- Design of a bimetallic Au/Ag system for dechlorination of organochlorides: Experimental and theoretical evidence for the role of the cluster effect
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The experimental study of dechlorination activity of a Au/Ag bimetallic system has shown formation of a variety of chlorinated bimetallic Au/Ag clusters with well-defined Au:Ag ratios from 1:1 to 4:1. It is the formation of the Au/Ag cluster species that mediated C-Cl bond breakage, since neither Au nor Ag species alone exhibited a comparable activity. The nature of the products and the mechanism of dechlorination were investigated by ESI-MS, GC-MS, NMR, and quantum chemical calculations at the M06/6-311G(d)&SDD level of theory. It was revealed that formation of bimetallic clusters facilitated dechlorination activity due to the thermodynamic factor: C-Cl bond breakage by metal clusters was thermodynamically favored and resulted in the formation of chlorinated bimetallic species. An appropriate Au:Ag ratio for an efficient hydrodechlorination process was determined in a joint experimental and theoretical study carried out in the present work. This mechanistic finding was followed by synthesis of molecular bimetallic clusters, which were successfully involved in the hydrodechlorination of CCl4 as a low molecular weight environment pollutant and in the dechlorination of dichlorodiphenyltrichloroethane (DDT) as an eco-toxic insecticide. High activity of the designed bimetallic system made it possible to carry out a dechlorination process under mild conditions at room temperature.
- Romashov, Leonid V.,Khemchyan, Levon L.,Gordeev, Evgeniy G.,Koshevoy, Igor O.,Tunik, Sergey P.,Ananikov, Valentine P.
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Read Online
- Photosensitizing catalysis of the B12 complex without an additional photosensitizer
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A cobalamin derivative, heptamethyl cobyrinate perchlorate, was activated by UV light irradiation to form a Co(i) species in the presence of triethanolamine and used for a dechlorination reaction, and this photochemical reaction was accelerated in an ionic liquid.
- Shimakoshi, Hisashi,Li, Li,Nishi, Masashi,Hisaeda, Yoshio
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Read Online
- A polymerized ionic liquid-supported B12 catalyst with a ruthenium trisbipyridine photosensitizer for photocatalytic dechlorination in ionic liquids
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By immobilizing a B12 complex and a Ru(ii) trisbipyridine photosensitizer in a polymerized ionic liquid (PIL), a visible light-driven photocatalyst was developed. The synthesized copolymer was characterized by GPC and DLS, and using UV-vis absorption spectra and luminescence spectra. The Ru(ii) trisbipyridine photosensitizer in the copolymer showed an enhanced emission compared to that of the monomer in the ionic liquid, 1-butyl-4-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C 4mim][NTf2]). Formation of the Co(i) species of the B 12 complex in the copolymer was confirmed by the UV-vis spectral change in [C4mim][NTf2] containing a sacrificial reductant (triethanolamine) under irradiation with visible light. The copolymer showed a high photocatalytic activity in various ionic liquids for 1,1-bis(4- chlorophenyl)-2,2,2-trichloroethane (DDT) dechlorination with ～99% conversion after visible light irradiation for 2 h. Furthermore, both the B 12 catalyst and photosensitizer in the polymer were easily recycled for use with the ionic liquid solvent without any loss of catalytic activity.
- Zhang, Wei,Shimakoshi, Hisashi,Houfuku, Noriyuki,Song, Xi-Ming,Hisaeda, Yoshio
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Read Online
- Aerobic Electrochemical Transformations of DDT to Oxygen-Incorporated Products Catalyzed by a B12 Derivative
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Electrochemical transformations of DDT into oxygen-incorporated products, amides and esters, catalyzed by a B12 derivative, heptamethyl cobyrinate perchlorate, have been developed under aerobic conditions. The dechlorinative oxygenation of DDT forms the acyl chloride as an intermediate for the synthesis of the amide and ester in the reaction with the amine and alcohol, respectively. This electrochemical method demonstrated with 20 oxygen-incorporated dechlorinated products up to 88% yields with 15 new compounds and was also successfully applied to the conversion of methoxychlor to an amide and ester.
- Hisaeda, Yoshio,Moniruzzaman, Mohammad,Ono, Toshikazu,Shimakoshi, Hisashi,Yano, Yoshio
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supporting information
p. 2784 - 2791
(2022/01/19)
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- Synthesis of a B12-BODIPY dyad for B12-inspired photochemical transformations of a trichloromethylated organic compound
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A B12complex-BODIPY dyad was synthesized by peripheral modification of cobalamin derivatives. The photophysical properties of the dyad were investigated by UV-vis, PL, and transient absorption spectroscopy. A visible light-driven dechlorination reaction of a trichlorinated organic compound, DDT, was reported. The dyad showed efficient catalysis for dechlorination under N2with turnover numbers of over 220 for the reaction. One-pot syntheses of an ester and amide from DDT and benzotrichloride were also achieved using the dyad under air.
