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Showing papers on "Aromatic hydrocarbon published in 2002"


Journal ArticleDOI
TL;DR: Results indicate that DK17 possesses two different ring-cleavage pathways for the degradation of aromatic compounds, although the initial oxidation reactions may be catalyzed by a common oxygenase.
Abstract: Rhodococcus sp strain DK17 was isolated from soil and analyzed for the ability to grow on o-xylene as the sole carbon and energy source Although DK17 cannot grow on m- and p-xylene, it is capable of growth on benzene, phenol, toluene, ethylbenzene, isopropylbenzene, and other alkylbenzene isomers One UV-generated mutant strain, DK176, simultaneously lost the ability to grow on o-xylene, ethylbenzene, isopropylbenzene, toluene, and benzene, although it could still grow on phenol The mutant strain was also unable to oxidize indole to indigo following growth in the presence of o-xylene This observation suggests the loss of an oxygenase that is involved in the initial oxidation of the (alkyl)benzenes tested Another mutant strain, DK180, isolated for the inability to grow on o-xylene, retained the ability to grow on benzene but was unable to grow on alkylbenzenes due to loss of a meta-cleavage dioxygenase needed for metabolism of methyl-substituted catechols Further experiments showed that DK180 as well as the wild-type strain DK17 have an ortho-cleavage pathway which is specifically induced by benzene but not by o-xylene These results indicate that DK17 possesses two different ring-cleavage pathways for the degradation of aromatic compounds, although the initial oxidation reactions may be catalyzed by a common oxygenase Gas chromatography-mass spectrometry and 300-MHz proton nuclear magnetic resonance spectrometry clearly show that DK180 accumulates 3,4-dimethylcatechol from o-xylene and both 3- and 4-methylcatechol from toluene This means that there are two initial routes of oxidation of toluene by the strain Pulsed-field gel electrophoresis analysis demonstrated the presence of two large megaplasmids in the wild-type strain DK17, one of which (pDK2) was lost in the mutant strain DK176 Since several other independently derived mutant strains unable to grow on alkylbenzenes are also missing pDK2, the genes encoding the initial steps in alkylbenzene metabolism (but not phenol metabolism) appear to be present on this approximately 330-kb plasmid

131 citations


Journal ArticleDOI
TL;DR: Ant 17 displayed greater tolerance to UV irradiation and freeze-thaw cycles than the hydrocarbon-degrading isolate Sphingomonas sp.
Abstract: Sphingomonas sp. strain Ant 17 was isolated from fuel-contaminated soil collected at Scott Base, Ross Island, Antarctica. We anticipated that Ant 17 would be a good model organism for studying cold climate bioremediation, and therefore determined its biodegradation capabilities and tolerance of potentially growth-limiting environmental conditions. Sphingomonas sp. Ant 17 degrades the aromatic fraction of several different crude oils, jet fuel, and diesel fuel at low temperatures and without nutrient amendment. It utilizes or transforms a broad range of pure aromatic substrates, including hydrocarbons, heterocycles, and aromatic acids and alcohols. Ant 17 grows at temperatures of 1 degree C to 35 degrees C and mineralizes radiolabeled phenanthrene over a range of more than 24 degrees C. This psychrotolerant isolate appears to utilize hydrocarbons more efficiently at low temperatures than would be predicted by mesophilic enzyme kinetics. The optimum pH for growth was 6.4 at 22 degrees C, with extended lag phases observed in more alkaline media. However, there was less effect of pH on lag phase at lower temperatures. Ant 17 displayed greater tolerance to UV irradiation and freeze-thaw cycles than the hydrocarbon-degrading isolate Sphingomonas sp. WPO-1, which may reflect adaptation to its Antarctic soil environment. However, it was more sensitive than expected to desiccation and to low concentrations of NaCl and CaCl(2). Ant 17 was phenotypically stable and lacked detectable plasmids, suggesting a chromosomal location for genes encoding aromatic degradation enzymes. Its broad aromatic substrate range and tolerance of low and fluctuating temperature and low nutrients make Sphingomonas sp. Ant 17 a valuable microbe for examining fuel spill bioremediation in cold soils.

