Vanillin, also called 3-Methoxy-4-Hydroxy Benzaldehyde, is a kind of synthetic phenolic aldehyde, and it is mainly used as flavoring agent for food, drinks, cosmetics. Vanillin has characteristic odor, and it is white to light yellow powder, easily soluble in ethanol or hot water, but slightly in cold water. Its molecular formula is C8H8O3 and its CAS number is 121-33-5.