- Anai, Yuki,Shichijo, Keita,Fujitsuka, Mamoru,Hisaeda, Yoshio,Shimakoshi, Hisashi
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supporting information
p. 11945 - 11948
(2020/10/15)
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- Enhanced photocatalytic activity of a B12-based catalyst co-photosensitized by TiO2 and Ru(II) towards dechlorination
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A novel hybrid photocatalyst denoted as B12-TiO2-Ru(ii) was prepared by co-immobilizing a B12 derivative and trisbipyridine ruthenium (Ru(bpy)32+) on the surface of a mesoporous anatase TiO2 microspheres and was characterized by DRS, XRD, SEM and BET et al. By using the hybrid photocatalyst, DDT was completely didechlorinated and a small part of tridechlorinated product was also detected in the presence of TEOA only after 30 min of visible light irradiation. Under simulated sunlight, the hybrid exhibited a significantly enhanced photocatalytic activity for dechlorination compared with B12-TiO2 under the same condition or itself under visible light irradiation due to the additivity in the contribution of UV and visible part of the sunlight to the electron transfer. In addition, this hybrid catalyst can be easily reused without loss of catalytic efficiency. This is the first report on a B12-based photocatalyst co-sensitized by two photosensitizers with wide spectral response.
- Sun, Ying,Zhang, Wei,Ma, Tian-Yi,Zhang, Yu,Shimakoshi, Hisashi,Hisaeda, Yoshio,Song, Xi-Ming
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p. 662 - 670
(2018/01/17)
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- Significant enhancement of visible light photocatalytic activity of the hybrid B12-PIL/rGO in the presence of Ru(bpy)32+ for DDT dehalogenation
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A new B12-PIL/rGO hybrid was prepared successfully through immobilizing a B12 derivative on the surface of poly(ionic liquid) (PIL)-modified reduced graphene oxide (rGO) by electrostatic attraction and π-π stacking attraction among the different components. The hybrid catalyst showed an enhanced photocatalytic activity in the presence of Ru(bpy)32+ for 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) dechlorination with ～100% conversion. Especially, the yield of didechlorinated products could reach 78% after 1 h of visible light irradiation, which should be attributed to a synergistic effect of B12, rGO and PIL in B12-PIL/rGO, including their respective catalytic performance, the excellent electron transport of rGO and the concentration of DDT and 1,1-bis(4-chlorophenyl)-2,2-dichloroethane (DDD) on the surface of B12-PIL/rGO. Furthermore, the hybrid catalyst was easily recycled for use without obvious loss of catalytic activity.
- Sun, Ying,Zhang, Wei,Tong, Jian,Zhang, Yu,Wu, Shuyao,Liu, Daliang,Shimakoshi, Hisashi,Hisaeda, Yoshio,Song, Xi-Ming
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p. 19197 - 19204
(2017/04/10)
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- Photocatalytic function of the B12 complex with the cyclometalated iridium(III) complex as a photosensitizer under visible light irradiation
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A visible light induced three-component catalytic system with the cobalamin derivative (B12) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF3)ppy}2(dtbpy)]PF6) as a photosensitizer and triethanolamine as an electron source under N2 was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)3]Cl2 as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B12, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B12 enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway.
- Tian, Hui,Shimakoshi, Hisashi,Park, Gyurim,Kim, Sinheui,You, Youngmin,Hisaeda, Yoshio
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p. 675 - 683
(2018/02/16)
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- Compounds and methods for the reduction of halogenated hydrocarbons
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The present application relates to methods for the reduction of halogenated hydrocarbons using compounds of Formula (I): wherein the reduction of the halogenated compounds is carried out, for example, under ambient conditions without the need for a transition metal containing co-factor. The present application also relates to methods of recovering precious metals using compounds of Formula (I) that are absorbed onto a support material.
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Page/Page column 20-21
(2017/12/27)
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- Supramolecular system composed of B12 model complex and organic photosensitizer: Impact of the corrin framework of B12 on the visible-light-driven dechlorination without the use of noble metals
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The visible-light-driven dechlorination system without the use of a noble metal has been developed. We screened the combination of cobalt catalysts having square-planar monoanionic ligands (hydrophobic B12 model complex 1/imine-oxime type complex 2) and typical red dyes (Rose Bengal 3/Rhodamine B 4/Nile Red 5) for the construction of a dehalogenation system via a noble-metal-free and visible-light-driven process. The combination of the hydrophobic B12 model complex 1 and Rose Bengal 3 exhibited the highest catalytic activity to 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) to form the monodechlorinated compound, 1,1-bis(4-chlorophenyl)-2,2-dichloroethane, as the major product. The prolonged photocatalysis of DDT by the B12-Rose Bengal system afforded the tri-dechlorinated compound, trans-4,4′-dichlorostilbene, as the major product. Furthermore, we investigated the mechanism of the dehalogenation cycle using various methods such as UV-vis spectroscopy and laser flash photolysis. Finally, we clarified the advantage of using the hydrophobic B12 model complex 1 as an electron acceptor as well as a cobalt catalyst in the organic dye-involved photocatalysis.
