106-46-7Relevant articles and documents
Facile Hydrodehalogenation with Hydrogen and Pd/C Catalyst under Multiphase Conditions
Marques, Carlos Alberto,Selva, Maurizio,Tundo, Pietro
, p. 5256 - 5260 (1993)
A multiphase system consisting of a hydrocarbon solvent, a strong alkaline solution, and a quaternary onium salt, in the presence of a Pd/C catalyst with hydrogen at atmospheric pressure, allows the rapid and progressive displacement of the chlorine atoms from polyhalogenated benzenes.The onium salt in this case constitutes a third liquid phase in which the reaction takes place.At 50 deg C, 1,2,4,5-tetrachlorobenzene is reduced to benzene in 30 min using a Pd/Cl molar ratio of 1/130.Halogenated compounds are partitioned between the hydrocarbon solution and the liquid phase of the phase-transfer agent; rapid removal of HCl adsorbed on Pd/C is effected by neutralization with the alkaline solution.The enhancement of the reaction rate compared with the known methods might be attributed to the facile adsorption of H2 by the catalyst under the reaction conditions.Different reaction rates result in the reduction of the three isomeric chlorotoluenes, whether the reaction is carried out in the presence or absence of the onium salt.
Photolyses of Polychloro- and Polybromobenzenes. Novel Isomerization in Solvents Resisting against Hydrogen Abstraction
Hirota, Minoru,Nakada, Masahiro
, p. 2926 - 2933 (1992)
Polychloro- and polybromobenzenes were photolyzed in acetonitrile and perfluorohexane.Photolyses of polychlorobenzenes in acetonitrile gave isomerized products in addition to dechlorinated products, which appeared exclusively in the photolyses in hexane and other solvents carrying hydrogen atoms active to hydrogen abstraction.The photolyses in perfluorohexane gave isomerized products to a lesser extent.The reaction in this solvent gave predominantly polyhalobiphenyls which are assumed to be produced through coupling.Without exception the isomerized products have the structure which can be expected to be formed via 1,3-migration of chlorine atom, though it is not sure at present whether it takes place actually.The isomerization was shown to proceed intramolecularly.Some evidence and theoretical rationalization in favor of the 1.3-chlorine migration mechanism are given.
Photo-Rearrangement of Polychlorobenzenes meta-Migration of Chlorine Atom
Morisaki, Kenji,Miura, Yasuki,Abe, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
, p. 1589 - 1592 (1987)
Several polychlorobenzenes were irradiated by ultraviolet light (254 nm) in acetonitrile and the products were determined by gas chromatography.In addition to the abstraction of hydrogen atom from the solvent, photo-isomerization was shown to proceed giving isomeric polychlorobenzenes one of which chlorine atoms migrated to meta to the original position.The meta-rearrangement was rationalized by an MNDO calculation on o-chlorophenyl free radical.
Dechlorination of Polychlorobenzenes over Triiron Tetraoxide in the Presence of Hydrogen Donating Solvents
Hao, Cui Xiang,Nakada, Masahiro,Yamaguchi, Tatsuaki,Fukushi, Sachio,Hirota, Minoru
, p. 1707 - 1710 (1985)
Dechlorination of polychlorobenzenes over Fe3O4 was investigated by a pulse micro-reactor technique.Dechlorinations of various polychlorobenzenes in hexane and cyclohexane were carried out in the gas phase at the temperatures ranging from 498 to 623 K.In the presence of such hydrogen donating solvents, dechlorination was shown to proceed almost exclusively.The relative rates of dechlorination were measured by gas chromatography.It was found that the solvents used to dissolve polychlorobenzenes plays a role of a hydrogen donor in this reaction.The different rates among unequivalent chlorine atoms in a molecule were interpreted by the effect of steric acceleration caused by the neighboring chlorine atom(s).The reaction will probably proceed via hydrogenolytic cleavage of C-Cl bonds.
Dechlorination of lindane, dieldrin, tetrachloroethane, trichloroethene, and PVC in subcritical water
Kubatova, Alena,Lagadec, Arnaud J. M.,Hawthorne, Steven B.
