Formation of bromochlorodibenzo-p-dioxins and dibenzofurans from the high-temperature oxidation of a mixture of 2-chlorophenol and 2-bromophenol.
The homogeneous, gas-phase oxidative thermal degradation of a 50:50 mixture of 2-bromophenol and 2-chlorophenol was studied in a 1 cm i.d., fused silica flow reactor at a concentration of 88 ppm, with a reaction time of 2.0 s, over a temperature range of 300 to 1000 degrees C. Observed products in order of decreasing yield included the following: dibenzo-p-dioxin (DD), 4-bromo-6-chlorodibenzofuran (4-B,6-CDF), phenol, 4,6-dibromodibenzofuran (4,6-DBDF), 2,6-dibromophenol, 4,6-dichlorodibenzofuran (4,6-DCDF), 2-bromo-4-chlorophenol, 2,4-dibromophenol, 2-chloro-4-bromophenol, 4-monobromodibenzofuran (4-MBDF), 4-monochlorodibenzofuran (4-MCDF), dibenzofuran (DF), 1-monobromodibenzo-p-dioxin (1-MBDD), 1-monochlorodibenzo-p-dioxin (1-MCDD), 2,4,6-tribromophenol, naphthalene, chloronaphthalene, bromonaphthalene, chlorobenzene, bromobenzene, and benzene. The results are compared and contrasted with previous results reported for the oxidations of pure 2-chlorophenol and 2-bromophenol as well as results for the pyrolysis of the mixture of 2-chlorophenol and 2-bromophenol. 4,6-DBDF and 4,6-DCDF were observed in higher yields than under pyrolytic conditions but considerably less than the yields observed for the individual oxidation of 2-chlorophenol and 2-bromophenol. The effect on chlorine and bromine on the concentration of hydroxyl radical is shown to control the dioxin-to-furan ratio.
Evans
Catherine S
CS
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Dellinger
Barry
B
D001572:Benzofurans / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry*; D004147:Dioxins / Q000737:chemistry*; D004777:Environment; D005740:Gases; D017665:Hydroxyl Radical; D008956:Models, Chemical; D009281:Naphthalenes / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D010636:Phenols / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000737:chemistry*; D013696:Temperature
D001572:Benzofurans; D002733:Chlorophenols; D004147:Dioxins; D005740:Gases; D009281:Naphthalenes; D010636:Phenols; D000072317:Polychlorinated Dibenzodioxins; C031721:naphthalene; C038902:1,4-dioxin; D017665:Hydroxyl Radical; C023614:dibenzofuran; C032038:2-bromophenol; C030683:2-chlorophenol; C020887:dibenzo(1,4)dioxin; D010100:Oxygen