SECTION ONE 



TRIARYLMETHANE GROUP 



Chromophore: Ar 



C=Ar=NX 



/ 

 Ar 



X = H or H2 or O or an aryl or aliphatic group, 

 where Ar = an aromatic nucleus ; 



The triarylmethane dyes, all of which are quinonoid dyes, can 

 be divided into three main sub-groups, namely: 



1. Triphenylmethane. 



2. Diphenylnaphthylmethane. 



3. Phenyldinaphthylmethane. 



Each of these can be further divided, but space does not 

 permit a discussion of these in this present work. 



Examples of the triarylmethane dyes are given below: 



ACID GREEN L EXTRA 



Michrome No. 647, Molecular weight 691. An acid triphenyl- 

 methane dye, pH 2'^*- Solubility at 15° C; water 5%, absolute 

 alcohol 5%. 



-O3S 



— SOsNa 



* 1% in neutral distilled water; see pages 17 and 29. 



65 



