Molecule structure of Methyl phenkapton (CAS NO.3735-23-7) :

IUPAC Name: (2,5-dichlorophenyl)sulfanylmethylsulfanyl-dimethoxy-sulfanylidene-λ5-phosphane 
Molecular Weight: 349.257201 g/mol
Molecular Formula: C₉H₁₁Cl₂O₂PS₃ 
Density: 1.47 g/cm³ 
Boiling Point: 382.1 °C at 760 mmHg 
Flash Point: 184.9 °C
Index of Refraction: 1.625
Molar Refractivity: 83.54 cm³
Molar Volume: 236.2 cm³
Polarizability: 33.11×10^-24 cm³
Surface Tension: 59.6 dyne/cm 
Enthalpy of Vaporization: 60.57 kJ/mol 
log P (octanol-water): 4.860 
Water Solubility: 0.445 mg/L 
Vapor Pressure: 4.21E-06 mm Hg 
Henry's Law Constant: 7.41E-08 atm-m³/mole 25 
Atmospheric OH Rate Constant: 2.11E-10 cm³/molecule-sec
XLogP3: 5.4
H-Bond Acceptor: 2
Rotatable Bond Count: 6
Exact Mass: 347.903584
MonoIsotopic Mass: 347.903584
Topological Polar Surface Area: 18.5
Heavy Atom Count: 17
Complexity: 275
Canonical SMILES: COP(=S)(OC)SCSC1=C(C=CC(=C1)Cl)Cl
InChI: InChI=1S/C9H11Cl2O2PS3/c1-12-14(15,13-2)17-6-16-9-5-7(10)3-4-8(9)11/h3-5H,6H2,1-2H3
InChIKey: IHCHKPCNDMQWGF-UHFFFAOYSA-N

 Methyl phenkapton (CAS NO.3735-23-7) is used as an acaricide, insecticide. Not registered as a pesticide in the U.S.

EPA Extremely Hazardous Substances List.

Poison by ingestion. When heated to decomposition it emits very toxic fumes of Cl⁻, SO_x and PO_x.
RIDADR: 3018
HazardClass: 6.1(b)
PackingGroup: III

 Methyl phenkapton (CAS NO.3735-23-7) is also called Caswell No. 362A ; ENT 25,554-X ; EPA Pesticide Chemical ; Code 362200 ; G 30494 ; Geigy 30494 ; Methanethiol, ((2,5-dichlorophenyl)thio)-, S-ester with O,O-dimethyl phosphorodithioate ; O,O-Dimethyl S-(2,5-dichlorophenylthio)methyl phosphorodithioate ; S-(((2,5-Dichlorophenyl)thio)methyl) O,O-dimethyl phosphorodithioate . Methyl phenkapton (CAS NO.3735-23-7) is liquid.  Organophosphates, such as Methyl phenkapton , 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. 
Organic phosphorus insecticides are absorbed by the skin, as well as by the respiratory and gastrointestinal tracts. Toxic hazard rating (oral) is high. Cylinder may explode in heat of fire. Heat may cause decomposition and evolution of highly toxic fumes of phosphorus oxides and chlorides.