- Synthesis, molecular structure, and chemical reactivity of azuleno[1,2-a]acenaphthylene
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The azuleno[1,2-a]acenaphthylene (1a) was prepared from 1-pyrrolidinylacenaphthylene (5) and 2H-cyclohepta[b]furan-2-one (6) by the method of the Takase-Yasunami azulene synthesis. Its 1H and 13C NMR spectra indicate that 1a comprises azulene and naphthalene rather than acenaphtylene and heptafulvene in accordance with speculation drawn from a previous study of the DEPE calculations. The solid-state structure of 1a was elucidated by X-ray crystallographical analysis, indicating that 1a is nearly planar and exhibits little bond alternation as seen in the optimized structure at the MB3LYP/6-311G* level of theory. All bond lengths observed by the X-ray analysis are in good agreement within 0.024? with those calculated. Under pyrolytic conditions 1a underwent azulene-naphthalene rearrangement to give 9 and 10. The electrophilic substitution of 1a was observed at the 7-position and the second reaction at the 3-position. The cycloaddition reaction of 1a with dimethyl acetylenedicarboxylate (DMAD) yielded the 1:1 cycloadduct with a heptalene skeleton 16a and the 1:2 cycloadduct 19, along with the substitution product 17. The X-ray structural analysis of the cycloadducts 16a and 19 is also described.
- Mouri, Masaru,Kuroda, Shigeyasu,Oda, Mitsunori,Miyatake, Ryuta,Kyogoku, Mayumi
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- High temperature gas phase syntheses of C20H12 cyclopenta-fused polycyclic aromatic hydrocarbons: Benz[l]acephenanthrylene and benz[j]acephenanthrylene and their selective rearrangement to benzo[j]fluoranthene
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The novel C20H12 cyclopenta-fused polycyclic aromatic hydrocarbon benz[l]acephenanthrylene (2) and its isomer benz[j]acephenanthrylene (3) have been obtained by flash vacuum thermolysis of 2-(1-chloroethenyl)benzo[c]phenanthrene (6) and 6-(1-chloroethenyl)chrysene (7), respectively. At T ≥ 900°C 2 and T ≥ 1000°C 3 rearrange selectively to the abundant combustion effluent benzo[j]-fluoranthene (1). No evidence for the presence of the related rearrangement products benz[l]aceanthrylene (12) and benz[j]aceanthrylene (13), respectively, is found. Semi-empirical AM1 calculations provide a rationalization for these observations; the conversion of 2 and 3 into 1, instead of 12 and 13, respectively, via consecutive ring-contraction-ring-expansion processes and vice versa is favoured.
- Sarobe, Martin,Jenneskens, Leonardus W.,Wesseling, Jolanda,Wiersum, Ulfert E.
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- Acid-Catalyzed Cyclization of 3,3',4,4'-Tetrahydro-1,1'-binaphthyl and Single-Crystal X-ray Structure Determination of a Polycyclic Stable Ozonide
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Amberlyst-15 (A-15) catalyzed cyclization of 3,3',4,4'-tetrahydro-1,1'-binaphthyl (1) in refluxing toluene during 12h provided , as the major product , (+/-)-1,2,3,6b,7,8-hexahydrobenzofluoranthene (2a).Ozonization of 2a gave a stable ozonide (3), mp 159-161 deg C.The structure of this ozonide was established by single-crystal X-ray analysis: monoclinic unit cell P21/c, a= 10.616(1) Angstoem, b= 9.607(3) Angstroem, c= 15.052(4) Angstroem, β= 105.06(2) deg, Dcalcd 1.372 g cm-1, Z= 4, final agreement factor 6.3percent.Prolonged treatment (12-100 h) of 1 or 2a with A-15 in refluxing toluene yielded a mixture of three1,2,3,6b,7,8,12b,12c-octahydrobenzofluoranthenes ( 4a, 4b, 4c) and 1,2,3,12c-tetrahydrobenzofluoranthene (5).Hydrocarbon 2a was readily dehydrogenated in the presence of hot Pd/C to benzofluoranthene (6).
- Dobbs, Thomas K.,Taylor, Arnold R.,Barnes, Julie A.,Iscimenler, Belma D.,Holt, Elizabeth M.,Eisenbraun, Edmund J.
