Cynmethylin

Cynmethylin (or cinmethylin) is a preёmergent cineole herbicide used in Australia on wheat, and commonly for rice and cereal crops. It is the only Group T (Aus) (Group Q, global, Group 30, numeric) herbicide. It controls annual ryegrass and the unusual mode of action avoids resistance. It works by inhibiting fatty acid thioesterase, disrupting cell membranes.^[1][2] It was introduced in 1989. As of 2025, approval is pending in Europe.^[1]

Cynmethylin

Names
Preferred IUPAC name rac-(1R,2S,4S)-1-methyl-2-[(2-methylphenyl)methoxy]-4-(propan-2-yl)-7-oxabicyclo[2.2.1]heptane
Other names WL 95481 SD 95481 rac-(1R,2S,4S)-1-methyl-4-(1-methylethyl)-2-((2-methylphenyl)methoxy)-7-oxabicyclo[2.2.1]heptane rel-(1R,2S,4S)-1-methyl-4-(1-methylethyl)-2-((2-methylphenyl)methoxy)-7-oxabicyclo[2.2.1]heptan
Identifiers
CAS Number	87818-31-3
3D model (JSmol)	Interactive image
ChEBI	CHEBI:145563
ChEMBL	ChEMBL1903971
ChemSpider	163945
ECHA InfoCard	100.100.423
EC Number	402-410-9
KEGG	C10903
PubChem CID	91745
UNII	ZV3871E43Y
CompTox Dashboard (EPA)	DTXSID3034456
InChI InChI=1S/C18H26O2/c1-13(2)18-10-9-17(4,20-18)16(11-18)19-12-15-8-6-5-7-14(15)3/h5-8,13,16H,9-12H2,1-4H3/t16-,17+,18-/m1/s1 Key: QMTNOLKHSWIQBE-UHFFFAOYSA-N
SMILES CC1=CC=CC=C1COC2CC3(CCC2(O3)C)C(C)C
Properties
Chemical formula	C18H26O2
Molar mass	274.404 g·mol−1
Appearance	Colourless[1]
Melting point	−56 °C (−69 °F; 217 K)[1]
Boiling point	330 °C (626 °F; 603 K) [1]
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	>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). Infobox references

Cynmethylin was first registered in Australia in 2003 (as an active product), but as a product only in 2019, by BASF, as a 750 g/l emulsifiable concentrate.^[3][4]

Cynmethylin can provide 12 weeks' residual control.^[2]

It is sold under the tradenames "Luximax", "Cinch" and "Argold".^[2][1]