| Uses | Insecticide primarily for soil applications. |
| Uses | Chlormephos is used to control soil insects such as wireworms in a
number of crops. |
| Uses | Chlormefos has agricultural applications. Useful for preparing compositions for controlling plant diseases. |
| Definition | ChEBI: Chlormephos is an organic thiophosphate, an organothiophosphate insecticide and an organochlorine insecticide. It has a role as an agrochemical and an EC 3.1.1.7 (acetylcholinesterase) inhibitor. |
| General Description | Colorless liquid. Used as a soil insecticide. Not registered as a pesticide in the U.S. |
| Air & Water Reactions | Slightly soluble in water [Farm Chemicals Handbook]. |
| Reactivity Profile | Organophosphates, such as CHLORMEPHOS, are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides. |
| Health Hazard | (Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) CHLORMEPHOS is poisonous; it may be fatal if inhaled, swallowed, or absorbed through the skin. |
| Fire Hazard | (Non-Specific -- Organophosphorus Pesticide, Liquid, n.o.s.) Container may explode in heat of fire. Fire and runoff from control water may produce irritating or poisonous gases. |
| Metabolic pathway | Chlormephos is a soil insecticide with considerable vapour phase activity.
The main soil metabolite is ethion. The mechanism of hydrolysis of
chlormephos is mainly by the nucleophilic attack of OH- on the Smethylene
carbon to yield O,O-diethyl phosphorodithioate and in this
respect it is similar to mecarbam. This mechanism may afford ethion
when the nucleophile is O,O-diethyl phosphorodithioate. The other
mechanism of hydrolysis is by attack on phosphorus to yield O,O-diethyl
phosphorothioate and these two routes of hydrolytic degradation
apparently dominate the metabolism of the insecticide. |
| Metabolism | In soils, chlormephos is converted to
ethion by reaction with the hydrolytic product, O,O-diethyl
hydrogen phosphorothioate. |
| Toxicity evaluation | The acute oral LD50 for rats
is 7 mg/kg. NOEL (90 d) for rats is 0.39 mg/kg diet
(0.002 mg/kg/d). In rats, orally administered chlormephos
is almost completely eliminated within 24 h in the urine
as diethyl hydrogen phosphate and O,O-diethyl hydrogen
phosphorothioate. |
| Degradation | In strongly basic solution (0.5 M aqueous KOH), hydroxide ion attack on
chlormephos may occur on the phosphorus atom with P-C bond cleavage
to yield O,O-diethyl phosphorothioate (2) or on the S-methylene carbon
atom to give O,O-diethyl phosphorodithioate (3), both of which may react
with chlormephos to give further products. Hudson et al. (1991) showed
that both hydrolysis products 2 and 3 could react with chlormephos via
attact on the ethoxy group to yield the transethylation products O,O,Striethyl
phophorothioate (4) and O,O,S-triethyl phophoroditluoate (5)
respectively. Compound 3 could also attack the phosphorus atom of
chlormephos to yield O,O,O’,O’-tetraethyl trithiopyrophosphate (6) and
the S-methylene carbon to give ethion (7). Reaction products were identified
by GC-MS after conversion of the acidic products into their methyl
esters by reaction with diazomethane. Routes by which these products
may be formed in strongly basic solution are shown in Scheme 1. |