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- Three-Step Synthesis of Fluoranthenes through Pd-Catalyzed Inter- and Intramolecular C-H Arylation
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A three-step synthetic method for the preparation of fluoranthenes, involving Miura's intermolecular C-H arylation, nonaflation, and intramolecular C-H arylation, has been developed. Various 1-naphthols and haloarenes were successfully used as substrates. Reaction conditions that afford high site selectivity have been developed for the intramolecular C-H arylation step.
- Yamaguchi, Miyuki,Higuchi, Mayu,Tazawa, Kanae,Manabe, Kei
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p. 3967 - 3974
(2016/05/24)
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- Use of external radical sources in flash vacuum pyrolysis to facilitate cyclodehydrogenation reactions in polycyclic aromatic hydrocarbons
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A new process to facilitate the cyclodehydrogenation of polycyclic aromatic hydrocarbons (PAHs) in flash vacuum pyrolysis (FVP) using an external radical source is described. Using hexanes as an external radical source the conversion of various PAHs to their cyclodehydrogenated products is vastly increased. Various other volatile organic compounds were also examined to determine their ability to act as external radical sources in FVP.
- Amick, Aaron W.,Martin, Sara E.
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p. 1338 - 1343
(2014/11/08)
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- Total synthesis of the natural product benzo[j]fluoranthene-4,9-diol: An approach to the synthesis of oxygenated benzo[j]fluoranthenes
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A synthetic sequence to the benzo[j]fluoranthene nucleus is described. Crucial steps of the procedure include a Suzuki coupling between appropriately substituted 2-bromo-acenaphthylene-1-carbaldehydes and 2-formylbenzeneboronates followed by McMurry ring closure. The synthesis represents a new approach to the benzo[j]fluoranthene ring system and specifically provides a method for the rapid preparation of differently substituted derivatives. Following this strategy, the first total synthesis of the recently isolated natural product benzo[j]fluoranthene-4,9-diol was carried out.
- Lahore, Santosh,Narkhede, Umesh,Merlini, Lucio,Dallavalle, Sabrina
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p. 10860 - 10866
(2013/11/19)
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- Microwave flash pyrolysis
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(Chemical Equation Presented) In a microwave reactor, graphite heats rapidly to high surface temperatures; applications of graphite thermal "sensitization" have been described previously. We report here that microwave thermal sensitization with graphite, carbon nanotubes, or silicon carbide can be used to carry out reactions more typically accomplished by flash vacuum pyrolysis (FVP) and which usually require temperatures much higher than the nominal limit of a microwave reactor. The graphite-sensitized microwave reaction of azulene in the solid phase at temperatures of 100 to 300°C affords rapid rearrangement to naphthalene, a reaction typically observed by FVP at 700-900°C. Multiwall carbon nanotubes give similar results when used as a thermal sensitizer. Other graphite-sensitized reactions that we have observed include the following: conversion of 2-ethynylbiphenyl to phenanthrene, fragmentation of phthalic anhydride to benzyne, cleavage of iodobenzene to phenyl radical, aryl-aryl bond cleavage, and a variety of cycloaromatizations. An advantage is seen for less volatile substrates. Rearrangement of azulene and generation of benzyne from phthalic anhydride have also been observed on powdered silicon carbide. Because of the high temperature, rapid heating, and frequent ejection of material from the irradiation zone, we refer to this general method as microwave flash pyrolysis (MFP).
- Hee, Yeon Cho,Ajaz, Aida,Himali, Dibya,Waske, Prashant A.,Johnson, Richard P.
