Bromocresol purple

• Bromocresol
• 5 ', 5 '' -dibromo -o- kresolsulfonphthalein

Pale yellow solid

Fixed

240 ° C ( dec.)

PKS2: 6.3

• Insoluble in water
• Soluble in alkalis and ethanol

Attention

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Bromocresol purple (also Bromocresol ) is a triphenylmethane dye and is a member of the sulfonphthaleins. It is used as pH indicator.

Properties and Uses

In acid media, the yellow-colored sultone form of bromocresol purple is stable. From pH = 5.2 the purple- colored quinoid form open manifests itself. This dominates at pH = 6.8, so that a bromocresol purple from this value is colored purple. Note that because of the greater absorbency of the open form of the indicator is already clear purple colored, even if the concentration of the acid form still predominates.