- 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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- 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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- On assembling polychlorinated aromatic hydrocarbons from carbon tetrachloride via dichlorocarbene intermediary by a solvothermal reaction: A reaction pattern from carbene-ylide interconversion
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(Chemical Equation Presented) The forced one-electron reduction of carbon tetrachloride with sodium in a sealed steel vessel is shown to have a narrow window of conditions to arrest the reaction at the polychlorinated aromatic hydrocarbons (PCAHs), as well as to prevent the reaction from proceeding all the way to the final stage of graphite and other carbon solids. The intermediates are quenched with toluene or benzene to give electrophilic substitution products and with water to give a quinomethine as the major product. The product pattern leads us to propose the carbene, perchlorobenzo[c,d]pyren-6-ylidene, or its reversible dimer as the major intermediate among others, that survives the severe conditions until coming into contact with these nucleophiles. Mainly from aromatic resonance stabilization, the carbene is proposed to have a delocalized singlet state analogous to a ylide electronic structure and, thus, undergoes observed ionic reactions instead of typical carbene reactions. This work serves as a mechanistic link on the structural evolution of carbon networks between molecular chemistry and nanomaterial chemistry.
- Xie, Su-Yuan,Peng, Yin,Chen, Meng,Huang, Rong-Bin,Chow, Yuan L.,Zheng, Lan-Sun
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p. 1400 - 1407
(2007/10/03)
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- Preparation of decachlorocorannulene and other perchlorinated fragments of fullerenes by electrical discharge in liquid chloroform
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The discharge reaction of decachlorocorannulene and other perchlorinated fragments of fullerenes is studied in liquid chloroform using electrical discharge. Results reveal various reaction products. It is shown that all the characterized products are perchlorinated fragments of C60.
- Huang,Huang,Wang,Tang,Zheng
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p. 5954 - 5955
(2007/10/03)
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- Thermolysis of phenoxyaluminum compounds and formation of PCDD/F and their precursors
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Within the study of the formation of chlorinated dioxins and dibenzofurans and their precursors the thermolysis of hexachloroethane over the aluminum melt was investigated. "De novo" synthesis of precursors of PCDD/F was studied in the model system AlCl3/elemental carbon. Totally chlorinated heterocyclic compounds have been detected parallel with the formation of organochlorine compounds. The possibility of inserting oxygen to aluminum organyls was presented. In order to gain more detailed knowledge of the catalytic behaviour of fly ash the chemistry of thermolysis of phenoxy- and chlorophenoxy aluminum compounds at 300°C with the presence and absence of Al2O3 was investigated. Reagent compounds and products of thermolysis were followed by mass spectrometry.
- Voncina,Medved,Zerjal
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p. 2029 - 2038
(2007/10/03)
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- Synthesis and Crystallography of 1,2,3,4,6,7-Hexachloronaphthalene and 1,2,3,5,6,7-Hexachloronaphthalene
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1,2,3,4,6,7-Hexachloronaphthalene (5) and 1,2,3,5,6,7-hexachloronaphthalene (6) have been synthesized via reductive dehalogenation of octachloronaphthalene by lithium aluminium hydride.The reduction proceeds via the substitution of one of the chlorine atoms in an α-position and the formation of 1,2,3,4,5,6,7-heptachloronaphthalene (4).The two sterically more crowded α-positions (positions four and five) in the heptachloronaphthalene were found to be preferentially reduced as the reduction proceeds.Only trace amounts of other isomers were formed.Crystal and molecular structure of the two title isomers were determined by single crystal X-ray diffraction methods.The compounds crystallize in the space group P21/c with the following cell dimensions: 5, a = 14.71(2) Angstroem, b = 3.828(4) Angstroem, c = 20.45(3) Angstroem, and β = 87.8(1) deg; 6, a = 9.381(4) Angstroem, b = 3.807(2) Angstroem, c = 16.168(8) Angstroem and β = 102.40(4) deg.The structures were determined by direct methods and the obtained models containing total of 95 parameters for 5 and 48 parameters for 6 were refined by full-matrix least-squares calculations that gave a final R value of: 5, 0.0619 for 486 unique reflections with I/?(I) 3 and 6, 0.0592 for 382 unique reflections with I/?(I) 3.
- Jakobsson, Eva,Eriksson, Lars,Bergman, Ake
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p. 527 - 532
(2007/10/02)
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