- Tahara, Keishiro,Mikuriya, Kumiko,Masuko, Takahiro,Kikuchi, Jun-Ichi,Hisaeda, Yoshio
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p. 141 - 150
(2016/02/09)
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- Structure determination of microbial metabolites by the crystalline sponge method
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The structures of metabolites produced in microgram quantities by enzymatic reductions with baker's yeast were analyzed using the crystalline sponge method. The X-ray data provided reliable structures for trace metabolites including their relative and absolute stereochemistries that are not fully addressed by conventional NMR and LC-MS analyses. Technically, combining two or more chromatographic purification techniques is essential because, unlike abundant synthetic compounds, extracted metabolites contain many low level UV-silent impurities. The crystalline sponge method coupled with HPLC purification (LC-SCD) would thus be a useful method for metabolic analysis and drug discovery.
- Inokuma, Yasuhide,Ukegawa, Tomoya,Hoshino, Manabu,Fujita, Makoto
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p. 3910 - 3913
(2016/06/09)
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- Development of metal-organic framework (MOF)-B12 system as new bio-inspired heterogeneous catalyst
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Abstract A novel bimetal complex {Zn4Ru2(bpdc)4·4C2NH8·9DMF}n (1) (H2bpdc = 4,4′-biphenyldicarboxylic acid) was synthesized by the solvothermal method. The results of the X-ray crystallographic analysis revealed that 1 crystallizes in the orthorhombic Pna21 space group, which has a 3D 2-fold interpenetrated hex framework, with open channel sizes along the [010] direction of ca. 1.4 nm × 1.4 nm. The photosensitizer [Ru(bpy)3]2+ was adsorbed into the 1 to form Ru@MOF by cation exchanging. A cobalamin derivative (B12), heptamethyl cobyrinate, was also effectively immobilized on Ru@MOF, and the resulting hybrid complex, B12-Ru@MOF, exhibited a high reactivity for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) under an N2 atmosphere by visible light irradiation in the solid state. The catalysis of B12-Ru@MOF can still reach more than a ca. 80% conversion after third recyclings. Furthermore, the heterogeneous catalyst, B12-Ru@MOF, was useful for the cobalamin-dependent reaction, such as the 1,2-migration of the acetyl group.
- Xu, Jing,Shimakoshi, Hisashi,Hisaeda, Yoshio
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- Elucidating turnover pathways of bioactive small molecules by isotopomer analysis: The persistent organic pollutant DDT
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The persistent organic pollutant DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) is still indispensable in the fight against malaria, although DDT and related compounds pose toxicological hazards. Technical DDT contains the dichloro congener DDD (1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene) as by-product, but DDD is also formed by reductive degradation of DDT in the environment. To differentiate between DDD formation pathways, we applied deuterium NMR spectroscopy to measure intramolecular deuterium distributions (2H isotopomer abundances) of DDT and DDD. DDD formed in the technical DDT synthesis was strongly deuterium-enriched at one intramolecular position, which we traced back to 2H/1H fractionation of a chlorination step in the technical synthesis. In contrast, DDD formed by reductive degradation was strongly depleted at the same position, which was due to the incorporation of 2H-depleted hydride equivalents during reductive degradation. Thus, intramolecular isotope distributions give mechanistic information on reaction pathways, and explain a puzzling difference in the whole-molecule 2H/1H ratio between DDT and DDD. In general, our results highlight that intramolecular isotope distributions are essential to interpret whole-molecule isotope ratios. Intramolecular isotope information allows distinguishing pathways of DDD formation, which is important to identify polluters or to assess DDT turnover in the environment. Because intramolecular isotope data directly reflect isotope fractionation of individual chemical reactions, they are broadly applicable to elucidate transformation pathways of small bioactive molecules in chemistry, physiology and environmental science.
