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Thymolphthalein

This article is about thymolphthalein. For other related dyes in the phthalein family, see Phthalein dye.
Thymolphthalein
Names
Preferred IUPAC name
3,3-Bis[4-hydroxy-2-methyl-5-(propan-2-yl)phenyl]-2-benzofuran-1(3H)-one
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.004.300 Edit this at Wikidata
EC Number
  • 204-729-7
UNII
  • InChI=1S/C28H30O4/c1-15(2)20-13-23(17(5)11-25(20)29)28(22-10-8-7-9-19(22)27(31)32-28)24-14-21(16(3)4)26(30)12-18(24)6/h7-16,29-30H,1-6H3 checkY
    Key: LDKDGDIWEUUXSH-UHFFFAOYSA-N checkY
  • InChI=1/C28H30O4/c1-15(2)20-13-23(17(5)11-25(20)29)28(22-10-8-7-9-19(22)27(31)32-28)24-14-21(16(3)4)26(30)12-18(24)6/h7-16,29-30H,1-6H3
    Key: LDKDGDIWEUUXSH-UHFFFAOYAV
  • O=C1OC(c2ccccc12)(c3cc(c(O)cc3C)C(C)C)c4cc(c(O)cc4C)C(C)C
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:
GHS08: Health hazard
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)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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

Thymolphthalein is also known to have use as a laxative[3] and for disappearing ink.[4]

  1. ^ "Thymolphthalein". pubchem.ncbi.nlm.nih.gov.
  2. ^ Hahn HH; Cheuk SF; Elfenbein S; Wood WB (April 1970). "Studies on the Pathogenesis of Fever: Xix. Localization of Pyrogen in Granulocytes". The Journal of Experimental Medicine. 131 (4): 701–9. doi:10.1084/jem.131.4.701. PMC 2138774. PMID 5430784.
  3. ^ Hubacher, MH; Doernberg, S; Horner, A (1953). "Laxatives: chemical structure and potency of phthaleins and hydroxyanthraquinones". Journal of the American Pharmaceutical Association. 42 (1): 23–30. doi:10.1002/jps.3030420108. PMID 13034620.
  4. ^ Katz, David A. (1982). "Disappearing Ink" (PDF). www.chymist.com. Retrieved August 14, 2017.
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