- Transformation of Chloropicrin and 1,3-Dichloropropene by Metam Sodium in a Combined Application of Fumigants
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Combined application of fumigants is a potential strategy to replace methyl bromide in the control of soil-borne pests. Unfortunately, abiotic and biotic interactions among fumigants restrict some combined application approaches. In this study, the kinetics and mechanisms of reaction between metam sodium (sodium methyldithiocarbamate) and the halogenated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) were investigated in aqueous solution. For chloropicrin, an extremely rapid oxidation-reduction process occurred in the presence of metam sodium. The second-order rate constant for the reaction between chloropicrin and metam sodium was approximately 2 orders of magnitude greater than that for the reaction between 1,3-D isomers and metam sodium. Transformation of 1,3-D by metam sodium was associated with an aliphatic SN2 nucleophilic substitution process. The nucleophilic reaction of ci-1,3-D with metam sodium was significantly faster than that of the trans isomer and was correlated with a lower reaction activation energy for the cis isomer in the transition state. Combining Telone C-35 (65% 1,3-D and 35% chloropicrin) and metam sodium in solution might yield some nucleophilic sulfur species, which played an important role in the dissipation of 1,3-D. The incompatibility of chloropicrin and 1,3-D with metam sodium was also examined in soil under different application scenarios. Simultaneous application of metam sodium with chloropicrin or 1,3-D accelerated the transformation of the two halogenated fumigants, reducing their availability in soil. A sequential strategy for multiple fumigants was developed, which could be applied without the loss of active ingredient that occurs due to the reaction between fumigants. The proposed methodology may enhance pest control while maintaining environmental protection.
- Zheng, Wei,Yates, Scott R.,Guo, Mingxin,Papiernik, Sharon K.,Kim, Jung Ho
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- Halonitromethane Drinking Water Disinfection Byproducts: Chemical Characterization and Mammalian Cell Cytotoxicity and Genotoxicity
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Halonitromethanes are drinking water disinfection byproducts that have recently received a high priority for health effects research from the U.S. Environmental Protection Agency (EPA). Our purpose was to identify and synthesize where necessary the mixed halonitromethanes and to determine the chronic cytotoxicity and the acute genotoxicity of these agents in mammalian cells. The halonitromethanes included bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromochloronitromethane (DBCNM), bromodichloronitromethane (BDCNM), chloronitromethane (CNM), dichloronitromethane (DCNM), and trichloronitromethane (TCNM). Low- and high-resolution gas chromatography/mass spectrometry (GC/MS) was used to identify the mixed chloro-bromonitromethanes in finished drinking waters, and analytical standards that were not commercially available were synthesized (BDCNM, DBCNM, TBNM, CNM, DCNM, BCNM). The rank order of their chronic cytotoxicity (72 h exposure) to Chinese hamster ovary (CHO) cells was DBNM > DBCNM > BNM > TBNM > BDCNM > BCNM > DCNM > CNM > TCNM. The rank order to induce genomic DNA damage in CHO cells was DBNM > BDCNM > TBNM > TCNM > BNM > DBCNM > BCNM > DCNM > CNM. The brominated nitromethanes were more cytotoxic and genotoxic than their chlorinated analogues. This research demonstrated the integration of the procedures for the analytical chemistry and analytical biology when working with limited amounts of sample. The halonitromethanes are potent mammalian cell cytotoxins and genotoxins and may pose a hazard to the public health and the environment.
- Plewa, Michael J.,Wagner, Elizabeth D.,Jazwierska, Paulina,Richardson, Susan D.,Chen, Paul H.,McKague, A. Bruce
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- Transformation of chlorinated aliphatic compounds by ferruginous smectite
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A series of chlorinated aliphatic compounds (RCI, including carbon tetrachloride (PCM), 1,1,1-trichloroethane (TCA), 1,1,2,2-tetrachloroethane (TeCA), pentachloroethane (PCA), hexachloroethane (HCA), trichloroethene (TCE), tetrachloroethene (PCE), trichloronitromethane (chloropicrin, CP), and trichloroacetonitrile (TCAN)) was reacted with ferruginuous smectite (sample SWa-1 from The Source Clays Repository), SWa, in aqueous suspension under anoxic conditions. Compounds highly polarizable or sharing substituents that facilitate charge delocalization adsorbed faster by reduced (SWa-R) than by unaltered (SWa-U) clay, indicating stronger dipole-dipole interactions between the substituents and the clay surface and/or hydrating water molecules. The reduction of the clay accelerated RCI adsorption up to 100-fold. Incubations with SWa-R promoted RCI reduction (CP, TCAN) or dehydrochlorination (TeCA and PCA). The reduction of structural Fe catalyzes the transformation of RCI via Bronsted and Lewis-basic promoted pathways. This study indicates that oxidation state of the structural Fe in SWa greatly alters surface chemistry and has a large impact on clay-organic interactions.
- Cervini-Silva,Larson,Wu,Stucki
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p. 805 - 809
(2007/10/03)
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- Method of preparing amino alcohols
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A method of preparing an amino alcohol of the formula STR1 where R1 is H, lower alkyl or R2, R2 is R3 CHOH in which R3 is H, alkyl or aryl. R3 preferably is hydrogen, lower alkyl or monocyclic aryl such as phenyl. The inventive method involves the reaction of halonitroalcohol with hydrogen in the presence of methanol, a suitable buffering agent such as ammonia, and a hydrogenation catalyst to form amino alcohol salt, neutralizing the amino alcohol salt, and recovering the resultant amino alcohol.
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- Method of preparing halogenated nitroalcohols
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A method of preparing bromonitroalcohols of the formula STR1 where R1 is H, lower alkyl or R2, R2 is R3 CHOH in which R3 is H, alkyl or aryl, and X is a halogen, which comprises reacting a halonitroalkane with a substantially nonaqueous solutioln of an aldehyde of the formula R3 CHO where R3 is as noted above, in the presence of an alkaline catalyst. R3 preferably is lower alkyl or monocyclic aryl such as phenyl.
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- Pathways in the Reactions of Nitronate Ions with Sulphonyl Halides
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Primary and tertiary nitronate ions and sulphonyl bromides and iodides rapidly equilibrate with the nitrohalides and sulphinate ion.Products are determined by solvent and by the occurence of cross-equilibrum reactions, some of which have single-electron-transfer mechanism.The reaction of arene-sulphinate and thiolate ions with 1,2-dibromo-2-nitro-1-phenylethane gave E-β-nitrostyrene by Z-philic elimination in both cases, but the more basic thiolate ion also gave, by protophilic elimination, 2-bromo-2-nitro-1-phenylethene.
- Pigou, Paul E.,Stirling, Charles J. M.
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p. 725 - 730
(2007/10/02)
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