Description
Sulfometuron-methyl is a herbicide. It has a moderate aqueous solubility, is non-volatile and, based on its chemical properties, is mobile and may be expected to leach to groundwater. It is not generally persistent in soil systems but may be persistent in aquatic systems under certain conditions. It has a low mammalian toxicity and has a high potential to bioaccumulate. It is moderately toxic to most aquatic species, honeybees and earthworms but is less toxic to birds.
Chemical Properties
The prodrug is white solid. m.p. 203～205℃, vapor pressure 7.39×10-14Pa, relative density 1.48. At 25℃, the solubility is: acetone 2.4g/kg, acetonitrile 1.5g/kg, ethanol 137mg/kg, ether 32mg/kg, xylene 37mg/kg, water 8mg/L (pH=5), 70mg/L (pH =7). The partition coefficient was 0.31 (pH=7). The hydrolysis half-life of the aqueous suspension was 18d at pH=5, and it was stable at pH=7-9. The half-life in soil was about 28d.
Uses
Metsulfuron-methyl is a sulfonylurea herbicide that inhibits the synthesis of branched-chain amino acids, thereby inhibiting cell division at the growing tips of plants, preventing the growth of weeds, and leading to chlorosis and necrosis. It is suitable for the control of annual and perennial grass weeds and broadleaf weeds in forestry.
Definition
ChEBI: Sulfometuron methyl is a benzoate ester that is the methyl ester of 2-{[(4,6-dimethylpyrimidin-2-yl)carbamoyl]sulfamoyl}benzoic acid. It has a role as a herbicide and an EC 2.2.1.6 (acetolactate synthase) inhibitor. It is a member of pyrimidines, a benzoate ester and a N-sulfonylurea. It is functionally related to a sulfometuron.
Preparation
Sulfometuron-methyl is produced by reaction of 2-sulfonylisocyanate methylbenzoate with 2-amino-4,6-dimethylpyrimidine.
Agricultural Uses
Herbicide: Used to control annual and perennial grasses and broadleaf
weeds on landscapes, rights-of-ways, fence rows, forests,
industrial structure areas and non-crop land. Not listed for use
in EU countries. Registered for use in the U.S.
Trade name
DPX-T5648®; KNOCKOUT®;
LANDMARK® MP (sulfometuron-methyl + chlorsulfuron);
OUST®; OUSTAR®; RIVERDALE®; STAMPRO®
Mechanism of action
Broad-spectrum and inhibits cell division. Inhibits plant amino acid synthesis - acetohydroxyacid synthase AHAS
Environmental Fate
Soil. In unsterilized soils, 58% of 14C-labeled sulfometuron-methyl degraded after 24
weeks. Metabolites identified were 2,3-dihydro-3-oxobenzisosulfonazole (saccharin),
methyl-2-(aminosulfonyl)benzoate, 2-aminosulfonyl benzoic acid, 2-(((aminocarbonyl)amino)sulfonyl)benzoate and [14C]carbon dioxide. The rate of degradation in aerobic
soils was primarily dependent upon pH and soil type (Anderson and Dulka, 1985). The
reported half-life in soil was approximately 4 weeks (Hartley and Kidd, 1987).
Chemical/Physical. Sulfometuron-methyl is stable in water at pH values of 7 to 9 but
is rapidly hydrolyzed at pH 5.0 forming methyl 2-(aminosulfonyl)benzoate and saccharin.
When sulfometuron-methyl in an aqueous solution was exposed to UV light (λ = 300–400
nm), it degraded to the intermediate methyl benzoate which then mineralized to carbon
dioxide (Harvey et al., 1985). The hydrolysis half-lives of metsulfuron-methyl at pH 5
and 25 and 45°C were 33 and 2.1 days, respectively. At pH 7 and 45°C, the hydrolysis
half-life is 33 days (Beyer et al., 1988).
Metabolic pathway
Sulfometuron methyl is relatively stable at neutral and
basic pH and undergoes cleavage of the sulfonylurea
linkage to yield methyl-2-(aminosulfonyl)benzoate and
4,6-dimethyl-2-aminopyrimidine as major hydrolysis
products, and saccharin as the terminal product.
These products are also observed as major
degradation products in soils. In plants,
monohydroxymethylsulfometuron methyl is the primary
metabolite which is also identified as a mammalian
and soil metabolite and undergoes further degradation
by mammals to give 2-amino-4-hydroxymethyl-6-
methylpyrimidine.
