- Influence of variation in combustion conditions on the primary formation of chlorinated organic micropollutants during municipal solid waste combustion
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The aim of this study was to investigate the influence of variation in combustion conditions on the primary formation of organic micropollutants (OMPs). The flue gas samples were taken at a relatively high flue gas temperature (650°C), to enable mechanistic studies on the high temperature formation (primary formation). Eleven experiments were performed in a laboratory scale fluidized bed reactor fed with an artificial municipal solid waste (MSW). The samples were analyzed for mono- to octachlorinated dibenzo- p-dioxins and dibenzofurans (CDDs/Fs), tri- to decachlorinated biphenyls (CBs), di- to hexachlorinated benzenes (CBzs), and di- to pentachlorinated phenols (CPhs). In addition to chlorinated OMPs, nonchlorinated dibenzo-p- dioxin (DD), dibenzofuran (DF), and biphenyl (BP) were analyzed. The experiments show that variations in the CE influence the degree of chlorination of the organic micropollutants. A correlation between low CE and formation of non- and low-chlorinated DMPs was seen and a distinct relationship of higher chlorinated homologues and efficient combustion condition. Thus, the DiCDFs and DiCBzs are formed during low combustion efficiency (CE), while the PeCDF and PeCBzs formation take place at higher CE. The distribution between primary and secondary air is important for the formation of higher CDD/Fs and CBzs. The primary formation of CDDs and CDFs is through different mechanisms. The CDDs are mainly formed by condensation of CPhs, while the CDFs are formed through a non- or a low-chlorinated precursor followed by further chlorination reactions.
- Wikstroem,Tysklind,Marklund
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- Formation of PCDDs and PCDFs during the combustion of polyvinylidene chloride and other polymers in the presence of HCl
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PVDC and three non-chlorinated polymers (PP, PET, and PA) were incinerated at 700-850°C in a laboratory-scale quartz tubular furnace in the presence of HCl (ca. 500 ppm?0.8 mg/l), and the gas-phase formation of PCDD/Fs, their putative precursors and their homologue profiles were investigated. The addition of HCl had little or no apparent effect on the level of PCDD/Fs formation during PVDC combustion, and their homologue profiles were quite different from those of the three non-chlorinated polymers. With PVDC, O 8CDD and particularly O8CDF were by far most prevalent, apparently as a result of the selective formation of the precursors. With each of the three non-chlorinated polymers, combustion at 800°C or higher in the presence of HCl resulted in PCDD/Fs formation at levels equaling or exceeding those observed with PVDC. In trials made with one of them (PP) under the same conditions but using a large polymer sample (100 mg vs 20 mg in all other trials), the level of PCDD/Fs formation was far higher than with the smaller polymer samples, and thus demonstrated the importance of appropriate combustion conditions for polymer incineration.
- Ohta, Minoru,Oshima, Shozo,Osawa, Naoki,Iwasa, Toshio,Nakamura, Tadashi
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- Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene
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The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C2 through C8 organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene. (C) 2000 Elsevier Science Ltd.
- Taylor, Philip H.,Wehrmeier, Andreas,Sidhu, Sukh S.,Lenoir, Dieter,Schramm,Kettrup
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- Reactions of selected molecular anions with oxygen
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An investigation of the gas-phase reactions of molecular oxygen with the molecular anions of 17 compounds formed by resonance electron capture was undertaken using a pulsed e-beam high-pressure mass spectrometer. The molecular anions of sulphur hexafluoride, perfluromethylcyclohexane, cis- and trans-perfluorodecalin, m-chloronitrobenzene, o, m-and p-fluoronitrobenzene and o-, m- and p-dinitrobenzene were found to be unreactive towards oxygen. Those of o- and p-chloronitrobenzene, penta- and perchlorobenzene, perfluorobenzene, and perfluoratoluene were found to react readily with oxygen The second-order rate constants for these reactions are shown to bear so inverse dependence on temperature. The reactions involving o- and p-chloronitrabenezene and penta-and perchlorobenzene proceed via a branched mechanism by which an ion of the type [M + O - Cl]- and Cl- ion are simultaneously produced. A greater variety of negative ions are formed in the reactions of the molecular anions of perfluorobenzene and perfluorotoluene with oxygen The electron affinities of pentachlorobenzene (0.7 eV) and perchlorobenzene (1.0 eV) are also reported for the first time.
