Tribenuron

Tribenuron in the form of tribenuron-methyl is a sulfonylurea herbicide.^[2] Its mode of action is the inhibition of acetolactate synthase, Group 2 / Group B of the Herbicide Resistance Action Committee's classification scheme.^[3][4]

Tribenuron methyl

Names
IUPAC name Methyl 2-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-methylcarbamoyl]sulfamoyl]benzoate
Other names DPX L5300
Identifiers
CAS Number	101200-48-0 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:9678
ChEMBL	ChEMBL1229780
ChemSpider	135649
DrugBank	DB03656
ECHA InfoCard	100.100.313
EC Number	401-190-1
KEGG	C10962
PubChem CID	153909
UNII	D0493A985P Y
CompTox Dashboard (EPA)	DTXSID8024101
InChI InChI=1S/C15H17N5O6S/c1-9-16-13(18-14(17-9)26-4)20(2)15(22)19-27(23,24)11-8-6-5-7-10(11)12(21)25-3/h5-8H,1-4H3,(H,19,22) Key: VLCQZHSMCYCDJL-UHFFFAOYSA-N
SMILES CC1=NC(=NC(=N1)OC)N(C)C(=O)NS(=O)(=O)C2=CC=CC=C2C(=O)OC
Properties[1]
Chemical formula	C15H17N5O6S
Molar mass	395.39 g·mol−1
Appearance	White to off-white solid
Density	1.46 g/cm3
Melting point	142
Solubility in water	2483 mg/L (20 °C)
log P	0.38
Acidity (pKa)	4.65
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H317, H373, H410
Precautionary statements	P260, P261, P272, P273, P280, P302+P352, P319, P321, P333+P317, P362+P364, P391, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemistry

In the 1970s, chemists at DuPont worked extensively on sulfonylurea herbicides, following the invention of this class of herbicides by George Levitt which had led to the commercialisation of chlorsulfuron.^[5] Tribenuron (the carboxylic acid) and its methyl ester^[6] were first disclosed in general terms in one of Levitt's patents^[7] and subsequently the ester was subject to further patenting^[8] and selected for development under the code name DPX L5300.^[1] In the final step of its synthesis, 2-methoxycarbonylbenzenesulfonyl isocyanate was condensed with 2-methylamino-4-methoxy-6-methyl-1,3,5-triazine to form the sulfonylurea product.^[8]

Mode of action

Tribenuron is an herbicide that acts as an acetolactate synthase inhibitor.^[2][3] For the purposes of herbicide resistance management, the Herbicide Resistance Action Committee has placed it in group 2 (legacy HRAC Group B).^[4]

Applications

US Geological Survey estimate of tribenuron methyl use in the USA to 2018

Tribenuron has a broad spectrum of activity on commercially important broadleaf weeds and grasses but at the recommended use rate it is safe to important crops such as wheat. When introduced by DuPont, its recommended application rate was 0.015–0.03 pounds per acre (17–34 g/ha).^[9] The estimated use in US agriculture is mapped by the US Geological Service and shows that from 1992 to 2018, up to 120,000 pounds (54,000 kg) were applied each year. The compound is used mainly in wheat but also in pasture.^[10]

Physicochemistry

In a clay-water suspension, tribenuron has increased sorption with decreasing pH and even more so with suspended load.^[11]

Resistant crops

A tribenuron-resistance transformation has been achieved in watermelon and validated by survival of the als mutants but not the controls, under tribenuron treatment.^[12]

Two oilseed type sunflower cultivars have been produced by USDA-ARS by conventional breeding.^[13]