- 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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- Iron(iii)porphyrin electrocatalyzed enantioselective carbon-chloride bond cleavage of hexachlorocyclohexanes (HCHs): Combined experimental investigation and theoretical calculations
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Enantioselective electrocatalysis of α-, β-, γ- and δ-hexachlorocyclohexanes (HCHs) by tetrakis-pentafluorophenyl-Fe(iii)porphyrin is described. The first example of the combined use of electrochemical measurements and theoretical calculations to determine the mechanism of the enantioselective C-Cl bond cleavage of the electrocatalysis is reported. The electrochemical measurements demonstrate that the reactivity of the HCHs follows the order γ-HCH > α-HCH > δ-HCH > β-HCH. Steric considerations and a molecular orbital theory approach can be used to rationalize the enantioselective nature of the catalysis based on the ease of approach of each Cl atom to the central Fe(i) ion and a consideration of the nodes on the C-Cl bonds that weaken these bonds in a manner that results in bond cleavage and the formation of an Fe-Cl bond.
- Liang, Xu,Li, Minzhi,Mack, John,Lobb, Kevin,Zhu, Weihua
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p. 11470 - 11476
(2018/08/28)
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- CONJUGATED POLYMERS
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The invention relates to novel conjugated polymers comprising in their backbone one or more divalent donor units, like for example benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl (BDT), that are linked on both sides to an acceptor unit, to methods of preparing the polymers and educts or intermediates used in such preparation, to polymer blends, mixtures and formulations containing the polymers, to the use of the polymers, polymer blends, mixtures and formulations as semiconductors organic electronic (OE) devices, especially in organic photovoltaic (OPV) devices and organic photodetectors (OPD), and to OE, OPV and OPD devices comprising these polymers, polymer blends, mixtures or formulations.
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Page/Page column
(2015/03/28)
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- Electroreductive dechlorination of α-hexachlorocyclohexane catalyzed by iron porphyrins in nonaqueous media
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Two iron porphyrins, (TPP)FeCl and (OEP)FeCl, where TPP and OEP are the dianions of tetraphenylporphyrin and octaethylporphyrin, respectively, were utilized as catalysts for the electroreductive dechlorination of α-hexachlorocyclohexane (α-HCH) which was monitored by electrochemistry, in situ UV-visible spectroelectrochemistry and controlled potential electrolysis in N,N′-dimethylformamide. GC-MS analysis of the α-HCH degradation products revealed the stepwise formation of pentachlorocyclohexene and tetrachlorocyclohexadiene as intermediates, prior to generation of the final dechlorination products which consisted of an isomeric mixture of trichlorobenzenes. Based on identification of the intermediates and final products in the reaction, an overall dechlorination mechanism of α-hexachlorocyclohexane is proposed.
- Zhu, Weihua,Ni, Cui,Liang, Lili,Li, Junwen,Li, Minzhi,Ou, Zhongping,Kadish, Karl M.