, p. 1337 - 1343 (2002)
Pure water has been used to dechlorinate aliphatic organics without the need for catalysts or other additives. Dehydrohalogenation (loss of HCl with the formation of a double bond) occurred at temperatures as low as 105-200 °C for 1,1,2,2-tetrachloroethane, lindane (1,2,3,4,5,6-hexachlorocyclohexane, γ-isomer), and dieldrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo, exo-1,4:5,8-dimethanonaphthalene). Complete loss of the parent compounds was achieved in less than 1 h at 150, 200, and 300 °C for 1,1,2,2-tetrachloroethane, lindane, and dieldrin, respectively. The initial dechlorination of lindane had an activation energy of 84 kJ mol-1 with an Arrhenius pre-exponential factor of 1.5 x 106 s-1. Dehydrohalogenation of lindane formed trichlorobenzenes, followed by subsequent hydrolysis and hydride/chloride exchange to form chlorophenols, lower chlorobenzenes, and phenol as the major final product. Reaction of poly(vinyl chloride) at 300 °C for 1 h formed aromatic hydrocarbons ranging from benzene to anthracene and a char residue with a ca. 1:1 carbon-to-hydrogen ratio (mol/mol). The residue contained 1 wt % of chlorine compared to 57 wt % chlorine in the original polymer. All compounds tested yielded chloride ion as the major product (at higher temperatures), indicating that complete dechlorination of some aliphatic organochlorines may be feasible.
Campaigne,Leal
, p. 230 (1953)
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Mathes
, p. 591 (1939)
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Transchlorination of o-Dichlorobenzene and Benzene into Chlorobenzene
Shinoda, Kiyonori
, p. 2051 - 2052 (1987)
The transchlorination of o-dichlorobenzene (o-DCB) and benzene into chlorobenzene (CB) was carried out in the presence of catalyst at 400 degC. o-C6H4Cl2 + C6H6 = 2 C6H5Cl Noble metal chloride supported on activated charcoal promoted remarkably the transchlorination.
Photodechlorination of polychlorobenzene congeners in surfactant micelle solutions
Wei Chu,Jafvert
, p. 2415 - 2422 (1994)
Photochemical reactions of polychlorobenzene congeners in aqueous solutions containing surfactant micelles have been investigated. Photoreduction through photodechlorination was shown to be the main decay pathway in which lesser chlorinated congeners and benzene were formed as intermediates. Final products included H+ and Cl- in approximately stoichiometric amounts. Several hydrogen sources were investigated with sodium borohyride shown to be a promising rate enhancer at elevated concentrations. -Authors
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Tamai,Othsuka
, p. 1996,1997, 1998, 1999 (1973)
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Prud'homme,Rabaut
, p. 223 (1892)
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Photochemistry of Polyhaloarenes. 9. Characterization of the Radical Anion Intermediate in the Photodehalogenation of Polyhalobenzenes
Freeman, P. K.,Ramnath, N.
, p. 3646 - 3651 (1991)
The product-determining intermediate in the photodehalogenation of polyhalobenzenes has been characterized by generating excimers and radical anions within a micellar core and by formation of corresponding radical anions by electron transfer from lithium p,p'-di-tert-butylbiphenyl radical anion (LiDBB).The photodechlorination of pentachlorobenzene (1; 254 nm, CH3CN) produces 1,2,3,5-tetrachloro- (2), 1,2,4,5-tetrachloro- (3), and 1,2,3,4-tetrachlorobenzene (4).The regiochemistry of this reaction is compared with that observed in the photodechlorination of 1 in a micellar solution of hexadecyltrimethylammonium bromide (CTAB) with occupancy numbers (n) principally /=2.Further comparisons with photodechlorination of 1 in a micellar CTAB solution (n 2) in the presence of triethylamine, as well as photodechlorination in CH3CN in the presence of triethylamine, were used to characterize unencumbered radical anions.The regiochemistries observed in photolytic dehalogenations of 1, 2, 1,2,4-trichlorobenzene, and pentafluorobenzene in the presence of triethylamine are in good agreement with those realized in the radical anion fragmentations induced by electron transfer from LiDBB.
Novel catalysts for dechlorination of polychlorinated biphenyls (PCBs) and other chlorinated aromatics
Fletcher, Andrew E. D.,Moss, James,Cowley, Andrew R.,O'Hare, Dermot
, p. 2971 - 2973 (2007)
Diiron complexes of fluorene and fluorene* (1,2,3,4,5,6,7,8,9- nonamethylfluorene) have been found to be catalysts for the dechlorination of chlorinated aromatics, such as PCBs. The Royal Society of Chemistry.
Rate of Reaction of Phenyl Radicals with Oxygen in Solution and in the Gas Phase
Sommeling, Paul M.,Mulder, Peter,Louw, Robert,Avila, David V.,Lusztyk, Janusz,Ingold, K. U.
