5,6-dihydro-2-methyl-1,4-oxathi-ine-3-carboxanilide

5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide

C₁₂H₁₃NO₂S

White crystals; (tech. is a pale yellow powder with a slight sulfurous odour)

91-92^oC (pure a.i.)

0.020 mPa (25^oC)

1.45

In water 0.147 g/l (20^oC). In acetone 221.2, methanol 89.33, ethyl acetate 107.7 (g/l, 20 ^oC).

Stable to hydrolysis at pH 5, pH 7 and pH 9 (25^oC). In aqueous solutions exposed to light, DT₅₀ 1.54 h (pH 7, 25^oC).

3.24×10_-5 Pa m3 mol^-1 (calc.)

2.3

<0.5 

Inhibits mitochondrial function by disrupting complex II (succinate dehydrogenase) in the respiratory electron transport chain.

Systemic fungicide.

Seed treatment for control of smuts and bunts (particularly loose smut, Ustilago spp.), at 50-200 g/100 kg seed, on barley, wheat, and oats; seedling diseases (particularly Rhizoctonia spp.) of barley, wheat, oats, rice, cotton, peanuts, soya beans, vegetables, maize, sorghum, and other crops. The dimorphic forms do not differ in fungicidal activity.

Not compatible with pesticides which are highly alkaline or acidic.

Acute oral LD₅₀ for rats 2864 mg/kg.

Acute percutaneous LD₅₀ for rabbits >4000 mg/kg. Non-irritating to eyes and skin (rabbits). 

LC₅₀ (4 h) for rats >4.7 mg/l air. 

NOEL for chronic toxicity (2 y) for rats 1 mg/kg b.w. daily.

0.01 mg/kg.

WHO (a.i.) U; EPA (formulation) III

Acute oral LD₅₀ for bobwhite quail 3302 mg/kg. Dietary LC₅₀ (8 d) for mallard ducks and bobwhite quail >5000 ppm. 

LC₅₀ (96 h) for rainbow trout 2.3, bluegill sunfish 3.6 mg/l.

EC₅₀ (48 h) >57 mg/l.

EC₅₀ (5 d) for Pseudokirchneriella subcapitata 0.48 mg/l.

LC₅₀ (14 d) for earthworms 500-1000 ppm.

Undergoes oxidation to carboxin sulfoxide and carboxin sulfone.

Extensively metabolised in rats and eliminated mainly in urine and to a lesser extent faeces. Major metabolites in urine are p-hydroxylated carboxin sulfoxide, 4-acetamidophenol and its O-glucuronide.

Soil DT₅₀ <1 d (20^oC). K_oc 71. 

Product analysis by hplc or gc;