Hexamethylphosphoric triamide, also known as hexaphosphoramine and hexamethylphosphoramide, is prepared by the reaction of dime-thylamine and phosphorus oxy-chloride. The molecular weight is 179.2. It is a colorless or light yellow transparent liquid. Slightly fishy and astringent. The relative density is 1.0253~1.0257 (20ºC), the refractive index is 1.4582~1.4589 (20ºC), the freezing point is 2Chemicalbook~7ºC, and the boiling point is 116~117ºC (1480Pa). Soluble in polar and non-polar solvents. It can be miscible with commonly used plasticizers such as dioctyl phthalate, dioctyl sebacate, and triphenyl pho-sphite in any ratio. The toxicity is similar to that of phosphate. Avoid contact with skin. The container should be tightly closed to prevent damage, leakage and deterioration of water absorption.