Title: Chromotrope 2B
CAS Registry Number: 548-80-1
CAS Name: 4,5-Dihydroxy-3-[(4-nitrophenyl)azo]-2,7-naphthalenedisulfonic acid disodium salt
Additional Names: C.I. Acid Red 176; p-nitrobenzeneazochromotropic acid sodium salt; C.I. 16575
Molecular Formula: C16H9N3Na2O10S2
Molecular Weight: 513.37
Percent Composition: C 37.43%, H 1.77%, N 8.19%, Na 8.96%, O 31.17%, S 12.49%
Literature References: Prepn from diazotized p-nitroaniline and chromotropic acid, see: Colour Index vol. 4 (3rd ed., 1971) p 4097.
Properties: Reddish-brown powder. Sol in water with a yellowish-red color. Insol in alcohol.
Use: As a dye; as a reagent for boric acid or borates.