Mollisin, a naturally occurring chlorine‐containing quinone: Part IV,. Revised structures for cochenillic acid and for the insect pigments, carminic and kermesic acids

Abstract 4‐Methoxy‐6‐methylhemimellitic acid and its isomers, 3‐methoxy‐5‐methyltrimellitic and 5‐methoxy‐3‐methyltrimellitic acid have been synthesized. 4‐Methoxy‐6‐methylhemimellitic acid is identical with a degradation product of mollisin methyl ether. Evidence is presented from which it must be concluded that cochenillic acid ‐ a degradation product of the well‐known insect pigments carminic and kermesic acids ‐ considered since 1897 to be 4‐hydroxy‐6‐methylhemimellitic acid is in fact 5‐hydroxy‐3‐methyltrimellitic acid. From this it follows that the current structural formulae of carminic and kermesic acids must be revised.