- Heterogeneous photocatalytic degradation of disulfoton in aqueous TiO 2 suspensions: Parameter and reaction pathway investigations
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The photocatalytic degradation of organophosphorus insecticide disulfoton is investigated by having titanium dioxide (TiO2) as a photocatalyst. About 99% of disulfoton is degraded after UV irradiation for 90 min. The effects of the solution pH, catalyst dosage, light intensity, and inorganic ions on the photocatalytic degradation of disulfoton are also investigated, as well as the reaction intermediates which are formed during the treatment. Eight intermediates have been identified and characterized through a mass spectra analysis, giving insight into the early steps of the degradation process. To the best of our knowledge, this is the first study reporting the degradation pathways of disulfoton. The results suggest that possible transformation pathways may involve in either direct electron or hole transfer to the organic substrate. The photodegradation of disulfoton by UV/TiO2 exhibits pseudo-first-order reaction kinetics and a reaction quantum yield of 0.267. The electrical energy consumption per order of magnitude for photocatalytic degradation of disulfoton is 85 kWh/(m3 order).
- Chen, Ming-Hung,Chen, Chiing-Chang,Wu, Ren-Jang,Lu, Chung-Shin
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p. 380 - 390
(2013/07/27)
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- Pathways for the hydrolysis of phorate: Product studies by 31P NMR and GC-MS
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A new intramolecular mechanism is proposed for the hydrolysis of phorate. 31P NMR was used to study the formation of P-containing products of phorate hydrolysis in situ. When hydrolysis was followed by 31P NMR, a dominant P-containing product was found and was identified to be diethyl dithiophosphate using methylation and GC-MS. Combining the data from phorate hydrolysis at three different temperatures, thermodynamic parameters were calculated. The contributions of various possible pathways to phorate hydrolysis are discussed.
- Hong, Feng,Pehkonen, Simo O.,Brooks, Elwood
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p. 3013 - 3017
(2007/10/03)
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- PRODUCTS OF THE ALKALINE HYDROLYSIS OF S-CHLOROMETHYL AND S-(N-ETHOXYCARBONYL-N-METHYLCARBAMOYLMETHYL) O,O-DIETHYLPHOPHORODITHIOATE
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The alkaline hydrolysis of S-chloromethyl O,O-diethyl phosphorodithioate (chlormephos) and of S-(N-ethoxycarbonyl-N-methylcarbamoylmethyl) O,O-diethyl phosphorodithioate (mecarbam) may involve attack by hydroxide ion at phosphorus with phosphorus-sulfur cleavage, at the substituted S-methyl carbon atom with sulfur-carbon cleavage or, in the case of mecarbam, at the carbonyl carbon atom with carbonyl-nitrogen cleavage.Further reaction of the initially-formed O,O-diethyl hydrogen phosphorodithioate with chlormephos may lead to the formation of additional products.
- Hudson, Harry R.,Lynch, Vincent P.,Pianka, Max,Soares, Vera M.
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p. 277 - 281
(2007/10/02)
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- Reactions of Alcohols with O,O-Diethylphosphorothioic and O,O-Diethylphosphorodithioic Acid in the Presence of Triphenylphosphine and Diethyl Azodicarboxylate, II. 31P-N.M.R. Studies
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Low temperature 31P-n.m.r. studies of the reaction of O,O-diethylphosphorothioic acid with triphenylphosphine and diethyl azodicarboxylate revealed that, at low temperatures, the only intermediate is the protonated betaine, even in the presence of neopentyl alcohol.Above 0 deg C this species reacts with neopentyl alcohol to produce the neopentoxytriphenylphosphonium salt which decomposes to isomeric diethyl neopentyl phosphorothioates and triphenylphosphine oxide, at elevated temperatures.The reaction of ethanol with O,O-diethylphosphorodithioic acid leads mainly to O,O,S-triethyl phosphorodithioate and triphenylphosphine oxide.In addition, a small amount of O,O,O-triethylphosphorothionate and triphenylphosphine sulfide were detected.The mechanism of these reactions is suggested.
- Mlotkowska, B.