- Knighton,Bognar,Grimsrud
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- Removal of dioxins and related aromatic hydrocarbons from flue gas streams by adsorption and catalytic destruction
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The dioxin removing capacity of the shell dedioxin system (SDDS a - Ti/V oxidative type catalyst) has been tested using the Umefa lab-scale incinerator over the temperature range 100 -230°C and at space velocities of 8000 and 40,000 h-1. Other analogous organic compounds, such as PCBs, PAHs, chlorobenzenes and chlorophenols have also been investigated. Results show a high degree of dioxin removal already at 100°C (82%), which occurs mainly by adsorption. When the temperature is raised a transition towards destruction is seen and at 150°C, gas hour space velocity (GHSV) 8000 and at 230°C, GHSV 40,000 virtually all removal is by destruction. High PCDD/F destruction efficiencies are reported (> 99.9%, based on I-TEQ); the other dioxin-related species and PAHs are also removed and destroyed to a significant extent. The SDDS has proved to be an effective means of destroying organic compounds in the gas phase, particularly dioxins, at temperatures as low as 150°C.
- Liljelind, Per,Unsworth, John,Maaskant, Onno,Marklund, Stellan
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- Formation of octachlorostyrene during the synthesis of chromium(iii) chloride
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Octachlorostyrene has been recovered from the reaction tube, along with previously reported hexachlorobenzene, during the synthesis of CrCl3 from Cr2O3 and CCl4 at high temperature. The region in the reaction tube where the octachlorostyrene was found, namely upstream from the Cr2O3 held at 890°C, suggests that this molecule is formed at a temperature below 890°C and that it decomposes if raised to that temperature. A low gas flow was used in this experiment, allowing products to diffuse countercurrently. Copyright
- Mataruse,Yuknis,McDonald,Booth,Cleary,Twamley
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- FLUORINATION WITH POSITIVE FLUORINE GENERATED FROM ISOELECTRONICALLY RELATED REAGENTS
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Compounds such as PhIF2, PhPF2 and XeF2, which have been used previously as unrelated fluorinating agents, are shown to be periodically related as isoelectronic molecules E3AF2 of trigonal-bipyramidal shape, where E represents a bonded or nonbonded electron pair and A a main Group V-VIII element.These compounds are arranged in order of halogenating ability by estimating the magnitude of reduction couples, approximated by ΔH0f(E3AF2-E3A), or by noting the direction of redox reactions involving the couples.The A sequence deduced Kr>Xe ca.Cl>Br>I>S>Se>Te-As-Sb>P agrees with the limited experimental data available.Evidence for an ionic mechanism involving 'onium' monohalide ions is given for halogenations with these reagents when carried out under "Friedel-Crafts" conditions although no stable salts containing these ions have as yet been isolated because of intramolecular halogenation.These ions act as sources of positive fluorine.The use of ring deactivated reagents to achieve halogenation is discussed.
- Cartwright, M.,Woolf, A. A.
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- Formation of octachloroacenaphthylene in the pyrolysis of decachlorobiphenyl
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The pyrolytic degradation of decachlorobiphenyl (PCB 209) in the temperature range of 700-1000°C and at a pyrolysis time of 10 seconds generated one main chloroaromatic product. This compound has been identified by HPLC-UV, GC-MS, GC-FTIR and 13C-NMR as octachloroacenaphthylene (OCAN). The mechanism of the nearly quantitative formation of octachloroacenaphthylene (OCAN) occurs via a nonachlorobenzobarrylene radical (Z1R) as an intermediate followed by a rearrangement and further dechlorination to form OCAN. Calculations with the program THERM based on the Benson-group-theory indicated that this mechanism is not possible for lower or nonchlorinated biphenyls.
- Bleise,Kleist,Guenther,Schwuger
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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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- Isomerization of perchlorohexatriene in three consecutive rearrangements to perchloro-2-vinylbutadiene
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Perchlorohexatriene isomerizes in three subsequent rearrangements to perchloro-2-vinylbutadiene. A radical-induced Z-E-equilibration of linear perchlorohexatrienes is followed by cyclization to a methylenecyclopentene. Under flash-vacuum pyrolysis conditions, a ring contraction to 1,2-dimethylenecyclobutane occurs. In the condensed phase, a radical-induced ring opening generates the branched perchloro-vinylbutadiene. All compounds are converted to hexachlorobenzene, but only at very high temperatures.
