Thymolphthalein
Appearance
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Names | |
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IUPAC name
3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-2-benzofuran-1-one
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Identifiers | |
3D model (JSmol)
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ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.004.300 |
EC Number |
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PubChem CID
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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 | |
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 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.[1]
Thymolphthalein (pH indicator) | ||
below pH 9.3 | above pH 10.5 | |
9.3 | ⇌ | 10.5 |
Thymolphthalein (pH indicator) | ||
below pH <0 | above pH 9.3 | |
<0 | ⇌ | 9.3 |
Thymolphthalein is also known to have use as a laxative [2] and for disappearing ink.[3]
Preparation
Thymolphthalein can be synthesized from thymol and phthalic anhydride by Friedel–Crafts alkylation:
References
- ^ Hahn HH; Cheuk SF; Elfenbein S; Wood WB (April 1970). "Studies on the Pathogenesis of Fever: Xix. Localization of Pyrogen in Granulocytes" (PDF). J. Exp. Med. 131 (4): 701–9. doi:10.1084/jem.131.4.701. PMC 2138774. PMID 5430784.
- ^ Hubacher MH, Doernberg S, Horner A. Laxatives: chemical structure and potency of phthaleins and hydroxyanthraquinones. J Am Pharm Assoc Am Pharm Assoc. 1953;42(1):23-30. PMID 13034620.
- ^ Katz, David A. (1982). "Disappearing Ink" (PDF). www.chymist.com. Retrieved August 14, 2017.
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