2. Thyme phenolphthalein is a kind of water-insoluble acid-base indicator, which is also called Thyme phenolphthalein, Thyme Phenol Bran and Thyme Phenolphthalein.

3. White or yellowish needle-like crystals, soluble in ethanol and acetone, insoluble in water, red in sulfuric acid, blue in dilute alkali solution, with pH ranging from 4 to 6, and color change, colorless to blue.

4. Acid-base indicator, colorless to 5 blue reagent, used for blood test.