1964 年 84 巻 11 号 p. 1134-1137
It has previously been proved by the authors that the direct bromination of fluorescein by two moles equivalent of bromine, afforded dibromofluorescein, whose 4′ and 5′-position were replaced.
Under the similar conditions, the bromination gave, besides 4′, 5′-dibromofluorescein (VI), some sorts of bromofluorescein derivatives, which were observed by paper chromatography with a developing solvent mixture of N-sodium hydroxide solution: 10% Phenol: water (2:1:7). The reaction products were separated, through alumina column chromatography with 2% ammonium hydroxide, into, besides (VI), 2′-bromofluorescein (XIII), 4′-bromofluorescein (XIV), 2′, 7′-dibromofluorescein (V) and eosine (VII), shown in Tables II and III.
These bromofluorescein derivatives had been identified with compounds, XII, XIV, V, VI, 2′, 4′-dibromofluorescein (XII) and (VII), synthesized by another process, illustrated in Chart 1.