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p. 519 - 527
(2014/07/21)
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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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- Effects of FeS on the transformation kinetics of γ-hexachlorocyclohexane
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Distinctly different rates and pathways were observed for abiotic transformation of γ-hexachlorocyclohexane (γHCH) between homogeneous systems and systems containing FeS solid. The observed half-lives of γ-HCH decrease from about 1136 and 126 d in homogen
- Liu, Xiangmei,Peng, Ping'an,Fu, Jiamo,Huang, Weilin
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p. 1822 - 1828
(2007/10/03)
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- Photoreductive dehalogenation of halogenated benzene derivatives using ZnS or CdS nanocrystallites as photocatalysts
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ZnS nanocrystallites (nc-ZnS) prepared in N,N-dimethylformamide (DMF) photocatalyze dehalogenation of halogenated benzenes to benzene as the final product from chlorinated benzenes and to difluorobenzenes from fluorinated benzenes in the presence of triethylamine (TEA) as an electron donor under UV light irradiation (λ > 300 nm). When CdS nanocrystallites (nc-CdS) are used as a photocatalyst (λ > 400 nm), halogenated benzenes are photoreductively dehalogenated, yielding trichlorobenzene from hexachlorobenzene and tetrafluorobenzene isomers from hexafluorobenzene as the final products. Photoformed electrons on nc-ZnS and nc-CdS have such negative reduction potentials that these electrons reduce polyhalogenated benzenes, leading to the successive dehalogenation. nc-ZnS exhibits higher photocatalytic activity than nc-CdS due to the more negative potential of the electrons on nc-ZnS than that on nc-CdS. The higher activities of nc-ZnS and nc-CdS compared to their bulk forms are explained as being due to their quantum size effects and the adsorptive interaction between the substrates and the nanosized photocatalysts. ZnS nanocrystallites (nc-ZnS) prepared in N,N-dimethylformamide (DMF) photocatalyze dehalogenation of halogenated benzenes to benzene as the final product from chlorinated benzenes and to difluorobenzenes from fluorinated benzenes in the presence of triethylamine (TEA) as an electron donor under UV light irradiation (λ>300 nm). When CdS nanocrystallites (nc-CdS) are used as a photocatalyst (λ>400 nm), halogenated benzenes are photoreductively dehalogenated, yielding trichlorobenzene from hexachlorobenzene and tetrafluorobenzene isomers from hexafluorobenzene as the final products. Photoformed electrons on nc-ZnS and nc-CdS have such negative reduction potentials that these electrons reduce polyhalogenated benzenes, leading to the successive dehalogenation. nc-ZnS exhibits higher photocatalytic activity than nc-CdS due to the more negative potential of the electrons on nc-ZnS than that on nc-CdS. The higher activities of nc-ZnS and nc-CdS compared to their bulk forms are explained as being due to their quantum size effects and the adsorptive interaction between the substrates and the nanosized photocatalysts.
- Yin, Hengbo,Wada, Yuji,Kitamura, Takayuki,Yanagida, Shozo
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p. 227 - 231
(2007/10/03)
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- Hydrodechlorination of polychlorinated benzenes in the presence of a bimetallic catalyst in combination with a phase-transfer catalyst
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Bimetallic supported catalysts (Pd-Ni/C and Ni-Cu/C) in combination with a phase-transfer catalyst were found efficient and selective in the liquid-phase hydrodechlorination of polychlorinated benzenes under mild conditions.
- Simagina,Stoyanova
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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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- 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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- Destruction of halogenated hydrocarbons with solvated electrons in the presence of water
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Model halogenated aromatic and aliphatic hydrocarbons and halogenated phenols were dehalogenated in seconds by solvated electrons generated from sodium in both anhydrous liquid ammonia and ammonia/water solutions. The minimum sodium required to completely dehalogenate these model compounds was determined by increasing the Na/substrate ratio until halogen loss was complete. Minimum sodium consumptions were determined in both anhydrous liquid ammonia and with a (5, 20, 50-fold molar excess of water per mole of halide). While more Na was consumed in the presence of water, these dehalogenations were still efficient when a 50-fold water excess was present. Dehalogenation is faster than competiting reactions with water. CCl4 and CH3CCl3 in the presence of a stoichiometric deficiency of sodium produced only CH4 and CH3CH3 and recovered CCl44 or CH3CCl3, respectively. No partially dechlorinated products were detected, indicating dechlorination was diffusion controlled. Na consumption per chlorine removed (as NaCl) was lower than that of Li, K or Ca and this advantage increased in the presence of water. Na consumption was lower using Na chunks instead of a thin Na mirror. Chloroaromatic compounds gave the parent aromatic hydrocarbon and aminated products in anhydrous ammonia but aminated products did not form when water was present. (C) 2000 Elsevier Science Ltd.
- Sun, Guang-Ri,He, Jin-Bao,Pittman Jr., Charles U.
