The main uses of phenolphthalein: 

1, pharmaceutical industry pharmaceutical raw materials: suitable for habitual stubborn constipation, there are tablets, suppositories and other dosage forms. 2, for organic synthesis: Mainly used for synthetic plastics, especially the synthesis of diazanadione polyaryl ether ketone polyaryl ether ketone polymer, which has excellent heat resistance, water resistance, chemical corrosion resistance, heat aging resistance and good processing formability. The fibers, coatings and composite materials made from it are soon widely used in electronic appliances, mechanical equipment, transportation, aerospace, atomic energy engineering and military fields. 3, used for acid-base indicator, indicator for non-aqueous titration, reagent for chromatography.