Thymolphthalein

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Thymolphthalein
Thymolphthalein-skeletal.png
Identifiers
CAS number 125-20-2 N
PubChem 31316
ChemSpider 29054 YesY
EC number 204-729-7
ChEMBL CHEMBL587849 YesY
Jmol-3D images Image 1
Properties
Molecular formula C28H30O4
Molar mass 430.54 g mol−1
Appearance White powder
Melting point 248 - 252 °C (decomp.)
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
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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[edit]

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

ThymolphthaleinSynthesis.png

References[edit]

  1. ^ Hahn HH, Cheuk SF, Elfenbein S, Wood WB (April 1970). "Studies on the Pathogenesis of Fever: Xix. Localization of Pyrogen in Granulocytes". J. Exp. Med. 131 (4): 701–9. doi:10.1084/jem.131.4.701. PMC 2138774. PMID 5430784.