- K-10 montmorillonite-catalyzed solid phase diazotizations: Environmentally benign coupling of diazonium salts with aromatic hydrocarbons to biaryls
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A new heterogeneous catalytic diazotization and subsequent coupling of diazonium salts with aromatics for the synthesis of biaryls is described. The method involves the solid phase diazotization of anilines and the successive C-C bond formation of the diazonium salt with alkylbenzenes. Excellent yields were obtained for a broad range of anilines and aromatic nucleophiles. The reaction was carried out using K-10 montmorillonite as an acid catalyst and medium as well. The high selectivity, metal-free, recyclable catalyst, easy work up, and absence of harmful waste make the process a sustainable alternative to available methods.
- Pandey, Garima,T?r?k, Béla
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- BENZODIAZABOROLE DERIVATIVES AND ORGANIC LIGHT-EMITTING DIODES USING THE SAME
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A benzodiazaborole derivative is shown in formula (1), wherein R1 is selected from the group consisting of hydrogen atom, formula (2), formula (3) and formula (4), R2 is selected from the group consisting of hydrogen atom, formula (3
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Paragraph 0067; 0068; 0069
(2019/03/01)
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- Iron(III)-Catalyzed Ortho-Preferred Radical Nucleophilic Alkylation of Electron-Deficient Arenes
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The untraditional iron-catalyzed, ortho-preferred, radical alkylation of electron-deficient (hetero)arenes is reported. A variety of electron-deficient arenes were shown to react with various primary alkyl sources, producing the alkylated (hetero)arenes in good yields. This reaction might be an alkyl radical, nucleophilic aromatic substitution reaction, rather than the traditional electrophilic Friedel-Crafts reaction. HOMO-LUMO analysis and DFT studies on the key transition states underlying the regioselectivity are consistent with the observed reactions and the conclusions.
- Yu, Fei,Wang, Ting,Zhou, Huan,Li, Yajun,Zhang, Xinhao,Bao, Hongli
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supporting information
p. 6538 - 6541
(2017/12/26)
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- Synthesis of chlorinated biphenyls by Suzuki cross-coupling using diamine or diimine-palladium complexes
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Several novel diimines (Salen-type ligands) 2a-2i and their reduced diamine counterparts 3b,3d-3g and 3i form complexes 4a-4i, 5b,5d-5g, and 5i with PdCl2 in DMF or methanol. Using 1 mol-% of the isolated complexes 4e and 5f many polychlorinated biphenyls (PCBs) can be prepared in moderate to excellent yields according to the Suzuki cross-coupling protocol with contact to air. Several 4-acetylbiphenyls prepared by this method can be converted in moderate yields into the corresponding biphenylcarboxylic acids (BCAs) by alkaline cleavage. An X-ray crystal structure determination confirms the structure of complex 5f. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Kylmaelae, Tuula,Kuuloja, Noora,Xu, Youjun,Rissanen, Kari,Franzen, Robert
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experimental part
p. 4019 - 4024
(2009/04/11)
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- Polychlorinated biphenyl reductive dechlorination by vitamin B12s: Thermodynamics and regiospecificity
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Microbial reductive dechlorination reactions play an important role in determining the environmental fate of polychlorinated biphenyls (PCBs), especially for PCB congeners with more than four chlorines. Powerful chemical catalysts such as vitamin B12s provide an effective tool for the study of reductive dechlorination reactions. The reductive dechlorination of PCBs by titanium(III) citrate-reduced vitamin B12s was studied in batch reactors. Long-term experiments demonstrated reductive dechlorination of aqueous and sediment-sorbed 2,3,4,5,6-pentachlorobiphenyl (2,3,4,5,6-PeCB) to tetra-, tri-, di-, and monochlorobiphenyl products. Approximately 10% chlorine removal was observed in 36 days in aqueous experiments at 20°C; the sediment experiment showed 40% chlorine removal in 42 days at 30°C. Nearly all possible intermediates were produced and reductively dechlorinated, with no apparent accumulation of individual congeners. Short-term experiments were conducted to determine the pathway forvitamin B12s-catalyzed reductive dechlorination of aqueous 2,3,4,5,6-PeCB and its dechlorinated products; relative product distributions were measured for all possible tetra-and trichlorobiphenyl reductive dechlorination reactions. Theoretical product distributions based on free energies of formation agreed with observed product distributions for short-and long-term experiments. Reductive dechlorination was favored at positions with adjacent chlorines; on average, chlorines were removed equally from ortho, meta, and para positions.
- Woods, Sandra L.,Trobaugh, Darin J.,Carter, Kim J.
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p. 857 - 863
(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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- Hydrogenolysis of polychlorinated biphenyls by sodium borohydride with homogeneous and heterogeneous nickel catalysts
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The hydrogenolysis (hydrodechlorination) of a series of pure PCB congeners with sodium borohydride was studied. In the absence of nickel compounds, very little reaction occurred, but in the presence of solid Raney-type nickel or in the presence of a soluble Ni(0)triphenylphosphine complex, extensive hydrogenolysis occurred at ambient temperatures in DMF. The selectivity of one congener versus another was studied and found to be low. The selectivity for 2-, 3-, and 4-chloro displacement from di- and trichlorobiphenyls in the presence of Ni(0) complexes, however, was found to be high. The selectivities are interpreted with respect to the known mechanism of oxidative addition of aryl halides with Ni(0) complexes.
- Roth,Dakoji,Hughes,Carmody
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