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Dr. Hofmann on Aniline-blue* 



[Nov. 19, 



Action of reducing agents upon Triphenylic Rosaniline. — Remembering 

 the facility with which rosanihne is attacked by reducing agents, and the 

 valuable help which the examination of the leucaniline thus produced 

 afforded in establishing the formula of rosaniline, I was led to study the 

 deportment of the triphenylic derivative under similar circumstances. This 

 substance indeed is readily reduced both by nascent hydrogen and by sul- 

 phide of ammonium. 



The alcoholic solution of the chloride, when left in contact with zinc 

 and hydrochloric acid, is rapidly decolorized. The clear liquid when 

 mixed with water yields a white, scarcely crystalline precipitate, which may 

 be freed from chloride of zinc by washing, and separated from accidental 

 impurities by solution in ether, in which it is easily soluble. 



If the reduction be effected by sulphide of ammonium, the product is 

 apt to be contaminated with sulphur and secondary products. In this case 

 the separation has to be accomplished by treating the crude mass obtained 

 in the reaction with bisulphide of carbon, which dissolves both the sulphur 

 and the product of the reduction, leaving behind a brown resinous sub- 

 stance, the nature of which is not yet investigated. The mixture remain- 

 ing after the evaporation of the bisulphide of carbon is repeatedly boiled 

 with soda, which dissolves the sulphur ; the residuary compound is then 

 finally purified by solution in ether, from which it is deposited on spon- 

 taneous evaporation in the form of a friable resin. 



Unfortunately this compound is no longer basic, so that it was im- 

 possible to combine it with acids ; but its combustion has furnished numbers 

 agreeing exactly with the composition assigned to it by theory, namely 



C33H33N,=C,„H„ (C,H,)3N3. 

 The compound accordingly is triphenylic leucaniline. It will be observed 

 that the triphenylic derivative, like leucaniline itself, is anhydrous — a 

 constancy of behaviour in the normal and derived compounds which has 

 already been pointed out in the case of rosaniline and its phenylic deriva- 

 tive. Under the influence of oxidizing agents, the hydrogenetted body is 

 rapidly reconverted into the compound from which it has been obtained. 

 The experiment succeeds best with platinum-chloride. The colourless 

 solution of triphenylic leucaniline, when boiled with a few drops of dichlo- 

 ride of platinum, immediately assumes the splendid blue colour which 

 distinguishes the salts of the non-hydrogenetted base. 



The transformation of aniline-red into aniline-blue possesses a variety of 

 interests. A lively imagination might feel tempted to speculate on the 

 relation between colour and composition ; but there are other questions 

 claiming more immediately the attention of the experimentalist. 



Up to the present moment chemists were unacquainted with a method 

 of phenylation. The chloride, bromide, and iodide of the phenyl- series 

 have been but imperfectly studied ; but we are sufficiently acquainted with 

 them to know that they are far from possessing the plastic character of 

 the corresponding compounds of the methyl- and ethyl-series, which 



