title: Formation of 2,6-dichloro-1,4-benzoquinone from aromatic compounds after chlorination.
abstract: Halobenzoquinones are a group of disinfection byproducts formed by chlorination of certain substances in water. However, to date, the identities of halobenzoquinone precursors remain unknown. In this study, the formation of 2,6-dichloro-1,4-benzoquinone (DCBQ), a typical halobenzoquinone, from 31 aromatic compounds was investigated after 60 min of chlorination. DCBQ was formed from 21 compounds at molar formation yields ranging from 0.0008% to 4.9%. Phenol and chlorinated phenols served as DCBQ precursors, as reported previously. Notably, DCBQ was also formed from para-substituted phenolic compounds. Compounds with alkyl and carboxyl groups as para-substituents led to relatively higher molar formation yields of DCBQ. Moreover, p-quinone-4-chloroimide, 2,6-dichloroquinone-4-chloroimide (2,6-DCQC), and para-substituted aromatic amines (e.g., aniline and N-methyl aniline) served as DCBQ precursors upon chlorination. It was deduced that DCBQ was formed from the para-substituted aromatic amines via 3,5-dichloroquinone-4-chloroimide, a structural isomer of 2,6-DCQC. These results suggested that DCBQ was formed by chlorination of natural organic matter containing para-substituted phenolic species and para-substituted aromatic amines, despite the absence of phenol in water.
authors.affiliation: Department of Environmental Health, National Institute of Public Health, 2-3-6 Minami, Wako, Saitama, 351-0197, Japan. Electronic address: kosaka@niph.go.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Kosaka
authors.affiliation: Yokohama Waterworks Bureau, 23 Yamasita-cho, Naka-ku, Yokohama, Kanagawa, 231-0023, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Nakai
authors.affiliation: Sendai City Waterworks Bureau, 29-1 Minami-Onoda, Taihaku-ku, Sendai, Miyagi, 982-8585, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Hishida
authors.affiliation: Department of Environmental Health, National Institute of Public Health, 2-3-6 Minami, Wako, Saitama, 351-0197, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Asami
authors.affiliation: Department of Environmental Health, National Institute of Public Health, 2-3-6 Minami, Wako, Saitama, 351-0197, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Ohkubo
authors.affiliation: National Institute of Public Health, 2-3-6 Minami, Wako, Saitama 351-0197, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Akiba
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D004203:Disinfection; D054879:Halogenation; D010636:Phenols / Q000737:chemistry; D018508:Water Purification
chemical_list: D016227:Benzoquinones; D010636:Phenols
keywords: 2,6-Dichloro-1,4-benzoquinone; 3,5-Dichloroquinone-4-chloroimide; Chlorination; Phenol; para-Substituted aromatic amine; para-Substituted phenolic compound