Acidity and stability of 10-substituted 1,8-dihydroxy-9(10H)-anthracenones

Article abstract of DOI:10.1002/ardp.19953280412

The decomposition of 10-substituted anthralin derivatives in dimethyl sulfoxide and ethanol was determined. While 10-ω-phenylalkylidene derivatives were thoroughly stable, 10-ω-phenylacyl-substituted compounds were slowly degraded to danthron and the corresponding carboxylic acids. However, the stability of these derivatives was markedly improved as compared to that of anthralin. Determination of the pK(a) values showed that the ω-phenylacyl derivatives were somewhat stronger acids than anthralin, while ω-phenylalkylidene-substitution generally leaves the acidity of the anthralin part unchanged.