A METHOD FOR MAKING METHYL VIOLET. CREIGHTON. 59 



aniline and one molecule of oxygen to form the hexa-carbinol 

 base: 



C6H4.N(CH3)2 



CH2O + 3C6H5.N(CH3)2 + Oo = (?^ C6H4.N(CH3)2 



C6H4.N(CH3)2. 



Treatment with hydrochloric acid converts these carbinol 

 bases into the corresponding hydrochlorides. 



In the manufacture of methyl violet at the present time, 

 copper sulphate is employed as the oxidizing agent. This 

 salt reacts with some of the sodium chloride present in the 

 reaction mass (melt) to form cupric chloride, and this is 

 reduced to cuprous chloride. As this latter compound is 

 easily reoxidized to the cupric salt, in situ, bj^ atmospheric 

 oxygen, the melt was formerly rendered porous by the ad- 

 mixture of a large quantity of sand so that the air might 

 have ready access. At the present time the use of sand has 

 been entirely replaced by common salt, as this can be easily 

 removed by dissolution immediately after oxidation, thus 

 considerably decreasing the bulk of the product to be worked 

 with. 



The following method for the manufacture of methjd 

 violet has been developed by the waiter and gives very good 

 results : ^ 



A quantity of finely -ground copper sulphate, correspond- 

 ing to 12 kilograms of the hydrated salt, is intimately mixed 

 with 190 kilograms of dried sodium chloride. To this mixture, 

 under constant stirring, is added 8 kilograms of phenol 

 dissolved in one liter of water, and this is followed by the 

 gradual addition of 20 kilograms of dimethylaniline. The 

 melt is transferred to a closed iron vessel equipped with a 

 stirring and mixing device, where it is continuously stirred 

 at a temperature of 57-60°C. until a sample when squeezed 

 in the hand forms a ball which does not fall apart. This 

 usually requires about eight hours. 



The reaction liberates a considerable amount of heat. 

 This may be increased by dehydrating the copper sulphate 

 prior to mixing with the salt. By employing the dehydrated 

 salt, or suitable proportions of hydrated and dehydrated 



