CAS Number: 76-59-5
Molecular Formula: C27H28Br2O5S
Molecular Weight: 624.38
IUPAC Name: 4,4'-(1,1-Dioxido-3H-2,1-benzoxathiole-3,3-diyl)bis(2-bromo-6-isopropyl-3-methylphenol)
Other Names: 3′,3″-Dibromothymolsulfonphthalein
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), such as managing the pH of pools and fish tanks.
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.
