Dechlorination of polychlorobiphenyls using NaBH(4) and NaBH(4)/LiCl at 120-310 degrees C in glyme solvents.
High temperature PCB dechlorination (Aroclor 1016) occurred using NaBH(4) alone in tetraglyme at 290-310 degrees C within 2h in a sealed tube. Aroclor 1016 dechlorination was also quantitatively achieved using NaBH(4)/LiCl/glyme solvents (di-, tri-, or tetraglyme) at 125-135 degrees C. The best results were obtained by prestirring NaBH(4), LiCl and the glyme solvent at room temperature before heating at 125-135 degrees C. At equivalent conditions, PCB dechlorination rates were found to depend on solvent in the order: tetraglyme>triglyme>diglyme. At 130 degrees C, Aroclor 1016 can be dechlorinated in NaBH(4)/LiCl/tetraglyme in 4h. 2-Chlorobiphenyl and 2,2'-dichlorobiphenyl were the least reactive congeners in dechlorinations with NaBH(4)/LiCl in diglyme. Competitive dechlorinations with NaBH(4)/LiCl in diglyme showed 3-chloro- and 4-chlorobiphenyl reacted faster than 2-chlorobiphenyl at 130 degrees C. The reactions were clean with no solvent decomposition in the range of 120-162 degrees C.
Department of Chemistry, University/Industry Chemical Research Center, Mississippi State University, Mississippi State, MS 39762-9573, USA. cpittman@ra.msstate.edu
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D001894:Borohydrides / Q000737:chemistry*; D004785:Environmental Pollutants; D004787:Environmental Pollution / Q000517:prevention & control; D018021:Lithium Chloride / Q000737:chemistry; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D013696:Temperature
D001894:Borohydrides; D004785:Environmental Pollutants; C025364:sodium borohydride; D011078:Polychlorinated Biphenyls; D018021:Lithium Chloride