Bromophenol blue

Bromophenol blue
Names
	Preferred IUPAC name 3,3-Bis(3,5-dibromo-4-hydroxyphenyl)-2,1λ6-benzoxathiole-1,1(3H)-dione
Identifiers
CAS Number	115-39-9 ; 34725-61-6 (sodium salt) ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:59424 ;
ChEMBL	ChEMBL2103765 ;
ChemSpider	7973 ;
ECHA InfoCard	100.003.715
PubChem CID	8272;
UNII	0R2969YC90 ;
CompTox Dashboard (EPA)	DTXSID6041682 ;
	InChI InChI=1S/C19H10Br4O5S/c20-12-5-9(6-13(21)17(12)24)19(10-7-14(22)18(25)15(23)8-10)11-3-1-2-4-16(11)29(26,27)28-19/h1-8,24-25H Key: UDSAIICHUKSCKT-UHFFFAOYSA-N ; InChI=1/C19H10Br4O5S/c20-12-5-9(6-13(21)17(12)24)19(10-7-14(22)18(25)15(23)8-10)11-3-1-2-4-16(11)29(26,27)28-19/h1-8,24-25H Key: UDSAIICHUKSCKT-UHFFFAOYAE;
	SMILES Brc1cc(cc(Br)c1O)C3(OS(=O)(=O)c2ccccc23)c4cc(Br)c(O)c(Br)c4;
Properties
Chemical formula	C19H10Br4O5S
Molar mass	669.96 g·mol−1
Odor	odorless
Density	2.2 g/mL
Melting point	273 °C (523 °F; 546 K)
Boiling point	279 °C (534 °F; 552 K)
Acidity (pKa)	4.0
	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

Bromophenol blue (3′,3″,5′,5″-tetrabromophenolsulfonphthalein, BPB), albutest is used as a pH indicator, an electrophoretic color marker, and a dye. It can be prepared by slowly adding excess bromine to a hot solution of phenolsulfonphthalein in glacial acetic acid.