Bromothymol blue

Bromothymol blue
Names
	Preferred IUPAC name 3,3-Bis[3-bromo-4-hydroxy-2-methyl-5-(propan-2-yl)phenyl]-2,1λ6-benzoxathiole-1,1(3H)-dione
Identifiers
CAS Number	76-59-5 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:86155 ;
ChEMBL	ChEMBL3392578;
ChemSpider	6208 ;
ECHA InfoCard	100.000.884
EC Number	200-971-2;
PubChem CID	6450;
UNII	VGU4LM0H96 ;
CompTox Dashboard (EPA)	DTXSID3058799 ;
	InChI InChI=1S/C27H28Br2O5S/c1-13(2)17-11-20(15(5)23(28)25(17)30)27(19-9-7-8-10-22(19)35(32,33)34-27)21-12-18(14(3)4)26(31)24(29)16(21)6/h7-14,30-31H,1-6H3 Key: NUHCTOLBWMJMLX-UHFFFAOYSA-N ; InChI=1/C27H28Br2O5S/c1-13(2)17-11-20(15(5)23(28)25(17)30)27(19-9-7-8-10-22(19)35(32,33)34-27)21-12-18(14(3)4)26(31)24(29)16(21)6/h7-14,30-31H,1-6H3 Key: NUHCTOLBWMJMLX-UHFFFAOYAD;
	SMILES Brc1c(O)c(cc(c1C)C3(OS(=O)(=O)c2ccccc23)c4cc(c(O)c(Br)c4C)C(C)C)C(C)C;
Properties
Chemical formula	C27H28Br2O5S
Molar mass	624.38 g·mol−1
Density	1.25 g/cm3
Melting point	202 °C (396 °F; 475 K)
Solubility in water	Sparingly soluble in water
Acidity (pKa)	7.0
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319
Precautionary statements	P264, P270, P280, P301+P312, P302+P352, P305+P351+P338, P321, P330, P332+P313, P337+P313, P362, P501
NFPA 704 (fire diamond)	2 1 0
Safety data sheet (SDS)	ThermoFisher Scientific
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid. It is typically sold in solid form as the sodium salt of the acid indicator.