Dechlorination of polychlorinated dibenzo-p-dioxins catalyzed by noble metal catalysts under mild conditions.
Dechlorination of polychlorinated dibenzo-p-dioxins such as 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) and 1,2,6,7-tetrachlorodibenzo-p-dioxin (1,2,6,7-TCDD) was carried out in a solution of NaOH in 2-propanol in the presence of carbon-supported noble metal catalyst (Pd/C or Rh-Pt/C) at temperatures between 23 and 35 degrees C. At initial concentrations of 140-240 micrograms/ml, 2,7-DCDD and 1,2,6,7-TCDD were efficiently converted to a chlorine-free product, dibenzo-p-dioxin (DD), in high yield (60-80%). The conversion of 2,7-DCDD and 1,2,6,7-TCDD and the yield of DD were hardly affected by the atmosphere (N2 or air). We postulate that the displacement of aromatic chlorines by hydrogen selectively occurs on the catalyst, involving hydrogen-transfer from 2-propanol to the substrates.
Ukisu
Yuji
Y
National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan. y-ukisu@aist.go.jp
Miyadera
Tatsuo
T
D019840:2-Propanol; D000397:Air Pollution / Q000517:prevention & control*; D002384:Catalysis; D002713:Chlorine / Q000737:chemistry*; D004147:Dioxins / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D005741:Noble Gases; D010084:Oxidation-Reduction; D000072317:Polychlorinated Dibenzodioxins
D004147:Dioxins; D005741:Noble Gases; D000072317:Polychlorinated Dibenzodioxins; C000925:2,7-dichlorodibenzo-4-dioxin; D002713:Chlorine; D006859:Hydrogen; C460719:1,2,6,7-tetrachlorodibenzo-p-dioxin; D019840:2-Propanol