, p. 8361 - 8364 (1993)
The rate constant for the title reaction, k1, is 3.8 X 109 M-1 s-1 in water at 298 K and is >/= 108 M-1 s-1 in the gas phase at 603 K.It is concluded that two reports that this reaction is very slow in the gas phase, k1 >/= 1.2 X 104 and ca.2.3 X 106 M-1 s-1, are in error.
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Orloff,Kolka
, p. 5484,5487 (1954)
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Electrochemical reductive dehalogenation of chlorobenzenes
Plekhanov, V. P.,Tsyganok, A. I.,Kulikov, S. M.
, p. 1091 - 1095 (1995)
Electrochemical dechlorination of 1,2,3,5-tetrachlorobenzene in methanol and chlorobenzene in dimethylsulfoxide with tetraalkylammonium salts as supporting electrolytes was carried out.The extent of dechlorination depends significantly on the electrode composition. - Key words: electrochemical dechlorination, cathodic materials, polychlorobenzenes.
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Aronheim
, p. 1400 (1875)
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MFI-type zeolite nanosheets for gas-phase aromatics chlorination: A strategy to overcome mass transfer limitations
Boltz, Marilyne,Losch, Pit,Louis, Benoit,Rioland, Guillaume,Tzanis, Lydie,Daou, T. Jean
, p. 27242 - 27249 (2014)
The continuous gas-solid (environmentally-friendly) chlorination of deactivated arenes using trichloroisocyanuric acid (TCCA, C3N 3O3Cl3) as a chlorination agent was chosen to compare the catalytic performances of various MFI-type catalysts in a reaction demanding a strong acidity. Mass transfer limitations were also evaluated by reacting either chloro- or nitrobenzene through a ZSM-5 zeolite porous network having different crystal sizes and morphologies. Whereas, the reaction rate was completely controlled by internal diffusion in 10-15 μm-sized big ZSM-5 zeolite crystals (Weisz modulus, big crystals ~ 10), the impact of internal diffusion could be ruled out for ZSM-5 nanocrystals (200-400 nm) and in stacked ZSM-5 nanosheets (thickness 2 nm). Based on reactivity differences in arene halogenation between the two nano-sized ZSM-5 zeolites, we were able to estimate the quantity of mild acidic silanol groups in ZSM-5 nanosheets to roughly 1/3 of the total amount of Brnsted acid sites.
Highly active polymer anchored palladium catalyst for the hydrodehalogenation of organic halides under mild conditions
Zhang, Yiping,Liao, Shijian,Xu, Yun
, p. 4599 - 4602 (1994)
Palladium anchored on poly(N-vinyl-2-pyrrolidone) (PVP-PdCl2) exhibits very high catalytic activity for the hydrodehalogenation of organic halides under atmospheric pressure in the presence of a base.
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Voegtli et al.
, p. 1627,1633 (1954)
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Kinetic study of the hydrogenolysis of polychlorobenzenes over a Pd/C catalyst in an alkaline aqueous-n-hexane system
Anusiewicz, Iwona,Janiak, Tadeusz,Okal, Janina
, p. 797 - 801 (2010)
The kinetics of the hydrogenolysis of chlorobenzene, dichlorobenzenes and some trichlorobenzenes over a 10% Pd/C catalyst was studied using a multiphase system. The reactions were carried out in a batch reactor with an aqueous NaOH/n-hexane solution of chloroaromatic compound as the liquid phase. Benzene was the final product of the hydrogenolysis of all the compounds studied. Hydrogenolysis was more effective in the presence of in situ generated hydrogen than gaseous hydrogen. The initial reaction rates and TOFs of dichlorobenzenes and trichlorobenzenes were slightly lower than those of chlorobenzene. The position of the chlorine atoms in trichlorobenzenes affects the kinetics of the removal of the first chlorine from these molecules. The differences in chlorine reactivity were explained by the inductive and steric effects induced by the benzene-Cl bonds.
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Hodgson,Walker
, p. 530 (1935)
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Blum
, p. 1605 (1966)
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The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
, p. 18040 - 18049 (2021/05/29)
An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
Direct Transformation of Arylamines to Aryl Halides via Sodium Nitrite and N-Halosuccinimide
Mukhopadhyay, Sushobhan,Batra, Sanjay
supporting information, p. 14622 - 14626 (2018/09/21)
A one-pot universal approach for transforming arylamines to aryl halides via reaction with sodium nitrite (NaNO2) and N-halosuccinimide (NXS) in DMF at room temperature under metal- and acid-free condition is described. This new protocol that is complementary to the Sandmeyer reaction, is suggested to involve the in situ generation of nitryl halide induce nitrosylation of aryl amine to form the diazo intermediate which is halogenated to furnish the aryl halide.