 German pharmacist Ludwig Andreas Buchner isolated angelic acid in 1842 from the roots of garden angelica ("Angelica archangelica") which gave the acid its name.Angelic acid is a volatile solid with a biting taste and pungent sour odor.It is the "cis" isomer of 2-methyl-2-butenoic acid, which easily converts to the "trans" isomer, tiglic acid, upon heating or reaction with inorganic acids.