3068. 2,6-Dichloroindophenol Sodium

Nomenclature

CAS number: 620-45-1
2,6-Dichloro-4-[(4-hydroxyphenyl)imino]-2,5-cyclohexadien-1-one sodium salt (1:1); sodium 2,6-dichloroindophenol; sodium 2,6-dichloro-N-(p-hydroxyphenyl)-p-benzoquinone imine; 2,6-dichloro-1,4-benzoquinone-4-(4-hydroxyanil) sodium; 2,6-dichlorophenol-indophenol sodium; Tillman's reagent.
C12H6Cl2NNaO2; mol wt 290.08.
C 49.69%, H 2.08%, Cl 24.44%, N 4.83%, Na 7.93%, O 11.03%.

Description and references

Prepd from 2,6-dichloro-p-quinone-4-chlorimide and phenol in alkaline soln: Gibbs et al., Public Health Rep. 40, 650 (1925); Tillmans et al., Z. Unters. Lebensm. 56, 273 (1932).

Chemical structure

Properties

Dark green powder. May contain up to 2 mols H2O. Freely sol in water, alc. The aq soln is deep blue, changed to red by acids. It liberates iodine from KI in acid solns.

Use

Analytical reagent in the determn of ascorbic acid (vitamin C) which reduces the dye to a colorless hydroxy compd. Indicator.