15862-07-4Relevant articles and documents
Synthesis of polychlorinated biphenyls and their metabolites with a modified Suzuki-coupling
Kania-Korwel, Izabela,Parkin, Sean,Robertson, Larry W.,Lehmler, Hans-Joachim
, p. 735 - 744 (2004)
A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-coupling reaction, is described. The coupling of (chlorinated) benzene boronic acids with bromochlorobenzenes, using Pd(dppf)2Cl2 (dppf=1,1 ′-bis(diphenylphosphino)ferrocene) as the catalyst and aqueous sodium carbonate as the base, gave the desired PCB congeners in moderate to good yields. Eleven PCB congeners, including environmentally important PCB congeners and metabolites, were synthesized using this modified procedure. This new catalyst Pd(dppf)2Cl2 offers the advantage of being less air-sensitive and has a longer shelf life compared to Pd(PPh4) 4. Three new (di-)methoxylated PCB congeners were synthesized using the same procedure by either coupling a chlorinated benzene boronic acid with a bromo (di-)methoxybenzene or by coupling a (di-)methoxy benzene boronic acid with a chlorinated bromobenzene. The dimethoxylated PCB congeners were readily converted into the respective dihydroxylated PCB derivatives using boron tribromide in dichloromethane. This approach offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.
Cross-coupling of polychloroarenes with phenylboronic acid and organozinc compounds catalyzed by palladium complexes
Burukin,Vasil'ev,Chizhov,Zlotin
, p. 970 - 974 (2005)
Hexachlorobenzene and 1,2,4,5-tetrachlorobenzene react with phenylboronic acid by a C-C cross-coupling mechanism with a Pd(dba)2/P(Bu t)3 system (dba is dibenzylideneacetone) or palladium-azole complexes as catalysts, or with organozinc compounds in the presence of Pd(PPh3)4 to afford substitution products of one or two chlorine atoms in moderate yields.
Buchwald ligand-assisted Suzuki cross-coupling of polychlorobenzenes
Burukin, Alexander S.,Vasil'ev, Andrei A.,Zhdankina, Galina M.,Zlotin, Sergei G.
, p. 400 - 402 (2021/06/07)
Screening of four Buchwald ligands for the cross-coupling of isomeric di-, tri- and tetrachlorobenzenes with arylboronic acids revealed that good yields of exhaustive substitution can be best provided by 2-dicyclohexylphosphino-2′-(dimethylamino) biphenyl (DavePHOS).
Selective and general exhaustive cross-coupling of di-chloroarenes with a deficit of nucleophiles mediated by a Pd-NHC complex
Groombridge, Benjamin J.,Goldup, Stephen M.,Larrosa, Igor
supporting information, p. 3832 - 3834 (2015/03/30)
We report the first example of a general, exhaustive Pd-mediated cross-coupling of polychloroarenes in the presence of a deficit of nucleophiles, mediated by the highly active PEPPSI-IPent catalyst. Our results indicate that this catalyst system may be applicable to the pseudo-living polymerisation of chloroarene monomers.
Synthesis of chlorinated biphenyls by Suzuki cross-coupling using diamine or diimine-palladium complexes
Kylmaelae, Tuula,Kuuloja, Noora,Xu, Youjun,Rissanen, Kari,Franzen, Robert
experimental part, p. 4019 - 4024 (2009/04/11)
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.
Cross-coupling of polychlorobenzenes with phenylboronic acid in the presence of [Pd]-imidazolium salts as catalytic systems
Burukin,Vasil'Ev,Merkulova,Chizhov,Mistryukov,Zlotin
, p. 1467 - 1469 (2008/09/18)
The reactions of di-, tetra-, and hexachlorobenzenes with phenylboronic acid in the presence of [Pd]-imidazolium salt-base as catalytic systems afford cross-coupling products in moderate yields. The highest conversions are attained when imidazolium salts bearing bulky aromatic substituents are used and the reaction is carried out in the presence of alkali alkoxides containing H α atoms. Cross-coupling is accompanied by hydrodechlorination of aromatic C-Cl bonds.
Bis(tetrazolyl)benzenes as ligands in the Suzuki reaction: Promoters or inhibitors?
Burukin,Vasil'ev,Merkulova,Struchkova,Zlotin
, p. 118 - 122 (2007/10/03)
The Suzuki cross-coupling with phenylboronic acid in the presence of the Pd(OAc)2/K3PO4/DMF catalytic system was successful for aryl bromides and somewhat poorer for aryl chlorides. Addition of 1,3-bis(tetrazol-1-yl)benzene or its analogs lowered the yields of biaryls.
Dechlorination of hexachlorobiphenyl by using potassium-sodium alloy
Miyoshi, Kumiko,Nishio, Takehiko,Yasuhara, Akio,Morita, Masatoshi
, p. 819 - 824 (2007/10/03)
2,2',4,4',5,5'-Hexachlorobiphenyl (HCB) was dechlorinated with potassium-sodium (K-Na) alloy under an inert gas atmosphere. Solvent effect was observed in the reaction. Dechlorination yields in benzene and cyclohexane were 99.9998% and 99.99996%, respecti
Polychlorinated biphenyl reductive dechlorination by vitamin B12s: Thermodynamics and regiospecificity
Woods, Sandra L.,Trobaugh, Darin J.,Carter, Kim J.
, p. 857 - 863 (2007/10/03)
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.
Physical, spectral and chromatographic properties of all 209 individual PCB congeners
Bolgar,et al.
, p. 2687 - 2705 (2007/10/03)
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
