Thymol blue (thymolsulfonephthalein) is a brownish-green or reddish-brown crystalline powder that is used as a pH indicator. It is insoluble in water but soluble in alcohol and dilute alkali solutions.
| Thymol blue (pH indicator) | ||
| below pH 8.0 | above pH 9.6 | |
| 8.0 | ⇌ | 9.6 |
| Thymol blue (pH indicator) | ||
| below pH 1.2 | above pH 2.8 | |
| 1.2 | ⇌ | 2.8 |
It transitions from red to yellow at pH 1.2–2.8 and from yellow to blue at pH 8.0–9.6. It is usually a component of Universal indicator.
At wavelength (378 - 382) nm, extinction coefficient > 8000 and at wavelength (298 - 302) nm, the extinction coefficient > 12000.[3]
Structures
Thymol blue has different structures at different pH.
thymol blue.
Safety
It may cause irritation. Its toxicological properties have not been fully investigated.[4] Harmful if swallowed, Acute Toxicity. Only Hazardous when percent values are above 10%.[5]
Bibliography
- Merck. "Thymol Blue." The Merck Index. 14th ed. 2006. Accessed via web on 2007-02-25.
References
- ^ a b Thymol Blue
- ^ "Thymol blue". pubchem.ncbi.nlm.nih.gov. Retrieved 12 December 2021.
- ^ "Product Specification: Thymol Blue- ACS reagent" (PDF). Sigma-Aldrich. 9 October 2017. p. 1.
- ^ "Thymol Blue MSDS". Fisher Scientific. Retrieved 2024-07-23.
- ^ "Thymol blue". PubChem. Retrieved 2017-10-09.