Thiophanate-methyl

Mol. wt. 342.4 M.f. C₁₂H₁₄N₄O₄S₂ Form Colourless crystals. M.p. 172 ºC (decomp.) V.p. 0.0095 mPa (25 ºC) K_OW 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

APPLICATIONS Thiophanate-methyl

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: eye spot and other diseases of cereals; scab on apples and pears; Monilia disease and Gloeosporium 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; Pyricularia oryzae 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. Selected tradenames: 'Topsin M' (Nippon Soda, Cerexagri); 'Aimthyl' (Aimco); 'Alert' (Nagarjuna Agrichem); 'Cekufanato' (Cequisa); 'Cycosin' (BASF); 'Do' (Sanonda); 'Hilnate' (Hindustan); 'Mildothane' (Aventis); 'Roko' (Biostadt); mixtures: 'Toram' (+ thiram) (Efthymiadis)

MAMMALIAN TOXICOLOGY Thiophanate-methyl

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. [1998]. Toxicity class WHO (a.i.) III (Table 5); EPA (formulation) IV EC hazard R40| N; R50, R53

ECOTOXICOLOGY Thiophanate-methyl

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.

ENVIRONMENTAL FATE Thiophanate-methyl

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 K_d 1.2.

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