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p. 907 - 916
(2007/10/03)
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- Catalytic Dehalogenation of Highly Chlorinated Benzenes and Aroclors Using PdCl2(dppf) and NaBH4: Efficiency, Selectivity, and Base Support
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Reported herein is a convenient one-pot system that can dehalogenate highly chlorinated benzenes at room temperature with reasonable conversion rates using PdCl2(dppf) (dppf = 1,1′-bis-(diphenylphosphino)ferrocene) as catalyst, NaBH4 as reducing agent, TMEDA (N,N,N',N'-tetra-methyl-1,2-ethylenediamine) as supporting base, and THF as solvent. Total conversion of substrate to less chlorinated isomers is achieved within 200 h when hexachloro-, pentachloro-, and tetrachlorobenzenes are used. Degradation to benzene is not achievable, but the efficiency shown in the partial dechlorination is encouraging. A pronounced selectivity is accomplished with removal of meta-substituted chlorines being preferred over ortho- or para-substituted Cl atoms. The sequence in which reagents are added is also critical, thus indicating a protective role of the base. The effectiveness of the method was tested on the PCB mixtures Aroclor 1242, 1248, and 1254. Dechlorination efficiency at 67 °C is satisfactory.
- Lassová, Luisa,Lee, Hian Kee,Hor, T.S. Andy
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p. 3538 - 3543
(2007/10/03)
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- Preparation of 1,2,4-Trichlorobenzene by Regioselective Chlorination of 1,2-Dichlorobenzene in the Presence of Catalytic Amounts of Zeolites
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1,2,4-Trichlorobenzene is synthesized in high yield by the chlorination of 1,2- and 1,4-dichlorobenzenes in the liquid phase using zeolites as catalysts and Cl2 gas as the chlorinating agent.
- Singh, Anand P.,Sharma, Sahida,Rojatkar, Supada R.
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p. 512 - 513
(2007/10/03)
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- Nickel Complexes as Soluble Catalysts for Reductive Dehalogenation of Aromatic Halides
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Nickel(II) complexes 1 and 2 are soluble catalysts for reductive dehalogenation of aromatic bromides and polychlorobenzenes by sodium borohydride at 25-45 deg C in aqueous ethanol, aqueous acetonitrile, or ethanol-acetonitrile.Deuterium incorporation experiments, and rate retardation by added cumene, point to a radical-chain mechanism.Hydrazine can replace borohydride as a source of reducing power.Reactivity toward this reducing system increases with increasing halogen content of the substrate, a finding that parallels prior observations of dechlorination in natural sediments.
- Stiles Martin
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p. 5381 - 5385
(2007/10/02)
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- DEHALOGENATION OF CHLOROBENZENES WITH SODIUM DIHYDRIDOBIS(2-METHOXYETHOXO)ALUMINATE
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The dehalogenation of a series of 9 mono- to pentachlorinated benzenes with the title hydride in toluene has been found to be first order in the substrate and half order in the hydride.The reactivities of the chlorobenzenes, expressed by rate constants for the first-step dehalogenation, increased with increasing number of chlorine atoms over three orders of magnitude.The rate data revealed the unexpected acceleration of benzene formation during exhaustive dehalogenation of the higher chlorinated benzenes.For comparison, dehalogenation of several isomeric dibromobenzenes and bromochlorobenzenes with the same hydride and the product distribution for the dehalogenation of some chlorobenzenes with LiAlH4 are also reported.
- Vcelak, Jaroslav,Friesova, Anna,Rericha, Roman,Hetflejs, Jiri
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p. 1368 - 1383
(2007/10/02)
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- Photochemistry of Polyhaloarenes. 9. Characterization of the Radical Anion Intermediate in the Photodehalogenation of Polyhalobenzenes
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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.
- Freeman, P. K.,Ramnath, N.
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p. 3646 - 3651
(2007/10/02)
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- Photochemistry of Polyhaloarenes. 8. The Photodechlorination of Pentachlorobenzene
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Measurements of the intersystem crossing yield of pentachlorobenzene triplet, the quenching of photodechlorination of pentachlorobenzene with fumaronitrile, the dependence of the fluorescence lifetime, and the quantum yield of photodechlorination of pentachlorobenzene upon substrate concentration and the dependence of relative product concentration upon light intensity provide evidence for three pathways to product: direct fission of singlet and triplet and fragmentation of triplet excimer.
- Freeman, Peter K.,Ramnath, N.,Richardson, Alan D.
