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Hydrolysis
Published in Richard A. Larson, Eric J. Weber, Reaction Mechanisms in Environmental Organic Chemistry, 2018
Richard A. Larson, Eric J. Weber
Base-catalyzed elimination becomes important relative to neutral hydrolysis (i.e., nucleophilic substitution) as the degree of chlorination increases, as long as adjacent carbons contain at least one chlorine substituent. This trend is a reflection of the increased acidity of protons that are bonded to the same carbon containing the electron-withdrawing chlorine substituents. Over the series 1,2-dichloroethane, 1.1.2-trichloroethane, 1,1,2,2-tetrachloroethane, and pentachloroethane, an increase in 5 orders of magnitude is observed for kb(2.26). As expected, 1,1,2,3-tetrachloropropane and 1,1,2,3,3-pentachloropropane also exhibit enhanced reactivity toward base-catalyzed elimination. The stability of 1,1,1-trichloroethane and 2.2-dichloropropane, suggests that perhalogenated carbon atoms are unreactive toward nucleophilic substitution by OH−. ()
Atomic, Molecular, and Optical Physics
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Name Carbon oxysulfide Carbon oxyselenide Carbon dioxide Carbon sulfide Carbon disulfide Dicarbon 1,2-Dibromotetrafluoroethane Chlorotrifluoroethylene Chloropentafluoroethane Dichloroacetylene 1,2-Dichlorotetrafluoroethane 1,1,1-Trichlorotrifluoroethane 1,1,2-Trichlorotrifluoroethane Tetrachloroethylene 1,1,2,2-Tetrachloro-1,2-difluoroethane Trichloroacetyl chloride Hexachloroethane Trifluoroacetonitrile Tetrafluoroethylene Hexafluoroethane Ethynyl Bromoacetylene 2-Bromo-2-chloro-1,1,1-trifluoroethane Chloroacetylene 1-Chloro-2,2-difluoroethylene Trichloroethylene Dichloroacetyl chloride Pentachloroethane Fluoroacetylene Trifluoroethylene Trifluoroacetic acid Acetylene 1,1-Dichloroethylene cis-1,2-Dichloroethylene trans-1,2-Dichloroethylene Chloroacetyl chloride 1,1,1,2-Tetrachloroethane 1,1,2,2-Tetrachloroethane 1,1-Difluoroethylene cis-1,2-Difluoroethylene Ketene Glyoxal Thiirene Bromoethylene Chloroethylene 1-Chloro-1,1-difluoroethane Acetyl chloride Chloroacetaldehyde Chloroacetic acid 1,1,1-Trichloroethane 1,1,2-Trichloroethane Fluoroethylene Acetyl fluoride 1,1,1-Trifluoroethane Acetonitrile Methylisocyanate Ethylene 1,2-Dibromoethane 1,1-Dichloroethane 1,2-Dichloroethane
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Butler and Hayes (1998) investigated the reductive dechlorination of hexachloroethane in water by iron sulfide. Tetrachloroethylene was the major product with pentachloroethane as a minor intermediate. Final reaction products were trichloroethylene, cis-1,2-dichloroethylene, and acetylene. The rate of reaction increased with increasing iron sulfide concentrations and pH. At pH 7.8, first-order rate constants were 0.0726, 0.086, and 0.533/h at iron sulfide concentrations of 10, 25, and 100 g/L, respectively. At an iron sulfide concentration of 100 g/L, first-order rate constants were 0.533/h at pH 7.8, 0.948/h at pH 9.3, 1.43/h at pH 8.8, and 3.21 at pH 9.5.
Electrochemical reduction of halogenated organic contaminants using carbon-based cathodes: A review
Published in Critical Reviews in Environmental Science and Technology, 2023
Jacob F. King, William A. Mitch
Electrochemical reduction (-0.9 V/SHE) of 11 halogenated alkanes (including compounds with chlorine, bromine and iodine substituents) using cathodes fashioned from GAC attached to carbon cloth achieved 90% degradation over timescales of 1-24 min for most compounds but 150 min for trichloromethane (King & Mitch, 2022). Degradation rates increased with increasing number of halogens on an individual carbon and depended on the halogen with rates in the order: iodine > bromine > chlorine. Halides were the predominant products, with bromide favored over chloride from compounds containing both bromine and chlorine. Lower order halogenated organic products were observed in some cases, including trichloromethane from tetrachloromethane or bromotrichloromethane and trichloroethylene from pentachloroethane. However, evidence for mono- or dihalogenated products was limited.