The invention relates to the field of preparation of
fluorescein probes with specific selectivity, and particularly discloses a preparation method of a
fluorescein probe with specific selectivity. The method comprises the following steps: (1) mixing 4-nitrophthalic anhydride,
resorcinol,
nitrocyclohexane and
anhydrous cobalt chloride, conducting heating and melting, adding
zinc chloride, conducting reacting, then adding
hydrochloric acid for
reflux, and conducting filtering, washing and
drying; (2) mixing a reducing solution containing Na2S and Na2SO3 with a product obtained in the step (1), conducting reacting, then dropwise adding glacial
acetic acid until complete
precipitation, and conducting filtering, washing and
drying; and (3) mixing a mixed
solvent containing
methanol and
triethylamine with a product obtained in the step (2), dropwise adding CS2, conducting reacting, dropwise adding a
copper chloride aqueous solution, continuing reacting after dropwise adding, adjusting the pH value of the
system to 1-2 by using
hydrochloric acid, and carrying out reduced pressure
distillation, washing,
drying and
column chromatography purification. According to the method, the conversion rate and the yield of the 5-
fluorescein isothiocyanate are greatly improved.