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.   |