Upon contact with iron oxide at 500 °C, 4-ethylphenol undergoes dehydrogenation to give 4-vinyllphenol:[1] It is found in wine and beer.

When it reaches concentrations greater than the sensory threshold, it can give the wine aromas described as barnyard, medicinal, band-aids, and mousy.

In wine, 4-vinylphenol can react with other molecules, such as anthocyanidins, to produce new chemical compounds.

[3] The enzyme cinnamate decarboxylase converts p-coumaric acid to 4-vinylphenol.

Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.