Bromothymol blue

3 ', 3 '' - Dibromthymolsulfonphthalein, BTB

Pink powder

Fixed

200-202 ° C

• Poorly in water
• Soluble in ethanol

Template: Infobox chemical / molecular formula search available

Bromothymol blue is a triphenylmethane dye and is a member of the sulfonphthaleins. It is accessible by bromination of thymol blue. The sodium salt is a pH indicator.

Properties

Bromothymol blue beats at a pH value of 5.8 to 7.6 from amber to blue. Neutral solutions (pH = 7.0) are colored green. Its pKa is 7.10. The color change based on a change of the chemical structure. In acidic medium, the molecule is in the pale yellow Sultonstruktur. A ring opening to form the intensely blue colored, quinoid triphenylmethane carried out in basic medium.

Use

Can be used in the titration of bromothymol blue as an indicator, the acid -base titration and determination of the neutral point (pH = 7.0), as at 7.0, a color change to green occurs.

Further bromothymol blue is used as the dye in the bacteriological culture media, and as a sensitizer in the electrophotography.

In obstetrics, bromothymol blue is used for the diagnosis of rupture of the membranes.