- Schollmeyer, Dieter,Detert, Heiner
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supporting information
p. 843 - 846
(2017/02/18)
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- Thermal rearrangements of perchlorohexatrienes-structures and experimental and theoretical evaluation of pathways to isomerization and cyclization
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We have prepared trans- (1) and cis-octachloro-1,3,5-hexatriene (2) by known routes and studied their thermal behavior experimentally and theoretically by ab initio calculations. The three double bonds in 1 and 2 are completely decoupled due to steric hindrance by the eight Cls, as indicated by calculations as well as the single-crystal X-ray structure of 1. The cis isomer 2 can be isomerized to the trans isomer 1 by heating it to 220-250 °C either neat or dissolved in highboiling solvents, leading to a roughly 2:1 mixture of trans and cis isomers. Calculations at several different levels of theory predict 1 and 2 to be isoenergetic within 2 kJmol-1. Unimolecular cis/trans isomerization is predicted to occur through an unusual vinylcyclobutene intermediate 7, whose formation faces a barrier of more than 150 kJmol -1, but whose stability is comparable to that of 1 and 2. The isomerization rate is strongly enhanced by the addition of small amounts of Br2 or Cl2 or by 3 and can be explained by a radical-induced isomerization mechanism. The heating of trienes 1 and 2 to 250 °C leads to cyclization, yielding 71% of the cyclopentene isomer 3. Compound 3 can be dechlorinated by treatment with copper powder to give fulvene derivative 4. Using flash vacuum pyrolysis, the thermal conversion of trienes 1 and 2 to hexachlorobenzene (5) occurs at higher temperatures between 600-1000 °C, likely via perchlorinated 1,3-cyclohexadiene (6) as an intermediate. The elimination of molecular Cl2 from 3 and 6 requires very high activitation energies in agreement with calculations. Wiley-VCH Verlag GmbH & Co. KGaA, 2009.
- Detert, Heiner,Lenoir, Dieter,Zipse, Hendrik
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experimental part
p. 1181 - 1190
(2009/07/11)
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- METHOD FOR THE PRODUCTION OF 1,3,5-TRIFLUORO-2,4,6-TRICHLOROBENZENE FROM FLUOROBENZENE DERIVATIVES
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Method for the production of 1,3,5-trifluoro-2,4,6-trichlorobenzene from fluorobenzene, comprising steps A) and B): A) chlorination of fluorobenzene derivatives of formula (II), in which X = fluorine or H, Z = nitro, bromo or chloro and n = 0 or 1-4 and B) fluorination of the distillation residue and separation by distillation of the 1,3,5-trifluoro-2,4,6-trichlorobenzene thus produced.
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Page/Page column 9
(2008/06/13)
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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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- Formation and destruction of chlorinated pollutants during sewage sludge incineration
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The limitations facing land filling and recycling and the planned ban on sea disposal of sludge leads to the expectation that the role of sludge incineration will increase in the future. The expected increase in sludge incineration will also increase scrutiny of the main drawback to sewage sludge incineration-the formation of hazardous air pollutants (HAPs). Despite the extensive body of knowledge available on sewage sludge combustion, very few studies have been conducted on the formation of HAPs during sludge combustion. In this work, the interactions between sewage sludge pyrolysis products and sludge ash were investigated using a dual chamber flow reactor system and a horizontal laboratory scale reactor. The results of this study shows that sludge ash can catalyze oxidation and chlorination of organics. In the absence of HCl in the gas stream, sludge ash acts as an oxidizing catalyst, but in the presence of HCl, sludge ash acts as a chlorination catalyst producing high yields of organochloride compounds.
- Fullana, Andres,Conesa, Juan A.,Font, Rafael,Sidhu, Sukh
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p. 2953 - 2958
(2007/10/03)
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- Organochlorine formation in magnesium electrowinning cells
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The formation of organochlorines during the electrolytic production of magnesium was investigated using a laboratory-scale electrolytic cell having a graphite anode, a liquid aluminium alloy cathode, and a molten chloride electrolyte. The cell was operated at current densities ranging from 3000 to 10,000 A m-2 and at temperatures ranging from 660°C to 750°C. Organochlorines were adsorbed from the cell off-gases onto silica gel, extracted with hexane, and determined by gas chromatography. All compounds identified were fully chlorinated aliphatic and aromatic compounds, the major components being hexachlorobutadiene, hexachlorobenzene, hexachloroethylene, and octachlorostyrene. The total amount of organochlorines per tonne of magnesium produced decreased with electrolysis time and with current density and increased with operating temperature; it was also dependent on the type of graphite employed. The output of organochlorines Varied from 5 to 20 g t-1 of magnesium.
