Acetolactate synthase (ALS), also known as acetohydroxyacid synthase (AHAS). Chlorimuron-ethyl inhibits acetolactate synthase (ALS), a key enzyme in the biosynthesis of branched-chain amino acids (valine, leucine, and isoleucine) in plants. ALS is the first common enzyme in the branched-chain amino acid biosynthesis pathway and is essential for plant growth and development. By inhibiting ALS, chlorimuron-ethyl disrupts protein synthesis and cell division, leading to growth inhibition and ultimately plant death. The compound has high selectivity for plant ALS over mammalian enzymes, contributing to its safety profile in non-target organisms. Inhibition of ALS can also lead to oxidative stress and a decrease in root nodule formation.

Chlorimuron-ethyl is a potent herbicide with high effectiveness against a range of broadleaf weeds without causing significant harm to soybean plants. The compound induces oxidative stress in target plants. As a sulfonylurea herbicide, it exhibits extremely high herbicidal activity at low application rates (typically grams per hectare). The compound's selectivity is based on differential metabolism between crops and weeds, with soybean plants able to rapidly metabolize the herbicide to inactive compounds. In vitro studies have shown that chlorimuron-ethyl inhibits ALS activity with IC₅₀ values in the nanomolar range. The compound also affects nitrogen fixation in legumes by inhibiting root nodule formation.

Treatment with chlorimuron-ethyl (30 mg/kg) significantly damages CHL accumulation[1].

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In vivo studies in plants have demonstrated the herbicidal efficacy of chlorimuron-ethyl. Following foliar application, the compound is absorbed and translocated systemically within the plant, accumulating in meristematic tissues where it inhibits cell division. Treatment with chlorimuron-ethyl at 30 mg/kg significantly damages chlorophyll accumulation. In soil, the compound undergoes pH-dependent degradation with a half-life of approximately 14-22 days in acidic soils (pH<7.0). The compound is effective as a post-emergence herbicide for the selective control of pigweed, velvetleaf, and yellow nutsedge in legume crops.

Non-cell-based assays for chlorimuron-ethyl include ALS enzyme inhibition assays using purified ALS from plant sources. The enzyme is incubated with the substrate pyruvate and various concentrations of chlorimuron-ethyl, and the production of acetolactate is measured colorimetrically. The IC₅₀ value is calculated from the dose-response curve. For compound characterization, standard analytical methods including HPLC-UV, LC-MS/MS, and NMR are used to confirm identity and purity. Solubility studies are performed in various solvents including acetone (71,000 ppm), acetonitrile (31,000 ppm), methylene chloride (153,000 ppm), and water (1,200 ppm at pH 7).

Cell-based assays for chlorimuron-ethyl are typically performed using plant cell cultures or isolated plant protoplasts. Plant cells are treated with the compound at various concentrations, and cell viability, growth inhibition, and chlorophyll content are measured. ALS activity in treated cells is assessed by measuring branched-chain amino acid levels or by enzyme activity assays. Oxidative stress markers such as reactive oxygen species (ROS), malondialdehyde (MDA), and antioxidant enzyme activities are measured to assess the compound's mechanism of action. Cytotoxicity in non-target cells is assessed using standard cell viability assays.

In vivo animal studies for chlorimuron-ethyl are primarily toxicological in nature. The compound has been studied in animal models for its potential toxicity and environmental impact. In rats, treatment with chlorimuron-ethyl at 30 mg/kg significantly damages chlorophyll accumulation. For herbicidal efficacy, field studies are conducted in soybean and peanut crops to assess weed control, crop selectivity, and yield effects. Standard protocols involve application of the herbicide at various rates and growth stages, followed by assessment of weed control efficacy, crop injury, and yield parameters.

Absorption, Distribution and Excretion
The compound chlorimuron-ethyl is absorbed via the gastrointestinal tract and excreted in equal amounts via urine and feces, with a biological half-life of approximately 50 hours. Chlorimuron-ethyl is distributed throughout the body, primarily in the liver. Metabolism/Metabolites Chlorimuron-ethyl is extensively metabolized in both male and female rats at both low and high doses. Excretion monitoring lasted up to 168 hours, with equal amounts of radioactive material excreted via urine and feces at both low and high doses. The half-life is 50 hours. Five major metabolites were identified. (14)C-chlorimuron-ethyl is readily absorbed by the roots of young, intact maize seedlings and by cuts in detached leaves, but not readily by intact leaves. Under the conditions employed, the metabolic rate of (14)C-chlorimuron-ethyl in both intact roots and detached leaves was moderate (approximately 2.4 nmol/g fresh weight tissue/hour). Based on high performance liquid chromatography analysis, the metabolic pathways of (14)C-chlorimuron-methyl appear to be similar in roots and leaves. Seven hours after herbicide treatment, (14)C-chlorimuron-methyl and 10 radioactive metabolites were detected in maize roots. (14) C-chloropyrimidine ethyl ester and its following metabolites (roughly ordered by abundance): chloropyrimidine ethyl ester (N-(4-chloro-6-methoxypyrimidine-2-yl)-N'-(2-ethoxycarbonylbenzenesulfonyl)urea; N-(4-chloro-5-hydroxy-6-methoxypyrimidine-2-yl)-N'-(2-ethoxycarbonylbenzenesulfonyl)urea, 2-ethoxycarbonylbenzenesulfonamide, N-(4-(S-glutathioneyl)-6-methoxypyrimidine-2-yl)-N'-(2-ethoxycarbonylbenzenesulfonyl)urea, N-(4-(S-glutathioneyl)-5-hydroxy-6-methoxypyrimidine-2-yl)-N'-(2-ethoxycarbonylbenzenesulfonyl)urea, N-(4-chloro-5-(O-β-D-glucosyl)-6-methoxypyrimidin-2-yl)-N'-ethoxycarbonylbenzenesulfonyl)urea and N-(4-(S-cysteyl)-6-methoxypyrimidin-2-yl)-N'-(2-ethoxycarbonylbenzenesulfonyl)urea. Chlorimuron-ethyl ester and its metabolites were purified by high-performance liquid chromatography (HPLC) and characterized by rapid atomic impact mass spectrometry (FABMS). In addition to FABMS, some metabolites were characterized by the following methods: synthesis, β-glucosidase hydrolysis, hydrolysis product analysis, electron impact mass spectrometry (EIMMS), and proton nuclear magnetic resonance (400 MHz).

