Appearance: Technical chlorpyrifos is an amber to white crystalline solid with a mild sulfur odor [13]. Chemical Name: O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate [13] CAS Number: 2921-88-2 Molecular Weight: 350.62 Water Solubility: 2 mg/L @ 25 C [13] Solubility in Other Solvents: benzene s.; acetone s.; chloroform s.; carbon disulfide s.; diethyl ether s.; xylene s.; methylene chloride s.; methanol s. [13] Melting Point: 41.5-44 C [13] Vapor Pressure: 2.5 mPa @ 25 C [13] Partition Coefficient: 4.6990 [13] Adsorption Coefficient: 6070 [19]