cyclons at the exit of the reactor and in a trap system formed by a condenser, a filter (20 μm), and an adsorbent. After PAH extraction with dimethylformamide (DMF) by sonication, fluorescence spectroscopy in the synchronous mode (FS) has been used as an analytical technique to quantify the PAHs emitted. It could be concluded that higher PAH emissions are generated when this waste material is burnt at the same conditions used for coal atmospheric fluidized-bed combustion (AFBC).
- Mastral, Ana M.,Callen, Maria S.,Murillo, Ramon,Garcia, Tomas
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p. 4155 - 4158
(2007/10/03)
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Supercritical water oxidation of 2-chlorophenol effected by Li+ and CuO/zeolites
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Catalytic oxidation of 2-chlorophenol (2CP) in supercritical water was investigated. Experimentally, conversion of 2CP in supercritical water oxidation (SCWO) process is effectively enhanced in the presence of Li+ that also reduces the formation of higher chlorinated phenols and PAHs. The global reaction rate of SCWO of 2CP in the presence of Li+ is expressed as: 92.5 exp (-10.5/RT)[2CP]0.95[O2]0.56[H2O]0.45. The undesired by-products in the SCWO of 2CP are also extensively reduced in the channels of zeolite catalysts. By EXAFS spectroscopy, Cu-O and Cu-Cu are identified as the main oxidation active species in the zeolite channels. Cl-bonded CuO species in zeolite Y are not observed.
- Lin, Kuen-Song,Wang, H. Paul,Yang
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p. 1385 - 1396
(2007/10/03)
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- Complexation of aromatic hydrocarbons with a macrocycle containing four tropolone units in water
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The stability constants K of nine complexes formed from aromatic hydrocarbons and the macrocycle 1 in water were measured by the transport method (1H nmr spectroscopy was used in the case of benzene as guest). Their values increase with the number of aromatic rings in the aromatic hydrocarbons. A value of -1.5 Kcal mol-1 was obtained for the aromatic π-π interaction energy at 25°C.
- Poh, Bo-Long,Ng, Yian Yian
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p. 11913 - 11918
(2007/10/03)
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- Formation of cyclopent[a]indene and acenaphthylene from allyl esters of biphenyl mono- and di-carboxylic acids and from biphenyl dicarboxylic anhydrides on flash vacuum pyrolysis at 1000-1100°C
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Flash vacuum pyrolysis at 1000-1100°C of the allyl esters of the three isomeric biphenylcarboxylic acids, of the allyl esters of the 12 biphenyldicarboxylic acids and of the three biphenyldicarboxylic anhydrides gave pyrolysates which were examined by 1H n.m.r. spectroscopy at temperatures below -50°C. In all cases the spectra showed the presence of cyclopent[a]indene and acenaphthylene together with other products. Possible mechanisms for these ring contraction and cyclization processes are discussed and the results of pyrolyses of [2,3-13C2]biphenyl-2,3-dicarboxylic anhydride, and [3,4-13C2]-and (2-2H1)-biphenyl-3,4-dicarboxylic anhydrides are reported.
- Bapat, Jayant B.,Brown, Roger F.C.,Bulmer, Glenn H.,Childs, Trevor,Coulston, Karen J.,Eastwood, Frank W.,Taylor, Dennis K.
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p. 1159 - 1182
(2007/10/03)
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- Novel Syntheses of Decacyclene by Deoxygenating Cyclotrimerisation of Acenaphthenequinone with Zero-valent Titanium or Phosphorus Pentasulfide
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Decacyclene (2) was obtained in 15-21% yield by reaction of acenaphthenequinone (6) with bis(η6-biphenyl)titanium(0) (9) in toluene or diglyme at 110°C and in 18% yield by reaction of 6 with phosphorus pentasulfide in boiling toluene. The new reactions are used to attempt the conversion of 3,8-dibromoacenaphthenequinone (7) to 3,4,9,10,15,16-hexabromodecacyclene (3) which is considered to serve as a suitable precursor for the bowl-shaped polycyclic aromatic hydrocarbon C 36H12 (1).
