 | |
| Names | |
|---|---|
| IUPAC name (5-cyclopropyl-1,2-oxazol-4-yl)-[2-methylsulfonyl-4-(trifluoromethyl)phenyl]methanone | |
Other names
| |
| Identifiers | |
3D model (JSmol) | |
| 8344543 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| DrugBank |
|
| ECHA InfoCard | 100.114.433 |
| EC Number |
|
| UNII | |
| |
| |
| Properties[1] | |
| C15H12F3NO4S | |
| Molar mass | 359.32 g·mol−1 |
| Appearance | Off-white or pale yellow solid |
| Density | 1.59 g/cm3 |
| Melting point | 138 °C (280 °F; 411 K) |
| 6.2 mg/L | |
| logP | 2.32 |
| Hazards | |
| GHS labelling: | |
  | |
| Warning | |
| H361d,H410 | |
| P203,P273,P280,P318,P391,P405,P501 | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Isoxaflutole is aselective herbicide used mainly inmaize crops.[1] It inhibits the enzyme4-hydroxyphenylpyruvate dioxygenase (HPPD)[2] and is sold under brand names including Balance and Merlin. It was first marketed byRhône-Poulenc in 1996.
In the mid-1980s, scientists atStauffer Chemical Company published patents to benzoyl-substituted cyclohexanediones (triketones) which led to their productmesotrione.[3] This encouraged workers atRhône-Poulenc to expand their own research into molecules with the same mode of action as these4-hydroxyphenylpyruvate dioxygenase inhibitors. In doing so, they found that isoxaflutole had commercial potential as a propesticide of a biologically active diketonitrile that it was converted into within plants.[4] It was developed under the code number RPA201772.[5][6]
Theisoxazole ring of theheterocycle product is formed whenhydroxylamine reacts in ethanol with an intermediate which is made from an appropriately substituted diketone withtriethyl orthoformate, using acetic anhydride as solvent.[7]
The crystal structure of isoxaflutole has been determined.[8] Within plants, it is converted to the diketonitrile shown, which is herbicidally active as anHPPD inhibitor.[2] The advantage of applying isoxafluole rather than the diketonitrile is that the former is more readily taken up into plants from a soil treatment.[5]
Isoxaflutole was first marketed by Rhône-Poulenc in 1996. It controls weeds which are important in crops including corn and sugarcane.[5][9][10] These include broad-leaved-weeds fromAmaranthus,Datura stramonium andragweed species and annual grass weeds ofAlopecurus,Eriochloa andPanicum species.[11]
The herbicide is usually applied to the soil in which the crop is growing,before the emergence of the weeds.[1] In the US it is applied almost exclusively in corn with annual use in 2018 about 600,000 pounds (270,000 kg).[12] The compound is oftenformulated in combination with theherbicide safener, cyprosulfamide.[13] For example, in the EU the product that was evaluated by regulators was a suspension concentrate containing 240 g/L isoxaflutole and 240 g/L cyprosulfamide.[14]
TheLD50 of isoxaflutole is over 5000 mg/kg (rats, oral),[1] TheEuropean Food Safety Authority set anacceptable daily intake for it at 0.02 mg/kg bodyweight.[14] TheCodex Alimentarius database maintained by the FAO lists the maximum residue limits for isozaflutole in various food products, most of which are set at its 0.01 mg/kg or 0.02 mg/kg limit of detection for the combination of the compound and its diketonitrile.[15]
Isoxaflutole is theISOcommon name[16] for the active ingredient which is formulated into the branded product sold to end-users. The brand names in use for herbicides containing isoxaflutole include Balance, Cadu Star, Merlin and Spade.[1]
