flufenacet
{{Chembox
| ImageFile = Flufenacet.svg
| ImageSize = 200px
| PIN = N-(4-Fluorophenyl)-N-(propan-2-yl)-2-
| OtherNames = Fluthiamide; Thiafluamide
|Section1={{Chembox Identifiers
| CASNo = 142459-58-3
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = OL44PP5145
| PubChem = 86429
| ChemSpiderID = 77944
| SMILES = CC(C)N(c1ccc(cc1)F)C(=O)COc2nnc(s2)C(F)(F)F
| InChI = 1/C14H13F4N3O2S/c1-8(2)21(10-5-3-9(15)4-6-10)11(22)7-23-13-20-19-12(24-13)14(16,17)18/h3-6,8H,7H2,1-2H3
| InChIKey = IANUJLZYFUDJIH-UHFFFAOYAX
| StdInChI = 1S/C14H13F4N3O2S/c1-8(2)21(10-5-3-9(15)4-6-10)11(22)7-23-13-20-19-12(24-13)14(16,17)18/h3-6,8H,7H2,1-2H3
| StdInChIKey = IANUJLZYFUDJIH-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| C=14 | H=13 | F=4 | N=3 | O=2 | S=1
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|Section3={{Chembox Hazards
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Flufenacet is an oxyacetanilide herbicide applied before crops have emerged.{{Cite journal | last1 = Rouchaud | first1 = J. | last2 = Neus | first2 = O. | last3 = Eelen | first3 = H. | last4 = Bulcke | first4 = R. | title = Persistence, Mobility, and Adsorption of the Herbicide Flufenacet in the Soil of Winter Wheat Crops | doi = 10.1007/s001280167 | journal = Bulletin of Environmental Contamination and Toxicology | volume = 67 | issue = 4 | pages = 609–616 | year = 2001 | pmid = 11779079| bibcode = 2001BuECT..67..609R | s2cid = 8544255 }} It was registered for use in the United States in 1998 and the European Union in 2004.{{cite web |title=Flufenacet (Ref: FOE 5043) |url=http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/331.htm |website=PPDB: Pesticide Properties DataBase |publisher=University of Hertfordshire}}
Mode of action
Flufenacet is related to the chloroacetamide class of herbicides and has the same mode of action through inhibiting the germination of seeds by inhibiting very long chain fatty acid synthesis.{{cite journal |title=Chloroacetamide Mode of Action, I: Inhibition of Very Long Chain Fatty Acid Synthesis in Scenedesmus acutus |journal=Zeitschrift für Naturforschung C |date=1 December 1998 |volume=53 |issue=11-12 |pages=995–1003 |doi=10.1515/znc-1998-11-1210|doi-access=free }}{{cite journal |last1=Matthes |first1=Bernd |last2=Schmalfuß |first2=Jochen |last3=Böger |first3=Peter |title=Chloroacetamide Mode of Action, II: Inhibition of Very Long Chain Fatty Acid Synthesis in Higher Plants |journal=Zeitschrift für Naturforschung C |date=1 December 1998 |volume=53 |issue=11-12 |pages=1004–1011 |doi=10.1515/znc-1998-11-1211|doi-access=free }}
In the model plant Arabidopsis thaliana it causes similar symptoms to the fiddlehead mutant.{{Cite journal | last1 = Lechelt-Kunze | first1 = C. | last2 = Meissner | first2 = R. C. | last3 = Drewes | first3 = M. | last4 = Tietjen | first4 = K. | title = Flufenacet herbicide treatment phenocopies the fiddlehead mutant in Arabidopsis thaliana | doi = 10.1002/ps.714 | journal = Pest Management Science | volume = 59 | issue = 8 | pages = 847–856 | year = 2003 | pmid = 12916765| doi-access = free }}
Usage
File:Flufenacet england usage.svg
In temperate Europe, flufenacet is commonly used in cereal crops to control grass weeds such as black-grass (Alopecurus myosuroides) that have evolved resistance to other herbicides and is applied in combination with other herbicides including pendimethalin, diflufenican, flurtamone, metribuzin and aclonifen.{{cite journal |last1=Dücker |first1=Rebecka |last2=Zöllner |first2=Peter |last3=Parcharidou |first3=Evlampia |last4=Ries |first4=Susanne |last5=Lorentz |first5=Lothar |last6=Beffa |first6=Roland |title=Enhanced metabolism causes reduced flufenacet sensitivity in black‐grass (Alopecurus myosuroides Huds.) field populations |journal=Pest Management Science |date=November 2019 |volume=75 |issue=11 |pages=2996–3004 |doi=10.1002/ps.5414}} {{asof|2019}} in the United Kingdom, resistance to flufenacet had began to be found in black-grass and rye-grass.