Napropamide 敌草胺, 萘丙酰草胺

敌草胺

敌草胺又名草胺、丙酰草胺。

药剂特性：
敌草胺为酰胺类除草剂。
纯品为白色结晶，易溶于乙醇,丙酮等有机溶剂，在碱性溶液中不稳定，在稀酸性溶液中稳定。
对人、畜、鱼低毒。
敌草胺为选择性芽前土壤处理剂，杂草根和芽鞘能吸收药液，抑制细胞分裂和蛋白质合成，使根生长受影响，心叶卷曲最后死亡。可杀死萌芽期杂草。
主要剂型：50%可湿性粉剂，20%乳油和50%水分散颗粒。

防除对象：
敌草胺可防除稗草、马唐、狗尾草、野燕麦、千金子、看麦娘、早熟禾、雀稗等一年生禾本科杂草，也能杀部分双子叶杂草，如藜、猪殃殃、繁缕、马齿苋等。

使用方法：50%敌草胺可湿性粉剂
1、辣椒、番茄、茄子等作物田，可在作物播后苗前或移栽后，灌水或降雨后，土壤潮湿的情况下施药，100～150克/667m2，兑水50kg喷雾。
2、油菜、白菜、芥菜、菜花、萝卜等十字花科作物直播或移植田，可在播后苗前或移植后，土壤湿润情况下施药，100～120克/667m2，兑水50kg喷雾，也可拌潮湿细土150kg，均匀撒施。
3、大豆、花生及其他豆科作物，在播后苗前，100～150克/667m2，兑水50kg喷雾。
4、烟草苗床，可于播前喷雾，100～150克/667m2，本田可于烟草移植后施药，120～200克/667m2，兑水50kg，喷雾，土壤干旱时，可浅湿土3～5cm。
5、果园、茶园、桑园，可在春秋季杂草萌发前，250～350克/667m2，兑水50kg定向喷雾。与其他除草剂混用，各自药量减半，可扩大杀草谱，提高除草效果。

注意事项：
（1）在土壤干燥的条件下用药，防除效果差，应在施药后进行混土或土壤干旱时进行灌溉。
（2）敌草胺对芹菜、茴香、胡萝卜等有药害，不宜使用。
（3） 敌草胺对已出土的杂草效果差，故应早施药。
（4）春夏季日照长，光解敌草胺多，用量应高于秋季。

napropamide
Herbicide
HRAC K3 WSSA 15; alkanamide (acetamide)

NOMENCLATURE
Common name napropamide (BSI, E-ISO, (m) F-ISO, WSSA, JMAF)
IUPAC name (RS)-N,N-diethyl-2-(1-naphthyloxy)propionamide
Chemical Abstracts name N,N-diethyl-2-(1-naphthalenyloxy)propanamide
CAS RN [15299-99-7] unstated stereochemistry; [41643-35-0] (R)-(-)- isomer; [41643-36-1] (S)-(+)- isomer Development codes R-7465 (Stauffer)

PHYSICAL CHEMISTRY
Composition Tech. grade is 92-96% pure. Mol. wt. 271.4 M.f. C17H21NO2 Form Colourless crystals; (tech., brown solid). M.p. 74.8-75.5 ºC; (tech., 68-70 ºC) V.p. 0.53 mPa (25 ºC) KOW logP = 3.3 (25 ºC) Henry 1.94 ´ 10-2 Pa m3 mol-1 (calc.) S.g./density Bulk density 0.584 g/ml Solubility In water 7.4 mg/l (25 ºC). In acetone, ethanol >1000, xylene 505, kerosene 62, hexane 15 (all in g/l, 20 ºC); miscible with acetone, ethanol, methyl isobutyl ketone. Stability No decomposition occurs over 16 h at 100 ºC. Decomposed by sunlight; DT50 25.7 min. Stable to hydrolysis between pH 4 and 10 at 40 ºC. F.p. >104 ºC