- Ehlers, Ina,Betson, Tatiana R.,Vetter, Walter,Schleucher, Jürgen
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- Electrochemical dechlorination of 4,4′-(2,2,2-trichloroethane-1,1-diyl)bis(chlorobenzene) (DDT) at silver cathodes
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Cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the reduction of 4,4′-(2,2,2-trichloroethane-1,1-diyl)bis(chlorobenzene) (DDT) at silver cathodes in dimethylformamide (DMF) containing 0.050 M tetramethylammonium tetrafluoroborate (TMABF4). In addition, this work has been extended to the individual reductions of two degradation products, namely 4,4′-(2,2-dichloroethane-1,1-diyl)bis(chlorobenzene) (DDD) and 4,4′-(ethene-1,1-diyl)bis(chlorobenzene) (DDNU). At a scan rate of 100 mV s-1, cyclic voltammograms for irreversible reduction of DDT at a silver electrode exhibit four prominent cathodic peaks in DMF and CH3CN, and three prominent cathodic peaks in DMSO. On the other hand, reduction of DDD and DDNU at silver in DMF-0.050 M TMABF4displays four and two irreversible peaks, respectively. Carbon-chlorine bonds of the -CCl3moiety of DDT and of the -CHCl2moiety of DDD are reduced more easily at silver than at glassy carbon. Bulk electrolyses of DDT at a silver gauze cathode in DMF-0.050 M TMABF4afford a potential-dependent mixture of products that includes DDD, DDNU, 4,4′-(2,2-dichloroethene-1,1-diyl)bis(chlorobenzene) (DDE), 4,4′-(2-chloroethene-1,1-diyl)bis(chlorobenzene) (DDMU), 4,4′-(2-chloroethane-1,1-diyl)bis(chlorobenzene) (DDMS), 1-chloro-4-(1-phenylvinyl)benzene (PVB), 1,1′-diphenylethylene (DPE), and 1,1′-ethylidenebisbenzene (EBB). However, at more negative potentials, the principal products are completely dechlorinated DPE and EBB. Dechlorination of DDT at silver appears to proceed via a series of steps involving carbanion intermediates arising from direct reduction of alkyl and aryl carbon-chlorine bonds along with hydroxide-promoted E2 elimination of chloride. When DMF-d7was used as solvent, no evidence for deuterium atom incorporation into any product was seen, which indicates that radical intermediates do not play a significant role in the reduction of DDT.
- McGuire, Caitlyn M.,Peters, Dennis G.
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p. 423 - 430
(2014/12/10)
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- Dechlorination of DDT catalyzed by visible-light-driven system composed of vitamin B12 derivative and Rhodamine B
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The visible-light-driven dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2- trichloroethane (DDT) was carried out in the presence of a hydrophobic vitamin B12, heptamethyl cobyrinate perchlorate and Rhodamine B. DDT was successfully dechlorinated to form 1,1-bis(4-chlorophenyl)-2,2-dichloroethane (DDD) as the mono-dechlorinated product upon visible light irradiation with a tungsten lamp (λ > 440 nm). Upon prolonged visible light irradiation to DDT, DDMU (1-chloro-2,2-bis(4-chlorophenyl)ethylene), DDMS (1-chloro-2,2-bis(4-chlorophenyl)ethane) and DCS (trans-4,4′- dichlorostilbene) were obtained as the di- and tri-dechlorinated products. The use of the photostable organic sensitizer enabled prolonged photocatalysis via a noble-metal-free process. The vitamin B12 derivative was replaced by an imine/oxime-type cobalt complex although the cobalt complex system showed a lower catalytic activity than the B12 derivative system. The dechlorination mechanism in the B12-Rhodamin B system was investigated by various methods such as UV-vis absorption and fluorescence quenching. Copyright
- Tahara, Keishiro,Mikuriya, Kumiko,Masuko, Takahiro,Kikuchi, Jun-Ichi,Hisaeda, Yoshio
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p. 135 - 141
(2013/05/08)
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- Synthesis, electrochemistry, spectroelectrochemistry and catalytic properties in DDT reductive dechlorinationin of iron(II) phthalocyanine, 2,3-and 3,4-tetrapyridinoporphyrazine complexes
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Iron(II) 2,3-and 3,4-tetrapyridinoporphyrazine complexes (2,3-PyD and 3,4-PyD) were synthesized and characterized as to their electrochemistry, UV-visible spectroelectrochemistry and catalytic properties towards the reductive dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (p,p′-DDT) in pyridine, dimethyl sulfoxide (DMSO), N,N′- dimethylacetamide (DMA) and N,N′-dimethylformamide (DMF). These properties were compared with those of the unsubstituted iron(II) phthalocyanine ((Pc)Fe). Electrochemistry indicates that there are up to three reductions and one oxidation in the three investigated derivatives. The easiest reduction takes place for 3,4-PyD while the most difficult one occurs for (Pc)Fe in all of the solvents investigated. The first reduction is metal-centered corresponding to the formation of [P(-2)Fe(I)]- while the second and third reductions are ring-centered leading stepwise to the generation of [P(-3)Fe(I)] 2- · and [P(-4)Fe(I)]3-, where P = phthalocyanine or tetrapyridinoporphyrazine rings. Aggregation exists in the solutions of all three iron complexes and its extent depends upon the nature and concentration of the iron compounds and the binding property of each solvent. The order of the extent of aggregation for the three iron derivatives is 3,4-PyD > 2,3-PyD > (Pc)Fe. Stronger binding solvents such as pyridine and DMSO do not favor the aggregation. The singly and doubly reduced species of investigated complexes, [P(-2)Fe(I)]- and [P(-3)Fe(I)]2- ·, are active in DDT reductive dechlorination, the latter of which has better catalytic performance. As a result, three products, 1,1-bis(4-chlorophenyl)-2,2- dichloroethane (p,p′-DDD), 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p′-DDE), and 1,1-bis(4-chlorophenyl)-2-chloroethylene (p,p′-DDMU), were obtained after the dechlorination of DDT catalyzed by each iron complex. The increasing order of catalytic performance is 3,4-PyD 2,3-PyD (Pc)Fe in pyridine, which is superior to DMSO and DMA for the DDT dechlorination reaction. An overall electrocatalytic mechanism is proposed for DDT reductive degradation based on the electrochemical and UV-visible spectroelectrochemical results.
