title: Ozonation of anilines: Kinetics, stoichiometry, product identification and elucidation of pathways.
abstract: Anilines as archetypes for aromatic amines, which play an important role in the production of, e.g., dyestuffs, plastics, pesticides or pharmaceuticals were investigated in their reaction with ozone. Due to their high reactivity towards ozone (1.2 × 10(5)-2.4 × 10(6) M(-1) s(-1)) the investigated aniline bearing different substituents are readily degraded in ozonation. However, around 4 to 5 molecules of ozone are needed to yield a successful transformation of aniline, most likely due to a chain reaction that decomposes ozone without compound degradation. This is inferred from OH radical scavenging experiments, in which compound transformation per ozone consumed is increased. Mechanistic considerations based on product formation indicate that addition to the aromatic ring is the preferential reaction in the case of aniline, p-chloroaniline and p-nitroaniline (high amounts of o-hydroxyaniline, p-hydroxyaniline, chloride, nitrite and nitrate, respectively were found). For aniline an addition to the nitrogen happens but to a small extent, since nitroso- and nitrobenzene were observed as well. In the case of N-methylaniline and N,N-dimethylaniline, an electron transfer reaction from nitrogen to ozone was proven due to the formation of formaldehyde. In contrast, for p-methylaniline and p-methoxyaniline the formation of formaldehyde may result from an electron transfer reaction at the aromatic ring. Additional oxidation pathways for all of the anilines under study are reactions of hydroxyl radicals formed in the electron transfer of ozone with the anilines (OH radical yields = 34-59%). These reactions may form aminyl radicals which in the case of aniline can terminate in bimolecular reactions with other compounds such as the determined o-hydroxyaniline by yielding the detected 2-amino-5-anilino-benzochinon-anil.
authors.affiliation: University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany; Westphalian University of Applied Sciences, Department of Environmental Engineering, Neidenburgerstraße 10, 45897 Gelsenkirchen, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Tekle-Röttering
authors.affiliation: University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany; Max Planck Institute of Bioinorganic Chemistry, Stiftstraße 34-36, 45413 Mülheim an der Ruhr, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: von Sonntag
authors.affiliation: University "Politehnica" of Timişoara, Faculty of Industrial Chemistry and Environmental Engineering, Bulevardul Vasile Pârvan Nr. 6, 300233 Timişoara, Romania.
authors.forename: Erika
authors.initials: E
authors.lastname: Reisz
authors.affiliation: University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany; Institut für Energie- und Umwelttechnik e.V. (IUTA), Institute of Energy- and Environmental Technology, Bliersheimer Straße 58-60, 47229 Duisburg, Germany.
authors.forename: Claudia Vom
authors.initials: CV
authors.lastname: Eyser
authors.affiliation: University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany; IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany.
authors.forename: Holger V
authors.initials: HV
authors.lastname: Lutze
authors.affiliation: Institut für Energie- und Umwelttechnik e.V. (IUTA), Institute of Energy- and Environmental Technology, Bliersheimer Straße 58-60, 47229 Duisburg, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Türk
authors.affiliation: Leibniz-Institut für Oberflächenmodifizierung (IOM), (Leibniz Institute for Surface Modification), Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Sergej
authors.initials: S
authors.lastname: Naumov
authors.affiliation: Westphalian University of Applied Sciences, Department of Environmental Engineering, Neidenburgerstraße 10, 45897 Gelsenkirchen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany.
authors.forename: Winfried
authors.initials: W
authors.lastname: Schmidt
authors.affiliation: University of Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany; Centre for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany; IWW Water Centre, Moritzstraße 26, 45476 Mülheim an der Ruhr, Germany. Electronic address: torsten.schmidt@uni-due.de.
authors.forename: Torsten C
authors.initials: TC
authors.lastname: Schmidt
mesh_terms: D000814:Aniline Compounds; D017665:Hydroxyl Radical; D007700:Kinetics; D010084:Oxidation-Reduction; D010126:Ozone
chemical_list: D000814:Aniline Compounds; D017665:Hydroxyl Radical; D010126:Ozone
keywords: Anilines; Ozone; Reaction kinetics; Reaction mechanism; Reaction stoichiometry; Transformation products