- Zimmermann, Klaus,Haenel, Matthias W.
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p. 609 - 611
(2007/10/03)
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- Synthetic approaches to the hypothetical lactone intermediate in the pyrolytic conversion of 8-methylcyclobuta[a]naphthalene-1,2-dione into acenaphthylene
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Synthetic approaches to the hypothetical lactone intermediate 8,8a-dihydro-2H-acenaphtho[1,8-bc]furan-2-one (2) based on intramolcular Diels-Alder reaction, and on intramolecular alkylation by diazoacetate groups, were not useful. Generation and pyrolysis of the 9-diazomethylnaphtho[1,2-c]furan-3(1H)-one (19) derived from the corresponding 9-formyl compound (15) gave products including acenaphthylene, consistent with the intermediacy of the lactone (2).
- Brown, Roger F.C.,Eastwood, Frank W.,Wong, Neil R.
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p. 793 - 800
(2007/10/03)
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- Partial Hydrogenation of Polycyclic Aromatic Hydrocarbons by Electroreduction in Protic Solvents
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Polycyclic aromatic hydrocarbons (PAH) such as anthracene (1), phenanthrene (5), acenaphthylene (15), pyrene (17), chrysene (22), and fluoranthene (28) are selectively hydrogenated upon electroreduction at a lead cathode in ethanolic solution. The degree of hydrogenation and the structure of the products depend on the reaction conditions, in particular on the applied reduction potential.
- Anowski,Voss
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p. 337 - 344
(2007/10/03)
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- Study of structural aspects of thermochemical conversions of compounds modeling oligophenylenes containing acenaphthylenyl and acenaphthenyl groups
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With the aim of elucidating the mechanism of the thermochemical conversion of oligophenylenes containing acenaphthylenyl groups, the thermolysis of model compounds: 1,3,5-tris(5-acenaphthylenyl)benzene (1), 1,3,5-tris(5-acenaphthenyl)benzene (2), acenaphthylene, and acenaphthene, was studied by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and mass spectrometry.Compounds 1 and 2 were studied by X-ray structural analysis.A scheme for the formation of secondary structures was suggested.Optimum temperature conditions were found for preparing thermostable, heat-resistant, and stable to thermooxidation polymers based on compounds containing the acenaphthylenyl groups. - Key words: 1,3,5-tris(acenaphthylenyl)benzene, 1,3,5-tris(acenaphthenyl)benzene, acenaphthylene, acenaphthene, thermochemical conversions; decacyclene; polymers, thermal properties; X-ray structural analysis.
- Kovalev, A. I.,Balykova, T. N.,Lindeman, S. V.,Teplyakov, M. M.,Khotina, I. A.,et al.
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p. 790 - 798
(2007/10/02)
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- On the Thermal Cycloisomerization of 1-Vinylnaphthalene to Acenaphthene. A Mechanistic D-Labeling Study
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Unlabeled 1-vinylnaphthalene (1) as well as positionally D-labeled 1 have been prepared and subjected to gas phase pyrolysis at low partial pressures of the educt compounds in nitrogen.At 700 deg C, 1 rearranges exclusively to acenaphthene (2).Under the conditions applied a significant H-D-exchange in the 1-vinylnaphthalene as well as in the formed acenaphthene takes place.The results obtained in this way and those resulting from pyrolysis in hydrogen (instead of nitrogen) show that despite the very high degree of dilution the high selectivity of cycloisomerization from 1 to 2 is firstly controlled by H-atom driven radical chain processes, in which the cyclization of the 2-naphthylethylradical dominates the reaction course.
- Zimmermann, Gerhard,Ondruschka, Bernd,Nuechter, Matthias,Kopinke, Frank-Dieter,Remmler, Matthias
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p. 415 - 420
(2007/10/02)
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