methyl benzimidazol-2-ylcarbamate

methyl 1H-benzimidazol-2-ylcarbamate 

Crystalline powder.

302-307ºC (decomp.)

0.09 mPa (20ºC); 0.15 mPa (25ºC); 1.3 mPa (50ºC); separate study gives <0.0001 mPa (20ºC)

1.45 (20ºC)

In water 29 mg/l (pH 4), 8 mg/l (pH 7), 7 mg/l (pH 8) (24ºC). In dimethylformamide 5, acetone 0.3, ethanol 0.3, chloroform 0.1, ethyl acetate 0.135, dichloromethane 0.068, benzene 0.036, cyclohexane <0.01, diethyl ether <0.01, hexane 0.0005 (all in g/l, 24ºC).

Decomposes at m.p.; stable for at least 2 y below 50ºC. Stable after 7 d at 20 000 lux. Slowly decomposed in alkaline solution (22ºC); DT₅₀ >350 d (pH 5 and pH 7), 124 d (pH 9). Stable in acids, forming water-soluble salts.

3.6×10^-3 Pa m³ mol^-1 (calc.)

4.2, weak base

Inhibits beta-tubulin synthesis.

Systemic fungicide with protective and curative action. Absorbed through the roots and green tissues, with translocation acropetally. Acts by inhibiting development of the germ tubes, the formation of appressoria, and the growth of mycelia.

Control of Septoria, Fusarium, Erysiphe and Pseudocercosporella in cereals; Sclerotinia, Alternaria and Cylindrosporium in oilseed rape; Cercospora and Erysiphe in sugar beet; Uncinula and Botrytis in grapes; Cladosporium and Botrytis in tomatoes; Venturia and Podosphaera in pome fruit and Monilia and Sclerotinia in stone fruit. Application rates vary from 120-600 g/ha, depending on crop. A seed treatment (0.6-0.8 g/kg) will control Tilletia, Ustilago, Fusarium and Septoria in cereals, and Rhizoctonia in cotton. Also shows activity against storage diseases of fruit as a dip (0.3-0.5 g/l).

Incompatible with alkaline materials. 

74, 76

Acute oral LD₅₀ for rats 6400, dogs >2500 mg/kg.

LD₅₀ for rabbits >10 000, rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs).

LC₅₀ (4 h) for rats, rabbits, guinea pigs or cats, no effect with suspension (10 g/l water).

(2 y) for dogs 300 mg/kg diet, corresponding to 6-7 mg/kg b.w.

(JMPR) 0.03 mg/kg b.w. [1995].

WHO (a.i.) U

R68

Acute oral LD₅₀ for quail 5826-15 595 mg/kg.

LC₅₀ (96 h) for carp 0.61, rainbow trout 0.83, bluegill sunfish >17.25, guppy >8 mg/l.

LC₅₀ (48 h) 0.13-0.22 mg/l.

EC₅₀ (72 h) for Scenedesmus subspicatus 419, Selenastrum capricornutum 1.3 mg/l.

LC₅₀ (4 w) for Eisenia foetida 6 mg/kg soil.

Readily absorbed by plants. One degradation product is 2-aminobenzimidazole.

In male rats, following a single oral administration of 3 mg/kg, 66% was eliminated in the urine within 6 hours.

2-Aminobenzimidazole has been found as a minor metabolite. DT50 in soil 8-32 d under outdoor conditions. Carbendazim decomposes in the environment, DT50 6-12 mo on bare soil, 3-6 mo on turf, and 2-25 mo in water under aerobic and anaerobic conditions, respectively. It is mainly decomposed by micro-organisms. Koc 200-250. 

Product analysis by u.v. spectrophotometry or hplc (CIPAC Handbook, 1998, H, 61).