The behavior of testosterone (I) and its related compounds such as 17-methyl-18-norandrosta-4, 13-dien-3-one (II), 17-methyl-18-norandrosta-4, 13 (17)-dien-3-one (III), androst-4-en-3-one (IV), 5α-androstan-17β-ol (VI), 13ξ, 14ξ-epoxy-17-methyl-18-norandrost-4-en-3-one (VIII), and 13ξ, 17ξ-epoxy-17-methyl-18-norandrost-4-en-3-one (IX) in concentrated sulfuric acid was studied, in order to elucidate the mechanism of the early stage in the chromogenic reaction of I with sulfuric acid. When I was dissolved into 97.2% sulfuric acid, the chromophoric species was produced indicating a maximum absorption at about 300nm. From the results of absorption and NMR spectroscopic studies and from the fact that the chromogenic reaction was accelerated by selenic acid as an oxidant, the species was proposed to be the dication (X) which is produced by the protonation, dehydration, angular methyl migration, and oxidation processes and retains the alkenyl as well as hydroxyalkenyl cation chromophores.