COMMERCIALISATION
History Herbicide reported by B. J. van den Brink et al. (Symp. New Herbic., 3rd, 1969, p. 35). Introduced by Stauffer Chemical Co. (now Syngenta AG). Divested to United Phosphorus Ltd. in 1997. Patents US 3480671; US 3718455 Manufacturers Gharda; United Phosphorus Ltd

APPLICATIONS
Biochemistry Cell division inhibitor. Mode of action Selective systemic herbicide, absorbed by the roots, with translocation acropetally. Inhibits root development and growth. Uses Pre-emergence control of annual grasses and broad-leaved weeds in asparagus, rhubarb, cucurbits, brassicas, oilseed rape, tomatoes, capsicums, potatoes, peas, nuts, fruit trees and bushes (including citrus), vines, strawberries, sunflowers, safflowers, ornamentals, tobacco, olives, figs, mint, turf, and other crops, at 2-6 kg/ha. The (R)-(-)- isomer is 8 times as toxic to 3 weed species as the (S)-(+)- isomer (J. H. Chan et al., J. Agric. Food Chem., 1975, 23,1008). Phytotoxicity Phytotoxic to wheat and barley. Formulation types EC; GR; SC; WP. Selected products: 'Devrinol' (Syngenta, United Phosphorus, Bayer CropScience); 'AC 650' (United Phosphorus Ltd); 'Naproguard' (Gharda)

OTHER PRODUCTS
'Kusaless' (Nihon Nohyaku)

ANALYSIS
Product analysis by glc. Residues in crops and soil determined by glc (G. G. Patchett et al., Anal. Methods Pestic. Plant Growth Regul., 1976, 8, 347). In drinking water, by glc with NPD (AOAC Methods, 17th Ed., 991.07). Details of analytical methods available from Syngenta.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD50 for male rats >5000 mg tech./kg, female rats 4680 mg/kg. Skin and eye Acute percutaneous LD50 for rabbits >4640, guinea pigs >2000 mg/kg. Moderate eye irritant; not a skin irritant (rabbits). Not a skin sensitiser (guinea pigs). Inhalation LC50 (4 h) for rats >5 mg/l. NOEL (2 y) for rats 30 mg/kg b.w. daily; (90 d) for dogs 40 mg/kg b.w. daily. Developmental toxicity NOEL for rats and rabbits 1000 mg/kg b.w. daily; multigeneration study (rats) 30 mg/kg b.w. daily. ADI 0.11 mg/kg. Other Negative genotoxicity. Not oncogenic. Toxicity class WHO (a.i.) U; EPA (formulation) III

ECOTOXICOLOGY
Birds In 7-d feeding trials, no-effect level for bobwhite quail >5620 mg/kg. Fish LC50 (96 h) for bluegill sunfish 13-15, rainbow trout 9.4, goldfish >10 mg/l. Daphnia EC50 (48 h) 24 mg/l. Algae EC50 (96 h) for Chlorella vulgaris 4.5 mg/l. Other aquatic spp. EbC50 (14 d) for Lemna minor 0.237 mg/l. Bees LD50 >100 mg/bee. Worms LC50 >799 mg/kg soil.

ENVIRONMENTAL FATE
Animals In mammals, following oral administration, napropamide is rapidly and extensively metabolised. The majority of the dose is excreted via urine and faeces. Similar effects have been observed in poultry. Plants Rapidly metabolised via ring hydroxylation and N-dealkylation, followed by conjugation with sugars to produce water-soluble metabolites. Soil/Environment Koc 600 (range 470-1200). In aerobic laboratory soil, degradation is slow, DT50 446 d (30 °C); however, in the field, typical DT50 is 25 d (range 9-131 d in N. America/Germany). Photodegradation is an important mechanism for loss from soil. Degradates identified in soil are 1-naphthoxypropionic acid, 2-(a-naphthoxy)-N-ethyl-N-hydroxyethylpropionamide, 2-(a-naphthoxy)-N-ethylpropionamide, 2-(a-naphthoxy)propionic acid, 2-hydroxy-1,4-naphthoquinone, 1,4-naphthoquinone and o-phthalic acid.