2,4,5-Trihydroxy-3-methylacetophenone: A Cellulosic Chromophore as a Case Study of Aromaticity.

The title compound (2,4,5-trihydroxy-3-methylacetophenone, ) was isolated as chromophore from aged cellulosic pulps. The peculiar feature of the compound is its weak aromatic system that can be converted into nonaromatic (quinoid or cyclic aliphatic) tautomers, depending on the conditions and reaction partners. In alkaline media, the participation of quinoid canonic forms weakens aromaticity, whereas in neutral and acidic media, the strong hydrogen bond between the 2-hydroxyl group and the acetyl moiety plays an important role in favoring quinoid tautomers.

Degradation of the Cellulosic Key Chromophore 5,8-Dihydroxy-[1,4]-naphthoquinone by Hydrogen Peroxide under Alkaline Conditions.

5,8-Dihydroxy-[1,4]-naphthoquinone (DHNQ) is one of the key chromophores in cellulosic materials. Its almost ubiquitous presence in cellulosic materials makes it a target molecule of the pulp and paper industry's bleaching efforts. In the presented study, DHNQ was treated with hydrogen peroxide under alkaline conditions at pH 10, resembling the conditions of industrial hydrogen peroxide bleaching (P stage).