TY - JOUR
T1 - Experimental and theoretical insights into the involvement of radicals in triclosan phototransformation
AU - Kliegman, Sarah
AU - Eustis, Soren N.
AU - Arnold, William A.
AU - McNeill, Kristopher
PY - 2013/7/2
Y1 - 2013/7/2
N2 - The phototransformation of triclosan has been a matter of longstanding interest due to both its prevalence in the environment and the discovery of 2,8-dichlorodibenzodioxin as a photoproduct. In this study, photolysis of triclosan resulted in several primary photoproducts including the following: 2,8-dichlorodibenzodioxin (4%), 4,5′-dichloro-[1,1′-biphenyl]-2, 2′-diol (10%), 5-chloro-2-(4-chlorophenoxy)phenol (0.5%), and 2,4-dichlorophenol (7%). Trapping studies using d8-isopropanol showed deuterium incorporation in 5-chloro-2-(4-chlorophenoxy)phenol, providing strong evidence for the involvement of organic radicals in this reaction. Density functional calculations of the excited states of triclosan support the involvement of a radical intermediate in the mechanisms responsible for the dioxin, biphenyl, and phenoxyphenol photoproducts. The pathways for C-Cl bond cleavage and cyclization reactions are discussed.
AB - The phototransformation of triclosan has been a matter of longstanding interest due to both its prevalence in the environment and the discovery of 2,8-dichlorodibenzodioxin as a photoproduct. In this study, photolysis of triclosan resulted in several primary photoproducts including the following: 2,8-dichlorodibenzodioxin (4%), 4,5′-dichloro-[1,1′-biphenyl]-2, 2′-diol (10%), 5-chloro-2-(4-chlorophenoxy)phenol (0.5%), and 2,4-dichlorophenol (7%). Trapping studies using d8-isopropanol showed deuterium incorporation in 5-chloro-2-(4-chlorophenoxy)phenol, providing strong evidence for the involvement of organic radicals in this reaction. Density functional calculations of the excited states of triclosan support the involvement of a radical intermediate in the mechanisms responsible for the dioxin, biphenyl, and phenoxyphenol photoproducts. The pathways for C-Cl bond cleavage and cyclization reactions are discussed.
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U2 - 10.1021/es3041797
DO - 10.1021/es3041797
M3 - Article
C2 - 23282071
AN - SCOPUS:84880104177
SN - 0013-936X
VL - 47
SP - 6756
EP - 6763
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 13
ER -