129 citations


Journal ArticleDOI
TL;DR: In this paper, the conversion of methanol over physical mixtures of Ga2O3 and H-ZSM-5 or WO3/γ-Al 2O3 is reported.

103 citations


Patent
22 Oct 2002
TL;DR: In this article, a pyrimidine compound having an excellent antagonistic activity against adenosine receptors (A1, A2A, and A2B receptors) was described.
Abstract: A novel pyrimidine compound having an excellent antagonistic activity against adenosine receptors (A1, A2A, and A2B receptors). Specifically, it is a compound represented by the following formula, a salt of the compound, or a solvate of either. (I) In the formula, R1 and R2 are the same or different and each represents hydrogen, optionally substituted C1-6 alkyl, etc.; R3 represents hydrogen, halogeno, etc.; R4 represents an optionally substituted C6-14 aromatic hydrocarbon ring group, optionally substituted 5- to 14-membered nonaromatic heterocyclic group having at least one unsaturated bond, etc.; and R5 represents an optionally substituted C6-14 aromatic hydrocarbon ring group or optionally substituted 5- to 14-membered aromatic heterocyclic group.

89 citations


Journal ArticleDOI
TL;DR: In this paper, four density-functional methods (B3LYP, B3PW91, MPW1PW 91, and B 3P86) are employed to compute the C−C homolytic bond dissociation enthalpies (BDE) of a set of aromatic hydrocarbons related to coal structures with aliphatic linkages.
Abstract: Four density-functional methods (B3LYP, B3PW91, MPW1PW91, and B3P86) are employed to compute the C−C homolytic bond dissociation enthalpies (BDE) of a set of aromatic hydrocarbons related to coal structures with aliphatic linkages. In comparison with the available experimental data, the B3P86 method can provide reasonably reliable BDE values for these model compounds. The BDE values for large aromatic hydrocarbon systems of interest are computed, and the substituent effects are discussed.

74 citations


Journal ArticleDOI
TL;DR: CP-PAHs 2b and 2c have potentially interesting fullerene-like photophysics and are poor singlet oxygen sensitizers with measured (1)O(2) quantum yields of 0.02 and 0.06, as expected from a simple Hückel analysis.
Abstract: A simple procedure for the synthesis of cyclopentafused polycyclic aromatic hydrocarbons (CP-PAH) with Pd(PPh3)2Cl2 catalyst has been applied to the one-pot palladium(0)-catalyzed coupling of 9,10-dibromoanthracene (1) with 2-methyl-3-butyn-2-ol. Reactions carried out in refluxing benzene in the presence of CuSO4/Al2O3 yielded 9,10-dialkynylanthracene 2a, alkynyl aceanthrylene 2b, and 2,7-disubstituted cyclopent[hi]aceanthrylene 2c in 13%, 23%, and 19% purified yields, respectively, with total conversions of 80−90%. Sealed tube reactions without copper at 110 °C improved the yield of 2c up to >75%. Single-crystal X-ray analyses of 2a and 2c reveal a three-dimensional hydrogen bonding network, producing a unique crystal packing. The packing structure of 2b is dominated by π−π stacking interactions between two aceanthrylene molecules. CP-PAHs 2b and 2c have potentially interesting fullerene-like photophysics. While the UV−vis and fluorescence spectra of 2a (ΦF = 0.87) show the characteristic vibronic struct...

60 citations


Journal ArticleDOI
20 Jul 2002-Langmuir
TL;DR: In this article, two samples of the silico-aluminophosphate HSAPO-18 with different acid site densities were prepared, characterized, and studied as methanol-to-olefin catalysts in comparison with the more widely s...
Abstract: Two samples of the silico-aluminophosphate HSAPO-18 with different acid site densities were prepared, characterized, and studied as methanol-to-olefin catalysts in comparison with the more widely s...

