4-Methoxyphenylacetaldehyde is used in perfume compositions as part of the floral theme, mainly in Lilac, Heliotrope, Wallflower, Acacia, New Mown Hay, Hawthorne, and also in Fougeres as a sweetener or modifier for Anisaldehyde, etc. It blends excellently with the conventional sweeteners and florals, and produces softer, less harsh notes than Anisaldehyde or the substituted Acetophenones. The aldehyde tends to polymerize on storage and should be kept at uniform temperature, preferably in dilution, protected from daylight and air. Polymerization causes increase in viscosity and loss of odor.
