title: Formation of chlorinated breakdown products during degradation of sunscreen agent, 2-ethylhexyl-4-methoxycinnamate in the presence of sodium hypochlorite.
abstract: In this study, a new degradation path of sunscreen active ingredient, 2-ethylhexyl-4-methoxycinnamate (EHMC) and 4-methoxycinnamic acid (MCA) in the presence of sodium hypochlorite (NaOCl), was discussed. The reaction products were detected using gas chromatography-mass spectrometry (GC-MS). Since HOCl treatment leads to more polar products than EHMC, application of polar extracting agents, dichloromethane and ethyl acetate/n-hexane mixture, gave better results in terms of chlorinated breakdown products identification than n-hexane. Reaction of EHMC with HOCl lead to the formation of C=C bridge cleavage products such as 2-ethylhexyl chloroacetate, 1-chloro-4-methoxybenzene, 1,3-dichloro-2-methoxybenzene, and 3-chloro-4-methoxybenzaldehyde. High reactivity of C=C bond attached to benzene ring is also characteristic for MCA, since it can be converted in the presence of HOCl to 2,4-dichlorophenole, 2,6-dichloro-1,4-benzoquinone, 1,3-dichloro-2-methoxybenzene, 1,2,4-trichloro-3-methoxybenzene, 2,4,6-trichlorophenole, and 3,5-dichloro-2-hydroxyacetophenone. Surprisingly, in case of EHMC/HOCl/UV, much less breakdown products were formed compared to non-UV radiation treatment. In order to describe the nature of EHMC and MCA degradation, local reactivity analysis based on the density functional theory (DFT) was performed. Fukui function values showed that electrophilic attack of HOCl to the C=C bridge in EHMC and MCA is highly favorable (even more preferable than phenyl ring chlorination). This suggests that HOCl electrophilic addition is probably the initial step of EHMC degradation.
authors.affiliation: Faculty of Chemical Technology and Engineering, University of Technology and Life Science, Seminaryjna 3, 85-326, Bydgoszcz, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Gackowska
authors.affiliation: Department of Physical Chemistry, Collegium Medicum, Nicolaus Copernicus University, 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 Science, 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 Science, Seminaryjna 3, 85-326, Bydgoszcz, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Gaca
mesh_terms: D002934:Cinnamates / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D015394:Molecular Structure; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013473:Sunscreening Agents / Q000737:chemistry*
chemical_list: D002934:Cinnamates; D013473:Sunscreening Agents; C118580:octylmethoxycinnamate; D012973:Sodium Hypochlorite
keywords: 2-Ethylhexyl-4-methoxycinnamate; Chlorination; Emerging pollutants; Fukui function; GC-MS; Halogenated disinfection byproducts; Local reactivity; Sunscreen