4-Anisaldehyde

4-Anisaldehyde, or p-Anisaldehyde, is an organic compound with the formula CH₃OC₆H₄CHO. The molecule consists of a benzene ring with a formyl and a methoxy group. It is a colorless liquid with a strong aroma. It provides sweet, floral and strong aniseed odor. Two isomers of 4-anisaldehyde are known, ortho-anisaldehyde and meta-anisaldehyde. They are less commonly encountered.

Production

Anisaldehyde is prepared commercially by oxidation of 4-methoxytoluene (p-cresyl methyl ether) using manganese dioxide to convert a methyl group to the aldehyde group. It can also be produced by oxidation of anethole, a related fragrance that is found in some alcoholic beverages, by oxidative cleavage of an alkene.

Uses

Being structurally related to vanillin, 4-anisaldehyde is a widely used in the fragrance and flavor industry. It is used as an intermediate in the synthesis of other compounds important in pharmaceuticals and perfumery. The related ortho isomer has a scent of licorice.

A solution of para-anisaldehyde in acid and ethanol is a useful stain in thin layer chromatography. Different chemical compounds on the plate can give different colors, allowing easy distinction.