55 citations


Journal ArticleDOI
TL;DR: In the vadose zone, intrinsic remediation by subsurface microbial populations in groundwater on the Swan Coastal Plain can control transport of aromatic hydrocarbon contamination, except for the transport of benzene in groundwater.
Abstract: A survey of soil gases associated with gasoline stations on theSwan Coastal Plain of Western Australia has shown that 20% leak detectable amountsof petroleum. The fates of volatile hydrocarbons in the vadose zone at one contaminatedsite, and dissolved hydrocarbons in groundwater at another site were followed in anumber of studies which are herein reviewed. Geochemical evidence from a plume ofhydrocarbon-contaminated groundwater has shown that sulfate reduction rapidly developedas the terminal electron accepting process. Toluene degradation but not benzene degradationwas linked to sulfate reduction. The sulfate-reducing bacteria isolated from the plumerepresented a new species, Desulfosporosinus meridiei. Strains of the speciesdo not mineralise 14C-toluene in pure culture. The addition of large numbersof cells and sulfate to microcosms did stimulate toluene mineralisation but not benzenemineralisation. Attempts to follow populations of sulfate-reducing bacteria byphospholipid signatures, or Desulfosporosinus meridiei by FISH in the plume were unsuccessful, but fluorescently-labeled polyclonal antibodies were successfully used.In the vadose zone at a different site, volatile hydrocarbons were consumed in thetop 0.5 m of the soil profile. The fastest measured rate of mineralisation of 14C-benzenein soils collected from the most active zone (6.5 mg kg-1 day-1) could accountfor the majority of the flux of hydrocarbon vapour towards the surface. The studiesconcluded that intrinsic remediation by subsurface microbial populations in groundwateron the Swan Coastal Plain can control transport of aromatic hydrocarbon contamination,except for the transport of benzene in groundwater. In the vadose zone, intrinsicremediation by the microbial populations in the soil profile can contain the transportof aromatic hydrocarbons, provided the physical transport of gases, inparticular oxygen from the atmosphere, is not impeded by structures.

55 citations


Journal ArticleDOI
TL;DR: Results for the analogous CpRh(CO)(2) molecule have shown that the coordination of the cyclopentadienyl ligand does not play a direct role in the dynamics of the reaction, in contrast to the C-H activation mechanism observed in eta(3)-TpRh (CO) studies.
Abstract: The photochemical C-H activation reactions of eta(3)-TpRh(CO)(2) (Tp = HB-Pz(3), Pz = 3,5-dimethylpyrazolyl) and CpRh(CO)(2) (Cp = C(5)H(5)) have been studied in a series of linear, cyclic, and aromatic hydrocarbon solvents on a femtosecond to microsecond time scale. These results have revealed that the structure of the hydrocarbon substrate affects the final C-H bond activation step, which is in accordance with the known preference of bond activation toward primary C-H sites. In the case of aromatic C-H activation, the reaction is divided into parallel channels involving sigma- and pi-solvated intermediates. Results for the analogous CpRh(CO)(2) molecule have shown that the coordination of the cyclopentadienyl ligand does not play a direct role in the dynamics of the reaction, in contrast to the C-H activation mechanism observed in eta(3)-TpRh(CO)(2) studies.

52 citations


Patent
26 Jul 2002
TL;DR: In this paper, methods and apparatus for remediating metal contaminants using hydrocarbons which stimulate the growth of hydrocarbon-utilizing bacteria are disclosed for applications such as the remediation of heavy metals, the mitigation of arsenic impacted surface water, groundwater and/or soil, and the treatment of spent metal plating solutions.
Abstract: Methods and apparatus are disclosed for remediating metal contaminants using hydrocarbons which stimulate the growth of hydrocarbon-utilizing bacteria. The metal contaminants may include heavy metals such as arsenic, antimony, beryllium, cadmium, chromium, copper, lead, mercury, iron, manganese, magnesium, radium, nickel, selenium, silver, thallium and zinc. The hydrocarbon may include alkanes, alkenes, Aalkynes, poly(alkene)s, poly(alkyne)s, aromatic hydrocarbons, aromatic hydrocarbon polymers and aliphatic hydrocarbons. Butane is a particularly suitable hydrocarbon which stimulates the growth of butane-utilizing bacteria. Remediation may occur in-situ or ex-situ, and may occur under aerobic, anaerobic or dual aerobic/anaerobic conditions. Examples of applications include the remediation of heavy metals, the remediation of arsenic impacted surface water, groundwater and/or soil, the remediation of acid mine drainage, and the treatment of spent metal plating solutions.