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supporting information; experimental part
p. 4137 - 4142
(2009/09/25)
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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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- Efficient routes to acenaphthylene-fused polycyclic arenes/heteroarenes and heterocyclic fluoranthene analogues
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The acenaphthenone-derived a-oxoketene dithioacetal 2 has been subjected to various [3 + 3] aromatic and heteroaromatic annulation and other heterocyclization reactions previously developed in our laboratory, providing short and efficient routes to a diverse range of known and unknown acenaphtho-annulated linear and angular PAHs, heteroaromatics and five-membered heterocycles in good yields. Thus, benzo- and naphthoannulation of 2 with various allyl and benzyl Grignard reagents afforded substituted fluoranthenes 4a-c and benzo[k]fluoranthene 8, respectively, in good yields. Similarly, the parent benzo[j]fluoranthene 15a and its substituted derivative 16b have been synthesized by base-induced conjugate 1,4-addition of arylacetonitriles to 2, followed by acid-induced cyclization of the conjugate adducts 12a-b to give 13a-b and subsequent further transformations. The adducts obtained by 1,4-addition of anions derived from acetophenone and acenaphthenone were subjected to heterocyclization in the presence of ammonium acetate to give 8-arylacenaphtho[1,2-b]pyridines 18a-b and bis(acenaphtho)-annulated pyridine 20. Heterocyclization of 2 with bifunctional nucleophiles such as 2-picolyllithium and guanidinium nitrate afforded the corresponding acenaphtho[1,2-b]quinolizinium salt 23 and acenaphtho[1,2-d]pyrimidine 24, respectively, in high yields. Finally, acenaphtho[1,2-c]-fused five-membered heterocycles such as 7-(methylthio)acenaphtho[1,2-c]thiophene (25), 7-(methylthio)acenaphtho[1,2-c]furan (27) and 7-(methylthio)acenaphtho[1,2-c] pyrrole-2-carboxylic acid (30) were obtained in good yields by subjection of 2 to Simmons-Smith reaction conditions or by treatment with dimethylsulfonium methylide or glycinate dianion. Some of these newly synthesized PAHs or fused heterocycles were subjected to Raney Ni desulfurization to furnish sulfurfree compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Panda, Kausik,Venkatesh, Chelvam,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
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p. 2045 - 2055
(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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- Investigations into the mechanism of action of nitrobenzene as a mild dehydrogenating agent under acid-catalysed conditions
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Protonated nitrobenzene can be used to dehydrogenate a range of hydrocarbons, which already possess at least one double bond. Kinetic and spectroscopic results, together with known electrode potentials, yield approximate limits within which protonated nitrobenzenes can be expected to effect dehydrogenation of hydroaromatic compounds. A high yielding synthesis of benzo[j]fluoranthene is described.
- Cristiano, M. Lurdes S.,Gago, David J.P.,Gonsalves, Antonio M. A. Rocha,Johnstone, Robert A.W.,McCarron, Moya,Varejao, Jorge M.T.B.
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p. 565 - 574
(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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- Flash vacuum thermolysis of acenaphtho[1,2-a]acenaphthylene, fluoranthene, benzo[k]- and benzo[j]fluoranthene - Homolytic scission of carbon-carbon single bonds of internally fused cyclopenta moieties at T ≥ 1100°C
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Flash vacuum thermolysis (FVT, 1000 °C ≥ T ≥ 1200 °C) of acenaphtho[1,2-a]acenaphthylene (3, C22H12) gave the C22H12 cyclopenta-fused polycyclic aromatic hydrocarbon (CP-PAH) acenaphtho[1,2- e]acenaphthylene (4), cyclopenta[cd]perylene (5) and cyclopenta[def]benzo[hi]chrysene (6). Whereas the formation of 4 is explained by a ring contraction/ring expansion rearrangement of 3, the identification of 5 and 6 suggests that 3 also undergoes homolytic scission of a five- membered ring's carbon-carbon single bond furnishing the transient diradical intermediate 7. Ring closure of 7 to form 8 after rotation around the carbon- carbon single bond of the intact five-membered ring followed by hydrogen shifts will give 6. The latter can rearrange subsequently into 5 by ring contraction/ring expansion. The structural assignment of 4 and 5 was supported by independent FVT of 6,12-bis(1-chloroethenyl)chrysene (14) and 3- (1-chloroethenyl)perylene (23), respectively. FVT of 14 (900-1200 °C) gave in a consecutive process 6,12-bis(ethynyl)chrysene (15), 9- ethynylbenz[j]acephenanthrylene (16) and bis(cyclopenta[hi,qr])chrysene (17). Although at T ≥ 900 °C 17 selectively rearranges into 4 by ring contraction/ring expansion, at 1200 °C the latter is converted into 5 presumably via a diradical intermediate obtained by homolytic scission of a single carbon-carbon bond of a five-membered ring. FVT of 23 gave in situ 3- ethynylperylene (25), which at 1000 °C is nearly quantitatively converted into 5. The propensity of internal cyclopenta moieties to undergo homolytic scission of a five-membered ring's carbon-carbon single bond was corroborated by independent FVT of benzo[k]- (11) and benzo[j]fluoranthene (12). Previously unknown thermal pathways to important (CP)-PAH combustion effluents are disclosed at T≥ 1000 °C.
