Herbicide

HRAC  C1; 1,3,5-triazine

NOMENCLATURE

Common name simetryn (BSI (since 1984), E-ISO, WSSA); simetryne ((f) F-ISO, Canada, JMAF, BSI (before 1984))

IUPAC name N2,N4-diethyl-6-methylthio-1,3,5-triazine-2,4-diamine; 2,4-bis(ethylamino)-6-methylthio-1,3,5-triazine 

Chemical Abstracts name N,N'-diethyl-6-(methylthio)-1,3,5-triazine-2,4-diamine 

CAS RN [1014-70-6]  EEC no. 213-801-7  Development codes G 32 911 (Geigy) 

PHYSICAL CHEMISTRY

Mol. wt. 213.3  M.f. C8H15N5S  Form Whitish crystals.  M.p. 82-83 ºC  V.p. 9.5 ´ 10-2 mPa (20 °C)  KOW logP = 2.6 (calc., unionised)  Henry 5.07 ´ 10-5 Pa m3 mol-1 (calc.)  S.g./density 1.02  Solubility In water 400 mg/l (20 °C). In methanol 380, acetone 400, toluene 300, n-hexane 4, n-octanol 160 (all in g/l, 20 °C).  pKa 4.0, weak base 

COMMERCIALISATION

History Herbicide reported by J. R. Geigy S.A. (became Novartis Crop Protection AG, who ceased to manufacture or market it). Introduced in Japan by Nihon Nohyaku Co., Ltd, Nippon Kayaku Co., Ltd (and formerly Sankyo Co., Ltd and Hokko Chemical Industry Co., Ltd).  Patents CH 337019 to Ciba-Geigy  Manufacturers Nippon Kayaku

APPLICATIONS

Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site.  Mode of action Selective herbicide.  Uses Used in combination with thiobencarb to control broad-leaved weeds in rice.  Formulation types GR.  Selected tradenames: 'Gy-bon' (Nihon Nohyaku)

OTHER TRADENAMES

Mixtures: 'Mamet SM' (+ MCPB+ molinate) (Yashima); 'Zerbex SM' (+ MCPB) (Aventis)

ANALYSIS

Product analysis by titration or by glc (CIPAC Handbook, 1983, 1B, 1984). In drinking water, by gc with FID (AOAC Methods, 1995, 991.07). 

MAMMALIAN TOXICOLOGY

Oral Acute oral LD50 for rats 750-1195 mg/kg.  Skin and eye Acute percutaneous LD50 for rats >3200 mg/kg. Not a skin or eye irritant (rabbits).  NOEL (2 y) for rats 1.2 mg/kg daily (2.5 mg/kg b.w.), mice 56 mg/kg daily, dogs 10.5 mg/kg daily.  ADI (Japan) 0.025 mg/kg b.w. (provisional value).  Toxicity class WHO (a.i.) III; EPA (formulation) III  EC hazard Xn; R22| N; R50, R53 

ECOTOXICOLOGY

Fish LC50 (96 h) for trout 7, guppy 5.2 ppm.  Algae Toxic.  Bees Non-toxic. 

ENVIRONMENTAL FATE