Thymolphthalein is a phthalein dye used as an

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

– base ( pH)

indicator Indicator may refer to: Biology * Environmental indicator of environmental health (pressures, conditions and responses) * Ecological indicator of ecosystem health (ecological processes) * Health indicator, which is used to describe the health o ...

. Its transition range is around pH 9.3–10.5. Below this pH, it is colorless; above, it is blue. The

molar extinction coefficient In chemistry, the molar absorption coefficient or molar attenuation coefficient () is a measurement of how strongly a chemical species absorbs, and thereby attenuates, light at a given wavelength. It is an intrinsic property of the species. The ...

for the blue thymolphthalein dianion is 38,000 M⁻¹ cm⁻¹ at 595 nm. Thymolphthalein is also known to have use as a laxative and for disappearing ink.

Preparation

Thymolphthalein can be synthesized from thymol and phthalic anhydride. : ThymolphthaleinSynthesis

References

PH indicators Triarylmethane dyes Phthalides Phenols Isopropyl compounds {{Ether-stub

Preparation

See also

References