48 citations


Patent
01 Aug 2002
TL;DR: In this paper, the problem of providing a compound enabling production of an organic electroluminescent element excellent in heat resistance and having low driving voltage and high luminous efficiency is addressed.
Abstract: PROBLEM TO BE SOLVED: To provide a compound enabling production of an organic electroluminescent element excellent in heat resistance and having low driving voltage and high luminous efficiency. SOLUTION: This anthracene-based compound is represented by general formula (I) [wherein Ar and Ar are each independently 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic monocyclic group or 2-5 condensed ring group which may have a substituent group; R and R are each independently a tertiary amino group or a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic monocyclic or 2-5 condensed ring, with the proviso that both of R and R are not tertiary amino groups at the same time and when R and/or R is a tertiary amino group, an aromatic hydrocarbon ring group or an aromatic heterocyclic group, they may further be substituted].

Journal ArticleDOI
TL;DR: In this article, it was found that the hydropyrolysis of Mae-Moh lignite in atmospheric pressure of hydrogen gas is suitable for aromatic hydrocarbon production, which is used as raw feed to produce value-added chemicals, especially aromatic hydrocarbons.

Journal ArticleDOI
TL;DR: In this article, the Gibbs−Helmholtz equation was used to compute the free energy, enthalpy, and entropy of adsorption using the inverse gas chromatography (IGC) technique.
Abstract: Experimental data on the adsorption of polycyclic aromatic hydrocarbons (PAHs) at the gas−water interface is lacking. The inverse gas chromatography (IGC) technique with Chromosorb P NAW as the packing support was used to obtain the thermodynamic parameters for the adsorption of three aromatic compounds (benzene, naphthalene, and phenanthrene) at the gas−water interface. The partition constants at different temperatures were measured and used to compute the free energy, enthalpy, and entropy of adsorption using the Gibbs−Helmholtz equation. The enthalpy of adsorption at the gas−water interface for all three compounds was larger than the enthalpy of condensation and the enthalpy of aqueous solvation. This supports the prevailing “critical cluster” model for the dynamics of the transfer of compounds to the gas−water interface. The thermodynamics of adsorption at the gas−solid interface was more favorable than that at the gas−water interface. The partition constant at the gas−water interface was correlated w...

Patent
25 Jun 2002
TL;DR: A function regulator for retinoid relative receptors (excluding retionic acid receptors) which contains a compound represented by the general formula (I) is useful as a preventive/remedy for diabetes, hyperlipidemia, impaired glucose tolerance, etc as mentioned in this paper.
Abstract: A function regulator for retinoid relative receptors (excluding retionic acid receptors) which contains a compound represented by the general formula (I) (wherein one of R1 and R2 represents an optionally substituted, monocyclic aromatic hydrocarbon group or an optionally substituted, monocyclic aromatic heterocyclic group containing one heteroatom and the other represents hydrogen, etc.; B represents a 5- or 6-membered heterocycle (excluding 1,3-azole); A represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group; and R3 represents hydrogen, etc.) or a salt thereof. The regulator is useful as a preventive/remedy for diabetes, hyperlipidemia, impaired glucose tolerance, etc.

Journal ArticleDOI
TL;DR: Primers were designed and successfully used to screen aromatic hydrocarbon-degrading bacteria for the presence of class II aromatic ring-hydroxylating dioxygenase genes and to amplify novel RHD genes from DNA extracted from soil using the polymerase chain reaction.
Abstract: Primers were designed and successfully used to screen aromatic hydrocarbon-degrading bacteria for the presence of class II aromatic ring-hydroxylating dioxygenase (RHD) genes and to amplify novel RHD genes from DNA extracted from soil using the polymerase chain reaction. Two previously undiscovered groups of genes encoding putative class II RHDs, designated the S and T clusters, were found in RHD different soil samples. Only one of 70 RHD gene fragments amplified from these soil samples could be assigned to a cluster of previously reported RHD genes. These results suggest that distinct and potentially numerically dominant groups of as-yet unrecognized aromatic hydrocarbon-degrading bacteria exist in soils.

