Bromothymol blue is a weak acid that belongs to the sulfonephthalein dye family. :

The most notable feature of bromothymol blue is its ability to change color based on the acidity or alkalinity of a solution. Its transition range is approximately . Solution Type Observed Color Below 6.0 Yellow Around 7.0 Green Above 7.6 Blue

This sensitivity around pH 7 makes it particularly useful for monitoring physiological processes where pH remains close to neutral, such as in enzyme activity studies . Safety Data Sheet: Bromothymol blue - Carl ROTH

(BTB), also known as -dibromothymolsulfonphthalein, is a widely used chemical compound primarily valued as a pH indicator in laboratory and industrial settings. Known for its high sensitivity near neutral pH levels, it is a staple in biological and chemical research. Core Properties and Chemical Structure

: It consists of three aromatic benzene rings, featuring two bromine atoms, hydroxyl groups, and a central sulfonphthalein core.