Specification :

Pirimiphos-Methyl

Common name: pirimiphos-methyl; pyrimiphos-mé thyl
IUPAC name: O-2-diethylamino-6-methylpyrimidin-4-yl O, O-dimethyl phosphorothioate
Chemical Abstracts name: O-[ 2-( diethylamino) -6-methyl-4-pyrimidinyl] O, O-dimethyl phosphorothioate
CAS RN: [ 29232-93-7]

PHYSICAL CHEMISTRY
Composition: Tech. material is 90% pure. Mol. wt.: 305.3; M.f.: C11H20N3O3PS; Form: Straw-coloured liquid. M.p.: 15-18 º C ( tech.) B.p.: Decomposes on distillation. V.p.: 2 mPa ( 20 º C) ; 6.9 mPa ( 30 º C) ; 22 mPa ( 40 º C) . KOW: logP = 4.2 ( 20 º C, unionised) . Henry: 6x10-2 Pa m3 mol-1 ( calc.) S.g./ density: 1.17 ( 20 º C) ; 1.157 ( 30 º C) . Solubility: In water 11 ( pH 5) , 10 ( pH 7) , 9.7 ( pH 9) ( all in mg/ l, 20 º C) . Miscible with most organic solvents, e.g. alcohols, ketones, halogenated hydrocarbons. Stability: Hydrolysed by concentrated acids and alkalis; DT50 2-117 d ( pH range 4-9, most stable at pH 7) . In sunlight, aqueous solution had DT50 46 º C.

APPLICATIONS
Biochemistry: Cholinesterase inhibitor.
Mode of action: Broad-spectrum insecticide and acaricide with contact and respiratory action. Penetrates the leaf tissue and exhibits translaminar action.
Uses: Control of a wide range of insects and mites in warehouses, stored grain, animal houses, domestic and industrial premises; chewing insects, sucking insects, boring insects, and mites on vegetables, ornamentals, bulb flowers, sugar cane, maize, sorghum, rice, citrus and other fruit, olives, vines, alfalfa, cereals, etc.; and glasshouse pests ( especially whitefly, thrips, mealybugs, aphids, and mites) on tomatoes, cucumbers, capsicums, aubergines, and other glasshouse crops.
Formulation types: AE; DP; EC; FU; HN; KN; LS; SG; UL.
Compatibility: Miscible with common insecticides and fungicides. Mixing with strongly alkaline or acidic substances should be avoided.

MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats 1414, mice 1180 mg/ kg.
Skin and eye: Acute percutaneous LD50 for rats > 2000 mg/ kg. Slight eye and mild skin irritation ( rabbits) . Mild skin sensitiser ( guinea pigs) .
Inhalation: LC50 ( 4 h) for rats > 5.04 mg/ l.
NOEL: ( 2 y) for rats 10 mg/ kg diet. No teratogenic effects, and no concentration in adipose tissue. NOEL ( 90 d) for dogs 0.5, rats 8 mg/ kg diet.
ADI: 0.03 mg/ kg b.w.
Toxicity class: WHO ( a.i.) III; EPA ( formulation) III
EC hazard: Xn; R22

ECOTOXICOLOGY
Birds: Acute oral LD50 for bobwhite quail 40, Japanese quail 140, mallard ducks 1695 mg/ kg.
Fish: LC50 ( 96 h) for rainbow trout 0.64 mg/ l; ( 48 h) for mirror carp 1.4 mg/ l.
Daphnia: EC50 ( 48 h) 0.21 ug/ l; ( 21 d) 0.08 ug/ l.
Algae: EC50 1.0 mg/ l.
Bees: Toxic to bees.
Worms: LC50 ( 14 d) 419 mg/ kg.

ENVIRONMENTAL FATE
Animals: In mammals, the P-O bond is cleaved extensively and N-dealkylation and/ or conjugation is a further step in the metabolism of the pyrimidine leaving group.
Plants: Rapidly evaporates. After 2-3 days, 2 mo.
Soil/ Environment: Soil DT50 ( aerobic and anaerobic) is typically 3.5-25 d.