Journal ArticleDOI
TL;DR: In this paper, both amorphous and polycrystalline films of the aromatic hydrocarbon perylene were found to accept as high as one lithium per 3.3± 0.1 carbon atoms.

Journal ArticleDOI
TL;DR: The pK(a) calculations indicate that the chromophore, i.e., the product of the ninhydrin-like reaction showing the blue color, is deprotonated in neutral aqueous solution, and the corresponding protonated structure has a different color as it absorbs in the blue region of the visible spectrum, and its chromogenic contribution in solution at low pH.
Abstract: We report the first computational study of the chromophores responsible for the chromogenic effects of aromatic neurotoxicants containing a 1,2-diacetyl moiety in their oxidation metabolites. A series of ab initio electronic structure calculations was performed on two representative aromatic compounds, 1,2-diacetylbenzene (1,2-DAB) and 1,2-diacetyl tetramethyl tetralin (1,2-DATT), the putative active metabolites of the neurotoxic aromatic hydrocarbon compounds 1,2-diethylbenzene (1,2-DEB) and acetyl ethyl tetramethyl tetralin (AETT), and on the products of their possible reactions with proteins that result in chromogenic effects. The electronic excitation energies determined by three different computational approaches were found to be consistent with each other. The calculated results are consistent with the conclusion/prediction that the chromogenic effects of 1,2-DAB (or 1,2-DEB) and 1,2-DATT (or AETT) could result from ninhydrin-like reactions, rather than the formation of pyrrole-like compounds. Our p...

Journal ArticleDOI
TL;DR: In this article, a series of copoly(methacrylates) with pendant phosphate and carbamoylphosphonate groups were synthesized, and the copolymer membranes were cross-linked by the chemical reaction of either ethylene glycol diglycidyl ether (EGDE) or toluene diisocyanate with hydroxyl or secondary amine groups in copolymers at 423 K.

Journal ArticleDOI
TL;DR: X-ray analysis of the crystals shows that (+)- and (-)-bis-beta-naphthol and benzoquinone form a quinhydrone-type crystalline lattice with aromatic stacking and hydrogen bonding in which the third aromatic hydrocarbon component is accommodated.

Patent
25 Dec 2002
TL;DR: In this article, a non-aqueous electrolytic solution consisting of a fluorine atom substitutional aromatic compound, an aromatic hydrocarbon compound consisting of carbon and hydrogen only, a nonaqueous solvent and a lithium contained electrolyte was proposed.
Abstract: PROBLEM TO BE SOLVED: To provide a non-aqueous electrolytic solution superior in overcharge preventing effect and high-temperature storage property and suitable for a lithium secondary battery. SOLUTION: The non-aqueous electrolytic solution comprises a fluorine atom substitutional aromatic compound, an aromatic hydrocarbon compound consisting of carbon and hydrogen only, a non-aqueous solvent and a lithium contained electrolyte. The non-aqueous electrolytic solution contains the 0.1-20 wt.% fluorine atom substitutional aromatic compound and the 0.1-3 wt.% aromatic hydrocarbon compound. In the desirable embodiment of the electrolytic solution, the fluorine atom substitutional aromatic compound is fluorine atom substitutional naphthalenes, fluolenes or biphenyls and the aromatic hydrocarbon compound is alkyl group or cylohexyl group substitutional benzenes or biphenyls. The electrolytic solution has improved high-temperature storage property if vinylene carbonates, alkenyl ethylene carbonates, unsaturated hydrocarbon group contained sultons, aryl group contained sulfonate, saturated hydrocarbon group contained sultons, or sulfonic imide is added thereto. COPYRIGHT: (C)2003,JPO