- Deutscher,Cathro
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p. 147 - 155
(2007/10/03)
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- Hazardous air pollutants formation from reactions of raw meal organics in cement kilns
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Thermally induced chlorination, condensation, and formation reactions of raw meal organic surrogates were investigated on different types of surfaces. The System for Thermal Diagnostic Studies provided a powerful tool to study these reactions under defined reaction conditions, which were related to typical conditions in the preheater zone of cement kiln. Experiments were conducted with benzene and benzene/myristic acid (C6H6/C13H27COOH) mixtures in a quartz reactor containing different chlorinating catalysts/reagents over a temperature range of 300-500°C. Reaction products were trapped in-line and analyzed by GC-MS. A mixture of chlorides of calcium, potassium, aluminium and iron was highly effective for chlorination/condensation reactions of benzene and benzene/myristic acid mix at temperatures above 300°C. The same behavior was observed only when calcium chloride and potassium chloride were used as chlorinating catalyst/reagent. This result showed that transition metal chlorides like FeCl3 are not necessary for chlorination/condensation of organics under post-combustion conditions. Methylene chloride was the major chlorinated product followed by chloroform and various other C1, C2 and C6 chlorinated products. Yields of chlorinated aliphatics were highest at 400°C for both benzene and benzene/myristic acid mix. C6 products were mainly mono- to hexa-chlorinated benzenes with trace amounts of chlorinated phenols. The major chlorinated products observed in this study (i.e., methylene chloride, chloroform, chloroethanes and monochlorobenzene) were also present as major chlorinated hydrocarbons in the cement kiln field emission data.
- Sidhu, Sukh,Kasti, Nabil,Edwards, Phil,Dellinger, Barry
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p. 499 - 506
(2007/10/03)
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- Identification of surrogate compounds for the emission of PCDD/F (I-TEQ value) and evaluation of their on-line realtime detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry
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Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination 4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.
- Blumenstock,Zimmermann,Schramm,Kettrup
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p. 507 - 518
(2007/10/03)
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- Reactions of 2,4,6-trichlorophenol on model fly ash: Oxidation to CO and CO2, condensation to PCDD/F and conversion into related compounds
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Thermal treatment of 2,4,6-trichlorophenol on a magnesium silicate-based model fly ash in the temperature range between 250°C and 400°C leads predominantly to carbon monoxide and carbon dioxide. The fraction of 2,4,6-trichlorophenol which is oxidized to CO and CO2 increases from 3% at 250°C to 75% at 400°C. Further products are polychlorinated benzenes, dibenzo-p-dioxins, dibenzofurans and phenols. The homologue and isomer patterns of the chlorobenzenes suggest chlorination in the ipso-position of the trichlorophenol. The formation of PCDD from 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol on municipal solid waste incinerator fly ashes and model fly ash were compared and the reaction order calculated.
- Hell,Stieglitz,Altwicker,Addink,Will
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p. 697 - 702
(2007/10/03)
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- Specificity and non-specificity in the sensitized CO2-laser-induced reaction of tetrachloroethene
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Previous workers have investigated the reaction of tetrachloroethene using thermal initiation and CO2-laser initiation via sensitizing species. In both instances, the principal product was found to be hexachlorobenzene. One group reported evidence of laser specificity in this reaction, in that BCl3 acted as a sensitizer to produce hexachlorobenzene as the principal product, but SF6 and BBr3 did not. We have found that specificity is highly dependent on reaction conditions. We reproduced the previous results using similar experimental conditions, but under different conditions, we found that the specificity is lost, with all three sensitizers which we used (BCl3, SF6, and SiF4) sensitizing the reaction to produce mainly hexachlorobenzene. There were some differences among the sensitizers, as, for example, the fact that SF6 produced the most nearly pure hexachlorobenzene product.
- Earl, Boyd L.,Titus, Richard L.