- Shao, Jianguo,Richards, Kema,Rawlins, Dwayne,Han, Baocheng,Hansen, Christopher A.
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p. 317 - 330
(2013/07/26)
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- Hydrogenation effects in metalloporphycenes: Synthesis and redox behavior of Ni(ii)-tetra(n-propyl)dihydroporphycene
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Hydrogenated tetrapropylporphycenes, 2,3-dihydro-2,7,12,17- tetrapropylporphycene 1 and its NiII complex 2, have been prepared and the hydrogenation effects on their electronic structure characterized. A one-electron reduction of 2 promotes dehalogenation of organic halides whose observation is unprecedented for the porphycene compounds.
- Okawara, Toru,Hashimoto, Koichi,Abe, Masaaki,Shimakoshi, Hisashi,Hisaeda, Yoshio
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supporting information; experimental part
p. 5413 - 5415
(2012/07/13)
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- Eco-friendly molecular transformations catalyzed by a vitamin B 12 derivative with a visible-light-driven system
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A new bio-inspired system composed of a vitamin B12 derivative and Rose Bengal, catalyzed the dehalogenations of various toxic alkyl halides such as 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) via a noble-metal-free and visible-light-driven process. This system also catalyzed radical-involved organic reactions such as the 1,2-migration of acyl group via a tin-free process. The Royal Society of Chemistry.
- Tahara, Keishiro,Hisaeda, Yoshio
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supporting information; scheme or table
p. 558 - 561
(2011/05/08)
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- Reductive dechlorination of DDT electrocatalyzed by synthetic cobalt porphyrins in N,N′-dimethylformamide
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Two cobalt porphyrins, (OEP)CoII and (TPP)CoII, where OEP and TPP are the dianions of octaethylporphyrin and tetraphenylporphyrin, respectively, were examined as electrocatalysts for the reductive dechlorination of DDT (1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane) in N,N′- dimethylformamide (DMF) containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). No reaction is observed between DDT and the porphyrin in its Co(II) oxidation state but this is not the case for the reduced Co(I) forms of the porphyrins which electrocatalyze the dechlorination of DDT, giving initially DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane), DDE (1,1-bis(4-chlorophenyl)-2, 2-dichloroethylene) and DDMU (1,1-bis(4-chlorophenyl)-2-chloroethylene) as determined by GC-MS analysis of the reaction products. A further dechlorination product, DDOH (2,2-bis(4-chlorophenyl)ethanol), is also formed on longer timescales when using (TPP)Co as the electroreduction catalyst. The effect of porphyrin structure and reaction time on the dechlorination products was examined by GC-MS, cyclic voltammetry, controlled potential electrolysis and UV-visible spectroelectrochemistry and a mechanism for the reductive dechlorination is proposed.
- Zhu, Weihua,Fang, Yuanyuan,Shen, Wei,Lu, Guifen,Zhang, Ying,Ou, Zhongping,Kadish, Karl M.