Journal ArticleDOI
TL;DR: In this paper, a negative ion photoelectron spectroscopic study on the solvation energetics of an excess electron in the size-selected aromatic hydrocarbon nanoclusters is presented.
Abstract: We present a negative ion photoelectron spectroscopic study on the solvation energetics of an excess electron in the size-selected aromatic hydrocarbon nanoclusters, (benzene)n− (n=53–124) and (toluene)n− (n=33–139). The formation and stability of these negatively charged clusters were investigated using mass spectrometry with two different sources: (1) low-energy (≈0.3 eV) electron attachment and (2) high-energy electron impact. The results reveal that very large coordination numbers (n∼25) are necessary for the formation of stable benzene and toluene cluster anions. This suggests that the second solvation layer (effect) is essential for stable binding of the excess electron in these clusters. The energetics of the cluster anions were also explored by negative ion photoelectron spectroscopy. The photoelectron spectra obtained were related to bulk parameters, e.g., solvent reorganization energy and conduction band minimum, via an analysis of vertical detachment energies versus n−1/3. The bulk solvent reor...

Journal ArticleDOI
TL;DR: In this paper, the utility of furfuryl alcohol as a solvent for the separation of aromatic and aliphatic hydrocarbons using solvent extraction was investigated and the compositions of the conjugated phases were correlated with the UNIQUAC and NRTL equations.
Abstract: Liquid−liquid equilibrium results for mixtures of furfury alcohol + an aromatic hydrocarbon + an alkane at T = 298.15 K are reported, where an aromatic hydrocarbon refers to benzene or methyl benzene or 1,2-dimethylbenzene and an alkane refers to hexane or dodecane or hexadecane. The data presented indicate the utility of furfuryl alcohol as a solvent for the separation of aromatic and aliphatic hydrocarbons using solvent extraction. The compositions of the conjugated phases were correlated with the UNIQUAC and NRTL equations.

Journal ArticleDOI
01 Nov 2002-Fuel
TL;DR: Isotope dilution mass spectrometry was developed for the determination of composition of paraffins, olefins, naphthenes and aromatics in distilled oil produced from the pyrolysis reaction of mixed waste plastics using labeled hydrocarbon internal standards.

Journal ArticleDOI
TL;DR: In this paper, two strategies are followed; the first one aims at tailoring the pore size in order to selectively trap and discriminate benzene and toluene, and the second one is to decrease pore polarity to eliminate the main interfering gas, water vapor.
Abstract: Low cost materials based on hybrid organic–inorganic sol–gel systems have been developed for use in the trapping and detection of monocyclic aromatic hydrocarbon contaminants emitted into the atmosphere. To this end, two strategies are followed; the first one aims at tailoring the pore size in order to selectively trap and discriminate benzene and toluene. The second is to decrease the pore polarity in order to eliminate the main interfering gas of the atmosphere, water vapor. The results of these strategies are reported in this paper. After describing the synthesis of silicon hybrid xerogels and thin films and the characterisation of their structural properties, we report the study of the local polarity of the pores, of the porosity and optical properties of the materials. These characterisation data will enable us to define the materials suited for hosting benzene and toluene.

Journal ArticleDOI
TL;DR: In this paper, the binding energies of halogen-ligated transition metal ions with benzene molecules were analyzed and it was concluded that binding of the first benzene molecule to the transition metal species is strongly enhanced by specific chemical interactions.

