Omethoate Chemical Properties
- Melting point:
- Boiling point:
- vapor pressure
- 3.3×10-3Pa (20 °C)
- Flash point:
- 100 °C
- storage temp.
- Water Solubility
- CAS DataBase Reference
- 1113-02-6(CAS DataBase Reference)
- NIST Chemistry Reference
- EPA Substance Registry System
- Omethoate (1113-02-6)
- Language:EnglishProvider:O,O-Dimethyl S-methylcarbamoylmethyl phosphorothioate
Omethoate Usage And Synthesis
Insecticidal, acaricidal, and fungicidal combinations of carboxamides and other pesticides.
Omethoate is a systemic insecticide used for the control of (mostly) sucking insects and mites in a wide variety of crops.
Contact dermatitis from omethoate-dimethoxon is rare.
Omethoate is the P=O analogue (oxon) of dimethoate. Dimethoate is metabolised via oxidative desulfuration to omethoate which is the active anti-acetylcholinesterase metabolite. This biotransformation occurs in all media: hence the metabolic pathways of both compounds have much in common. However, degradative pathways acting directly on dimethoate such as O-demethylation, N-demethylation and hydrolysis of the amide function mean that the balance between activation and degradative metabolism will influence their respective selective toxicities. In mammals there are two main routes of degradation: (i) glutathione transferase mediated O-demethylation (ii) hydrolysis to N-methylthioglycolamide which is S-methylated by S-adenosylmethionine and subsequently thiooxidised. In soil and plants the N-methylthioglycolamide moiety formed from the hydrolysis of omethoate undergoes a complex series of C1, C2 and C3 biotransformations ultimately leading to oxalate and citrate respectively and total degradation to C02. The information reported below is derived largely from an evaluation prepared by the UK MAFF Pesticide Safety Directorate (PSD, 1993).
Omethoate was slowly hydrolysed in acidic media but more rapidly under alkaline conditions. The half-lives for hydrolysis at pH 4,7, and 9 were 102 days, 17 days and 28 hours, respectively (PM). Omethoate does not absorb light at wavelengths above 250 nm and it is thus unlikely to be subject to photodecomposition. An aqueous solution of omethoate was irradiated for 14 hours with a high pressure filtered mercury vapour lamp without detectable photolysis occurring (PSD, 1993).