Methidathion 杀扑磷

杀扑磷

简介
中文通用名: 杀扑磷
英文通用名: Methidathion
化学名称: S-2,3-二氢-5-甲氧基-2-氧代-1,3,4-噻二唑-3-基甲基0,0-二甲基二硫代磷酸酯。

理化性质: 无色晶体，熔点39－40℃，蒸气压2.5×10^(－4)Pa(20℃)，密度1.51(20℃)， KowlogP=2.2，溶解度水200mg/L(25℃)，乙醇150，丙酮670，甲苯720，己烷 11，正辛醇14(g/L，20℃)，强酸和碱中水解， 中性和微酸环境中稳定。
分析方法：气谱法(Ciba-Geigy)

作用特点：是一种广谱的有机磷杀虫剂，具有触杀、胃毒和渗透作用，能渗入植物组织 内，对咀嚼式和刺吸式口器害虫均有杀灭效力，尤其对介壳虫有特效，对螨 类有一定的控制作用。适用于果树、棉花、茶树、蔬菜等作物上防治多种害 虫，残效期10－20天。

中毒症状：急性中毒多在12小时内发病，口服立即发病。轻度：头痛、头昏、恶心、呕 吐、多汗、无力、胸闷、视力模糊、胃口不佳等，全血胆碱酯酶活力一般降 至正常值的70－50%；中度：除上述症状外还出现轻度呼吸困难、肌肉震颤 、 瞳孔缩小、精神恍惚、行走不稳、大汗、流涎、腹疼、腹泻。重者还会出 现昏迷、抽搐、呼吸困难、口吐白沫、大小便失禁，惊厥，呼吸麻痹。

急救治疗：急性中毒多在12小时内发病，口服立即发病。轻度：头痛、头昏、恶心、呕 吐、多汗、无力、胸闷、视力模糊、胃口不佳等，全血胆碱酯酶活力一般降 至正常值的70－50%；中度：除上述症状外还出现轻度呼吸困难、肌肉震颤 、 瞳孔缩小、精神恍惚、行走不稳、大汗、流涎、腹疼、腹泻。重者还会出 现昏迷、抽搐、呼吸困难、口吐白沫、大小便失禁，惊厥，呼吸麻痹。

注意事项：急性中毒多在12小时内发病，口服立即发病。轻度：头痛、头昏、恶心、呕 吐、多汗、无力、胸闷、视力模糊、胃口不佳等，全血胆碱酯酶活力一般降 至正常值的70－50%；中度：除上述症状外还出现轻度呼吸困难、肌肉震颤 、 瞳孔缩小、精神恍惚、行走不稳、大汗、流涎、腹疼、腹泻。重者还会出 现昏迷、抽搐、呼吸困难、口吐白沫、大小便失禁，惊厥，呼吸麻痹。

毒性：高毒 半衰期：土中移动小，半衰期3-18天(实验室和田间结果)

methidathion
Insecticide, acaricide
IRAC 1B; organophosphate

NOMENCLATURE
Common name methidathion (BSI, E-ISO, F-ISO, ANSI, ESA); DMTP (JMAF)
IUPAC name S-2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl O,O-dimethyl phosphorodithioate; 3-dimethoxyphosphinothioylthiomethyl-5-methoxy-1,3,4-thiadiazol-2(3H)-one
Chemical Abstracts name S-[(5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)methyl] O,O-dimethyl phosphorodithioate
CAS RN [950-37-8] EEC no. 213-449-4 Development codes GS 13 005 (Geigy) Official codes OMS 844; ENT 27 193

PHYSICAL CHEMISTRY
Mol. wt. 302.3 M.f. C6H11N2O4PS3 Form Colourless crystals. M.p. 39-40 ºC V.p. 2.5 ´ 10-1 mPa (20 ºC) KOW logP = 2.2 (OECD 107) Henry 3.3 ´ 10-4 Pa m3 mol-1 (calc.) S.g./density 1.51 (20 ºC) (OECD 109) Solubility In water 200 mg/l (25 ºC). In ethanol 150, acetone 670, toluene 720, hexane 11, n-octanol 14 (all in g/l, 20 ºC). Stability Rapidly hydrolysed in alkaline and strongly acidic media; DT50 (25 ºC) 30 min at pH 13. Relatively stable to hydrolysis in neutral and slightly acidic media.

