Fungicide, wound protectant
Common name thiophanate-methyl (BSI, E-ISO, (m) F-ISO, ANSI, JMAF)
IUPAC name dimethyl 4,4'-(o-phenylene)bis(3-thioallophanate)
Chemical Abstracts name dimethyl [1,2-phenylenebis(iminocarbonothioyl)]bis[carbamate]
CAS RN [23564-05-8] EEC no. 245-740-7
Mol. wt. 342.4 M.f. C12H14N4O4S2 Form Colourless crystals. M.p. 172 ºC (decomp.) V.p. 0.0095 mPa (25 ºC) KOW logP = 1.50 Solubility Practically insoluble in water (23 ºC). In acetone 58.1,
cyclohexanone 43, methanol 29.2, chloroform 26.2, acetonitrile
24.4, ethyl acetate 11.9 (all in g/kg, 23 ºC). Slightly soluble in
hexane. Stability Stable in neutral, aqueous solution at room temperature. Stable to
air and sunlight. Quite stable in acidic solution at room
temperature; unstable in alkaline solution; DT50 24.5 h (pH 9, 22
ºC). Formulated product is stable ³2 y below 50 ºC. pKa 7.28
Biochemistry Carbendazim precursor. Mode of action Systemic fungicide with protective and curative action. Absorbed
by the leaves and roots. Uses A fungicide used at 30-50 g/ha and effective against a wide range
of fungal pathogens including: eyespot and other diseases of
cereals; scab on apples and pears; Monilia disease and bitter rot on apples; Monilia spp. on stone fruit; canker on fruit trees; powdery mildews on
pome fruit, stone fruit, vegetables, cucurbits, strawberries,
vines, roses, etc.; Botrytis and Sclerotinia spp. on various crops; leaf spot diseases on beet, oilseed rape,
celery, celeriac, etc.; club root on brassicas; dollar spot, Corticium, and Fusarium spp. on turf; grey mould in vines; blast in rice; sigatoka disease
in bananas; and many diseases in floriculture. Also used on
almonds, pecans, tea, coffee, peanuts, soya beans, tobacco,
chestnuts, sugar cane, citrus fruit, figs, hops, mulberries, and
many other crops. Used additionally as a wound protectant for
pruning cuts on trees. Formulation types DP; PA; SC; WP. Compatibility Incompatible with alkaline and copper-containing compounds.
Product analysis by rplc (CIPAC Handbook, 1988, D, 162). Residues determined by colorimetry (Pestic. Anal. Man., 1979, II; V. L. Miller et al., J. Assoc. Off. Anal. Chem., 1977, 60, 1154), by glc (A. Ambrus et al., ibid., 1981, 64, 733), or by hplc (S. Ono, Nihon Noyaku Gakkaishi, 1982, 7, 363; N. Shiga et al., ibid., 1977, 2, 27; Anal. Methods Residues Pestic., 1988, Part I, M3).
Reviews FAO/WHO 83, 85 (see part 2 of the Bibliography). Oral Acute oral LD50 for male rats 7500, female rats 6640, male mice
3510, male rabbits 2270 mg/kg. Skin and eye Acute percutaneous LD50 for male and female rats >10 000 mg/kg.
Mild skin and eye irritant. Inhalation LC50 (4 h) for rats 1.7 mg/l air. NOEL (2 y) for rats and mice 160 mg/kg diet, for dogs 50 mg/kg diet. ADI (JMPR) 0.08 mg/kg b.w. . Toxicity class WHO (a.i.) U; EPA (formulation) IV EC classification R68| Xn; R20| R43| N; R50, R53
Birds Acute oral and percutaneous LD50 for Japanese quail >5000
mg/kg. Fish LC50 (48 h) for rainbow trout 7.8, carp 11 mg/l. Daphnia LC50 (48 h) 20.2 mg/l. Algae EC50 (96 h) for Chlorella 0.8 mg/l. Bees Not toxic to bees; LD50 (topical) >100 mg/bee.
Animals In rats, following oral administration, 61% is excreted in the
urine and 35% in the faeces within 90 minutes after the last dose.
Metabolism involves cyclisation to carbendazim (q.v.). The principal metabolite in rats is methyl
5-hydroxybenzimidazol-2-carbamate. Plants In plants, cyclisation occurs, leading to the formation of
carbendazim (q.v.). Soil/Environment Soil persistence is c. 3-4 weeks. In soil, in aqueous solution, and under the influence
of u.v. light, cyclisation occurs, leading to the formation of
carbendazim (q.v.). This then undergoes degradation to 2-aminobenzimidazole and
5-hydroxy-2-aminobenzimidazole. Soil adsorption Kd 1.2.