White acicular crystals,; Melting point 170~174 ℃; It turns brown or black when it is stored for a long time. Pure products are white needle shaped crystals, soluble in water, ether or alcohol, slightly soluble in benzene, heated for sublimation, easy to be oxidized in the air, and then turn brown or black...

Pale yellow acicular or prismatic crystals. The melting point is 44-45 ℃, the boiling point is 216 ℃, the flash point is 102 ℃, the relative density (40/4 ℃) is 1.2941, and the refractive index is 1.5723. Toxic. It smells of almonds...

White blocky crystals, crystalline powders or recrystallized particles (yellowish or grayish is allowed), tasteless...

The product is light yellow or yellow crystalline powder, melting point: 140-145 ℃, relative density: 1.416g/cm3, toxic, irritant and bitter..

Orange yellow or light yellow crystal, flammable in case of open fire and high temperature, melting point ＞ 300 ℃, flash point 90 ℃...