2576. o-Cresolphthalein

Nomenclature

CAS number: 596-27-0
3,3-Bis(4-hydroxy-3-methylphenyl)-1(3H)-isobenzofuranone; 3,3′-dimethylphenolphthalein.
C22H18O4; mol wt 346.38.
C 76.28%, H 5.24%, O 18.48%.

Description and references

Prepn: F. J. Welcher, Organic Analytical Reagents vol. 4 (Van Nostrand, New York, 1948) p 482; Hubacher et al., J. Am. Pharm. Assoc. 42, 23 (1953).

Chemical structure

Properties

Crystals from alc, mp 223°. Slightly sol in water; sol in alcohol. pK 9.4.

Use

As indicator: pH range, 8.2 colorless, 9.8 red. Analytical reagent.