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p. 1593 - 1602
(2007/10/03)
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- Reactions of dimethoxycarbene with cyclic perchlorinated olefins and ketones
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Reactions of dimethoxycarbene (2), a carbonyl group equivalent, with perchlorinated olefins and ketones were investigated. Thermolysis of 2,2- dimethoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazoline (1) at 110 °C generated 2, which reacted with hexachlorocyclopentadiene (4), octachlorocycloheptatriene (12), octachlorobicyclo[3.2.0]hepta-3,6-diene (24), hexachlorotropone (28), hexachlorobicyclo[3. 2.0]-hepta-3,6-dien-2-one (32), and tetrachloro-1,4- benzoquinone (35). Reactions of 2 with perchlorinated olefins 4, 12, and 24 led to esters or, in the case of 12, to a ketene acetal. Their formation is rationalized in terms of Michael-like addition and displacement (S(N)2' or S(N)2', if concerted) of allylic chlorine atoms by 2, yielding ion pairs that either dechloromethylate to esters or dechlorinate to a ketene acetal. In contrast, the reactions of 2 with unsaturated perchloroketones 28, 32, and 35 led to ring contraction, ring expansion, and aromatization, respectively. The products from these reactions are consistent with nucleophilic addition of 2 at the carbonyl moiety rather than Michael-type addition. Dimethoxycarbene- d3 was used to show that demethylation in the latter reaction was intermolecular. Mechanisms for the different reaction courses are proposed.
- Dunn, James A.,Pezacki, John Paul,McGlinchey, Michael J.,Warkentin, John
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p. 4344 - 4352
(2007/10/03)
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- Chemistry of superacids: 35. * NO2Cl-3MXN systems: Superelectrophilic aprotic nitrating agents for deactivated aromatics
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Superelectrophilic nitration of deactivated aromatics with NO2Cl-3MXn complexes in aprotic nonpolar solvents such as CH2Cl2 makes it possible to obtain the corresponding nitro derivatives in good to almost quantitative yields under mild conditions.
- Olah,Orlinkov,Ramaiah,Oxyzoglou,Prakash
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p. 924 - 927
(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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- Aprotic diazotization in the presence of cuprous cyanide
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In a procedure of extreme simplicity and rapidity a mixture of an aromatic primary amine, copper (I) cyanide and an alkyl nitrite in dimethyl sulphoxide yielded fair to moderate yields of the corresponding nitriles. Side processes observed were reduction (NH2&[H), nitration (NH2←NO2) and hydroxylation (NH2&[OH). In the case of polyhaloanilines halogen dance products could be detected.
- Giumanini, Angelo G.,Verardo, Giancarlo,Geatti, Paola,Strazzolini, Paolo
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p. 7137 - 7148
(2007/10/03)
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- NOVEL PRODUCTS IN THE CO2-LASER INDUCED REACTION OF TRICHLOROETHYLENE
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Previous report on the thermal or CO2-laser induced decomposition of trichloroethylene have identified only one condensable product, hexachlorobenzene (in addition to HCl and mono- and dichloroacetylene).We have found that trichloroethylene vapor exposed to cw irradiation on the P(24) line of the (001-100) band of the CO2 laser at incident power levels from 8-17 W procedures numerous products, of which the 13 major ones have been identified using IR, GC/MS, GC/FTIR, and NMR methods.All of these products have 4, 6, or 8 carbons, are highly unsaturated, and are completely chlorinated or contain a single hydrogen.C4HCl5 and C6Cl6 isomers (three of each) account for ca. 55percent to 85percent of total products (based on peak area in the total ion chromatograms in GC/MS runs), depending on reaction conditions.In addition to characterizing the products, we discuss the dependence of the product distribution on laser power, irradiation time, and cell geometry, and we outline a possible mechanism.
- Earl, Boyd L.,Titus, Richard L.
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p. 104 - 114
(2007/10/02)
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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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- THERMALLY-CONTROLLED FORMATION OF CRYSTALLINE HEXACHLOROBENZENE, HEXACHLOROETHANE, AND ANHYDROUS CHROMIUM CHLORIDE
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The high-temperature preparation of purple crystalline anhydrous chromium chloride (CrCl3) by passing CCl4 vapors over green Cr2O3 powder in an inert atmosphere is an instructive experiment in the inorganic chemistry laboratory.A systematic investigation of this synthesis (using a carefully calibrated tube furnace, X-ray powder diffraction, infrared spectroscopy, and gas chromatography) revealed that the products formed as a consequence of the pyrolysis of CCl4 are sensitive to the reaction temperature.When Cr2O3 is present, the formation of CrCl3 dominates at temperatures between 600 deg C and 800 deg C; at temperatures above 900 deg C, C6Cl6 forms preferentially (presumably from the linking of the C-Cl free radicals produced by the pyrolysis) as the unreacted metal oxide is sintered to form eskolaite.In the absence of Cr2O3, the pyrolysis products are crystalline hexachloroethane (C2Cl6) at 600 deg C and needle-shaped crystals of hexachlorobenzene at temperatures above 900 deg C.