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p. 3643 - 3646
(2007/10/02)
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- Magnetic susceptibilities of organic compounds: Part V - Influence of substituents on diamagnetic susceptibilities of disubstituted and trisubstituted benzenes
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The magnetic susceptibilities of a number of triads of isomeric disubstituted benzenes have been determined, choosing the compounds in such a way that the substituents are present in the following combinations: (i) two electron-releasing substituents, (ii) a halogeno and an electron-releasing substituent, (iii) a halogeno and an electron-attracting substituent, and (iv) two halogeno substituents.The data show that for types (i), (ii) and (iv), the ortho isomers have the highest magnetic susceptibilities, the susceptibilities decreasing in the order: ortho > meta > para; for type (iii), the meta-isomers have the highest susceptibilities, the susceptibilities decreasing in the order: meta > para > ortho.The diamagnetic susceptibilities of some isomeric trisubstituted benzenes have also been determined and the data reveal that the susceptibility is the highest where the crowding of substituents is the highest (1,2,3-isomer) and lowest where the substituents are staggered and least crowded (1,3,5-isomer).Another observation made in the case of trisubstituted benzene is the applicability of a principle of additivity of their diamagnetic susceptibilities.
- Baliah, V.,Jeyanthy, J. Judith Diana
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p. 472 - 476
(2007/10/02)
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- Substantially linear monomeric composition and liquid crystal polymeric compositions derived therefrom
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Described herein are novel substantially linear monomeric compositions which can be polymerized with one or more difunctional monomers to give novel polymeric compositions having liquid crystal properties. This invention is also directed to a process for preparation of the novel substantially linear monomeric compositions.
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- Preparation of aryl halides
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A process for selectively substituting an aromatic nitro group with a halo group which comprises contacting the nitroaromatic compound with a phosphorushalide of formula: Rn PX5-n wherein n is selected from 0, 1, 2 and 3; R is selected from the group consisting of C-6 to C-10 aryl and substituted aryl wherein the substituents are selected from the group consisting of: straight and branched chain alkyl, alkoxy, and haloalkyl; halogen, sulfonate and mixtures thereof; and X is a halogen in the presence of an arylphosphorusoxydihalide solvent. The use of an arylphosphorustetrahalide and particularly phenylphosphorustetrachloride is preferred. The arylphosphorustetrahalide can be prepared in situ by contacting a solution of the corresponding arylphosphorusdihalide in an arylphosphorusoxydihalide solvent with a halogen. The process can further comprise the step of heating the reaction mixture to maintain a temperature of from about 100° C. to about 175° C. for from about 1 hour to about 24 hours.
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- Photo-Rearrangement of Polychlorobenzenes meta-Migration of Chlorine Atom
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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.
- Morisaki, Kenji,Miura, Yasuki,Abe, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
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p. 1589 - 1592
(2007/10/02)
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- Transchlorination of o-Dichlorobenzene and Benzene into Chlorobenzene
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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.
- Shinoda, Kiyonori
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p. 2051 - 2052
(2007/10/02)
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- The Photochemistry of Polyhaloarenes. 5. Fragmentation Pathways in Polychlorobenzene Radical Anions
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Negative chemical ionization mass spectroscopy of polychlorobenzenes reveals that parent radical anion undergoes fission by two pathways--(a) cleavage to aryl radical plus Cl- (kCl-) and (b) fission to aryl carbanion plus chlorine atom (kCl*)--and that there is a Hammett relationship between log(kCl*/kCl-) and Σ?.The dependence of the reciprocal of the quantum yield for photochemical dechlorination of trichlorobenzenes through pentachlorobenzene upon the reciprocal of the concentration of the electron donor, triethylamine, was analyzed in order to establish the optimum concentration for radical anion formation.The regiochemistries for the photodechlorination of trichlorobenzenes through pentachlorobenzene in the presence of triethylamine, with and without acetophenone sensitizer, were determined and found to be very similar and quite different from those observed for the direct photolysis in the absence of triethylamine for the comparison cases of 1,2,3,5-tetrachloro- and pentachlorobenzene.The regiochemistry of the fragmentation of polychlorobenzene radical anion to aryl radical plus chloride ion is rationalized in terms of a bent transition state.
- Freeman, Peter K.,Srinivasa, Ramanujan,Campbell, J.-A.,Deinzer, Max L.