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p. 380 - 386
(2007/10/02)
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- Multinuclear magnetic resonance studies of the reactions of bidentate ligands with Pt(S2P{OEt}2)2. Crystal and molecular structure of (apeS)Pt(S2P{OEt}2)2 (ApeS = Ph2AsCH2CH2P(S)Ph2)
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The interactions in dichloromethane solution of Pt(S2P{OEt}2)2 with a number of potentially bidentate ligands have been studied by multinuclear (31P, 77Se, 195Pt) magnetic resonance techniques. The ligands used (L-L′) were Ph2PCH2CH2PPh2 (dpe), Ph2AsCH2CH2PPh2 (ape), Ph2PCH2PPh2 (dpm), Ph2PCH2P(E)Ph2 (E = S, Se to give dpmS, dpmSe), and Ph2AsCH2CH2P(E)Ph2 (apeS, apeSe). All the ligands except apeS and apeSe react with Pt(S2P{OEt}2)2 in 1:1 proportions to give initially [(L-L′)Pt-(S2P{OEt}2)]+ and free [S2P(OEt)2]-, but a slower reaction gives (L-L′)Pt(S2P{O}OEt) and EtS2P(OEt)2 by attack of the free anion on the coordinated dithiophosphate ligand. In 1:2 proportions these ligands give [Pt(L-L′)2]2+ and free [S2P(OEt)2]-, except for dpm which gives [(η1-dpm)(η2-dpm)Pt(η1-S 2P{OEt}2)]+. The same products are obtained by reacting 1 mol of L-L′ with 1 mol of [(L-L′)Pt(S2P{OEt}2)]+, but the (L-L′)Pt(S2P{O}OEt) compounds do not react with further L-L′ ligand. The ligands apeE react with Pt(S2P{OEt}2)2 to give only (η1-apeE)Pt(η1-S2P{OEt} 2)(η2-S2P{OEt}2). The structures of all the complexes in solution were determined by multinuclear magnetic resonance studies and that of (η1-apeS)Pt(η1-S2P{OEt} 2)(η2-S2P{OEt}2) in the solid state was confirmed by a single-crystal X-ray diffraction study. Crystal data for (apeS)Pt(S2P{OEt}2)2: Mr = 1039.98, monoclinic space group P21, a = 10.107 (1) A?, b = 20.002 (2) A?, c = 11.278 (2) A?, β = 114.23 (2)°, Z = 2, ρmeasd = 1.65 (1) g cm-3, Mo Kα radiation, R = 0.030, Rw = 0.034 for 7695 independent reflections. The structure contains discrete molecules with the square-planar stereochemistry about platinum being defined by three sulfur atoms from one bidentate and one monodentate [S2P(OEt)2]- ligand and an arsenic atom from the monodentate apeS ligand.
- Colton,Ebner,Hoskins
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p. 1993 - 1999
(2008/10/08)
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- Reaction of Carbodiimides with Phosphorothioic, Phosphorodithioic, and Phosphoroselenoic Acids: Products, Intermediates, and Steps
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The reaction of the title acids with dicyclohexylcarbodiimide (DDC) used in a 2:1 ratio was found to give a complex mixture of products consisting of thio(seleno)pyrophosphates, thiolo(selenolo)phosphates, thiono(selenono)phosphates, dicyclohexylthiourea (DCTU), and a polymeric alkyl metaphosphate.When both reaction components are mixed in a 1:1 ratio, N-phosphoryl-N,N'-dicyclohexylthio(seleno)ureas (B) were formed.The formation of equimolar adducts (B) was also observed with other dialkyl- and diarylcarbodiimides.The spectral properties (especially the value of 3JP-H) and reactivity of these adducts are strongly dependent on their conformation.The distinct conformational differences between the adducts B derived from DCC and diisopropylcarbodiimide (DiPC) and those obtained from dibenzylcarbodiimide (DBC) and diarylcarbodiimides were revealed by X-ray analysis of the selected N-phosphorylthioureas.By means of low temperature FT 31P NMR spectra it was demonstrated that the adducts (B) arise from the first formed unstable S(Se)-phosphorylisothio(seleno)ureas (A) as a result of S(Se)->N-phosphoryl migration.The differences in ability of the phosphoryl group to undergo S(Se)->N and O->N 1,3-shifts are briefly described.N-Phosphorylthio(seleno)ureas (B) obtained from DCC and DiPC, in contrast to those prepared from DBC and diarylcarbodiimides, reacted with a second thio(seleno)acid molecule.Crossover experiments and the use of O,O-diethyl phosphorothioate containing 35S-labeled sulfur showed that the adducts (B) are in equilibrium with their unstable isomers (A), the latter being active phosphorylating agents.The formation of the final reaction products was rationalized in terms of the threedirectional attack of the thioacid anion at the phosphorus, alkoxy carbon, and central carbon atoms of the protonated adduct (A).
- Mikolajczyk, Marian,Kielbasinski, Piotr,Basinski, Wlodzimierz
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p. 899 - 908
(2007/10/02)
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