9776. Tropaeolin OO

Nomenclature

CAS number: 554-73-4
4-[[4-(Phenylamino)phenyl]azo]benzenesulfonic acid monosodium salt; C.I. Acid Orange 5; p-[(p-anilinophenyl)azo]benzenesulfonic acid sodium salt; sodium p-[(p-anilinophenyl)azo]benzenesulfonate; Diphenylamine Orange; Orange GS; Orange N; Orange IV; Fast Yellow; Acid Yellow D; C.I. 13080.
C18H14N3NaO3S; mol wt 375.38.
C 57.59%, H 3.76%, N 11.19%, Na 6.12%, O 12.79%, S 8.54%.

Description and references

Prepd from diphenylamine and p-sulfobenzenediazonium chloride, followed by reaction with NaOH: Witt, Ber. 12, 258 (1879); Colour Index vol. 4 (3rd ed., 1971) p 4045.

Chemical structure

Properties

Orange-yellow scales or yellow powder. Sol in water.

Use

As indicator. pH: red 1.4 to yellow 2.6.