(.820 ) 
Chemistry. — “On the action of nitrous acid on dinitrodialkyl- 
anilines’. By Prof. P. van Rompuren. 
According to Hanrzscn (B. 48, 1674 [1910)) there is formed by 
the action of nitric acid (D. 1.3) on dimethylaniline, 3.4 dinitrodimethyl- 
aniline which is regarded by him as a new compound. Apart from 
the fact that I obtained this substanee many years ago (Rec. VI, 253 
[1887 }) and explained its structure in 1895 *), the communication of 
Hantzscu attracted my attention because in my investigations as to 
the action of nitric acid of widely different concentrations on dime- 
thylaniline, I always obtained — dependent on circumstances — 
besides tetranitrotetramethylbenzidine *), derivatives of mono- and 
dimethylaniline in which the nitro groups occupied in regard to the 
amino group, the ortho or para-position, but never the meta-position. 
Derivatives with a nitro group in the meta-position could only be 
obtamed by nitrating dimethylaniline in the presence of a large 
excess of strong sulphuric acid. 
I therefore, have had the action of nitric acid (D 1.3) on dime- 
thylaniline repeated by one of my students, Mr. Jansen. As one 
of the reaction products there is formed indeed a yellow substance 
(m.p. 175°—176°) which, however, is nothing else but the well 
known 2.4 dinitromonomethylaniline, as was shown from the analytical 
results, and also by a comparison with a preparation obtained by 
oxidation of 2.4 dinitrodimethylaniline, and with one obtained 
from methylamine and bromodinitrobenzene with which it did not 
cause a depression of the melting point. 
On the other hand when it is mixed with the 3.4 dinitrodimethyl- 
aniline (m.p. 176°) previously obtained by me, it causes a strong 
decrease of the melting point. 
As in the reaction described nitrous acid is generated, it is obvious 
to assume that by its action on the dimethylamino-group one methyl- 
group is split off, a reaction of which, moreover, many instances are 
known. 
If to the nitric acid (D.1.3) a little urea is first added to remove 
any nitrous acid generated, the monomethyl derivative is not 
formed, but as main product 2.4 dinitrodimethylaniline (m.p. 87°) is 
obtained. 
In an experiment where a solution of dimethylaniline in ten times 
its volume of nitrie acid (D. 1.8) had stood over night, there- was 
1) Meeting Febr. 23, 1895. 
2) Rec. 5, 244 [1886], 
