Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Rhodizonic acid is a chemical compound with formula C6H2O6 or (CO)4(COH)2. It can be seen as a two-fold alcohol and four-fold ketone of cyclohexene, more precisely 1,2-dihydroxycyclohexene-3,4,5,6-tetrone. Rhodizonic acid is usually obtained in the form of a colorless "dihydrate" C6H2O6·2H2O. The latter is actually 1,2,4,4,5,5-hexaxydroxycyclohexene-3,6-dione, where two of the original ketone groups are replaced by two pairs of geminal hydroxyls. The orange to deep-red and highly hygroscopic anhydrous acid can be obtained by low-pressure sublimation of the dihydrate.