Substance profile
Methamidophos
Methamidophos is colorless crystals with a mercaptan-like odor.
01 · Identification
What Methamidophos is
Methamidophos is colorless crystals with a mercaptan-like odor. Its molecular formula is C2H8NO2PS and its molecular weight is 141.13 g/mol. It melts at 44.9 °C.
Under the GHS it carries the signal word Danger.
Other names for Methamidophos
- methamidophos (ISO)
- O,S-dimethyl phosphoramidothioate
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H330 | Fatal if inhaled. |
| H300 | Fatal if swallowed. |
| H311 | Toxic in contact with skin. |
| H400 | Very toxic to aquatic life. |
Precautionary statements: P260, P270, P271, P273, P280, P301, P302, P304, P310, P330, P352, P391, P501
03 · Physical and chemical properties
Methamidophos properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | Decomposes on heating without boiling | decomposes | HSDB |
| Decomposes (EPA, 1998) | decomposes | CAMEO | |
| Melting point | 44.9 °C (112.8 °F) | HSDB | |
| 44.44 °C (112 °F) | CAMEO | ||
| 44 °C (111.2 °F) | ICSC | ||
| Density | 1.3 g/cm³ | ICSC | |
| 1.27 g/cm³ | at 20 °C | HSDB | |
| 1.31 g/cm³ | at 44.5 °C | CAMEO | |
| Solubility | Soluble in aliphatic chlorinated hydrocarbons, alcohols; slightly soluble in ether. | HSDB | |
| Readily sol in n-hexane, dichloromethane, 2-propanol, toluene | HSDB | ||
| Solubility (g/l) at 20 °C in: isopropanol: >200; dichloromethane: >200; hexane: 0.1-1; toluene: 2-5 | at 20 °C | HSDB | |
| Vapor pressure | 0.000015 mmHg | at 20 °C | ICSC |
| 35250 mmHg | at 25 °C | HSDB | |
| 0.0003 mmHg | at 25 °C | DOE PAC | |
| Corrosivity | Slightly corrosive to mild steel and copper-containing alloys. | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Handling and storage
Storing and handling Methamidophos
Storage conditions
...Concentrates... should not be stored in mild steel containers.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Attacks mild steel and copper-containing alloys (technical grade).
Source: Hazardous Substances Data Bank (HSDB)
Reactivity
Organophosphates, such as METHAMIDOPHOS, 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. Avoid strong acids or alkalis. [EPA, 1998].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Methamidophos in the storage compatibility matrix →