{{cite news |last1=Impey |first1=Louise |title=How to get effective weed control when using flufenacet |url=https://www.fwi.co.uk/arable/crop-management/weed-management/how-to-get-effective-weed-control-when-using-flufenacet |access-date=23 February 2025 |work=Farmers Weekly |date=12 July 2019}} {{asof|2022}} it was the most widely applied herbicide and third most widely applied pesticide in England, being used on 2.9 million hectares.{{cite web |title=PESTICIDE USAGE SURVEY REPORT 309 |url=https://pusstats.fera.co.uk/api/report-download/699 |website=Pusstats |publisher=FERA |access-date=23 February 2025}}
Environmental fate
Flufenacet and its metabolites can be classified as PFAS substances, or so-called "forever chemicals". They break down to produce trifluoroacetic acid (TFA), a persistent substance that pollutes groundwater.{{cite journal |last1=Arp |first1=Hans Peter H. |last2=Gredelj |first2=Andrea |last3=Glüge |first3=Juliane |last4=Scheringer |first4=Martin |last5=Cousins |first5=Ian T. |title=The Global Threat from the Irreversible Accumulation of Trifluoroacetic Acid (TFA) |journal=Environmental Science & Technology |date=12 November 2024 |volume=58 |issue=45 |pages=19925–19935 |doi=10.1021/acs.est.4c06189|pmc=11562725 }}{{cite journal |author1=European Food Safety Authority |title=Peer review of the pesticide risk assessment of the active substance flufenacet |journal=EFSA Journal |date=September 2024 |volume=22 |issue=9 |doi=10.2903/j.efsa.2024.8997|pmc=11427894 }}
Toxicity
In September 2024, the European Food Safety Authority has concluded that flufenacet is an endocrine disruptor of humans and wild mammals via the thyroid (T)-modality. The active substance falls under the exclusion criteria of the Plant Protection Products Regulation. Re-authorisation of the active substance by the EU Commission is therefore no longer possible. The EU Commission will draw up a proposal for the non-authorisation of flufenacet, including withdrawal and sunset periods, which the EU member states are expected to vote on in spring 2025.{{Cite web |last=Bockholt |first=Karl |date=2024-10-02 |title=Schlag ins Kontor: Behörde streicht wichtigen Wirkstoff gegen Unkraut |url=https://www.agrarheute.com/pflanze/getreide/schlag-ins-kontor-behoerde-streicht-wichtigen-wirkstoff-gegen-unkraut-626748 |access-date=2025-02-23 |website=agrarheute.com |language=de}}{{Cite web |date=2024-09-27 |title=Pflanzenschutz. Es ist soweit: auch Flufenacet fällt weg |url=https://www.dlg-mitteilungen.de/artikel/pflanzenschutz-es-ist-soweit-auch-flufenacet-faellt-weg |access-date=2025-02-23 |website=DLG-Mitteilungen |language=de}} In March 2025, the EU agreed to ban flufenacet, effective from June 2025, but with the option for individual states to allow use for a further year.{{cite news |last1=Birch |first1=Rachel |title=EU agrees to ban herbicide flufenacet due to its toxicity |url=https://www.agriland.ie/farming-news/eu-agrees-to-ban-herbicide-flufenacet-due-to-its-toxicity/ |access-date=1 April 2025 |work=Agriland.ie |date=25 March 2025}}
Synthesis
Flufenacet can be obtained by reacting equivalent amounts of 2-methylsulfonyl-5-trifluoromethyl-1,3,4-thiadiazole with 2-hydroxy[N-(4-fluoropheny)-N-isopropyl]acetamide in the presence of sodium hydroxide in acetone.Hatzios KK, ed; Herbicide Handbook of the Weed Science Society of America. 7th ed. Suppl. Champaign, IL: Weed Sci Soc Amer, S. 9 (1998).
References
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