SOME ABSORPTION AND FLUORESCENT PROPERTIES OF THE α-ESTRADIOL SULPHURIC ACID COMPLEX

Abstract

Three processes take place when α-estradiol is dissolved in concentrated sulphuric acid: (1) a reaction involving the C₃—OH group, characterized by the development of an absorption maximum at 220 , (2) a reaction involving the C_n-OH group, characterized by the development of an absorption maximum at 235 to 230 and (3) intramolecular rearrangements. The use of diluted acid as a reagent favors the C₃ reaction. Subsequent dilution with water of a solution of α-estradiol in concentrated acid results in a reversible solvent effect and accelerates an irreversible rearrangement or reaction; this is characterized by the development of an absorption maximum at 207 when the C₁₇ group is involved, and at 195 when the C₃ group is involved. Published results by Cohen and Bates, as well as by Umberger and Curtis, show that these processes are general for the estrogens. This explains the accurate timing, temperature, and concentration measurements required for the colorimetric assay of estrogens in acid solution. The reaction of α-estradiol with phenolsulphonic acid, and with phosphoric acid, involves only the C₃ group. Dehydrating reagents are necessary before an acid reaction involving the C₁₇—OH group can occur.