Patent
01 Oct 2002
TL;DR: In this paper, a soluble, multifunctional vinyl aromatic copolymer with improved heat resistance, resistance to thermal decomposition, solubility to solvents and processibility was obtained by polymerizing 20-99.5 mol% divinyl aromatic compounds and 0.5-80 mol% monovinyl aromatic compound in an organic solvent with a dielectric constant of 2-15 in the presence of an initiator such as chloroethylbenzene.
Abstract: PROBLEM TO BE SOLVED: To obtain a soluble, multifunctional vinyl aromatic copolymer with an improved heat resistance, resistance to thermal decomposition, solubility to solvents and processibility. SOLUTION: The soluble, multifunctional vinyl aromatic copolymer is obtained by polymerizing 20-99.5 mol% divinyl aromatic compound and 0.5-80 mol% monovinyl aromatic compound in an organic solvent with a dielectric constant of 2-15 in the presence of an initiator such as chloroethylbenzene at 20-100°C. The soluble, multifunctional vinyl aromatic copolymer has an indane structure of formula (1) in its main chain backbone and structural units of formulae (a1) and (a2) (wherein R 1 and R 2 are each a 6-30C aromatic hydrocarbon group) whose molar fractions satisfy the relation: (a1)/[(a1)+(a2)]≥0.5. COPYRIGHT: (C)2004,JPO

Patent
22 Oct 2002
TL;DR: The pyrimidone compounds exhibiting excellent antagonism against adenosine receptors (A1, A2A, and A2B receptors), particularly, compounds represented by the general formula (I), salts thereof, or solvates of both: as discussed by the authors.
Abstract: The invention provides novel pyrimidone compounds exhibiting excellent antagonism against adenosine receptors (A1, A2A, and A2B receptors), particularly, compounds represented by the general formula (I), salts thereof, or solvates of both: (I) wherein R1 and R2 are each independently hydrogen, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-8 cycloalkyl, C3-8 cycloalkenyl, a 5- to 14-membered nonaromatic heterocyclic group, a C6-14 aromatic hydrocarbon group, a 5- to 14-membered aromatic heterocyclic group, C1-6 acyl, or C1-6 alkylsulfonyl; R3 is hydrogen, C1-6 alkyl, C2-6 alkenyl, or C2-6 alkynyl; R4 is a C6-14 aromatic hydrocarbon group; a 5- to 14-membered aromatic heterocyclic group, or a 5- to 14-membered nonaromatic heterocyclic group having at least one unsaturated bond; and R5 is a C6-14 aromatic hydrocarbon group or a 5- to 14-membered aromatic heterocyclic group (with the proviso that every group except hydrogen may be substituted).


01 Jan 2002
TL;DR: Novel halogen-ligated transition metal ions MXn+ are generated and their reactions with benzene, a typical aromatic hydrocarbon, are explored, it is concluded that binding of the first benzene molecule to the transition-metal species is strongly enhanced by specific chemical interactions, whilebinding of the second Benzene molecule is more nearly electrostatic.
Abstract: We have generated novel halogen-ligated transition metal ions MXn (M Sc, Ti, V, and Fe, X Cl, Br and I, n 1 3). We have explored their reactions with benzene, a typical aromatic hydrocarbon. Attachment of one benzene molecule is usually rapid, whereas attachment of a second benzene molecule is generally much slower. The kinetics were analyzed to estimate binding energies, modeling the attachment reaction as a radiative association process. In all cases the Standard Hydrocarbon semiquantitative estimation approach was employed, and in some cases the more accurate variational transition state (VTST) kinetic modeling approach was also applied. Density functional (DFT) quantum calculations were also performed to give computed binding energies for some of the complexes. Taking previously determined binding energies for halogen-ligated alkaline-earth ions as benchmarks, it is concluded that binding of the first benzene molecule to the transition-metal species is strongly enhanced by specific chemical interactions, while binding of the second benzene molecule is more nearly electrostatic. The binding energies are not strongly dependent on the identity of the transition metal ion, and the metal-ion dependences can be rationalized in terms of valence-orbital occupations of the metals. The binding energies are nearly independent of the identity of the halogen ligands. (J Am Soc Mass Spectrom 2002, 13, 477– 484) © 2002 American Society for Mass Spectrometry

Journal ArticleDOI
TL;DR: The flash vacuum pyrolysis of 1,2-bis(2-bromophenyl)-4,9-dibromocorannulene leads to a new C(32)H(12) buckybowl.
Abstract: The flash vacuum pyrolysis (FVP) of 1,2-bis(2-bromophenyl)-4,9-dibromocorannulene leads to a new C(32)H(12) buckybowl.