The chemical name for diazinon is O, O-diethyl O-2-isopropyl-6-methylpyrimidinyl-4-yl phosphorothioate. The pure material forms a colourless liquid with a faint ester-like odour. The technical active ingredient is a yellow/brown liquid with a slight compound-specific odour. The boiling point is 83-84°C at 26.6 mPa and the vapour pressure (volatility) is low (9.7 mPa at 20°C). The solubility in water at room temperature is 60 mg/litre. Diazinon is soluble in most organic solvents and has an octanol/water partition coefficient (log Pow) of 3.40. It is stable in neutral media, but is slowly hydrolysed in alkaline media and more rapidly in acid media. It decomposes at temperatures above 120°C.