- Sarobe, Martin,Kwint, Huibert C.,Fleer, Theun,Havenith, Remco W.A.,Jenneskens, Leonardas W.,Vlietstra, Edward J.,Van Lenthe, Joop H.,Wesseling, Jolanda
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p. 1191 - 1200
(2007/10/03)
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- Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
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The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
- Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
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p. 2301 - 2307
(2007/10/03)
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- An Intramolecular Arene-Triflate Coupling Reaction for the Regiospecific Synthesis of Substituted Benzofluoranthenes
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An intramolecular triflate-arene coupling reaction mediated by bis(triphenylphosphine)palladium(II) chloride has been developed for the synthesis of each of the isomeric benzofluoranthenes.This reaction, which results in formation of a new five-membered ring, proceeds in highest yields when performed using 0.1 equiv of the palladium catalyst, 3 eqiv of lithium chloride, and 1.2 eqiv of 1,8-diazabicycloundec-7-ene in N,N-dimethylformamide at 140 deg C.The biaryl precursors needed for the coupling reaction can be prepared by nickel(II) chloride catalyzed coupling of an aryl bromide with an magnesium bromide (prepared by ortho-lithiation of an aryl methoxymethyl ether followed by transmetalation with magnesium bromide).Using this procedure benzofluoranthene, benzofluoranthene, benzofluoranthene, and benzofluoranthene were prepared in yields of 84percent, 85percent, 93percent and 64percent, respectively.The reaction to prepare benzofluoranthene was regiospecific and afforded none of the six-membered ring product, perylene.This method was extended to the preparation of benzofluoranthene (BbF) derivatives with fluoro or methoxy groups on the benzo ring.The cyclization of compounds posessing a methoxy group on the same ring as the triflate required the addition of 0.4 equiv of triphenylphosphine to the reaction mixture.Strategies are reported for the regiospecific preparation of 4-, 5-, 6-, and 7-substituted benzofluoranthenes.Evidence is presented wich suggests the intermediacy of radicals in the oxidative-addition of aryl triflates to the palladium catalyst.
- Rice, Joseph E.,Cai, Zhen-Wei
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p. 1415 - 1424
(2007/10/02)
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- Mechanisms of Condensation of Biaryl Hydrocarbons
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Results of kinetic studies of the condensed phase thermal reactions of the following biaryl hydrocarbons are reported; 1,1'-binaphthyl, 1,2'-binaphthyl, 1-phenylnaphthalene, and 9-phenylanthracene.Condensation generally occurred in parallel with both isomerization and dissociation and rates depended on concentrations of hydrogen donors.In order to simplify mechanisms, detailed studies used donors capable of providing just one H atom.These were xanthene, fluorene, and diphenylmethane.Condensation of 1,1'-binaphthyl in the presence of xanthene, the most effective donor, followed a second-order rate low (first order in both xanthene and binaphthyl concentration), k/M-1s-1=105.9+/-0.6exp(-36.0+/-2.0 kcal/RT)(360-560 deg C).Fluorene was one-fifth as effective as xanthene while diphenylmethane was nearly inert.A mechanism is proposed in which the key intermediates in all reactions are radicals created by H-atom transfer to the biaryls.In the condensation of naphthyl-containing biaryls, it is suggested that reactions are initiated by H transfer to a position next to the condensation site.Details of the unimolecular steps leading to condensation and isomerization, however remain unclear.Over the conditions studied, the reaction order with respect to donor varied between one and zero.It is proposed that this variability is a result of competition between two pathways for H transfer, one involving a simple, selective H transfer from the donor to a biaryl molecule, the other involving a free H-atom intermediate.
- Senthilnathan, V.P.,Stein, S.E.
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p. 3000 - 3007
(2007/10/02)
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