Difethialone

Last updated
Difethialone
Difethialone.png
Names
Preferred IUPAC name
3-[3-(4′-Bromo[1,1′-biphenyl]-4-yl)naphthalen-1-yl]-4-hydroxy-2H-1-benzothiopyran-2-one
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.118.383 OOjs UI icon edit-ltr-progressive.svg
KEGG
PubChem CID
UNII
  • InChI=1S/C31H23BrO2S/c32-24-15-13-20(14-16-24)19-9-11-21(12-10-19)23-17-22-5-1-2-6-25(22)27(18-23)29-30(33)26-7-3-4-8-28(26)35-31(29)34/h1-16,23,27,33H,17-18H2 X mark.svgN
    Key: JHELOZJAKXYVBE-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C31H23BrO2S/c32-24-15-13-20(14-16-24)19-9-11-21(12-10-19)23-17-22-5-1-2-6-25(22)27(18-23)29-30(33)26-7-3-4-8-28(26)35-31(29)34/h1-16,23,27,33H,17-18H2
    Key: JHELOZJAKXYVBE-UHFFFAOYAX
  • O=c1c(C2CC(c3ccc(-c4ccc(Br)cc4)cc3)Cc3ccccc32)c(O)sc2ccccc12
Properties
C31H23BrO2S
Molar mass 539.49 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Difethialone is an vitamin K antagonist anticoagulant used as a rodenticide. [1] It is considered a second generation agent. [2]

It belongs to the 4-thiochromenone or benzothiopyranone class of rodenticides, which differs from 4-hydroxycoumarins by the substitution of an oxygen atom with sulfur. It is especially similar to brodifacoum. It shares the same mechanism of inhibiting Vkorc1. It is effective for warfarin-resistant and warfarin-susceptible rodents. [1] Its high potency makes resistance harder to evolve, though a few populations of rodents have nevertheless managed to do so. [3]

In May 2008, the Environmental Protection Agency (EPA) added restrictions on the sale of difethialone in consumer-use rodenticide products and also for exterior use by commercial applicators. [4] [5]

Regulations

The EPA began analyzing anticoagulant-based rodenticide products (AR) in the 1990s. [6] The results were published in 1998 "in the Registration Eligibility Decision (RED) rodenticide cluster (US EPA 1998)." [6] Difethialone was classified as suitable for registration. A further in-depth environmental risk assessment using the "stochastic risk assessed method" targeted the nine active ingredients in rodenticides. [6] Products containing difethialone were identified as hazardous to non-target animals. In 2008, to protect children and prevent animal exposure, the EPA published its final decision. California further restricted the use of difethialone. "Assembly Bill No. 2657 prohibits the use of brodifacoum, bromadiolone, difenacoum, and difethialone in 'wildlife habitat areas,'" and "Assembly Bill 2596" prohibits their use in the state, with an exemption for agricultural use. [6]

In the EU, rodenticides are regulated as pesticides when used to protect growing or stored crops, and as biocides when used to protect processed agricultural produce stored in farm buildings. [6] The EU, however, still allows the use of ARs; however, manufacturers of difethialone have not sought authorization for crop protection. [6]

In Australia, difethialone is classified as a Schedule 6 anticoagulant rodenticide. "Schedule 6. – Poison – Substances with a moderate potential for causing harm, the extent of which can be reduced through the use of distinctive packaging with strong warnings and safety directions on the label." [7] [6] The sale and use of difethialone is legal according to the Australian Government Department of Health, Therapeutic Goods Administration, 2017. [7]

References

  1. 1 2 Nahas K, Lorgue G, Mazallon M (1989). "Difethialone (LM-2219): a new anticoagulant rodenticide for use against warfarin-resistant and -susceptible strains of Rattus norvegicus and Mus musculus". Annales de Recherches Vétérinaires. 20 (2): 159–64. PMID   2751229.
  2. ↑ Saravanan K, Kanakasabai R, Thiyagesan K (June 2003). "Field evaluation of difethialone, a new second generation anticoagulant rodenticide in the rice fields". Indian Journal of Experimental Biology. 41 (6): 655–8. PMID   15266918.
  3. ↑ McGee, C.F.; McGilloway, D.A.; Buckle, A.P. (September 2020). "Anticoagulant rodenticides and resistance development in rodent pest species – A comprehensive review". Journal of Stored Products Research. 88 101688. doi:10.1016/j.jspr.2020.101688.
  4. ↑ EPA, OCSPP, OPP, US (2014-03-04). "Restrictions on Rodenticide Products". United States Environmental Protection Agency .
  5. ↑ "Regulations.gov". www.regulations.gov.
  6. 1 2 3 4 5 6 7 Eisemann, John D.; Fisher, Penny M.; Buckle, Alan; Humphrys, Simon (2018), van den Brink, Nico W.; Elliott, John E.; Shore, Richard F.; Rattner, Barnett A. (eds.), "An International Perspective on the Regulation of Rodenticides", Anticoagulant Rodenticides and Wildlife, Cham: Springer International Publishing, pp. 287–318, doi:10.1007/978-3-319-64377-9_11, ISBN   978-3-319-64377-9 , retrieved 2025-12-13
  7. 1 2 Lohr, Michael T.; Davis, Robert A. (2018-09-01). "Anticoagulant rodenticide use, non-target impacts and regulation: A case study from Australia". Science of The Total Environment. 634: 1372–1384. doi:10.1016/j.scitotenv.2018.04.069. ISSN   0048-9697.
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