Bixlozone

Last updated
Bixlozone
Bixlozone.svg
Names
IUPAC name
2-(2,4-dichlorobenzyl)-4,4-dimethylisoxazolidin-3-one
Preferred IUPAC name
2-[(2,4-dichlorophenyl)methyl]-4,4-dimethyl-1,2-oxazolidin-3-one
Other names
2-[(2,4-dichlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
EC Number
  • 701-330-4
PubChem CID
UNII
  • InChI=1S/C12H13Cl2NO2/c1-12(2)7-17-15(11(12)16)6-8-3-4-9(13)5-10(8)14/h3-5H,6-7H2,1-2H3
    Key: FHUKASKVKWSLCY-UHFFFAOYSA-N
  • CC1(CON(C1=O)CC2=C(C=C(C=C2)Cl)Cl)C
Properties
C12H13Cl2NO2
Molar mass 274.14 g·mol−1
AppearanceWhite crystalline solid [1] [2]
Density 1.37 g/mL [2]
Melting point 81.5 °C (178.7 °F; 354.6 K) [1]
Boiling point Degrades at 188 °C (370 °F) before boiling [1]
42 mg/L [2]
Solubility in acetone >250 g/L [2]
Solubility in methanol 120 g/L [2]
Solubility in ethyl acetate >250 g/L [2]
Solubility in toluene >250 g/L [2]
Vapor pressure 2.3 mPa [2]
Hazards
GHS labelling:
GHS-pictogram-pollu.svg
382 °C (720 °F; 655 K) [2]
Lethal dose or concentration (LD, LC):
>2000 mg/kg (rat, oral) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Bixlozone is a herbicidal active ingredient, announced by FMC in 2018, [3] for commercial release in April 2021 in Australia. It is used to control broadleaf and grassy weeds [4] [5]

Contents

Bixlozone is a isoxazolidinone class herbicide, and is mildly lipophilic. [2] It is the second herbicide with its mode of action, the other being clomazone (differing only by a single atom); they work by preventing carotenoid biosynthesis by inhibiting DXP synthase. [5]

Mechanism of action

Like clomazone, bixlozone blocks carotenoid synthesis in plants. The lack of protective carotenoid causes bleaching of leaves. Bixlozone is uptaken by the roots and shoots in germinating weed seedlings. It is mobile in xylem, but does not seem to move downward or between leaves. [2]

Specifically, it blocks the terpenoid synthesis pathway, between isopentenyl pyrophosphate and geranylgeranyl pyrophosphate, which prevents the synthesis of plant pigments, chlorophyll, and carotenoids. [2]

Bixlozone's HRAC Group is Group 13, Group F3 / F4, Group Q. (Numeric, Global, Australian) [6]

Symptoms

Symptoms vary, but on grasses, typically bleaching in lines or streaks on the leaf, or whitening of the whole leaf. Chlorosis may occur at lower application rates between the veins and leaf margins. Some plants turn white. In particular, lolium (ryegrass) tends to turn pink. [5]

Crop injury can happen under heavy rainfall after application, since bixlozone might wash into the seedbed. [5]

Safety

Bixlozone has low dermal, oral and inhalational actue toxicity, according to the APVMA. Nor is it an eye irritant or skin sensitiser, though it may be a mild skin irritant. If absorbed, it is excreted mainly in urine and the remainder in faeces. In the body, bixlozone and related metabolites have a half-life of 10-16 hours. Applied dermally, under 16% was absorbed from 0.25 g/L solution, and less at higher concentrations. It has a 21-day NOAEL of 1000 mg/kg/day, the highest dose tested on rats. On a chronic test, it has a NOAEL of 53 mg/kg/day, and showed no evidence of oncogenicity. [2]

Synthesis

3-Chloro-2,2-dimethylpropionyl chloride is transformed with hydroxylamine hydrochloride to a hydroxamic acid, which is then cyclised under strongly basic conditions to an isoxazolidinone. The isoxazolidinone can then be alkylated with 2,4-dichlorobenzyl chloride to produce bixlozone. [3]

Tradenames

Overwatch is a 400 g/L bixlozone suspension concentrate. Its viscosity is 103 mPa.s at 20°C, [2] comparable to olive oil. Isoflex Active is technical grade bixlozone. [5]

Weeds controlled

Bixlozone can control annual grasses including ryegrass, barnyardgrass, crabgrass, foxtail, canarygrass, goosegrass, bluegrass, and (suppression only) blackgrass. It controls the broadleaf weeds common chickweed, speedwells, shepherd's purse and wild chamomile. [5]

Herbicide resistance to this mode of action is rare, with only three global populations so reported by 2022. [5]

References

  1. 1 2 3 4 "Bixlozone (Ref: F9600)". sitem.herts.ac.uk. Pesticide Properties Database. Retrieved 17 September 2025.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 "Public Release Summary on the evaluation of the new active bixlozone in the product Overwatch Herbicide APVMA product number 86427" (PDF). www.apvma.gov.au. Australian Pesticides and Veterinary Medicines Authority. Retrieved 17 September 2025.
  3. 1 2 Jeanmart, Stephane; Edmunds, Andrew J. F.; Lamberth, Clemens; Pouliot, Martin; Morris, James A. (1 June 2021). "Synthetic approaches to the 2015–2018 new agrochemicals" . Bioorganic & Medicinal Chemistry. 39 116162. doi:10.1016/j.bmc.2021.116162. PMID   33895705 . Retrieved 17 September 2025.
  4. ↑ Li, Congdi; Chen, Zenglong; Qin, Dongmei; Liu, Rong; Li, Li; Li, Wei; He, Yujian; Yuan, Longfei (2021). "Simultaneous determination of the herbicide bixlozone and its metabolites in plant and animal samples by liquid chromatography–tandem mass spectrometry". Journal of Separation Science. 44 (4): 822–832. doi:10.1002/jssc.202000992. PMID   33289303.
  5. 1 2 3 4 5 6 7 "Isoflex Active - Global Technical Bulletin" (PDF). FMC Corporation. Retrieved 31 October 2025.
  6. ↑ "23033 - Web Label_AU_Overwatch Herbicide 31102023 v1.pdf". ag.fmc.com. Retrieved 17 September 2025.
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