- Scholl Cyclizations of Aryl Naphthalenes: Rearrangement Precedes Cyclization
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In 1910, Scholl, Seer, and Weitzenbock reported the AlCl3-catalyzed cyclization of 1,1′-binaphthyl to perylene. We provide evidence that this classic organic name reaction proceeds through sequential and reversible formation of 1,2′- and 2,2′-binaphthyl isomers. Acid-catalyzed isomerization of 1,1′-binaphthyl to 2,2′-binaphthyl has been noted previously. The superacid trifluoromethanesulfonic acid (TfOH), 1 M in dichloroethane, catalyzes these rearrangements, with slower cyclization to perylene. Minor cyclization products are benzo[k]fluoranthene and benzo[j]fluoranthene. At ambient temperature, the observed equilibrium ratio of 1,1′-binaphthyl, 1,2′-binaphthyl, and 2,2′-binaphthyl is 1:3:97. DFT calculations with the inclusion of solvation support a mechanistic scheme in which ipso-arenium ions are responsible for rearrangements; however, we cannot distinguish between arenium ion and radical cation mechanisms for the cyclization steps. Under similar reaction conditions, 1-phenylnaphthalene interconverts with 2-phenylnaphthalene, with the latter favored at equilibrium (5:95 ratio), and also converts slowly to fluoranthene. Computations again support an arenium ion mechanism for rearrangements.
- Skraba-Joiner, Sarah L.,McLaughlin, Erin C.,Ajaz, Aida,Thamatam, Rajesh,Johnson, Richard P.
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p. 9578 - 9583
(2015/10/12)
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- Alkenes as alkyne equivalents in radical cascades terminated by fragmentations: Overcoming stereoelectronic restrictions on ring expansions for the preparation of expanded polyaromatics
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Chemoselective interaction of aromatic enynes with Bu3Sn radicals can be harnessed for selective cascade transformations, yielding either Sn-substituted naphthalenes or Sn-indenes. Depending on the substitution at the alkene terminus, the initial regioselective 5-exo-trig cyclizations can be intercepted at the 5-exo stage via either hydrogen atom abstraction or C-S bond scission or allowed to proceed further to the formal 6-endo products via homoallylic ring expansion. Aromatization of the latter occurs via β-C-C bond scission, which is facilitated by 2c,3e through-bond interactions, a new stereoelectronic effect in radical chemistry. The combination of formal 6-endo-trig cyclization with stereoelectronically optimized fragmentation allows the use of alkenes as synthetic equivalents of alkynes and opens a convenient route to α-Sn-substituted naphthalenes, a unique launching platform for the preparation of extended polyaromatics.
- Mohamed, Rana K.,Mondal, Sayantan,Gold, Brian,Evoniuk, Christopher J.,Banerjee, Tanmay,Hanson, Kenneth,Alabugin, Igor V.
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supporting information
p. 6335 - 6349
(2015/06/02)
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- Polycondensation of naphthalene and its alkyl derivatives
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Polycondensation of naphthalene and its alkyl derivatives (stripping oil, 2,5-dimethylnaphthalene) in the presence of aluminum halides was performed. Under the action of an ultrasonic field on a benzene solution of naphthalene in the presence of the catalyst, intermolecular condensation and benzene addition are observed.
- Golounin,Marakushina,Khramenko
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experimental part
p. 2137 - 2140
(2009/06/05)
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- Iron (III) perchlorate adsorbed on silica gel: A reagent for organic functional group transformations
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Adsorption of Fe(ClO4)3(H2O)6 onto chromatographic-grade silica gel in the presence of organic solvents (S=water, acetonitrile, or lower fatty acids) produces a supported reagent, Fe(ClO4)3(S)6/SiO2. This reagent has been found to be effective for the rapid organic functional group transformations such as dimerization of alkynes, aromatic hydrocarbons, selective oxidation of thiols to disulfides, and transannular reactions in 1,5-cyclooctadienes on grinding using pestle and mortar in the solid state. Copyright Taylor & Francis Group, LLC.
- Parmar, Anupama,Kumar, Harish
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p. 2301 - 2308
(2008/02/10)
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- Equatorial preference in the C-H activation of cycloalkanes: GaCl 3-catalyzed aromatic alkylation reaction
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GaCl3 catalyzes the aromatic alkylation of naphthalene or phenanthrene using cycloalkanes. The C-C bond formation predominantly takes place at the least hindered positions of the substrates, and equatorial isomers regarding the cycloalkane moiety are generally obtained. The reaction of bicyclo[4.4.0]decane and naphthalene occurs at the 2-position of naphthalene and at the 2- or 3-carbons of the cycloalkane, and the products possess a trans configuration at the junctures and an equatorial configuration at the naphthyl groups. Notably, cis-bicyclo[4.4.0]decane turns out to be much more reactive than the trans isomer, and a turnover number "TON" up to 20 based on GaCl3 is attained. 1,2-Dimethylcyclohexane reacts similarly, and the cis isomer is more reactive than the trans isomer. Monoalkylcycloalkanes react at the secondary carbons provided that the alkyl group is smaller than tert-butyl. Adamantanes react at the tertiary 1-position. The alkylation reaction is considered to involve the C-H activation of cycloalkanes with GaCl3 at the tertiary center followed by the migration of carbocations and electrophilic aromatic substitution yielding thermodynamically stable products. The stereochemistry of the reaction reveals that GaCl 3 activates the equatorial tertiary C-H bond rather than the axial tertiary C-H bond.
