50 Dr. A. W. Hofmann on Aromatic Monamines. [Dec. 5) 



dine, of methylxylidine, and small quantities of dimethylxylidine. Of the 

 two dimethyltoluidines, the one has the vol. w. 0-9324, and boils constantly 

 at 186° ; the other has the vol. w. 0-9368, and boils at 205°, i. e. 19° higher 

 than the former one. The nature of these two bases was fixed by the 

 analysis of their platinum salts, 



2[(C 6 H 4 . CH 3 ) (CH 3 ) 2 N . H CI] . Pt Cl 4 , 



and also of the quartary iodide, 



(0 S H 4 .CH 3 )(CH 3 ) 3 NI, 



into which they were converted by the action of methyl iodide, and the 

 platinum salts corresponding to these iodides, 



2[(C.H 4 XH 3 )(CH 3 ) 3 NCl].PtCl 4 . 



The two dimethylated toluidines here described obviously correspond 

 to two of the three modifications of toluidine, and very probably to the 

 two liquid modifications. Dimethyltoluidine, obtained by converting 

 solid toluidine into the trimethylated toluylammonium iodide, and then 

 submitting the corresponding hydrate to distillation, has a vol. w. 0-988, 

 and boils at 210°. The substance thus obtained, the composition of which 

 was likewise established by analysis of the platinum salt, essentially differs 

 from the isomeric base boiling at 186° ; it is less easily distinguished from 

 the base boiling at 205°, with which more particularly it agrees in odour ; 

 in fact these two compounds exhibit only a slight difference of 5° in 

 their boiling-points. Still I believe them to be isomeric, not identical. 



It deserves to be noticed that while the boiling-point of solid toluidine 

 (202°), by the introduction of two methyl groups, is raised by 8°, the 

 boiling temperature of one of the liquid modifications (198°) is lowered 

 by not less than 12°. Phenomena of this kind have been observed re- 

 peatedly in the course of this inquiry. 



It has been already mentioned that, in addition to the two dimethylated 

 toluidines, the product of the action of heat on trimethylated phenyl- 

 ammonium iodide contains methylxylidine. I have not been able to 

 isolate this compound ; but it was not difficult to prove its presence by 

 the action of methyl iodide on the mixed bases. The two dimethylated 

 toluidines are thus converted into quartary iodides ; but, together with 

 these compounds, there is formed a tertiary iodhydrate, the base of which 

 is readily separated by distillation of the product with an alkali. The 

 base thus liberated has the vol. w. 0-9293, and boils at 196°. Analysis 

 of the platinum salt proved it to be dimethylated xylidine, 

 C 10 H 15 N=[C e H 3 (CH 3 )J(CH 3 ) 2 N, 



which previous to methylation must have obviously existed in the form 

 of monomethylated xylidine, 



0. H.3 N =[C 6 H 3 (CH 3 )J CH 3 . HN. 

 The presence of methylxylidine being only indirectly proved by analysis 



