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 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.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-017-8477-8) contains supplementary material, which is available to authorized users.

Photodegradable Antimicrobial Agents: Synthesis and Mechanism of Degradation

“…Conceivably, the suggested products originate from a photo-retro-aldol-type reaction, initially forming N -methyl-4-nitroaniline and phenylacetaldehyde (Scheme B). The former product, known to undergo photochemical N -demethylation, , subsequently reacts and furnishes formaldehyde and p -nitroaniline (Scheme B, reaction a). Phenylacetaldehyde then undergoes oxidation to phenylacetic acid (Scheme B, reaction b) (which can suffer cleavage and form benzaldehyde and formaldehyde/formic acid (Scheme B, reaction e)) or reacts in a Norrish type 1 process and forms formaldehyde and benzaldehyde (Scheme B, reaction c).…”

Application of the Swimming Pool Backwash Water Recovery System with the Use of Filter Tubes

“…When the chlorine compounds finish oxidizing the bacteria, they combine with another chemical. This process leads to the formation of disinfection by-products (DBPs) [35][36][37].…”

Effect of Activated Sludge on the Degradation of 2-Ethylhexyl 4-Methoxycinnamate and 2-Ethylhexyl 4-(Dimethylamino)Benzoate in Wastewater

“…Green line indicates 5% of sludge, red line indicates 10% of sludge, and blue line indicates 20% of sludge Gago-Ferrero et al (2011), biodegradation processes of ODPABA in the sewer and during wastewater and/or sludge treatment cannot be ruled out. Moreover, our previous studies have shown that EHMC and ODPABA transform under influence of oxidising agents with formation of products significantly more toxic than the substrates themselves (Studziński et al 2017;Gackowska et al 2018). In order to verify whether biochemical transformations of UV filters occur under the influence of activated sludge, studies were carried out on model systems.…”