:Thymolphthalein

{{About|thymolphthalein|other related dyes in the phthalein family|Phthalein dye}}

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 470609780

| ImageFile = Thymolphthalein skeletal.svg

| ImageClass = skin-invert-image

| ImageSize =

| PIN = 3,3-Bis[4-hydroxy-2-methyl-5-(propan-2-yl)phenyl]-2-benzofuran-1(3H)-one

| OtherNames =

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 29054

| 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

| InChIKey = LDKDGDIWEUUXSH-UHFFFAOYAV

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 587849

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 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

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = LDKDGDIWEUUXSH-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 125-20-2

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = YG5I28WSQP

| EINECS = 204-729-7

| PubChem = 31316

| SMILES = O=C1OC(c2ccccc12)(c3cc(c(O)cc3C)C(C)C)c4cc(c(O)cc4C)C(C)C

}}

|Section2={{Chembox Properties

| C=28 | H=30 | O=4

| Appearance = White powder

| Density =

| MeltingPtC = 248 to 252

| MeltingPt_notes = (decomposes)

| BoilingPt =

| Solubility =

}}

|Section7={{Chembox Hazards

| MainHazards =

| NFPA-H = 1

| NFPA-F = 0

| NFPA-R = 0

| NFPA-S =

| Hazards_ref={{cite web |title=Thymolphthalein |url=https://pubchem.ncbi.nlm.nih.gov/compound/31316#section=Safety-and-Hazards |website=pubchem.ncbi.nlm.nih.gov |language=en}}

| GHSPictograms = {{GHS08}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|341|350|361}}

| PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|280|281|303+361+353|308+313|370+378|403+235|405|501}}

| FlashPt =

| AutoignitionPt =

}}

}}

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.{{cite journal |author=Hahn HH |author2=Cheuk SF |author3=Elfenbein S |author4= Wood WB |title= Studies on the Pathogenesis of Fever: Xix. Localization of Pyrogen in Granulocytes|journal= The Journal of Experimental Medicine|volume=131 |issue=4 |pages=701–9 |date=April 1970 |pmid=5430784 |pmc=2138774 |doi= 10.1084/jem.131.4.701}}

{{pH_indicator_template|indicator_name=Thymolphthalein |low_pH=9.3 |high_pH=10.5|low_pH_color=white|high_pH_color=blue|high_pH_text=white}}

Thymolphthalein is also known to have use as a laxative{{cite journal | last1 = Hubacher | first1 = MH | last2 = Doernberg | first2 = S | last3 = Horner | first3 = A | year = 1953 | title = Laxatives: chemical structure and potency of phthaleins and hydroxyanthraquinones | journal = Journal of the American Pharmaceutical Association | volume = 42 | issue = 1| pages = 23–30 | pmid = 13034620 | doi = 10.1002/jps.3030420108 }} and for disappearing ink.{{Cite web|url=https://www.chymist.com/Disappearing%20Ink.pdf|title=Disappearing Ink|last=Katz|first=David A.|date=1982|website=www.chymist.com|access-date=August 14, 2017}}