Abstract
The color reaction of estrone with the antimony trichloride reagent was investigated in order to clarify the reaction mechanism. Two reaction products, 3'-methyl-7-acetoxy-1, 2-cyclopenteno-3, 4-dihydrophenanthrene (I) and estrone acetate (II), were isolated from the colored reaction mixture. It was found that acetyl chloride is indispensable for the color reaction, and that the respective steroids are colored by the formation of the cation-radicals. It was assumed that the cation-radical of the substance I should be responsible for the coloration. The reaction mechanism for the formation of the substance I was inferred, and the relationship between the absorption maxima observed in the absorption spectra and the cation-radicals was discussed.