- Yonehara, Fumi,Kido, Yoshiyuki,Sugimoto, Hiraku,Morita, Satoshi,Yamaguchi, Masahiko
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p. 6752 - 6759
(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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- 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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- 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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- Iron (III) perchlorate: A novel reagent for functional group as well as ring transformations in organic synthesis
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Oxidative dimerization of some aromatic hydrocarbons, diphenylacetylene and diphenyl amine, selective oxidation of thiols to disulfides, and transformation of 1,5-cyclooctadiene to the corresponding bicyclooctane derivatives through trans-annular reactions have been achieved using iron (III) perchlorate(ITP).
- Kumar, Baldev,Parmar, Anupama,Rajpal, Anita,Kumar, Harish
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p. 593 - 595
(2007/10/03)
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- PYROLYSIS OF BENZENE-NAPHTHALENE MIXTURES: A TEMPERATURE DEPENDENCE STUDY
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The pyrolysis of benzene-naphthalene mixtures was carried out in the range 450-570 deg C and the principal products were determined. The yields of all the products increased at higher temperatures. A measure of rates of formation of biphenyl and 1,2'-binaphthyl indicates the occurance of a slight difference between their activation energies. The presence of alumina in the system has also been investigated.
- Stefanis, A. De,Perez, G.,Possagno, E.,Lilla, E.
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p. 1255 - 1260
(2007/10/03)
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- Reactivity of Polycyclic Aromatic Aryl Radicals
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Results of experimental and theoretical studies of the properties and reactions of polycyclic aromatic aryl radicals are reported.Reactions of phenyl, 1- and 2-naphthalenyl, and 9-anthracenyl radicals with toluene and naphthalene were examined in the gas phase at 400 and 450 deg C.Arylation rates for each radical were measured relative to hydrogen abstraction from toluene (kar/kabs).For reactions with toluene of both phenyl and 2-naphthalenyl radicals, this ratio was 0.20-0.25.For the 1-naphthalenyl and 9-anthracenyl radicals, these ratios were significantlylower (0.05 and 0.01, respectively).Relative rates for arylating the different available positions in toluene and naphthalene, however, were not nearly as different.Differences in arylation/abstraction rates of the different radicals are explained in terms of differing degrees of reversibility for the initial addition step.Results are consistent with literature dissociation rate constants measured by Ladaki and Szwarc for aryl bromides.MNDO calculations on a range of arene-aryl radical pairs suggest that these differences originate primarily from differences in radical stabilities.Calculations also suggest that, on the basis of bond strenghts, aryl radicals can be roughly divided into three groups, which depend on the nature of the two neighboring aromatic carbon atoms and are independent of the size of the aromatic cluster.
- Chen, R. H.,Kafafi, S. A.,Stein, S. E.
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p. 1418 - 1423
(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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- Preparation and Conformational Properties of Several 1,8-Diarylnaphthalenes
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Six new 1,8-diarylnaphthalenes, each having closely held parallel aromatic rings, were synthesized by a Kharash-type Grignard cross-coupling of arylmagnesium iodide and 1,8-diiodonaphthalene in the presence of N,N'-bis(1-methyl-3-oxobutylidene)ethylenediaminatonickel(II) as a catalyst.Among them, 1,8-di(1-naphthyl)naphthalene was obtained as cis and trans rotamers, caused by the restricted rotation at the 1,8-position.Interconversion between the rotamers on heating above their melting points was confirmed by differential scanning calorimetry.The proton magnetic resonance spectral studies of the 1,8-diarylnaphthalenes indicated the presence of a face-to-face arrangement of aromatic rings in the peri-position.Two new 8,8'-diaryl-1,1'-binaphthyls, each having two sets of closely held parallel aromatic rings, were isolated as minor coupling products.Trans-trans conformations were proposed for them on the basis of their thermal behavior.Several nickel(II) complexes were found to be effective catalysts for preparative Grignard cross-coupling reaction involving closely crowded geometry.
- Ibuki, Eiichi,Ozasa, Shigeru,Fujioka, Yasuhiro,Mizutani, Hiroshi
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p. 845 - 851
(2007/10/02)
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