Bromocresol purple

Bromocresol purple
Names
	Preferred IUPAC name 3,3-Bis(3-bromo-4-hydroxy-5-methylphenyl)-2,1λ6-benzoxathiole-1,1(3H)-dione
	Other names 5′,5′′-Dibromo-o-cresolsulfonephthalein; Bromcresol purple
Identifiers
CAS Number	115-40-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:86154 ;
ChemSpider	7974 ;
ECHA InfoCard	100.003.716
EC Number	204-087-8;
PubChem CID	8273;
UNII	201C22C3EC;
CompTox Dashboard (EPA)	DTXSID3059428 ;
	InChI InChI=1S/C21H16Br2O5S/c1-11-7-13(9-16(22)19(11)24)21(14-8-12(2)20(25)17(23)10-14)15-5-3-4-6-18(15)29(26,27)28-21/h3-10,24-25H,1-2H3 Key: ABIUHPWEYMSGSR-UHFFFAOYSA-N ; InChI=1/C21H16Br2O5S/c1-11-7-13(9-16(22)19(11)24)21(14-8-12(2)20(25)17(23)10-14)15-5-3-4-6-18(15)29(26,27)28-21/h3-10,24-25H,1-2H3 Key: ABIUHPWEYMSGSR-UHFFFAOYAH; InChI=1/C21H17BrO5S/c1-12-9-14(7-8-18(12)23)21(15-10-13(2)20(24)17(22)11-15)16-5-3-4-6-19(16)28(25,26)27-21/h3-11,23-24H,1-2H3;
	SMILES Brc1c(O)c(cc(c1)C3(OS(=O)(=O)c2ccccc23)c4cc(c(O)c(Br)c4)C)C;
Properties
Chemical formula	C21H16Br2O5S
Molar mass	540.22 g·mol−1
Appearance	Purple powder
Melting point	241 to 242 °C (466 to 468 °F; 514 to 515 K) (decomposition)
Solubility in water	< 0.1 %
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
NFPA 704 (fire diamond)	1 0 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

Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a dye of the triphenylmethane family (triarylmethane dyes) and a pH indicator. It is colored yellow below pH 5.2, and violet above pH 6.8. In its cyclic sulfonate ester form, it has a pK_a value of 6.3, and is usually prepared as a 0.04% aqueous solution.