ACIDITY AND STABILITY OF 10-SUBSTITUTED 1,8-DIHYDROXY-9(10H)-ANTHRACENONES

The decomposition of 10-substituted anthralin derivatives in dimethyl sulfoxide and ethanol was determined. While 10-omega-phenylalkylidene derivatives were thoroughly stable, 10-omega-phenylacyl-substituted co mpounds were slowly degraded to danthron and the corresponding carboxy lic acids. However, the stability of these derivatives was markedly im proved as compared to that of anthralin. Determination of the pK(a) va lues showed that the omega-phenylacyl derivatives were somewhat strong er acids than anthralin, while omega-phenylalkylidene-substitution gen erally leaves the acidity of the anthralin part unchanged.