Phenyl Methane Dyes 



157 



The various dyes denoted methyl violet are mixtures of tetra-, 

 penta-, and hexa-methyl pararosanilin : 



CH3 



CH, 



tetra-methyl pararosanilin 

 C23H26N3CI; Mol. Wt. 379.919 



CH, CI 



CH, 



penta-methyl pararosanilin 

 C24H28N3CI; Mol Wt. 393.945 



CH, CI 



hexa-methyl pararosanilin 

 (crystal violet) 



C25H30N3CI; Mol. Wt. 407.971 



{Basic dyes; absorption maxima: 583-587 in 90% alcohol) 



Solubility at 26°C: in water 2.93%; in alcohol 15.21%o 



In the case of these compounds, as in the case of other series of 

 homologs differing in extent of methylation, the shade is deepened 

 by the introduction of each methyl group. Hence the various 

 mixtures known to the trade as methyl violet vary from reddish to 

 bluish violets according to the relative amounts of the more and 

 the less completely methylated compounds present in the mixture. 

 This is the significance of the various shade designations listed 

 above, R's indicating the reddish shades, and B's the bluish shades. 

 Of these various shades the bluer ones seem to be best for biological 



