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Finding Fluorine: Photoproduct Formation during the Photolysis of Fluorinated Pesticides
[Image: see text] The photolysis of pesticides with different fluorine motifs was evaluated to quantify the formation of fluorinated products in buffered aqueous systems, advanced oxidation (AOP) and reduction processes (ARP), and river water. Simulated sunlight quantum yields at pH 7 were 0.0033, 0...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2022
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9454825/ https://www.ncbi.nlm.nih.gov/pubmed/35972505 http://dx.doi.org/10.1021/acs.est.2c04242 |
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author | Bhat, Akash P. Pomerantz, William C. K. Arnold, William A. |
author_facet | Bhat, Akash P. Pomerantz, William C. K. Arnold, William A. |
author_sort | Bhat, Akash P. |
collection | PubMed |
description | [Image: see text] The photolysis of pesticides with different fluorine motifs was evaluated to quantify the formation of fluorinated products in buffered aqueous systems, advanced oxidation (AOP) and reduction processes (ARP), and river water. Simulated sunlight quantum yields at pH 7 were 0.0033, 0.0025, 0.0015, and 0.00012 for penoxsulam, florasulam, sulfoxaflor, and fluroxypyr, respectively. The bimolecular rate constants with hydroxyl radicals were 2 to 5.7 × 10(10) M(–1) s(–1) and, with sulfate radicals, 1.6 to 2.6 × 10(8) M(–1) s(–1) for penoxsulam, florasulam, and fluroxypyr, respectively. The rate constants of sulfoxaflor were 100-fold lower. Using quantitative (19)F-NMR, complete fluorine mass balances were obtained. The maximum fluoride formation was 53.4 and 87.4% for penoxsulam and florasulam under ARP conditions, and 6.1 and 100% for sulfoxaflor and fluroxypyr under AOP conditions. Heteroaromatic CF(3) and aliphatic CF(2) groups were retained in multiple fluorinated photoproducts. Aryl F and heteroaromatic F groups were readily defluorinated to fluoride. CF(3) and CF(2) groups formed trifluoroacetate and difluoroacetate, and yields increased under oxidizing conditions. (19)F-NMR chemical shifts and coupling analysis provided information on hydrogen loss on adjacent bonds or changes in chirality. Mass spectrometry results were consistent with the observed (19)F-NMR products. These results will assist in selecting treatment processes for specific fluorine motifs and in the design of agrochemicals to reduce byproduct formation. |
format | Online Article Text |
id | pubmed-9454825 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-94548252023-08-16 Finding Fluorine: Photoproduct Formation during the Photolysis of Fluorinated Pesticides Bhat, Akash P. Pomerantz, William C. K. Arnold, William A. Environ Sci Technol [Image: see text] The photolysis of pesticides with different fluorine motifs was evaluated to quantify the formation of fluorinated products in buffered aqueous systems, advanced oxidation (AOP) and reduction processes (ARP), and river water. Simulated sunlight quantum yields at pH 7 were 0.0033, 0.0025, 0.0015, and 0.00012 for penoxsulam, florasulam, sulfoxaflor, and fluroxypyr, respectively. The bimolecular rate constants with hydroxyl radicals were 2 to 5.7 × 10(10) M(–1) s(–1) and, with sulfate radicals, 1.6 to 2.6 × 10(8) M(–1) s(–1) for penoxsulam, florasulam, and fluroxypyr, respectively. The rate constants of sulfoxaflor were 100-fold lower. Using quantitative (19)F-NMR, complete fluorine mass balances were obtained. The maximum fluoride formation was 53.4 and 87.4% for penoxsulam and florasulam under ARP conditions, and 6.1 and 100% for sulfoxaflor and fluroxypyr under AOP conditions. Heteroaromatic CF(3) and aliphatic CF(2) groups were retained in multiple fluorinated photoproducts. Aryl F and heteroaromatic F groups were readily defluorinated to fluoride. CF(3) and CF(2) groups formed trifluoroacetate and difluoroacetate, and yields increased under oxidizing conditions. (19)F-NMR chemical shifts and coupling analysis provided information on hydrogen loss on adjacent bonds or changes in chirality. Mass spectrometry results were consistent with the observed (19)F-NMR products. These results will assist in selecting treatment processes for specific fluorine motifs and in the design of agrochemicals to reduce byproduct formation. American Chemical Society 2022-08-16 2022-09-06 /pmc/articles/PMC9454825/ /pubmed/35972505 http://dx.doi.org/10.1021/acs.est.2c04242 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by-nc-nd/4.0/Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
spellingShingle | Bhat, Akash P. Pomerantz, William C. K. Arnold, William A. Finding Fluorine: Photoproduct Formation during the Photolysis of Fluorinated Pesticides |
title | Finding Fluorine:
Photoproduct Formation during the
Photolysis of Fluorinated Pesticides |
title_full | Finding Fluorine:
Photoproduct Formation during the
Photolysis of Fluorinated Pesticides |
title_fullStr | Finding Fluorine:
Photoproduct Formation during the
Photolysis of Fluorinated Pesticides |
title_full_unstemmed | Finding Fluorine:
Photoproduct Formation during the
Photolysis of Fluorinated Pesticides |
title_short | Finding Fluorine:
Photoproduct Formation during the
Photolysis of Fluorinated Pesticides |
title_sort | finding fluorine:
photoproduct formation during the
photolysis of fluorinated pesticides |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9454825/ https://www.ncbi.nlm.nih.gov/pubmed/35972505 http://dx.doi.org/10.1021/acs.est.2c04242 |
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