cyhalofop-butyl 氰氟草酯

氰氟草酯

英文通用名：cyhalofop-butyl
其他名称 千金、踏金、烁金、直播龙 XDE-537，DEH-112，Clincher
CA登记号：122008-85-9
化学名称：(R)-2-[4(4-氰基-2-氟苯氧基)苯氧基]-丙酸丁酯
经验式：C20H20FNO4
分子量：357.4

理化性能
原药为白色结晶固体，比重为1.2375(20℃)，沸点363℃，熔点48-49℃，蒸气压8.8×10(-9)mmHg(20℃)，溶于大多数有机溶剂中：乙腈57.3%，甲醇37.3%，丙酮60.7%，氯仿59.4%，不溶于水，制剂比重0.989(20℃)。

毒性
低毒除草剂。原药大鼠急性经口LD50>5000毫克/公斤，大鼠急性经皮LD50>2000毫克/公斤。对皮肤无刺激作用，对眼睛有轻微刺激。无致癌、致畸、致突变作用。
每日允许摄入量：0.003mg/kg/day
中国毒性：低毒

剂型
10%、15%或100g/L乳油。国外剂型为：10%氰氟草酯水乳剂、10%氰氟草酯微乳剂。

特点
属芳氧基苯氧基丙酸类除草剂。水稻田选择性除草剂，只能作茎叶处理，芽前处理无效，主要防除稗草，千金子等禾本科杂草。

作用机理
氰氟草酯是芳氧苯氧丙酸类除草剂中惟一对水稻具有高度安全性的品种，和该类其他品种一样，也是内吸传导性除草剂。由植物体的叶片和叶鞘吸收，韧皮部传导，积累于植物体的分生组织区，抵制乙酰辅酶A羧化酶（ACCase），使脂肪酸合成停止，细胞的生长分裂不能正常进行，膜系统等含脂结构破坏，最后导致植物死亡。从氰氟草酯被吸收到杂草死亡比较缓慢，一般需要1－3周。杂草在施药后的症状如下：四叶期的嫩芽萎缩，导致死亡。二叶期的老叶变化极小，保持绿色。

适宜作物与安全性
水稻（移栽和直播），对水稻等具有优良的选择性，选择性基于不同的代谢速度，在水稻体内，氰氟草酯可被迅速降解为对乙酰辅酶A羧化酶无活性的二酸态，因而对水稻具有高度的安全性。因其在土壤中和典型的稻田水中降解迅速，故对后茬作物安全。

防除对象
主要用于防除重要的禾本科杂草。氰氟草酯对千金子高效，对低龄稗草有一定的防效，还可防除、马唐、双穗雀稗、狗尾草、牛筋草、看麦娘等。对莎草科杂草和阔叶杂草无效。

注意事项
该药对水生节肢动物毒性大，避免流入水产养殖场所。其与部分阔叶除草剂混用时有可能会表现出拮抗作用，表现为氰氟草酯药效降低。

cyhalofop-butyl
Herbicide
HRAC A WSSA 1; aryloxyphenoxypropionate

NOMENCLATURE
Common name cyhalofop-butyl (pa ISO, ANSI)
IUPAC name butyl (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propionate
Chemical Abstracts name butyl (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoate
CAS RN [122008-85-9]; [122008-78-0] (for acid) Development codes DE-537; XDE-537; XRD-537; DEH112; EF 1218; NAF-541

PHYSICAL CHEMISTRY
Composition Purity 96.5% nominal. Material is the resolved (R)- isomer. Mol. wt. 357.4 M.f. C20H20FNO4 Form White crystalline solid. M.p. 49.5 °C B.p. decomp. >270 °C V.p. 5.3 ´ 10-2 mPa (25 ºC) KOW logP = 3.31 (25 °C) Henry 9.51 ´ 10-4 Pa m3 mol-1 (calc.) S.g./density 1.172 (20 °C) Solubility In water 0.44 (unbuffered), 0.46 (pH 5), 0.44 (pH 7.0) (all mg/l, 20 °C). In acetonitrile >250, n-heptane 6.06, n-octanol 16.0, dichloroethane >250, methanol >250, acetone >250, ethyl acetate >250 (all in g/l, 20 °C). Stability Stable at pH 4, hydrolysed slowly at pH 7. At pH 1.2 or pH 9, decomposition is rapid.

COMMERCIALISATION
History Discovered in the mid-1980s by The Dow Chemical Company (now Dow AgroSciences) and reported by P. G. Ray et al. (Proc. 10th Australian & 14th Asian-Pacific Weed Conference, Brisbane, Australia, September 1993, p. 41). Introduced in Asia in 1995; now marketed in rice-growing territories worldwide. Patents US 4894085 (1990); US 4897481 (1990); EP 302203 (1989) Manufacturers Dow AgroSciences

APPLICATIONS
Biochemistry Fatty acid synthesis inhibitor, by inhibition of acetyl CoA carboxylase (ACCase). Selectivity between susceptible grasses and dicotyledonous plants is attributed to the forms of ACCase present and their compartmentalisation within plant cells. Susceptible grasses contain the susceptible eukaryotic form of ACCase; dicotyledonous plants contain both susceptible eukaryotic and herbicide-resistant prokaryotic forms of ACCase, rendering them resistant to cyhalofop-butyl. Rice tolerance to cyhalofop-butyl is due to rapid metabolism to the herbicidally inactive diacid (t1/2 <10 hr), whereas susceptible grasses metabolise cyhalofop-butyl to the herbicidally active monoacid. Mode of action Post-emergence herbicide with foliar uptake only and no soil activity. A systemic herbicide that is readily absorbed by plant tissue, is moderately phloem-mobile and accumulates in meristematic regions. Grass weeds cease growth immediately after treatment, with yellow patches appearing within 2-3 days to one week, leading to necrosis and death of the whole plant within 2 to 3 weeks. Uses For post-emergence control of grass weeds in rice. Applied at 75-100 g/ha in tropical rice and 180-310 g/ha in temperate rice. For selectivity in Poaceae species, see M. Ito et al., J. Weed Sci. & Tech. 43(2) 122-128 (1998). Phytotoxicity Rice is completely tolerant to due to rapid metabolism to the inactive diacid. Formulation types EC; EW; GR. Compatibility Not compatible with most broadleaf and sedge herbicide products. Selected products: 'Cleaner' (Dow AgroSciences); 'Clincher' (Dow AgroSciences); mixtures: 'Clincher Bas' (+ bentazone-sodium) (Dow AgroSciences)

