- 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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- 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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- 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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- 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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- 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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- 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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- Kinetic Behavior of Cetyltrimethylammonium Hydroxyde. The Dehydrochlorination of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane and Some of Its Derivatives.
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The dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), and 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDM) with hydroxide ion was studied in the presence of hexadecyltrimethylammonium hydroxide (CTAOH) micelles at 25.0 deg C.The experimental results clearly deviate from the theoretical behavior expected by the pseudophase-ion-exchange model and can be explained by considering an additional reaction pathway across the micellar boundary.This additional reaction pathway in which hydroxide ion in the aqueous phase reacts directly with the organic substrate in the micelle is probably of a phase-transfer catalysis type.
- Stadler, Eduardo,Zanette, Dino,Rezende, Marcos C.,Nome, Faruk
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- Use of Relative Counterion Type Micelles for the Determination of Selectivity Coefficients
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Monovalent/monovalent and divalent/monovalent ion exchange in hexadecyltrimethylammonium hydroxide (CTAOH), a relative counterion type micelle, was investigate by using as a probe the dehydroshlorination reactions of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD).Selectivity coefficients for the ion exchange of bromide, chloride, fluoride, nitrate, acetate, sulfate, and carbonate anions with the reactive counterion (OH-) and between the anions themselves were evaluated from the kinetic treatment of the data using a simple pseudophase ion-exchange-type formalism.
- Nascimento, Maria da Graca,Miranda, Sebastiao A. F.,Nome, Faruk
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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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- Limitations of the Pseudophase Model of Micellar Catalysis. The Dehydrochlorination of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane and Some of Its Derivatives
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The dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), and 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDM) with hydroxide ion was studied in the presence of hexadecyltrimethylammonium bromide (CTAB) micelles at 25.0 deg C.The experimental results indicate that there is good agreement between the experimental results and theoretical models of micellar catalysis for (OH) in the range of 1E-3-1E-2 M.For (OH) values higher than 1E-2 M, the pseudophase model fails there is a significant deviation between the theoretically calculated and observed values of the pseudo-first-order rate constant.The experimental results can be explained by considering an additional reaction pathway across the micellar boundary, in which hydroxide ion in the aqueous phase reacts directly with the organic substrate in the micelle.This additional reaction pathway is probably of a phase transfer catalysis type.
- Nome, Faruk,Rubira, Adley F.,Franco, Cesar,Ionescu, Lavinel G.
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- DDT, DDD, and DDE dechlorination by zero-valent iron
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Traditionally, destruction of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] for environmental remediation required high-energy processes such as incineration. Here, the capability of powdered zero-valent iron to dechlorinate DDT and related compound
- Sayles, Gregory D.,You, Guanrong,Wang, Maoxiu,Kupferle, Margaret J.
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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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- 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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- Effect of Normal and Functional Micelles in Elimination Reactions of Polyhalogenated Pesticides
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The dehydrochlorination of pesticides of the DDT family in the presence of functional and cationic micelles has been studied.Catalytic factors of (2 620+/-504), (2 190+/-404), and (1 470+/-215)-fold were observed for 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT), 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane (DDD), and 1-chloro-2,2-bis-(p-chlorophenyl)ethane (DDM) respectively, when hexadecyldimethyl-(2-hydroxyethyl)ammonium bromide (CHEDAB) was used as catalyst.Hexadecyltrimethylammonium bromide (CTAB) also showed catalytic effects (417+/-77), (208+/-40), and (70+/-14)-fold increases for DDT, DDD, and DDM, respectively, though smaller than those observed with CHEDAB.The higher catalytic activities of CHEDAB are explained in terms of the participation of the alkoxide moiety.
- Rezende, Marcos Caroli,Rubira, Adley Forti,Franco, Cesar,Nome, Faruk
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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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- Halogenation of 1,1-diarylethylenes by N-halosuccinimides
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An efficient method for the preparation of 2,2-diarylvinyl halides from the corresponding 1,1-diarylethylenes has been developed. N-Halosuccinimides (N-bromosuccinimide or N-chlorosuccinimide) were used as the halogenation reagents. The practicability of this method is highlighted by its simple operation, broad substrate scope and capability for large-scale reaction.
