Studies on the hydroxylation of sodium 9,10-dihydro-9,10-dioxoanthracene-α-sulphonates

Abstract

The reaction of disodium-9,10-dihydro-9,10-dioxoanthracene-1,8-disulphonate with hydroxide ion at 145° leads to the formation of the sodium salts of 9,10-dihydro-8-hydroxy-9,10-dioxoanthracene-1-sulphonate, 9,10-dihydro-8-hydroxy-9,10-dioxoanthracene-1,7-disulphonate, 9,10-dihydro-4-hydroxy-9,10-dioxoanthracene-1,3,5-trisulphonate, 9,10-dihydro-7,8-dihydroxy-9,10-dioxoanthracene-1-sulphonate, 9,10-dihydro-1,8-dihydroxy-9,10-dioxoanthracene-2-sulphonate, and 9,10-dihydro-1,8-dihydroxy-9,10-dioxoanthracene-2,7-disulphonate, together with 1,8-dihydroxyanthraquinone and 1,2,8-trihydroxyanthraquinone. The general mechanism of this reaction is discussed and evidence is presented to show that 9,10-dihydrohydroxy-9,10-dioxoanthracene-β-sulphonates are formed by attack of the sulphite radical anion on the respective substrate. A good correlation has been found between the experimentally determined position of radical attack and that calculated by MO theory.