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Studies on the formation of formaldehyde during 2-ethylhexyl 4-(dimethylamino)benzoate demethylation in the presence of reactive oxygen and chlorine species
Environmental Science and Pollution Research (2017)
  • Waldemar Studziński, University of Technology and Life Sciences in Bydgoszcz
  • Alicja Gackowska, University of Technology and Life Sciences in Bydgoszcz
  • Maciej Przybyłek, Nicolaus Copernicus University of Torun
  • Jerzy Gaca, University of Technology and Life Sciences in Bydgoszcz
Abstract
In order to protect the skin from UV radiation, personal care products (PCPS) often contain chemical UV-filters. These compounds can enter the environment causing serious consequences on the water ecosystems. The aim of this study was to examine, the effect of different factors, such as UV light, the presence of NaOCl and H2O2 on the formaldehyde formation during popular UV filter, 2-ethylhexyl 4-(dimethylamino)benzoate (ODPABA) demethylation. The concentration of formaldehyde was determined by VIS spectrophotometry after derivatization. The reaction mixtures were qualitatively analyzed using GC/MS chromatography. The highest concentration of formaldehyde was observed in the case of ODPABA/H2O2/UV reaction mixture. In order to describe two types of demethylation mechanisms, namely, radical and ionic, the experimental results were enriched with Fukui function analysis and thermodynamic calculations. In the case of non-irradiated system containing ODPABA and NaOCl, demethylation reaction probably proceeds via ionic mechanism. As it was established, amino nitrogen atom in the ODPABA molecule is the most susceptible site for the HOCl electrophilic attack, which is the first step of ionic demethylation mechanism. In the case of irradiated mixtures, the reaction is probably radical in nature. The results of thermodynamic calculations showed that abstraction of the hydrogen from N(CH3)2 group is more probable than from 2-ethylhexyl moiety, which indicates higher susceptibility of N(CH3)2 to the oxidation.
Keywords
  • Formaldehyde,
  • 2-ethylhexyl 4-(dimethylamino)benzoate,
  • Padimate O,
  • 2-ethylhexyl dimethyl PABA,
  • Demethylation,
  • Sunscreen,
  • Reactivity,
  • Disinfection by-products,
  • Reactive oxygen and chlorine species
Publication Date
2017
DOI
10.1007/s11356-017-8477-8
Citation Information
Waldemar Studziński, Alicja Gackowska, Maciej Przybyłek and Jerzy Gaca. "Studies on the formation of formaldehyde during 2-ethylhexyl 4-(dimethylamino)benzoate demethylation in the presence of reactive oxygen and chlorine species" Environmental Science and Pollution Research Vol. 24 Iss. 9 (2017) p. 8049 - 8061
Available at: http://works.bepress.com/maciej-przybyek/21/