Thymol Blue CAS 76-61-9

Brown-green crystalline powder with peculiar odor; soluble in ethanol, it turns yellow, soluble in dilute lye, it turns blue, insoluble in water; the maximum absorption wavelength is 594 (376) nm, insoluble in water, soluble in ethanol, and it turns yellow. It is prepared by the condensation of Liphenol and o-sulfobenzoic anhydride, and there are two discoloration ranges: (1) the acid range is pH 1.2-2.8, from red to yellow; (2) the alkali range is pH 8.0-9.6, from Yellow to blue.