( 605 ) 



NH, also between CO and CH 2 , and, according to the rule, it ought 

 to yield readily a dinitro-derivative ; either stable or unstable. Still 

 it might be that it was not attacked at all by absolute nitric acid, 

 for if we remember that diacetamide, although slowly, still evolves 

 N 2 with nitric acid and, therefore, presumably forms an unstable 

 nitro-compound under those circumstances, and if we compare this 

 with the cyclic succinimide, which is not attacked at all even on 

 warming and which is connected with it in such a manner that it 

 contains two hydrogen atoms less, and thus causes the cyclic combi- 

 nation, one feels inclined to attribute to the cyclic combination the 

 prevention of the action of the nitric acid. We might also compare 

 ethyleneoxamide to dimethyloxamide which is readily nitrated, ami 

 is related to it in the same manner as diacetamide to succinimide, 

 and if the cycle formation has the same effect here as it has in 

 the other case, ethyleneoxamide should not be attacked. 



Preliminary experiments with the impure substance showed that 

 no stable dinitro-derivate appears to be formed ; at most, one which 

 is at once decomposed by nitric acid, or it is not attacked at all. 

 A very slow evolution of N 2 and C0 2 takes place, but this may 

 be due to the impurity. 



Of the eleven possible isomers there are only two urea derivatives 

 namely hydro-uracil, which, as stated, conforms to the rule and gives 



CH 2 — CO— CH 2 

 a mononitroderivative. The second is . Rügheimer 



NH — CO— NH 

 acetoneureïne 

 thought in 1892 that he had obtained this substance by the action 

 of chloro-formic ester on diaminoacetone, but it was merely a surmise; 

 no analysis was made and the properties were not investigated ; and 

 from our investigations it is extremely doubtful whether he had this 

 substance in hand, for although we made the experiments in various 

 ways we could obtain nothing else but acetondiurethane, from which 

 a dinitro-derivative was readily obtained. A number of other methods 

 for preparing acetonureine from diaminoacetone were tried but always 

 without good result. In the meanwhile we are continuing our experi- 

 ments for, we attach great importance to this substance as a second 

 urea derivative, seeing that the first one conforms to the rule. 



CO— CH S — CO 



A fifth isomer would be which we have tried in 



NH— CH 2 — NH 

 methylenenialonamide 

 vain to prepare from malonamide and formaldehyde. In this case 

 'it is the group CH a of the malonic acid which appears t<> react 