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scheme or table
p. 66 - 74
(2012/03/10)
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- B12-TiO2 hybrid catalyst for dehalogenation of organic halides
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A cobalamin derivative, cobyrinie acid, was effectively immobilized on TiO2, and the hybrid TiO2 was characterized by UV-vis, XPS, MALDI-TOFMS as well as TEM analysis. The hybrid TiO2 exhibits high reactivity for dehalogenation of various organic halides such as phenethyl bromide, benzyl bromide, and 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) under irradiation with UV light at room temperature. Copyright
- Shimakoshi, Hisashi,Sakumori, Emiko,Kaneko, Kenji,Hisaeda, Yoshio
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scheme or table
p. 468 - 469
(2010/03/04)
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- Facile and catalytic degradation method of DDT using Pd/C-Et3N system under ambient pressure and temperature
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The catalytic degradation method of p,p′-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] and its regioisomer o,p′-DDT [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane] using the Pd/C-Et3N system under ambient hydrogen pressure and temperature was established. The presence of Et3N was necessary for the quick and complete breakdown of DDT. The independent degradation study of two intermediates, p,p′-DDD [2,2-bis(p-chlorophenyl)-1,1-dichloroethane] and p,p′-DDE [2,2-bis(p-chlorophenyl)-1,1-dichloroethylene] using GC-MS let us to speculate the degradation pathway of p,p′-DDT. In the initial phase of the reaction, p,p′-DDT degradation splits into two ways: a dehydrochlorination pathway and a hydrodechlorination pathway. In each pathway, reaction starts from an aliphatic moiety and subsequent hydrodechlorination from the benzene moieties takes place in a stepwise manner. The former pathway leads to the formation of 1,1-diphenylethane and the latter leads to the formation of 1,1-dichloro-2,2-diphenylethane. These diphenylethane analogs, which are less toxic compared with p,p′-DDT, are terminal degradation products in our system. The distinctive features of our catalytic degradation method of DDTs are reliability, simplicity, efficiency, and inexpensiveness.
- Monguchi, Yasunari,Kume, Akira,Sajiki, Hironao
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p. 8384 - 8392
(2007/10/03)
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- Recycled catalysis of a hydrophobic vitamin B12 in an ionic liquid
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Recycled use of a hydrophobic vitamin B12, heptamethyl co-byrinate perchlorate, in the dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2- trichloroethane (DDT) with a visible light irradiation system containing a [Ru(II)(bpy)3]Cl2 photosensitizer was achieved using an ionic liquid as reaction medium. Copyright
- Shimakoshi, Hisashi,Kudo, Sei,Hisaeda, Yoshio
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p. 1096 - 1097
(2007/10/03)
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- Physical, chemical, and isotopic (atomic) labels
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Chemical or isotopic labels are added to, e.g., a potentially lethal drug formulation, to generate a unique chemical fingerprint. Combinations of chemical additives are mixed with the drug to aid in their isolation and identification, especially when such drugs are used for illicit purposes. When stable isotopes are incorporated into lethal drugs, the labeling process conveys a very unique internal chemical signature and greatly aids in the identification of the parent drug in body fluids and tissues. When heath-care providers become aware that certain drugs can now be easily tracked and identified in a victim, individuals may be reluctant to utilize these agents for ill purposes.
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- Hydrophobic vitamin B12· part 19: Electroorganic reaction of DDT mediated by hydrophobic vitamin B12
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The controlled-potential electrolysis of 1,1-bis(4-chlorophenyl)-2,2,2- trichloroethane (DDT) was carried out at -1.4 V vs. Ag-AgCl in the presence of a hydrophobic vitamin B12, heptamethyl cobyrinate perchlorate. DDT was dechlorinated to form 1,1-bis(4-chlorophenyl)-2,2-dichloroethane (DDD), 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (DDE), 1-chloro-2,2-bis(4- chlorophenyl)ethylene (DDMU) and 1,1,4,4-tetrakis(4-chlorophenyl)-2,3-dichloro- 2-butene (TTDB) (E/Z), and quantitative recovery of the catalyst after the electrolysis was confirmed by electronic spectroscopy. A photo-sensitive intermediate having a cobalt-carbon bond formed during the electrolysis was characterized by electronic spectroscopy. A mechanism for the formation of various dechlorinated products was investigated by using deuterium solvents and various spectroscopic measurements such as UV-VIS and the EPR spin-trapping technique.
- Shimakoshi, Hisashi,Tokunaga, Mami,Hisaeda, Yoshio
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p. 878 - 882
(2007/10/03)
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- Photochemical dechlorination of DDT catalyzed by a hydrophobic vitamin B12 and a photosensitizer under irradiation with visible light.
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Dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) was catalyzed by a hydrophobic vitamin B(12), heptamethyl cobyrinate perchlorate, with a visible light irradiation system containing a [Ru(ii)(bpy)(3)]Cl(2) photosensitizer, and the hydrophobic vitamin B(12) showed high catalytic efficiency and stability during the reaction.
- Shimakoshi, Hisashi,Tokunaga, Mami,Baba, Tatsushi,Hisaeda, Yoshio
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p. 1806 - 1807
(2007/10/03)
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- Zinc metal assisted hydro-de-halogenation of DDT into DDEthane under sonic conditions
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An efficient method for the hydro-de-halogenation of DDT to 1,1-bis (p-chlorophenyl)ethane (DDEthane) exclusively by a simple reaction using commercial zinc dust, is reported. The rate of the reaction is enhanced by irradiating at 35 KHz in a sonic bath at 25°C.
