Title:  Benzopurpurine 4B 
CAS Registry Number:  992-59-6 
CAS Name:  3,3¢-[(3,3¢-Dimethyl[1,1¢-biphenyl]-4,4¢-diyl)bis(azo)]bis[4-amino-1-naphthalenesulfonic acid] disodium salt 
Additional Names:  disodium o-tolidinediazobis(1-naphthylamine-4-sulfonate);  C.I. Direct Red 2;  C.I. 23500;  azamin 4B;  eclipse red;  fast scarlet 
Trademarks:  Paper Red 4B (Crompton & Knowles);  Sultan Red 4B;  Cotton Red 4B 
Molecular Formula:  C34H26N6Na2O6S2 
Molecular Weight:  724.72 
Percent Composition:  C 56.35%, H 3.62%, N 11.60%, Na 6.34%, O 13.25%, S 8.85% 
Literature References:  Prepn from diazotized o-tolidine and sodium 4-amino-1-naphthalenesulfonate:  DE 35615 (1885 to A. G. für Anilinfabrikation Berlin), Frdl. 1, 473; F. J. Welcher, Organic Analytical Reagents vol. 4 (Van Nostrand Co., New York, 1948) pp 338-339; Colour Index vol. 4 (3rd ed., 1971) p 4189.  See also: H. J. Conn's Biological Stains, R. D. Lillie, Ed. (Williams & Wilkins, Baltimore, 9th ed., 1977) p 154. 
Properties:  Brown powder.  Soluble in water, sodium hydroxide, sulfuric acid, ethanol, acetone, Cellosolve.  Practically insol in other organic solvents. 
Use:  For dyeing primarily cotton and viscose rayon:  Colour Index vol. 2 (3rd ed., 1971) p 2101.  As an analytical reagent in detection of Al, Mg, Hg, Ag, U; as a biological stain; as pH indicator, violet 1.2 to red 4.0.   |