9401. Thymolphthalein

Nomenclature

CAS number: 125-20-2
3,3-Bis[4-hydroxy-2-methyl-5-(1-methylethyl)phenyl]-1(3H)-isobenzofuranone; 5′,5″-diisopropyl-2′,2″-dimethylphenolphthalein.
C28H30O4; mol wt 430.54.
C 78.11%, H 7.02%, O 14.86%.

Description and references

Obtained by heating phthalic anhydride with thymol at 110° in the presence of stannic chloride.

Chemical structure

Properties

Needles, mp ≈253°. Insol in water; sol in alcohol, acetone; also sol in dil alkalies with a blue color, in H2SO4 with a carmine-red color.

Use

As pH indicator: colorless 9.3 to blue 10.5. Also as reagent for blood after decolorizing the alkaline soln by boiling with zinc dust.