- Rudman, Reuben,Stevenson, Cynthia
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p. 105 - 112
(2007/10/02)
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- Photochemical Behavior of Stable Free Radicals: The Photochemistry of Perchlorodiphenylmethyl Radical
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The excitation of perchlorodiphenylmethyl radical (PDM) at 530 nm leads to the lowest excited doublet, D1 (τ = 31 ns), from which emission is observed (Φ = 1 x 10-3 +/- 0.0003).This state is quenched by electron donors and acceptors at a rate at or close to diffusion control and at much slower rates by oxygen and hydrogen atom donors.Fragmentation of PDM (Φd = 0.06) occurs from a higher excited doublet (Dn, n > = 2) producing intermediates that are trapped by O2, chlorine, or hydrogen donors, yielding products 1-6.Experimental evidence suggests a structure-photoreactivity correlation in the perchlorinated arylmethyl radicals in which the partitioning between photochemical cyclization or fragmentation depends on the twist angle between the appended phenyl rings.
- Ruberu, Shiyamalie,Fox, Marye Anne
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p. 143 - 149
(2007/10/02)
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- PYROLYSIS-GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF POLYCHLOROPHENOLS AND POLYCHLOROPHENATES
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Pentachlorophenol, 1, its sodium salt and the sodium salts of 2,3,4,5-tetrachlorophenol, 2, and 2,4,6-trichlorophenol, 3, have been submitted to pyrolysis-gas chromatography-mass spectrometry for 20 s at 990 deg C and at 500 deg C.Polychlorophenols (PCPs) and polychlorodibenzodioxins (PCDDs) were formed at the lower temperature.PCPs, PCCDs and polychlorobenzenes (PCBzs) were formed at the higher temperature.Compounds derived from loss of one or two carbon atoms were also formed from the sodium salt of 1 at the higher temperature.A mechanism based on the formation of ketocarbenes and arynes is suggested.
- Bassoli, Angela,Parrilli, Daniele,Rindone, Bruno,Pitea, Demetrio,Siniscalco, Falco
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p. 333 - 339
(2007/10/02)
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- 2,4,6,8,9,10-Hexachlor-2,4,6,8,9,10-hexaboradamantan
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The pyrolysis of alkyldichloroboranes such as MeBCl2, Cl2BCH=CHBCl2, Cl2BCH2BCl2 or (Cl2B)3CH at 450 deg C leads to the formation of hexachloro-hexaboraadamantane, C4H4B6Cl6 (I).The structure - determined by X-ray diffraction - and the spectroscopic data of 2,4,6,8,9,10-hexachloro-2,4,6,8,9,10-hexaboradamantane are in agreement with the classical description as an organoborane, rather than as a molecule with a carborane framework.Substitution reactions are described.The bromo compound C4H4B6Br6 can be prepared by heating Me2BBr or MeBBr2 to 520 deg C.
- Haubold, Wolfgang,Keller, Willi,Sawitzki, Gisela
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- Inert Carbon Free Radicals. 9. The First Perchlorinated Triarylmethyl and Fluorenyl Radicals with a Heteroaromatic Ring, and Related Compounds
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Perchlorodiphenyl(4-pyridyl)methyl (13), perchlorodiphenyl(2-pyridyl)methyl (14), and perchloro-9-(4-pyridyl)fluorenyl (15) radicals, the first inert carbon free radicals with a heteroaromatic ring, have been synthesized from αH-tetradecachlorodiphenyl(4-pyridyl)methane (3), αH-tetradecachlorodiphenyl(2-pyridyl)methane (7), and 9H-dodecachloro-9-(4-pyridyl)fluorene (12), respectively.The thermal and chemical stabilities of these radicals have been studied.The thermolysis of radical 13 gives a mixture of radical 15 and perchloro-3-aza-9-phenylfluorenyl radical (16).The oxidative hydrolysis of radicals 13 and 15 with oleum yields perchloor-4-(phenyl(4-pyridyl)methylene)cyclohexa-2,5-dienone (17) and perchloro-9-(pyridyl)fluoren-3-one (18), respectively.While the oxidation of radical 14 with concentrated HNO3 affords perchloro-2-(diphenylmethylene)pyridin-5(2H)-one (19), with concentrated H2SO4 it gives a mixture of perchloro-9-phenylindenopyridin-3-one (22) and perchloro-10-phenylpyridoindole (9), a cyclization product that is also obtained in the thermolysis of radical 14 or αH compound 7.The ESR, IR, and UV-vis spectra of the radicals and other compounds here synthesized are reported and studied.The variation of the magnetic susceptibility of those radicals with temperature has been measured, giving purities nearly 100percent.
