- Sterically controlled C-H/C-H homocoupling of arenes: Via C-H borylation
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A mild one-pot protocol for the synthesis of symmetrical biaryls by sequential Ir-catalyzed C-H borylation and Cu-catalyzed homocoupling of arenes is described. The regiochemistry of the biaryl formed is sterically controlled as dictated by the C-H borylation step. The methodology is also successfully extended to heteroarenes. Some of the products obtained by this approach are impossible to obtain via the Ullmann or the Suzuki coupling protocols. Finally, we have shown a one-pot sequence describing C-H borylation/Cu-catalyzed homocoupling/Pd-catalyzed Suzuki coupling to obtain π-extended arene frameworks.
- Pei, Xiaocong,Zhou, Guan,Li, Xuejing,Xu, Yuchen,Panicker, Resmi C.,Srinivasan, Rajavel
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supporting information
p. 5703 - 5707
(2019/06/19)
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- Ultrasound induced, copper mediated homocoupling using polymer supported aryltrifluoroborates
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Using Dowex polymer supported aryltrifluoroborates, we are able to achieve homocoupling for a variety of compounds. The reactions were completed in 6 h, while producing high yields of the desired products. The reaction proceeds under mild conditions, using ultrasound as the energy source, copper acetate as the metal co-reactant, and aqueous ethanol as solvent.
- Musolino, Bryan,Quinn, Michael,Hall, Kelly,Coltuclu, Vitali,Kabalka, George W.
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p. 4080 - 4082
(2013/07/25)
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- METHOD FOR SEPARATING AND CLEANING UP POLYHALOGENATED BIPHENYLS
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The method for separating and cleaning up polyhalogenated biphenyls (PHBs) is characterized by comprising the following three steps: (1) the step of bringing a sample containing PHBs into contact with a fibrous activated carbon; (2) the step of washing the fibrous activated carbon with hexanes; and (3) the step of eluting PHBs from the fibrous activated carbon.
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Page/Page column 20-26
(2008/06/13)
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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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- 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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p. 615 - 623
(2007/10/03)
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- Physical, spectral and chromatographic properties of all 209 individual PCB congeners
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Through the use of two capillary GC columns: 40% octadecyl/ 15% phenyl methyl siloxane and 50% phenyl methyl siloxane, it was possible to separate 201 PCB congeners with only four unresolved pairs. The data compiled in this study for all 209 congeners will aid in the identification of selected individual components of these environmental pollutants. The use of this data also presents the opportunity for the improved quantification of the commercial PCB formulations. -from Authors
- Bolgar,et al.
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p. 2687 - 2705
(2007/10/03)
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- Studies of the antenna effect in polymer molecules. 23. Photosensitized dechlorination of 2,2′,3,3′,6,6′-hexachlorobiphenyl solubilized in an aqueous solution of poly(sodium styrenesulfonate-co-2-vinylnaphthalene)
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Photodechlorination of 2,2′,3,3′,6,6′-hexachlorobiphenyl (HCB) solubilized in an aqueous solution of poly(sodium styrenesulfonate-co-2-vinylnaphthalene) (PSSS-VN) was studied with use of solar-simulated radiation. The reaction was found to be photosensitized by the naphthalene antenna units present in the copolymer. Studies performed in a low molecular weight model system have shown that dechlorination of HCB may occur via an exciplex intermediate. Exciplex formation in the system is efficient because of the high local concentration of HCB in proximity to the naphthalene polymeric units.
- Nowakowska,Sustar,Guillet
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p. 253 - 258
(2007/10/02)
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- The Reactions of Superoxide Ion with Arylhydrazines
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Arylhydrazines react with potassium superoxide to give a variety of products, most of which are derived from interaction of aryl radicals with the solvent.Phenylhydrazine in toluene gives three isomeric metylbiphenyls, diphenylmethane and bibenzyl.In pyridine, the products identified were 2-, 3-, and 4-phenylpyridine.A more complex range of products was obtained from substituted phenylhydrazines.Products are consistent with a process in which superoxide ion abstracts hydrogen atoms from the hydrazines giving radical intermediates, including aryl radicals, which react with the solvents.
- Crank, George,Gately, Garry E.,Makin, Mohammad I. H.
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p. 2499 - 2507
(2007/10/02)
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