DIAZINON
IDENTIFICATION
Common name: Diazinon
Other name: diazinon (BSI, E-ISO, (m) F-ISO, ANSI, ESA, BAN, JMAF); dimpylate (INN)
Iupac name: O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate
Chemical abstracts name: O,O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate
Type: Insecticide for Agriculture
CAS RN: [333-41-5]
M.F.: C12H21N2O3PS
Mol Wt: 304.3
PHYSICAL CHEMISTRY
Form (appearance): Clear colourless liquid; (tech., yellow liquid)
Composition: Tech. is ≥ 95% pure.
B.P.: 83-84℃/0.0002 mmHg; 125℃/1 mmHg
V.P.: 1.2× 101 mPa (25℃) (OECD 104)
F.P.: ≥ 62℃
S.G.:1.11 (20℃)
Solubility.: In water 60 mg/l (20℃). Completely miscible with common organic solvents, e.g. ethers, alcohols, benzene, toluene, hexane, cyclohexane, dichloromethane, acetone, petroleum oils.
Stability: Susceptible to oxidation above 100℃. Stable in neutral media, but slowly hydrolysed in alkaline media, and more rapidly in cidic media; DT5020℃) 11.77 h (pH 3.1), 185 d (pH 7.4), 6.0 d (pH 10.4). Decomposes above 120℃. pKa 2.6 (OECD 112)
Henry: 6.09 × 10-2 Pa m3 mol-1 (calc.)
KowlogP:3.30 (OECD 107)
APPLICATION
Formulation types: CS; EC; DP; DS; FT; GR; KN; SD; WP; Aerosol; Coating agent.
Biochemistry: Cholinesterase inhibitor.
Mode of action: Non-systemic insecticide and acaricide with contact, stomach, and respiratory action.
Uses: Control of sucking and chewing insects and mites on a very wide range of crops, including deciduous fruit trees, citrus fruit, vines, olives, bananas, pineapples, vegetables, potatoes, beet, sugar cane, coffee, cocoa, tea, tobacco, maize, sorghum, alfalfa, flax, cotton, rice, ornamentals, glasshouse crops, forestry, etc., at 300-600 g/ha; soil insects (by soil application); phorid and sciarid flies in mushroom cultivation; flies, lice, mites, fleas, cockroaches, bedbugs, ants, and other insect pests in animal houses and household use. Seed treatment for maize, for control of frit flies and also conferring bird-repellent properties. Also used as a veterinary ectoparasiticide. Phytotoxiclty Non-phytotoxic when used as directed. Russetting may occur on green and yellow apple varieties
Compatibility: Incompatible with copper-containing
MAMMALIAN TOXICOLOGY
Reviews: FAO/WHO 68, 70 (see part 2 of the Bibliography).
Oral : Acute oral LD50 for rats 1250, mice 80-135, guinea pigs 250-355 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >2150, rabbits 540-650 mg/kg. Not an irritant (rabbits).
Inhalation: LC50 (4 h) for rats >2330 mg/m3.
Noel: (2 y) for rats 0.06 mg/kg b.w.; (1 y) for clogs 0.015 mg/kg b.w. daily, humans 0.02 mg/kg b.w.
ADI: (JMPR) 0.002 mg/kg b.w. [1993].
Toxicity: WHO (a.i.) II; EPA (formulation) II or III
EC hazard: Xn; R22| N; R50, R53
ECOTOXICOLOGY
Birds: Acute oral LD50 for mallard ducklings 2.7, young pheasants 4.3 mg/kg.
Fish: LC50 (96 h) for bluegill sunfish 16, rainbow trout 2.6-3.2, carp 7.6-23.4 mg/l.
Daphnia: LC50 (48 h) 0.96 μg/l.
Algae: >1 ppm.
Worms: Slightly toxic to earthworms.
Bees: Highly toxic to bees.
ENVIRONMENTAL FATE
Studies with 14C-labelled diazinon show a rapid absorption and translocation in plants. Metabolism proceeds via hydrolysis and subsequent transformation and degradation of the hydroxypyrimidine derivatives to CO2.
Animals: The principal metabolites are diethyl thiophosphate and diethyl phosphate.
Soil/Environment: Degradation involves oxidation to the phosphate (diazoxon) and hydrolysis (J. Pardue et al., J. Agric. Food Chem., 1970, 18, 405-408). DT50 c. 11-21 d (laboratory). Diazinon is fairly strongly adsorbed onto soil; Kom 332 mg/g o.m. Mobility is low. |