- Julia, L.,Ballester, M.,Riera, J.,Castaner, J.,Ortin, J. L.,Onrubia, C.
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p. 1267 - 1273
(2007/10/02)
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- DESTRUCTIVE CHLORINATION OF ALKYLBENZENES ON HETEROGENEOUS CATALYSTS.
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A study was made of the destructive chlorination of alkylbenzenes in the vapor phase on metal oxides and metal chlorides. This work shows that 380-400 degree C, 11-12 sec contact time, 0. 3-0. 8 mass % MoO//3 on alumina, 7-10% stoichiometric excess of chlorine, and 1:9 toluene/chlorine mole ratio were optimal for the chlorination of toluene to give C//6Cl//6 and CCl//4. The optimal conditions for the preparation of pentachlorobenzyl chloride were 295-320 degree C, 18-22 sec contact time, 1:6 toluene/chlorine mole ratio, and 4-8. 5 mass % MgCl//2 on KSK silica gel. The optimal yields of CCl//4 and C//6Cl//6 were 97. 4-98. 2 and 93. 8-96. 3 mole %, respectively, with 91-93 mole % conversion of chlorine.
- Potapov,Valitov,Evdokimova
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p. 321 - 324
(2007/10/02)
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- Chlorination process
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Process for nuclear chlorination of non-phenolic aromatic compounds, said process comprising contacting and reacting a non-phenolic aromatic compound having a net Hammett ? value of about -0.1 to about 2.0 with chlorine monoxide in the presence of at least one-half an equivalent amount, based on the chlorine monoxide, of an acid having a pKa no greater than that of trichloroacetic acid, provided, however, when the net Hammett ? value is about 0.7 to about 2.0, the acid has a pKa no greater than that of trifluoroacetic acid.
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- SYNTHESIS OF 2,4,5,6-TETRANITRO-3-HALOGENOANILINES
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The reaction of pentanitroaniline with hydrohalic acids leads to substitution of the nitro group at the meta position to the amino group by the halogen atom.
- Legostaeva, E. K.,Novatskaya, N. I.,Nikonov, A. A.,Nikolaev, V. D.
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p. 2323 - 2324
(2007/10/02)
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- Zeolite ZSM-5 and related materials as catalyst in benzene chlorination
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ZSM-5 type zeolites and related high siliceous materials induce addition of chlorine to benzene yielding hexachlorocyclohexanes, whereas Y-type zeolites favour substitution to yield chlorobenzenes.
- Huizinga,Scholten,Wortel,van Bekkum
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p. 3809 - 3812
(2007/10/02)
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- Synthesis of C 14 labeled environment contaminants
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Upon the reaction of benzene-14C via nitrobenzene-14C and aniline-14C, some 14C-labelled environmental contaminants were were synthesized. By chlorination of aniline-14C and acetanilide-14C the authors prepared chloroanilines-14C. Gomberg-Bachmann or Cadogan reaction of diazotated chloroanilines-14C with different chlorobenzenes gave di, tri- and pentachlorobiphenyls-14C. By boiling anilinediazonium sulfate-14C the authors prepared phenol-14C, which was chlorinated to give 2,4,6-trichlorophenol-14C. Hexachlorobenzene-14C and pentachloronitrobenzene-14C were prepared by chlorination of nitrobenzene- 14C. Chloralkylene 9-14C was synthesized by Friedel-Crafts alkylation of 2,4'-dichlorobiphenyl-14C with 2-chloropropane.
- Sandrock,Attar,Bieniek,et al.
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p. 197 - 204,199,200
(2007/10/16)
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