58 A METHOD FOR MAKING METHYL VIOLET.— CREIGHTON. 



according as the number of alkyl groups is greater or less. 

 The red or blue shades of the various alkyl substitution 

 products of para-rosaniline are ilsually denoted by affixing 

 to the name methyl violet the letters R, 2R, 3K, B, 2b 6ti, 

 etc Thus Hofmann's violet, which is a mixture of the 

 lowest substitution products of para-rosaniline, gives shades 

 corresponding to the letters R, 2R and 3R. On the other 

 hand methyl violet, as prepared in the manner described 

 below, is essentially a mixture of the hydrochlorides of penta- 

 and hexamethyl-rosaniline, 



C6H4.NH(CH,) /^ C6H4.H(CH3)2 



C6H4.N(CH3)2 and ^^^^^ C6H4.N(CH3)2 



CeH4:N(CH3).Cl CeH4:N(CH.Cl, 



and accordingly gives bluer shades than Hofmann's violet, 

 which correspond to the letters B and 2B. A preponderance 

 of the penta-compound gives a methyl violet B, while an 

 increase in the proportion of the hexa-derivative produces 

 a methyl violet 2B. 



Methyl violet B or 2B is formed by the action of a number 

 of oxidizing agents on dimethylaniline. The first step in its 

 formation is the production of formaldehyde and monomethyl- 

 aniline : 



2C6H5.N(CH3)2 + 02 = 2CH2O + 2C6H5.NH(CH3). 

 Part of the formaldehyde, which supplies the so-called 

 methane carbon, then combines with one molecule of mono- 

 methylaniline, two molecules of dimethylaniline and one 

 molecule of oxygen to form the penta-carbinol base: 



CH2O + CeHs.NHCCHs) + 2C6H5.N(CH3)2 + 02 = 



C6H4,NH(CH3) 

 C6H4.N(CH3)2 + 2H20; 



)H ^ C6H4.N(CH3)2 

 while part of it combines with three molecules of dimethyl- 