- Zhang, Ge,Bai, Rui-Xue,Li, Chu-Han,Feng, Chen-Guo,Lin, Guo-Qiang
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p. 1658 - 1662
(2018/12/11)
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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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(2017/12/27)
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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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- 1,2-H shift in copper-chlorocarbenoid intermediate during CuCl/bpy-promoted stereoselective dechlorination of 2,2,2-trichloroethyl alkyl ethers to (Z)-1-alkoxy-2-chloroethenes
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(Chemical Equation Presented) Reaction of 2,2,2-trichloroethyl alkyl ethers with 2 molar equiv of CuCl/bpy in refluxing DCE yielded (Z)-1-alkoxy-2- chloroethenes stereoselectively as the major product via 1,2-H shift in copper-chlorocarbenoid intermediate. 2,2,2-Trichloroethyl carboxylates undergo a radical 1,2-acyloxy shift under similar conditions.
- Ram, Ram N.,Manoj
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supporting information; experimental part
p. 2243 - 2246
(2009/05/11)
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- Kinetic method to estimate dissociation degrees of micellar aggregates in TTAB-alcohol aqueous micellar solutions
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The reactions of dehydrochlorination of 1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, DDT, and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane, DDD, with hydroxide ions were studied in various TTAB-alcohol (TTAB = tetradecyltrimethylammonium bromide) aqueous micellar solutions as a function of alcohol content. The alcohols used were heptanol, hexanol, pentanol, butanol, isobutanol, tert butanol, propanol and isopropanol. Kinetic data show that the dissociation degree of the micelles is the main factor controlling reactivity in all the TTAB-alcohol micellar solutions. This fact permits the development of a kinetic method in order to estimate the dissociation degree of the micellar aggregates present in the alcohol-TTAB aqueous micellar solutions.
- Munoz, Maria,Rodriguez, Amalia,Del Mar Graciani, Maria,Moya, Maria Luisa
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p. 204 - 209
(2007/10/03)
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- A facile and high yielding synthesis of symmetrical and unsymmetrical diarylalkynes using diethyl dichloromethylphosphonate as precursor
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The reaction, under internal quench conditions, of diethyl dichloromethylphosphonate and symmetrical or unsymmetrical diaryl ketones in the presence of n-BuLi, leads to the corresponding symmetrical or unsymmetrical diarylalkynes via a Fritsch-Buttenherg-Wiechell rearrangement in a simple, high yielding, one-pot reaction.
- Mouriès, Virginie,Waschbüsch, Rachel,Carran, John,Savignac, Philippe
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p. 271 - 274
(2007/10/03)
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- Substituted ethylene imidazole and triazoles
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This invention relates to substituted ethylenic imidazoles and triazoles, their enantiomorphs, acid addition salts and metal complexes as well as their methods of preparation and use as broad spectrum systemic fungicides useful in controlling phytopathogenic fungi such as barley net blotch (Helminthosporium teres), bean powdery mildew (Erysiphe polygoni), peanut cercospora (Cercospora arachidicola), and wheat stem rust (Puccinia graminis f. sp. tritici race 15B-2).
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- SOLVENT DEUTERIUM ISOTOPE EFFECTS ON THE RATES OF DEHYDROCHLORINATION OF DDT AND DDD BY ALKOXIDE BASES IN ALCOHOLS
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Solvent isotope effects are reported for the dehydrochlorination reactions of 2,2-di(p-chlorophenyl)1,1,1-trichloroethane (DDT) and 2,2-di(p-chlorophenyl)1,1-dichloroethane (DDD) by methoxide-methanol-d and ethoxide-ethanol-d.DDT shows large effects, kROD/kROH ca. 2, whereas DDD gives a ratio much closer to unity.These solvent isotope effects are discussed in relation to the mechanisms of the reactions, determined by other methods.
- Jarczewski, Arnold,Schroeder, Grzegorz,Leffek, K. T.
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p. 521 - 525
(2007/10/02)
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