OTHER PRODUCTS
Mixtures: 'Agrostar' (+ pyrazosulfuron-ethyl+ butamifos) (Sumitomo); 'Bazooka 36' (+ thenylchlor+ azimsulfuron+ bensulfuron-methyl) (Nihon Nohyaku); 'Bazooka A' (+ azimsulfuron+ bensulfuron-methyl) (Nihon Nohyaku, Hokko, Tokuyama, DuPont); 'Bazooka' (+ thenylchlor+ bensulfuron-methyl) (Nihon Nohyaku, Hokko, Tokuyama, DuPont); 'Inegreen D' (+ daimuron+ mefenacet+ bensulfuron-methyl) (Nihon Bayer, Hokko); 'Inegreen' (+ mefenacet+ bensulfuron-methyl) (Nihon Bayer); 'Joystar' (+ daimuron+ bensulfuron-methyl+ cafenstrole) (Kumiai); 'Joyster' (+ daimuron+ bensulfuron-methyl+ cafenstrole) (Kumiai); 'Papika A I Kilo' (+ thenylchlor+ azimsulfuron+ bensulfuron-methyl) (Nihon Nohyaku, Hokko, Tokuyama, Dow AgroSciences, DuPont); 'Papika A' (+ thenylchlor+ azimsulfuron+ bensulfuron-methyl) (Tokuyama, Nihon Nohyaku, Hokko, DuPont, Dow AgroSciences); 'Papika' (+ thenylchlor+ bensulfuron-methyl) (Tokuyama, Nihon Nohyaku, Hokko, DuPont, Dow AgroSciences); 'Redstar' (+ daimuron+ halosulfuron-methyl+ cafenstrole) (Nissan); 'Revolver' (+ mefenacet+ pyrazosulfuron-ethyl) (Nissan); 'Sheriff' (+ dimethametryn+ imazosulfuron+ pretilachlor) (Otsuka, Sumitomo Chemical Takeda); 'Striker' (+ pyrazosulfuron-ethyl+ cafenstrole) (Nissan, Yashima) Discontinued products mixtures: 'Tabijin A' * (+ pretilachlor+ pyriminobac-methyl+ azimsulfuron+ bensulfuron-methyl) (Kumiai)

MAMMALIAN TOXICOLOGY
Oral Acute oral LD50 for male and female rats, and for male and female mice >5000 mg/kg. Skin and eye Acute percutaneous LD50 for male and female rats >2000 mg/kg. Inhalation LC50 for rats >5.63 mg/l. NOEL For male rats 0.8 mg/kg b.w. daily, female rats 2.5 mg/kg b.w. daily. Other Non-mutagenic in Ames, DNA repair and micronucleus tests. Not teratogenic. In in vivo cytogenetic studies, no induction of structural chromosomal aberration observed. Rat and rabbit studies indicate cyhalofop-butyl is not teratogenic. Toxicity class WHO (a.i.) U; EPA (formulation) II (EC)

ECOTOXICOLOGY
The high toxicity of cyhalofop-butyl to fish and other aquatics is mitigated by the rapid degradation to less-toxic metabolites. Birds Acute oral LD50 for bobwhite quail and mallard ducks >5620 mg/kg. Dietary LC50 for bobwhite quail and mallard ducks >2250 ppm. Fish LC50 for rainbow trout >0.49, bluegill sunfish 0.76 mg/l. These values are at or above the aqueous solubility of cyhalofop-butyl. Daphnia LC50 >100 mg/l. Algae EC50 for Selenastrum capricornutum >1, Navicula sp. 0.64-1.33 mg/l. Soil and plant transformation products are less toxic to Selenastrum capricornutum. Other aquatic spp. EC50 for eastern oyster (Crassostrea virginica) 0.52, scud (Gammarus sp.) 0.81 mg/l. These values are at or above the aqueous solubility of cyhalofop-butyl. Bees NOEC for honeybees >100 mg/bee. Worms LD50 (14 d) for earthworms >1000 mg/kg.

ENVIRONMENTAL FATE
Animals Rats, dogs, ruminants and poultry readily metabolise cyhalofop-butyl by hydrolysis to the acid. Depending on the animal, the acid may also break down to other metabolites. The acid and any additional degradates are then rapidly excreted. Residue levels of cyhalofop-butyl and its metabolites are low in milk, eggs and tissues. Plants Rice tolerance is due to rapid metabolism to the inactive diacid (DT50 <10 h) and to subsequent formation of polar and non-polar metabolites. Susceptible grass sensitivity is due to rapid metabolism of cyhalofop-butyl to the herbicidally active monoacid. Soil/Environment Laboratory metabolism and field dissipation studies show that cyhalofop-butyl is rapidly metabolised in soil and sediment/water systems to cyhalofop acid; in the field, cyhalofop-butyl DT50 2-10 h in soil, <2 h in sediment/water. In turn, cyhalofop acid has DT50 <1 d in soil, c. 7 d in sediment/water. Cyhalofop-butyl is relatively immobile in soil adsorption studies.