Thymolphthalein

Thymolphthalein
Names
IUPAC name
3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-2-benzofuran-1-one
Identifiers
125-20-2 N
ChEMBL ChEMBL587849 YesY
ChemSpider 29054 YesY
EC Number 204-729-7
Jmol interactive 3D Image
PubChem 31316
Properties
C28H30O4
Molar mass 430.54 g·mol−1
Appearance White powder
Melting point 248 to 252 °C (478 to 486 °F; 521 to 525 K) (decomposes)
Hazards
R-phrases 4, 10
S-phrases S22 S24/25
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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 38000 M−1cm−1 at 595 nm.[1]

Thymolphthalein (pH indicator)
below pH 9.3 above pH 10.5
9.3 ⇌ 10.5

Preparation

Thymolphthalein can be synthesized from thymol and phthalic anhydride by Friedel-Crafts alkylation:

References

  1. ↑ 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.
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