( 46 ) 



"amide d'un acide oxalylbiurétiqne" prepared by Grimaüx which in 

 the German literature is wrongly called oxalyldiureïd. The oxalyl- 

 diiireïd obtained by me not only shows complete insolubility in all 

 the ordinary solvents, but also gives no biuret reaction. 



Symmetric dimethylurea whether in ether at the ordinary temperature 

 or in boiling benzene gave the well-known cholestiophane, whereas 

 with asymmetric dimethylurea, when boiled in benzene, carbonyl- 



,NH CO N (CH3), 



di-(as. dimethylurea) CO . 7^ H^O is obtained in parti- 



^NH CO N (CH3), 

 cularly beautifully formed prismatic crystals melting at J 40° C. 



Chemistry. — "■Additive compoimds of ju. Dinitrohenzene." By 



Prof. P. VAN ROMBURGH. 



(Communicated in the meeting of Apiil 28, 1911). 



The increased interest taken in the coloured compounds of polynitro- 

 substances with aromatic amines induces me to call attention again 

 to the fact that m. dinitrobenzene is also capable of yielding with 

 different amines beautifully coloured crystallised compounds as I 

 mentioned casuallj' many years ago ^). 



Generally speaking, these compounds are obtained less readih', and 

 many are less stable than those of s. ti-initrobenzene. This probably ex- 

 plains why NoELTTNG and Sommerhoff ") have not succeeded in isolating 

 such products. Kremann ^) has studied the equilibrium between aniline 

 and m. dinitrobenzene and states that no data occur in the literature 

 as to the existence of a compound between these substances although 

 I had already mentioned having isolated the same. 



If we dissolve m. dinitrobenzene in aniline the liquid turns intensely 

 red on warming and when cold, a beautiful red compound crystallises 

 in large crystals, which melt at 41° — 42° (in a capillary tube). According 

 to Kremann the melting point lies at 40°. The compound consists of 

 an equal number of molecules of the components. On exposure to 

 the air, the crystals lose the aniline. 



Analysis: Found 64.1% C^H^NOJ,. Calculated 64.37„. 



Dimethyl p. toluidine when heated with m. dinitrobenzene gives 

 an intensely coloured solution from which, on cooling, crystallises a 



1) R. 6, 366 (1887). 



2) B. 39. 76 (1906). 



3) M. 25, 1298 (1904). 