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p. 5531 - 5536
(2007/10/02)
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- OXIDATION BY METAL SALTS. OXIDATIVE HALOGENATION OF BENZENE AND HALOBENZENES PROMOTED BY Co(III) AND Mn(III) ACETATES IN TRIFLUOROACETIC ACID AND ITS AQUEOUS SOLUTIONS
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A study was carried out on the oxidation of benzene and halobenzenes by Co(III) and Mn(III) acetates in the presence of alkali metal chlorides and bromides in CF3CO2H and its aqueous solutions (10-33 vol. percent H2O).The optimal water content in the solution is a function both of the nature of the metal oxidizing agent and the aromatic substrate.The reaction presumably proceeds through the formation of an aromatic radical-cation which then reacts with the halide anion.The oxidative chlorination of bromobenzene is complicated by ipso substitution and bromine redistribution.Phenyl iodosodichloride may be isolated in preparative yield in the chlorination of iodobenzene.In other cases, variation of the reaction conditions may give high yields of the corresponding chlorine and bromine derivatives.The feasibility of polychlorination was studied.Possible reaction mechanisms were considered.
- Makhon'kov, D. I.,Cheprakov, A. V.,Beletskaya, I. P.
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p. 609 - 615
(2007/10/02)
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- A safe and economical synthesis of 3-(trifluoromethoxy) aniline from 2-chlorophenol
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A simple, safe and realistic synthesis of 3-(trifluoromethoxy) aniline from 2-chlorophenol is proposed, the key step being a regiospecific arynic amination of 2-chloro (trifluoromethoxy) benzene.This method has been extended to the synthesis of 4-chloro-3-(trifluoromethoxy) aniline from 2,6-dichlorophenol.Some unusual products are obtained during the reaction between sodium amide and 2-chloro (chlorodifluoromethoxy) benzene, the formation of which is discussed.
- Langlois, Bernard,Soula, Gerard
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p. 925 - 929
(2007/10/02)
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- Dechlorination of Polychlorobenzenes over Triiron Tetraoxide in the Presence of Hydrogen Donating Solvents
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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.
- Hao, Cui Xiang,Nakada, Masahiro,Yamaguchi, Tatsuaki,Fukushi, Sachio,Hirota, Minoru
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p. 1707 - 1710
(2007/10/02)
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- Nucleophilic Displacement in Polyhalogenoaromatic Compounds. Part 11. Kinetics of Protiodeiodination of Iodoarenes in Dimethyl Sulphoxide-Methanol
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The rates of methoxide-ion induced protiodeiodination of a number of polychloroiodobenzenes and their derivatives have been measured in dimethyl sulphoxide-methanol (9:1 v/v; 323.2 K).The true reagent under these conditions appears to be the dimethyl sulphoxide anion, and the rates of reaction in some cases appear to approach that expected of a diffusion controlled process.This corresponds to a major decrease in the efficacy of further activating substituents in the aromatic system, altough deactivating groups such as p-OMe still show large effects.Chlorine promotes protiodeiodination in the order of efficiency o-Cl > m-Cl > p-Cl; the trifluoromethyl group activates displacement in the order o-CF3 > p-CF3 > m-CF3, although with much less difference between isomeric sites. o-Nitro-groups promote protiodeiodination whereas the p-nitro-group encourages methoxydeiodination.No evidence of methoxydeiodination was found in attack of the polychloroiodobenzenes, although the rates of methoxydechlorination of the corresponding polychlorobenzenes suggest that in some cases this might occur.Evidence rejecting the possible SRN1 mechanism and supporting nucleophilic attack by a carbanionic species upon iodine is presented.
- Bolton, Roger,Moore, Clive,Sandall, John P.B.
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p. 1593 - 1598
(2007/10/02)
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- Process for the preparation of bis(aminophenyl)alkanes
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An improved process is described for the preparation of bis(aminophenyl)alkanes which comprises heating the corresponding bis(di-alkoxyphenyl)alkane or corresponding cyclic ethers of bis(phenyl)alkanes with an at least stoichiometric proportion of an aniline acid addition salt, optionally in the presence of an inert organic solvent.
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