Product name: Caffeic acid Other name: 3,4-dihydroxy cinnamic acid CAS No: 331-39-5 Chemical name: 2-Propenoic acid, 3-(3,4-dihydroxy-phenyl)- MF: C9H8O4 Molecular Weight: 180.15 what is caffeic acid? Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. caffeic acid found in what products?It is found in all plants because it is an intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues