Penta-2,3-dienedioic acid

Penta-2,3-dienedioic acid (one of two chemicals called glutinic acid), is in allene-containing dicarboxylic acid. It was the first allene to be synthesized, in 1887, but the structure of it was thought to be a propyne core instead of an allene. The correct structural isomeric identity was not determined until 1954.

Literature confusion
A diterpene, chemical name (4aR,5S,6R,8aR)-5-[(Z)-4-carboxy-3-methylbut-3-enyl]-5,6,8a-trimethyl-3,4,4a,6,7,8-hexahydronaphthalene-1-carboxylic acid, is also called glutinic acid. Some database entries for "glutinic acid" incorrectly identify it as this diterpene rather than the allene meaning in the underlying publications.