Thymolphthalein is a phthalein dye used as an acid–base (pH) indicator.
The molar extinction coefficient for the blue thymolphthalein dianion is 38,000 M−1 cm−1 at 595 nm.
[2] Thymolphthalein is also known to have use as a laxative[3] and for disappearing ink.
[4] Thymolphthalein can be synthesized from thymol and phthalic anhydride.
This article about an organic compound is a stub.