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Biological half-life
Approximately 50 hours

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Chlorimuron-ethyl has a molecular weight of 414.82 g/mol and a molecular formula of C₁₅H₁₅ClN₄O₆S. It has low solubility in water (1.2 mg/mL at pH 7) and is more soluble in organic solvents: acetone 71,000 ppm, acetonitrile 31,000 ppm, methylene chloride 153,000 ppm. The compound is a white powder with a pH of 3.0-5.0. It should be stored at 2-8°C. In soil, the compound undergoes pH-dependent hydrolysis with a half-life of approximately 14-22 days in acidic soils. The compound is for research and agricultural use.

Toxicity Data
LC50 (Rat) > 5,000 mg/m³/4h

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Non-human toxicity values
Rat inhalation LC50 >5 mg/L/4 hours
Rabbit dermal LD50 >2000 mg/kg
Rat oral LD50 >5000 mg/kg

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Chlorimuron-ethyl has low acute toxicity to mammals. The compound is a selective herbicide that targets plant ALS with high specificity, minimizing toxicity to non-target organisms. However, as a sulfonylurea herbicide, it may have effects on soil microorganisms and nitrogen-fixing bacteria. The compound should be handled with appropriate safety precautions, including the use of personal protective equipment. In rotational cropping systems, carryover injury may occur if the compound persists in soil. No significant carcinogenic or genotoxic effects have been reported for chlorimuron-ethyl at agricultural exposure levels.

[1]. Effects of Herbicide Chlorimuron-Ethyl on Physiological Mechanisms in Wheat (Triticum Aestivum). Ecotoxicol Environ Saf. 2006 Jun;64(2):190-7.

Chlorimuron-methyl ethyl ester is a colorless crystal used as a herbicide. Chlorimuron-methyl ethyl ester is an ethyl ester formed by the condensation of the carboxyl group of chlorimuron with ethanol. As a precursor herbicide of chlorimuron, it is used as a herbicide against broadleaf weeds in peanuts, soybeans, and other crops. It has multiple functions, including as a precursor herbicide, an EC 2.2.1.6 (acetolactate synthase) inhibitor, and an agrochemical. It is a sulfonylurea ester, N-sulfonylurea compound, aromatic ether, ethyl ester, organochlorine pesticide, and pyrimidine compound. Its function is similar to that of chlorimuron. It is the conjugate acid of chlorimuron-methyl ethyl ester (1-). Mechanism of Action: A sulfonylurea herbicide that inhibits acetolactate synthase, thereby regulating plant growth. A branched-chain amino acid synthesis (ASL or AHAS) inhibitor. It works by inhibiting the biosynthesis of the essential amino acids valine and isoleucine, thereby preventing cell division and plant growth. Crop selectivity stems from its effects on plant metabolism, including homoglutathione binding and deesterification. ...acetolactate synthase is a target enzyme of chlorimuron-methyl.

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Chlorimuron-ethyl is a widely used sulfonylurea herbicide developed by DuPont (DPX-F6025) for the selective post-emergence control of broadleaf weeds in soybeans, peanuts, and other leguminous crops. Its primary mode of action is the inhibition of acetolactate synthase (ALS), a key enzyme in branched-chain amino acid biosynthesis in plants. The compound exhibits predictable, pH-dependent degradation in soil, enabling manageable plant-back intervals. It is available as an analytical standard (≥98%) for research, quality control, and environmental monitoring applications. The compound is for research and agricultural use only.

C15H15CLN4O6S

414.82

414.04

90982-32-4

56160

Crystals from butyl chloride
White solid
Colorless crystals

1.493 g/cm3

181 °C

1.598

3.37

2

8

7

27

628

0

O=C(C1C(S(NC(NC2N=C(OC)C=C(Cl)N=2)=O)(=O)=O)=CC=CC=1)OCC

NSWAMPCUPHPTTC-UHFFFAOYSA-N

InChI=1S/C15H15ClN4O6S/c1-3-26-13(21)9-6-4-5-7-10(9)27(23,24)20-15(22)19-14-17-11(16)8-12(18-14)25-2/h4-8H,3H2,1-2H3,(H2,17,18,19,20,22)

ethyl 2-[(4-chloro-6-methoxypyrimidin-2-yl)carbamoylsulfamoyl]benzoate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: 250 mg/mL (602.67 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)