Phenolphthalein exerts laxative effects by stimulating the intestinal mucosa and constricting smooth muscles. Phenolphthalein, (C 20 H 14 O 4), an organic compound of the phthalein family that is widely employed as an acid - base indicator. Phenolphthalein is used as an acid or base indicator where, in contact or presence of acid, it will turn colorless and with a base, it will turn into a fuchsia color. Phenolphthalein is an organic compound used as a laboratory reagent and pH indicator. MDL number MFCD00005913. Phenolphthalein pH indicator Synonym: 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone CAS Number 77-09-8. However, phenolphthalein is no longer used as a laxative due to the suspected carcinogenicity of this compound. It is also a component in universal indicator, a solution consisting of a mixture of pH indicators (usually phenolphthalein, methyl red, bromothymol blue, and thymol blue). Each pH indicator is defined by a useful pH range. For example Phenolphthalein changes from colorless at 8.2 to pink at 10. EC Number 201-004-7. Beilstein/REAXYS Number 284423 . As an indicator of a solution’s pH, phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0. Molecular Weight 318.32 . And Bromthymol Blue has a useful range from 6.0 (yellow) to 7.6 (blue). Colour Index Number 764 . Empirical Formula (Hill Notation) C 20 H 14 O 4. PubChem Substance ID 24899058