Thymolphthalein

Thymolphthalein
IUPAC name 3,3-bis(4-hydroxy-2-methyl- 5-propan-2-ylphenyl)- 2-benzofuran-1-one
Identifiers
CAS number	125-20-2 Y
PubChem	31316
ChemSpider	29054 Y
EC number	204-729-7
ChEMBL	CHEMBL587849 Y
Jmol-3D images	Image 1
SMILES O=C1OC(c2ccccc12)(c3cc(c(O)cc3C)C(C)C)c4cc(c(O)cc4C)C(C)C
InChI 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 Y Key: LDKDGDIWEUUXSH-UHFFFAOYSA-N Y 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
Properties
Molecular formula	C28H30O4
Molar mass	430.53 g/mol
Appearance	White powder
Melting point	248 - 252 °C (decomp.)
Hazards
R-phrases	4, 10
S-phrases	S22 S24/25
NFPA 704	0 1 0
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Thymolphthalein is an acid-base (pH) indicator. Its transition range is at approximately pH 9.3-10.5. Below this pH, it is colorless; above this pH, it is blue. The molar extinction coefficient for the blue thymolphthalein dianion is 38000 M^-1cm^-1 at 595 nm.

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