182 Biological Stains 



q25 RHOD AMINE 6g C. I. NO. J ^2. 



Synonyms: Rhodamine 6GX and 6GDN extra. 

 Calcozine red 6G extra. 



By esterification of a compound closely related to rhodamine B, 

 the following is obtained: 



CH3 • CH2— HN_/\_0_/\_NH— CH2 • CH3 



\ 

 CI 



"C= 



COOCHoCHa 



C26H27N2O3CI; Mol. Wt. 450.949 

 {A basic dye; absorption maxima [492] 52&) 



This dye has not been specified as frequently as rhodamine B, 

 but is mentioned by Strugger and by Monlie (cited above), each 

 of whom employed both dyes. Whether this ethyl ester has any 

 advantage over Rhodamine B is not stated. 



A somewhat different dye, known as Rhodamine S (C. I. No. 

 743) has been mentioned in the same connection and may have 

 been used for some of the above-mentioned purposes. It is not a 

 true rhodamine, however, but belongs to a closely related group of 

 compounds, the succineins; for it does not have the three benzene 

 rings, the radical C6H4 • COOH being replaced by C2H4 • COOH. 



q26 VIOLAMINE R C. I. NO. 758 



Synonyms : Acid violet JfR. Fast acid violet SRL, A2R and R. 



Na-S03_/-\_ /l |_ =1 1 N 



NH V/ C \, 



/ / \ 



CH3 /\_COONa CH3 







C34H2406N2SNa2; Mol. Wt. 634.608 

 (An acid dye) 



Lillie (1945 c) has mentioned this dye, among others, as a stain 

 for collagen in tissue sections. 



