Ozonation of anilines: Kinetics, stoichiometry, product identification and elucidation of pathways

Agnes Tekle-Röttering; Clemens von Sonntag; Erika Reisz; Claudia Vom Eyser; Holger V Lutze; Jochen Türk; Sergej Naumov; Winfried Schmidt; Torsten C Schmidt

doi:10.1016/j.watres.2016.04.001

Ozonation of anilines: Kinetics, stoichiometry, product identification and elucidation of pathways

Water Res. 2016 Jul 1:98:147-59. doi: 10.1016/j.watres.2016.04.001. Epub 2016 Apr 7.

Authors

Agnes Tekle-Röttering¹, Clemens von Sonntag², Erika Reisz³, Claudia Vom Eyser⁴, Holger V Lutze⁵, Jochen Türk⁶, Sergej Naumov⁷, Winfried Schmidt⁸, Torsten C Schmidt⁹

Affiliations

¹ 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.
² 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.
³ University "Politehnica" of Timişoara, Faculty of Industrial Chemistry and Environmental Engineering, Bulevardul Vasile Pârvan Nr. 6, 300233 Timişoara, Romania.
⁴ 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.
⁵ 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.
⁶ 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.
⁷ Leibniz-Institut für Oberflächenmodifizierung (IOM), (Leibniz Institute for Surface Modification), Permoserstraße 15, 04318 Leipzig, Germany.
⁸ 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.
⁹ 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.

PMID: 27088249
DOI: 10.1016/j.watres.2016.04.001

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.

Keywords: Anilines; Ozone; Reaction kinetics; Reaction mechanism; Reaction stoichiometry; Transformation products.

MeSH terms

Aniline Compounds*
Hydroxyl Radical
Kinetics
Oxidation-Reduction
Ozone*

Substances

Aniline Compounds
Hydroxyl Radical
Ozone