Methyl Violet 2B, 6B

Property Data
Common name
Suggested name
 
Other names
C.I. number
C.I. name
Class
Ionisation
Solubility aqueous
Solubility ethanol
Absorption maximum
Colour
Empirical formula
 
Formula weight
 
Methyl violet
a) Methyl violet 2B
b) Methyl violet 6B
Gentian violet
42535

Triarylmethane
Basic
2.93%
15.21%
583-587 (Conn)
Violet-blue
a) C23H26N3Cl
b) C24H28N3Cl
a) 380
b) 394

Methyl violets are mixtures of tetramethyl, pentamethyl and hexamethyl pararosanilins (this last is also known as crystal violet or methyl violet 10B). Due to this, the particular shade differs depending on the amount of each present. The more methylated the dyes are, the darker blue the sample will be. Methyl violet 6B is usually darker than methyl violet 2B, and methyl violet 10B is usually even darker. Their commonest use is in Gram's stain for the demonstration and primary classification of bacteria. Methyl violets are metachromatic, and are sometimes used to demonstrate amyloid.

The name gentian violet is often used for the dyes in this general group, but it can not be relied upon for any consistency in identification. It is preferable to avoid the name altogether.

 

Reference
R. D. Lillie.
Conn's Biological Stains
Williams & Wilkins, Baltimore, MD., U.S.A.

Aldrich chemical catalogue, 1992
Aldrich Chemical Company, Milwaukee, WI, USA.

 


 

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