- Pasha,Nagaraja
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p. 1747 - 1748
(2007/10/03)
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- Electrochemical reduction and oxidation of DDT
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Electrolysis has been studied as a possible method to treat DDT wastes. In methanol, the major process was dehydrochlorination to DDE followed by further reduction. In an aqueous emulsion containing 1% heptane and 0.1% Triton SP-175, DDT was reduced at a deposited lead electrode with sodium sulphate as the supporting electrolyte by sequential hydrodechlorination of the aliphatic chlorine atoms. An excellent material balance was achieved, but the current efficiency was poor, even at low current densities. Electrooxidation of DDT was also investigated; in aqueous solutions or emulsion, little oxidation occurred because of competing oxidation of water at the highly positive potentials needed to oxidize DDT. In acetonitrile, electrooxidation occurred with high current efficiency by way of 'electrochemical combustion' of DDT and its intermediate oxidation products to CO2. We conclude that development of an electrolytic technology for destroying DDT wastes is unlikely.
- Merica, Simona G.,Jedral, Wojceich,Lait, Susan,Keech, Peter,Bunce, Nigel J.
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p. 1281 - 1287
(2007/10/03)
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- Mechanochemical reaction of DDT with calcium oxide
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Evidence is presented that, in the mechanochemical destruction of DDT [2,2-bis(4-chlorophenyl)1,1,1-trichloroethane] by ball milling in the presence of calcium oxide, a complex series of reactions occurs along the pathway to a product that appears to be essentially graphitic, though aromatic chloro and hydroxy substituents are retained to some degree. The production of the various intermediates can be understood in terms of processes initiated at both CaO and steel (of the milling device) surfaces. With the exception of DOE [2,2-bis(4-chlorophenyl)1,1-dichloroethene], most of these intermediates attain maximum concentrations corresponding to 1 mol % of the original DDT and have been characterized only by their mass spectra. In the case of dichlorotolane [bis(4-chlorophenyl)ethyne], however, yields are sufficient for it to be isolated chromatographically as a pure, crystalline solid and characterized further by NMR spectroscopy. After 12 h of milling, no organic materials volatile enough to be detected by conventional GC/MS procedures are present, but the black, graphitic residue does retain some chlorine that is only slowly removed by extended milling.
- Hall, Annegret K.,Harrowfield, Jack M.,Hart, Reinhold J.,Mccormicr, Paul G.
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p. 3401 - 3407
(2007/10/03)
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- Electrolytic Dechlorination of DDT In a Bicontinuous Microemulsion
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Electrolytic reduction in a bicontinuous microemulsion of surfactant, oil, and water removed aliphatic and aromatic chlorines from DDT. Microemulsions of didodecyldimethylammonium bromide/dodecane/water used with graphite felt cathodes provided a less expensive, less toxic approach to DDT electrolysis compared to using conventional organic solvents and metal electrodes. Good rates of aliphatic dechlorination were achieved by applying -1 V vs. Ag/AgBr and using the catalyst Co(bpy)32+, but the best yield (34 percent in 3 hr) of the fully dechlorinated hydrocarbon 1,1-diphenylethane was achieved by using -2 V with oxygen in the reaction medium.
- Schweizer, Silvia,Rusling, James F.,Huang, Qingdong
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p. 961 - 970
(2007/10/03)
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- Syntheses and NMR spectra of Co3(CO)9[μ3-CCHAr2] clusters derived from DDT and related molecules: X-ray crystal structures of [[bis(4-chlorophenyl)methyl]carbynyl]tricobalt nonacarbonyl and of its bis(4-chloronaphthyl) analogue
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The reaction of Co2(CO)8 with a series of 1,1,1-trichloro-2,2-bis(aryl)ethanes yields the corresponding Co3(CO)9[μ3-CCHAr2] tetrahedral clusters, where Ar = 4-chlorophenyl (3), 4-methoxyphenyl (4), or 4-chloronaphthyl (6). Co3(CO)9[μ3-CCH(p-C6H 4Cl)2] (3) crystallizes in the monoclinic space group P21/n with a = 13.0834 (27) A?, b = 14.2224 (16) A?, c = 14.1649 (24) A?, β = 95.871 (15)°, V = 2621.9 (8) A?3, and Z = 4; treatment of all 3434 unique data led to final values of RF = 3.7% and RwF = 3.3%. (RF = 2.5% and RwF = 3.0% for those 2781 data with |Fo| > 6σ(|Fo|).) The chloronaphthyl cluster of Co3(CO)9[μ3-CCH(C10H 6Cl)2] (6) crystallizes in the triclinic space group P1 with a = 8.839 (3) A?, b = 12.156 (4) A?, c = 16.513 (5) A?, α = 105.974 (25)°, β = 92.280 (25)°, γ = 115.512 (22)°, V = 1513.57 (84) A?3, and Z = 2; treatment of the 3620 unique data led to final values of RF = 4.8% and RwF = 5.3%. At -120°C, the cobalt carbonyl ligands of the phenyl clusters 3 and 4 exhibit a 6:3 splitting in their 13C NMR spectra; however, the naphthyl cluster 6 does not show this effect. These data are discussed in terms of the ability of the aryl groups to obstruct the fluxionality of the cobalt carbonyl ligands.
