Saflufenacil
Names
Preferred IUPAC name
2-Chloro-4-fluoro-5-[3-methyl-2,6-dioxo-4-(trifluoromethyl)-3,6-dihydropyrimidin-1(2H)-yl]-N-[methyl(propan-2-yl)sulfamoyl]benzamide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.124.700 Edit this at Wikidata
UNII
  • InChI=1S/C17H17ClF4N4O5S/c1-8(2)25(4)32(30,31)23-15(28)9-5-12(11(19)6-10(9)18)26-14(27)7-13(17(20,21)22)24(3)16(26)29/h5-8H,1-4H3,(H,23,28) checkY
    Key: GNHDVXLWBQYPJE-UHFFFAOYSA-N checkY
  • CC(C)N(C)S(=O)(=O)NC(=O)C1=CC(=C(C=C1Cl)F)N2C(=O)C=C(N(C2=O)C)C(F)(F)F
Properties[1]
C17H17ClF4N4O5S
Molar mass 500.85 g·mol−1
Density 1.595 g/mL
Melting point 189.9 °C (373.8 °F; 463.0 K)
2100 mg/L (20 °C)
Hazards[2]
GHS labelling:
GHS09: Environmental hazard
Warning
H410
P273, P391, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Saflufenacil is the ISO common name[3] for an organic compound of the pyrimidinedione chemical class used as an herbicide. It acts by inhibiting the enzyme protoporphyrinogen oxidase to control broadleaf weeds in crops including soybeans and corn.

History

In 1985, chemists at the Dr R. Maag subsidiary of Hoffmann-La Roche filed patents to 3-aryl uracil derivatives which had herbicidal activity.[4] The work was continued by Ciba-Geigy and further patents claiming additional esters were published, including to butafenacil (CGA276854), which was marketed in 2001.[5][6] BASF scientists investigated the chemistry and patented an analog where the carboxylic ester of butafenacil was replaced by a sulfamoyl carboxamide. It was developed under the code number BAS800H and first marketed in 2008 with the brand name Kixor.[7][1]

Synthesis

As described in the BASF patent, the key step in the preparation of saflufenacil involved the reaction between a substituted aniline and an oxazinone. 2-chloro-4-fluoro-5-aminobenzoic acid and 2-dimethylamino-4-(trifluoromethyl)-6H-1,3-oxazin-6-one were heated in acetic acid to form the ring systems of the herbicide in over 90% yield, with further standard chemical transformations to generate the final product.[7]

Mechanism of action

Saflufenacil works by inhibiting protoporphyrinogen IX oxidase (PPO), preventing chlorophyll formation, and resulting in accumulation of protoporphyrin IX which is a potent photosensitizer. This activates oxygen, causing lipid peroxidation with rapid loss of membrane integrity and function. The effects visible on whole plants are chlorosis and necrosis.[8] In corn and some varieties of soyabean the effects are insufficient to cause serious damage, leading to useful selectivity.[9][10]

Usage

Saflufenacil is registered for use in the United States, where the Environmental Protection Agency (EPA) is responsible for regulating pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the Food Quality Protection Act (FQPA) and the Pesticide Registration Improvement Act (PRIA). A pesticide can only be used legally according to the directions on the label that is included at the time of the sale.[9][11]

The herbicide controls only broadleaf weeds but is effective both pre- and post-emergence on a very wide range of these species including Abutilon theophrasti, Acalypha virginica, Acanthospermum hispidum, Amaranthus hybridus, Amaranthus palmeri, Amaranthus powellii, Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album, Conyza canadensis, Datura stramonium, Galinsoga parviflora, Helianthus annuus, Hibiscus trionum, Ipomoea hederacea, Ipomoea purpurea, Kochia scoparia, Mollugo verticillata, Physalis angulata, Polygonum convolvulus, Polygonum persicaria, Portulaca oleracea, Richardia scabra, Salsola kali, Sicyos angulatus, Sinapis arvensis, Solanum nigrum, Stellaria media, Thlaspi arvense, Tribulus terrestris and Xanthium strumarium. The product is typically used at application rates of 0.1 lb a.i. per acre and may also be applied for crop desiccation pre-harvest.[9]

The estimated annual use of saflufenacil in US agriculture is mapped by the US Geological Service and shows that in 2018, the latest date for which figures are available, approximately 600,000 pounds (270,000 kg) were applied — mainly in corn and soybean.[12] The compound is also registered for use in Australia but not in the European Union.[1]

References

  1. ^ a b c Pesticide Properties Database. "Saflufenacil". University of Hertfordshire.
  2. ^ "Saflufenacil". pubchem.ncbi.nlm.nih.gov. Retrieved 2021-03-15.
  3. ^ "Compendium of Pesticide Common Names: saflufenacil". BCPC.
  4. ^ US patent 4746352, Wenger J. & Winternitz P., "3-(5-Carboxy-4-Substituted-Phenyl)-(thio) Uracil esters and salts", issued 1988-05-24, assigned to Hoffmann-La Roche Inc. 
  5. ^ US patent 5183492, Suchy M.; Winternitz P. & Zeller M., "Herbicidal 3-aryluracils", issued 1993-02-02, assigned to Ciba-Geigy Ag 
  6. ^ Pesticide Properties Database. "Butafenacil". University of Hertfordshire.
  7. ^ a b US patent 6534492, Carlsen M.; Guaciaro M. A. & Takasugi J. J., "Uracil substituted phenyl sulfamoyl carboxamides", issued 2003-03-18, assigned to BASF SE 
  8. ^ Theodoridis, George (2016). "Carboxylic-Acid-Containing Protoporphyrinogen-IX-Oxidase-Inhibiting Herbicides". Bioactive Carboxylic Compound Classes: Pharmaceuticals and Agrochemicals. pp. 347–356. doi:10.1002/9783527693931.ch26. ISBN 9783527339471.
  9. ^ a b c BASF. "Sharpen: powered by Kixor herbicide" (PDF). www3.epa.gov. Retrieved 2021-03-15.
  10. ^ Grossmann, Klaus; Niggeweg, Ricarda; Christiansen, Nicole; Looser, Ralf; Ehrhardt, Thomas (2010). "The Herbicide Saflufenacil (Kixor™) is a New Inhibitor of Protoporphyrinogen IX Oxidase Activity". Weed Science. 58: 1–9. doi:10.1614/WS-D-09-00004.1. S2CID 86227686.
  11. ^ "About Pesticide Registration". US EPA. Retrieved 2021-03-15.
  12. ^ US Geological Survey (2021-12-21). "Estimated Agricultural Use for Saflufenacil, 2018". Retrieved 2022-12-02.
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