Common name:   Dimethenamid

Chemical Name:2-Chloro-N-((1-methyl-2-methoxy)-ethyl)-N-(2,4-dimethyl-thien-3-yl)acetamide

Formula: C₁₂H₁₈ClNO₂S

Molecular weight: 275.7927

CAS No.: 87674-68-8

Specification:

Physical & Chemical Properties

Form: Yellowish-brown viscous liquid.

B.p.: 127 °C/26.7 Pa

V.p.: 36.7 mPa (25 °C)

Henry: 8.32 ×10-3 Pa m3 mol-1S.g.

Density: 1.187 (25 °C)

Solubility: In water 1.2 g/l (pH 7, 25 °C). In heptane 282, iso-octane 220 (both in g/kg, 25°C). In ether, kerosene, ethanol all >50% (25°C).

Stability: Stable in storage at 54°C for 4 weeks, and at 70°C for 2 weeks. Estimated decomposition at 20°C within 2 years is <5%. Stable at pH 5-9 (buffered, 25°C) for 30 d.

F.p.: 91°C (Pensky Martens closed cup)

Toxicity

Oral: Acute oral LD₅₀ for rats 1570 mg/kg.

Skin and eye Acute percutaneous LD50: for rats and rabbits >2000 mg/kg.

Non-irritating to skin; mild eye irritant (rabbits). Sensitising to skin.

Inhalation: (4 h) for rats >4990 mg/m³ air.

Birds: Acute oral LD₅₀ for bobwhite quail 1908 mg/kg b.w. Dietary LC₅₀ for bobwhite quail and mallard ducks >5620 mg/kg b.w.

Fish: LC₅₀ (96 h) for bluegill sunfish 6.4, rainbow trout 2.6 mg/l. LC₅₀for sheepshead minnow 7.2 mg/l.

Bees: Contact LD₅₀ >1 mg/bee.

Daphnia: LC₅₀ 16 mg/l.Algae: LC₅₀ forScenedesmus subspicatus 0.062 mg/l.

Worms: LC₅₀ 459.8 mg/kg dry soil.Other aquatic spp.: LC₅₀ for mysid shrimp (Mysidopsis bahia) 4.8, eastern oyster (Crassostrea virginica) 5.0 mg/l.

Application

Biochemistry: Alkylation of sulfhydryl groups of certain enzymes is probably involved.

Mode of action: Herbicide which is absorbed by the coleoptile, whereas practically no activity occurs after application to seeds, roots, or developed leaves.

Uses: Control of annual grasses and many broad-leaved weeds pre-emergence in maize, soya beans, and other crops.