- Gates, Reginald A.,D'Agostino, Michael F.,Sutin, Karen A.,McGlinchey, Michael J.,Janik, Thomas S.,Churchill, Melvyn Rowen
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- Electrochemical Reduction of DDT at the Hanging Mercury Drop Electrode
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The electrochemical reduction of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)-ethane (DDT) involving carbon-halogen bond has been studied using cyclic voltammetric, chronoamperometric and chronopotentiometric techniques.The data have been utilised in the evaluation of transfer and diffusion coefficients of the electroactive species under consideration.Mechanism of the reduction process has been proposed on the basis of the electrochemical data.
- Sivarami Reddy, A.,Jayarama Reddy S.
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p. 619 - 620
(2007/10/02)
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- PULSE MICROREACTOR PESTICIDES HYDRODECHLORINATION
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Catalytic hydrodechlorination of chlorinated pesticides and other environmentally chlorinated materials into lower chlorine content compounds has been studied in a pulse microreactor .Chlorine can be catalytically removed and replaced by hydrogen to prduce partially chlorinated intermediates as well as completely dechlorinated hydrocarbons.Intermediates are equivalent to some of those obtained by natural degradation.The pulse microreactor is a simple technique to predict both product composition and reaction severity required for laboratory scale preparation of such degradation products.
- Weiss, A. H.,LaPierre, R. B.
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p. 111 - 122
(2007/10/02)
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- Organometallic Compounds: Part II - Reaction of Cyclohexylmethylmagnesium Bromide with 1,1,1-Trichloro-2,2-bis(4-substituted-phenyl)ethanes
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The reaction of cyclohexylmethylmagnesium bromide (II) with 1,1,1-trichloro-2,2-bis(4-chlorophenyl)- and 1,1,1-trichloro-2,2-bis(4-methoxyphenyl)-ethanes (Ia,b) follows mainly a reduction pathway to give the corresponding dichloroethanes (IIIa,b) and the butenes, 1,1,4,4-tetrakis(4-chlorophenyl)- and 1,1,4,4-tetrakis(4-methoxyphenyl)-2,3-dichlorobut-2-enes (IVa and IVb).However, in the case of Ib, 1,1,4,4-tetrakis(4-methoxyphenyl)-2,2,3,3-tetrachlorobutane (Vb) has also been obtained.Magnesium subiodide does not effect the reduction of I.
- Habashi, Adiba,Shams, Hoda Zaki,Tadros, Wadie
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p. 724 - 725
(2007/10/02)
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- Alkyl 4-[o-(substituted methyleneamino)phenyl]-3-thioallophanates
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Various alkyl 4-[o-(substituted methyleneamino)phenyl] 3-thioallophanates are useful as fungicides and mite ovicides. The compounds are prepared by reacting alkyl 4-(o-aminophenyl)-3-thioallophanates with aldehydes or trialkyl orthoformates. Some of the compounds are prepared by further reacting the reaction product of an alkyl 4-(o-aminophenyl)-3-thioallophanate and a trialkyl orthoformate with a primary or secondary amine. Exemplary species are methyl 4-[o-(o-fluorobenzylideneamino)phenyl]-3-thioallophanate, methyl 4-[o-(4-methylbenzylideneamino)phenyl]-3-thioallophanate and methyl 4-[o-(2-furfurylideneamino)phenyl]-3-thioallophanate.
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- Propynyl benzyl ethers
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Propynyl benzyl ethers having juvenile hormone-like activity which are 4-halogen, lower alkyl, lower alkoxy or propynyloxy substituted or 3,4-lower alkylenedioxy substituted and which can also be 3,5- and/or α-substituted, and insecticide compositions that include at least one propynyl benzyl ether and that can also include a conventional insect-poison.
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- Alkyl 4-(o-aminophenyl)-3-thioallophanates
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Various alkyl 4-(o-aminophenyl)-3-thioallophanates and alkyl 4-(o-alkylaminophenyl)-3-thioallophanates are useful as fungicides and mite ovicides. The compounds are prepared by reacting an o-phenylenediamine with the appropriate alkoxycarbonylisothiocyanate and an exemplary species is methyl 4-(o-aminophenyl)-3-thioallophanate.
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