Pyrasulfotole
Weed control herbicide
From Wikipedia, the free encyclopedia
Pyrasulfotole is a herbicide used to control broadleaf weeds in what and barley.[2] It is a selective benzoylpyrazolone,[3] pyrazole compound, registered in Canada and Australia in 2004, and the USA in 2007.[1] Bayer patented it in Australia in 2006, and the patent expired in March 2026.[3]
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| Names | |
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| IUPAC name
(5-Hydroxy-1,3-dimethylpyrazol-4-yl)(α,α,α-trifluoro-2-mesyl-p-tolyl)methanone | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.123.578 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C14H13F3N2O4S | |
| Molar mass | 362.32 g·mol−1 |
| Appearance | Beige coloured powder[1] |
| Density | 1.53 kg/L, 15.3 lb/gal Imp[1] |
| Melting point | 201°C, 394°F[1] |
| 69.1g/L[1] | |
| Solubility in ethanol | 21.6 g/L[1] |
| Solubility in toluene | 6.9 g/L[1] |
| Solubility in acetone | 89.2 g/L[1] |
| Solubility in ethyl acetate | 37.2 g/L[1] |
| Vapor pressure | 270 nPa (3.9 x10-11 psi)[1] |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H373, H410 | |
| P260, P273, P319, P391, P501 | |
| Flash point | 96°C, 205°F[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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Application
Pyrasulfotole is generally sold as an emulsifiable concentrate of 75-230 g/L, or 37.5 g/L in a mixture with bromoxynil.[4][5][6][7][8]
Some pyrasulfotole formulations include mefenpyr-diethyl as a safener.[9] Bayer's patent also covers other safeners: cloquintocet-mexyl and 4-cyclopropylaminocarbonyl-N-(2-methoxybenzoyl)benzenesulfonamide.[3]
Mechanism
It acts by one mechanism of action, inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD), placing it in the Group H (Australia), Group F2 (global), Group 27 (numeric) HRAC class.[8][10]
An APVMA report claims pyrasulfotole acts by two mechanisms of action: inhibiting "4-hydroxyphenylpyruvate deoxygenase" (sic) (HPPD) and disrupting plant cell growth, with a dual HRAC class of Groups F & I (Australia),[11][12] though inhibiting HPPD is the MoA of Group H (Group 27),[10] and as of 2026, pyrasulfotole is listed as only as Group H.[13]