Definition
ChEBI: An organic thiophosphate that is O,O-diethyl hydrogen phosphorothioate in which the hydrogen of the hydroxy group is replaced by a 5-phenyl-1,2-oxazol-3-yl group.
Description
Isoxathion is a pale yellow liquid, bp 160 ?C/0.15 mm
Hg, vp <0.133mPa (25 ?C). Solubility in water is 1.9 mg/L
(25 ?C). It is readily soluble in most organic solvents. Log
Kow = 3.88. It is unstable to alkali.
Uses
Isoxathion is used as a pesticide.
Uses
Isoxathion is used to control sucking pests, leaf miners and some
chewing pests in a variety of fruit, vegetables and ornamental plants.
Metabolic pathway
The principal route of isoxathion metabolism in soil, plants and mammals
is by hydrolysis, probably via the oxon to 3-hydroxy-5-phenylisoxazole
which is rapidly conjugated in both plants and rats. In soils, and to a
lesser extent in plants and mammals, further metabolism of 3-hydroxy-
5-phenylisoxazole proceeds via opening of the isoxazole ring to give
various metabolites of which benzoic acid is one of the more important.
De-ethylation of the phosphate moiety has not been observed.
Metabolism
The principal degradation route of isoxathion in animals,
plants, and soil is cleavage of P?O-isoxazole through
oxidative desulfuration to the oxon followed by hydrolysis
to 3-hydroxy-5-phenylisoxazole, which is conjugated in
both plants and rats.
Degradation
Isoxathion is unstable to alkalis (PM). The hydrolysis product, 3-hydroxy-
5-phenylisoxazole (2), yielded 5-phenyl-3H-oxazolin-2-one (3) as the
major photoproduct via a photolytic rearrangement (Nakagawa et al.,1974).
Toxicity evaluation
The acute oral LD50 for rats is 112 mg/kg. NOEL
(2 yr) for rats is 1.2 mg/kg b.w. DT50 in soil is 9–40 d.
