title: Studies on the formation of formaldehyde during 2-ethylhexyl 4-(dimethylamino)benzoate demethylation in the presence of reactive oxygen and chlorine species.
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 H2O2on 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)2group is more probable than from 2-ethylhexyl moiety, which indicates higher susceptibility of N(CH3)2to the oxidation.
authors.affiliation: Faculty of Chemical Technology and Engineering, University of Technology and Life Sciences, Seminaryjna 3, 85-326, Bydgoszcz, Poland.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Studziński
authors.affiliation: Faculty of Chemical Technology and Engineering, University of Technology and Life Sciences, Seminaryjna 3, 85-326, Bydgoszcz, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Gackowska
authors.affiliation: Department of Physical Chemistry, Faculty of Pharmacy, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Kurpińskiego 5, 85-950, Bydgoszcz, Poland. m.przybylek@cm.umk.pl.
authors.forename: Maciej
authors.initials: M
authors.lastname: Przybyłek
authors.affiliation: Faculty of Chemical Technology and Engineering, University of Technology and Life Sciences, Seminaryjna 3, 85-326, Bydgoszcz, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Gaca
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D005557:Formaldehyde / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D013473:Sunscreening Agents / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects; D062366:para-Aminobenzoates / Q000737:chemistry / Q000528:radiation effects
chemical_list: D013473:Sunscreening Agents; D014874:Water Pollutants, Chemical; D062366:para-Aminobenzoates; D005557:Formaldehyde; D002713:Chlorine; D006861:Hydrogen Peroxide; C041981:padimate-O
keywords: 2-ethylhexyl 4-(dimethylamino)benzoate; Demethylation; Disinfection by-products; Formaldehyde; Reactive oxygen and chlorine species; Reactivity; Sunscreen