title: Covalent bonding of chloroanilines to humic constituents: pathways, kinetics, and stability.
abstract: Covalent coupling to natural humic constituents comprises an important transformation pathway for anilinic pollutants in the environment. We systematically investigated the reactions of chlorine substituted anilines with catechol and syringic acid in horseradish peroxidase (HRP) catalyzed systems. It was demonstrated that although nucleophilic addition was the mechanism of covalent bonding to both catechol and syringic acid, chloroanilines coupled to the 2 humic constituents via slightly different pathways. 1,4-addition and 1,2-addition are involved to catechol and syringic acid, respectively. 1,4-addition showed empirical 2nd order kinetics and this pathway seemed to be more permanent than 1,2-addition. Stability experiments demonstrated that cross-coupling products with syringic acid could be easily released in acidic conditions. However, cross-coupling with catechol was relatively stable at similar conditions. Thus, the environmental behavior and bioavailability of the coupling products should be carefully assessed.
authors.affiliation: Department of Environmental Science and Engineering, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Deyang
authors.initials: D
authors.lastname: Kong
authors.forename: Qing
authors.initials: Q
authors.lastname: Xia
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Liu
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Huang
authors.forename: Junhe
authors.initials: J
authors.lastname: Lu
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D055598:Chemical Phenomena; D006812:Humic Substances; D007700:Kinetics; D008956:Models, Chemical
chemical_list: D000814:Aniline Compounds; D006812:Humic Substances
keywords: Bound residue; Chloroaniline; Horseradish peroxidase