Insecticide

organophosphorus

NOMENCLATURE

Common name phoxim (BSI, E-ISO, ESA); phoxime ((f) F-ISO)

IUPAC name O,O-diethyl a-cyanobenzylideneamino-oxyphosphonothioate; 2-(diethoxyphosphinothioyloxyimino)-2-phenylacetonitrile 

Chemical Abstracts name a-[[(diethoxyphosphinothioyl)oxy]imino]benzene-acetonitrile 

CAS RN [14816-18-3]  EEC no. 238-887-3  Development codes BAY 5621; Bayer 77 488; BAY SRA 7502 (all Bayer)  Official codes OMS 1170 

PHYSICAL CHEMISTRY

Mol. wt. 298.3  M.f. C12H15N2O3PS  Form Yellow liquid; (tech., reddish-brown oil).  M.p. 6.1 ºC  B.p. Decomposes on distillation  V.p. 2.1 mPa (20 ºC)  KOW logP = 3.38  Henry 4.18 ´ 10-1 Pa m3 mol-1 (calc.)  S.g./density 1.178 (20 ºC)  Solubility In water 1.5 mg/l (20 ºC). In toluene, n-hexane, dichloromethane, isopropanol >200 g/l. Slightly soluble in aliphatic hydrocarbons, vegetable and mineral oils.  Stability Relatively slowly hydrolysed; DT50 (est.) 26.7 d (pH 4), 7.2 d (pH 7), 3.1 d (pH 9) (22 ºC). Gradually decomposed under u.v. irradiation. 

COMMERCIALISATION

History Insecticide reported by A. Wybou & I. Hammann (Meded. Rijksfac. Landbouwwet. Gent, 1968, 33, 817). Introduced by Bayer AG.  Patents BE 678139; DE 1238902  Manufacturers Bayer

APPLICATIONS

Biochemistry Cholinesterase inhibitor.  Mode of action Non-systemic insecticide with contact and stomach action. Short duration of activity.  Uses Control of stored-product insects in granaries, mills, silos, ships, etc.; ants and other insects in households and in public health; caterpillars (mainly Spodoptera spp.) and soil insects in maize, vegetables, potatoes, beet and cereals, at 5 kg/ha; also migratory locusts.  Phytotoxicity May exhibit some phytotoxicity to cotton.  Formulation types DP; EC; GR; KN; UL; WP; Seed treatment.  Compatibility Incompatible with alkaline materials.  Selected tradenames: 'Baythion' (public health) (Bayer); 'Volaton' (agricultural use) (Bayer)

OTHER TRADENAMES

'Valexon' (Bayer); 'Volathion' (Bayer) mixtures: 'Mieling' (+ deltamethrin) (Zhong-Xi); 'Pre Ling' (+ fenvalerate) (Zhong-Xi); 'Yuzhouxing' (+ ZXI 8901) (Zhong-Xi)

ANALYSIS

Product analysis by hplc (CIPAC Handbook, 1985, 1C, 2187); details available from Bayer AG. Residues determined by glc (Man. Pestic. Residue Anal., 1987, I, 6, S19; Anal. Methods Residues Pestic., 1988, Part I, M2, M12; A. Ambrus et. al., J. Assoc. Off. Anal. Chem., 1981, 64, 733). Methods for the determination of residues are available from Bayer. 

MAMMALIAN TOXICOLOGY

Reviews JECFA 52 (see part 2 of the Bibliography).  Oral Acute oral LD50 for rats >2000 mg/kg.  Skin and eye Acute percutaneous LD50 for rats >5000 ml/kg. Not irritating to eyes or skin (rabbits).  Inhalation LC50 (4 h) for rats >4.0 mg/l air (aerosol).  NOEL (2 y) for rats 15, mice 1 mg/kg diet; (1 y) for male dogs 0.3, female dogs 0.1 mg/kg diet.  ADI (JMPR) 0.004 mg/kg b.w. [1999].  Toxicity class WHO (a.i.) II; EPA (formulation) III  EC hazard Xn; R22 

ECOTOXICOLOGY

Birds LD50 for hens 40 mg/kg.  Fish LC50 (96 h) for rainbow trout 0.53, bluegill sunfish 0.22 mg/l.  Daphnia LC50 (48 h) 0.00081 mg/l (80% premix).  Bees Toxic to bees by contact and respiratory action. 

ENVIRONMENTAL FATE