Abstract
The structure of skyrin and its reductive cleavage with Na2S2O4 giving emodin were discussed using some model compounds, 4, 4'-dihydroxy-, 2, 2'-dihydroxy-, and 2, 2'-dimethoxy-4, 4'-dihydroxy-bianthraquinones-(1, 1'). The latter two compounds were subjected to the cleavage reaction with Na2S2O4. Dimethyl ether of skyrin prepared by the action of methanol and conc. H2SO4 was proved to be different from dimethyl ether prepared with diazomethane, the latter yielded physcion by reductive cleavage. It was considered that the latter is a genuine dimethyl ether of skyrin while an isomerized form was suggested for the former compound designating pseudoskyrin dimethyl ether. A formula, 2, 4, 5, 2', 4', 5'-hexahydroxy-7, 7'-dimethylbianthraquinone-(1, 1') was proposed for skyrin.
