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Thymolphthalein
Chemical compound / From Wikipedia, the free encyclopedia
This article is about thymolphthalein. For other related dyes in the phthalein family, see Phthalein dye.
Thymolphthalein is a phthalein dye used as an acid–base (pH) indicator. Its transition range is around pH 9.3–10.5. Below this pH, it is colorless; above, it is blue. The molar extinction coefficient for the blue thymolphthalein dianion is 38,000 M−1 cm−1 at 595 nm.[2]
Thymolphthalein (pH indicator) | ||
below pH 9.3 | above pH 10.5 | |
9.3 | ⇌ | 10.5 |
Quick Facts Names, Identifiers ...
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Names | |
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Preferred IUPAC name
3,3-Bis[4-hydroxy-2-methyl-5-(propan-2-yl)phenyl]-2-benzofuran-1(3H)-one | |
Identifiers | |
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3D model (JSmol) |
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ChEMBL | |
ChemSpider |
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ECHA InfoCard | 100.004.300 ![]() |
EC Number |
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PubChem CID |
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UNII | |
CompTox Dashboard (EPA) |
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Properties | |
C28H30O4 | |
Molar mass | 430.544 g·mol−1 |
Appearance | White powder |
Melting point | 248 to 252 °C (478 to 486 °F; 521 to 525 K) (decomposes) |
Hazards[1] | |
GHS labelling: | |
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Warning | |
H341, H350, H361 | |
P201, P202, P210, P233, P240, P241, P242, P243, P280, P281, P303+P361+P353, P308+P313, P370+P378, P403+P235, P405, P501 | |
NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Thymolphthalein is also known to have use as a laxative[3] and for disappearing ink.[4]