Molecule structure of Methyl demeton methyl (CAS NO.2587-90-8) :

IUPAC Name: 1-dimethoxyphosphorylsulfanyl-2-methylsulfanylethane 
Molecular Weight: 216.258681 g/mol
Molecular Formula: C₅H₁₃O₃PS₂
Density: 1.229 g/cm³  
Boiling Point: 270.3 °C at 760 mmHg 
Flash Point: 117.3 °C
Index of Refraction: 1.498
Molar Refractivity: 51.57 cm³
Molar Volume: 175.8 cm³
Polarizability: 20.44×10^-24 cm³
Surface Tension: 40.5 dyne/cm 
Enthalpy of Vaporization: 48.8 kJ/mol 
log P (octanol-water): 0.620 
Water Solubility: 300 mg/L 
Vapor Pressure: 2.34E-03 mm Hg 
Henry's Law Constant: 1.94E-09 atm-m³/mole 
Atmospheric OH Rate Constant: 4.08E-11 cm³/molecule-sec
XLogP3: 0.7
H-Bond Acceptor: 3
Rotatable Bond Count: 6
Exact Mass: 216.004372
MonoIsotopic Mass: 216.004372
Topological Polar Surface Area: 35.5
Heavy Atom Count: 11
Complexity: 134
Canonical SMILES: COP(=O)(OC)SCCSC
InChI: InChI=1S/C5H13O3PS2/c1-7-9(6,8-2)11-5-4-10-3/h4-5H2,1-3H3
InChIKey: PSTWJANBJOHFQJ-UHFFFAOYSA-N
EINECS: 219-971-9

 Methyl demeton methyl (CAS NO.2587-90-8) is used as a systemic insecticide and acaricide effective against sucking insects.

EPA Extremely Hazardous Substances List.

Poison by ingestion and skin contact. Mutation data reported. Caution: It is a cholinesterase inhibitor. When heated to decomposition it emits very toxic fumes of PO_x and SO_x. See also PARATHION and DEMETON; DEMETON-O + DEMETON-S; DEMETON-O-METHYL; DEMETON-O-METHYL SULFOXIDE; DEMETON-S; DEMETON-S-METHYL; DEMETON-S-METHYL-SULPHONE.

 Methyl demeton methyl (CAS NO.2587-90-8) is also called 2-Methylthioethyl O,O-dimethyl phosphorothioate ; 4-01-00-02460 (Beilstein Handbook Reference) ; BRN 1707090 ; Caswell No. 369A ; Cebetox ; Cymetox ; Demephion ; Demephion-S ; EPA Pesticide Chemical Code 369200 ; Ethanethiol, 2-(methylthio)-, O,O-dimethyl phosphorothioate ; Ethanethiol, 2-(methylthio)-, S-ester with O,O-dimethyl phosphorothioate ; Isotinox ; O,O-Dimethyl S-(2-(methylthio)ethyl) phosphorothioate . Methyl demeton methyl (CAS NO.2587-90-8) is a straw-colored liquid. Methyl demeton methyl , like other thiophosphate esters, may react with strong reducing agents such as hydrides to give highly toxic and flammable phosphine gas. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides. May be fatal if inhaled, swallowed or absorbed through the skin. Contact may cause burns to skin and eyes. May cause respiratory failure. 
Methyl demeton methyl  may burn but does not ignite readily. Container may explode in heat of fire. Fire may produce irritating or poisonous gases. Runoff from fire control water may give off poisonous gases.