Fonofos is a pale yellow liquid with a pungent,mercaptan-like odor. Molecular weight=246.34; Boilingpoint=130℃ at 0.1 mm; Freezing/Melting point=30℃;Vapor pressure=0.0003 mmHg at 20℃; Flashpoint=94℃ (cc). Hazard Identification (based on NFPA-704 M Rating System): Health 4, Flammability 1,Reactivity 0. Insoluble in water.