COMMERCIALISATION
History Insecticide reported by H. Grob et al. (Proc. Br. Insectic. Fungic. Conf., 3rd, 1965, p. 451). Introduced by J. R. Geigy S.A. (now Syngenta AG). Patents BE 623246; GB 1008451 Manufacturers Makhteshim-Agan; Sannong; Sharda; Sundat; Syngenta

APPLICATIONS
Biochemistry Cholinesterase inhibitor. Mode of action Non-systemic insecticide and acaricide with contact and stomach action. Uses Control of a wide range of sucking and chewing insects (especially scale insects) and spider mites in many crops, e.g. pome fruit, stone fruit, citrus fruit, vines, olives, hops, cotton, potatoes, beet, alfalfa, oilseed rape, maize, sunflowers, safflowers, tobacco, hazels, and some vegetables, at 30-60 g/hl (0.3-1.8 kg/ha). Formulation types EC; UL; WP. Compatibility Mixing with alkaline materials may reduce effectiveness. Selected products: 'Supracide' (Syngenta, Gowan); 'Ultracide' (Syngenta); 'Suprathion' (Makhteshim-Agan); 'Ultracidin' (Vapco)

OTHER PRODUCTS
'Oleo Supracide' (Syngenta); 'Oleo Ultracide' (Syngenta); 'Ultracid' (Syngenta); 'Advathion' (Chemvet); 'Mediatex' (Aragro); 'Siacide' (Siapa) mixtures: 'Maktion' (+ dimethoate) (Makhteshim-Agan)

ANALYSIS
Product analysis by glc. Residues determined by glc (A. Ambrus et al., J. Assoc. Off. Anal. Chem., 1981, 64, 773; Man. Pestic. Residue Anal., 1987, I, 6, S8, S13, S19; Anal. Methods Residues Pestic., 1988, Part I, M2, M5, M12; D. O. Eberle & R. Suter, Anal. Methods Pestic. Plant Growth Regul., 1976, 8, 141).

MAMMALIAN TOXICOLOGY
Reviews FAO/WHO 80, 82 (see part 2 of the Bibliography). Oral Acute oral LD50 for rats 25-54, mice 25-70, rabbits 63-80, guinea pigs 25 mg/kg. Skin and eye Acute percutaneous LD50 for rabbits 200, rats 297-1663 mg/kg. Non-irritating to eyes and skin (rabbits). Not a skin sensitiser (Buehler test). Inhalation LC50 (4 h) for rats 140 mg/m3 air. NOEL Human volunteers tolerated daily oral doses of up to 0.11 mg/kg for at least 42 d without reaction. In 2 y feeding trials, NOEL for rats 4 mg/kg diet (0.2 mg/kg daily), for dogs 0.25 mg/kg daily. ADI 0.001 mg/kg b.w. [1997]. Toxicity class WHO (a.i.) Ib; EPA (formulation) I EC classification T+; R28| Xn; R21| N; R50, R53

ECOTOXICOLOGY
Birds Acute oral LD50 for mallard ducks 23.6-28 mg/kg. LC50 (8 d) for bobwhite quail 224 ppm. Fish LC50 (96 h) for rainbow trout 0.01, bluegill sunfish 0.002 mg/l. Algae EC50 (72 h) for Scenedesmus subspicatus 22 mg/l. Bees Slightly toxic to bees. Worms LC50 (14 d) for earthworms 5.6 mg/kg soil. Other beneficial spp. To be rated as detrimental to most beneficial arthropods in the short term. It has a limited surface residual effect which allows a re-immigration of beneficials from untreated parts.

ENVIRONMENTAL FATE
EHC 63 (WHO, 1986; a general review of organophosphorus insecticides). Animals In mammals, methidathion is rapidly metabolised and excreted. Plants In plants, rapid metabolism occurs. The overall metabolic pattern indicates hydrolysis of the ester bond, cleavage of the heterocyclic moieties into fragments which are further oxidised to CO2. Soil/Environment Methidathion and its metabolites have a low mobility in soils. The compound is rapidly degraded in soil and water by chemical, photolytic and biological processes. DT50 3-18 d (laboratory and field results).