^71 * 



lo Thiele and Lachman ^) et/ti/Iurea is nitrated at llic ^^//^mo-iiitrogen 

 atom. The nitration products thus should bc : 



a, a-methylnitro-urea, CH3-N(N0,)-C0-NH„ 

 a, />aetlivhiitro-nrea, C.H^-NH-CO-NH-NO,. 



It has now been found that the idea as to the ' nitration of 

 methyl urea is not correct. 



D. and v. P. carried out tlic reaction by treating the sulphuric 

 acid solution of methylurea at a low temperature with the theore- 

 tical quaijtitj' of ethyl nitrate. As products, they obtained methyl- 

 nitramine and a methylnitro-urea melting with decomposition at 

 156—157°. 



I have carried out the nitration in vai-ious ways, namely with the 

 theoretical quantity of ethyl nitrate or absolute nitric acid in sul- 

 phuric acid solution, and also by introducing the nitric acid compound 

 of methylurea into sulphuric acid. Tnvariably, a compound was obtained 

 decomposing between 90 and 100° with evolution ot gas and having 

 the composition of methylnitro-urea; methylnitramine was not formed. 



If this product is dissolved in cold aqueous ammonia and then 

 mixed with dilute sulphuric acid, methylnitro-urea is precipitated, 

 melting with decomposition against 159°. 



D. and v. P. state that this compound is decomposed by ammonia 

 at 100° and then yields methylnitramine ; from this they conclude 

 that it consists of «,a-methylnitro-urea. 



It has now appeared, however, that this compound m.p. 159° is 

 the fl!, ^-methylnitro-urea ; I have proved this structure tirstly by 

 reduction to the corresponding semicarbazide and further by studying 

 the behaviour towards ditferent bases. 



a. Reduction. This was carried out electrochemically, because 

 also in the non-substituted urea the electrical reduction gives far 

 better results than the chemical one ^). The operation took place in 

 dilute sulphuric acid with a cathode of tinned copper gauze. 



The generated product witii benzaldehyde gave a semicarbazone 

 m.p. 166°. From the latter was formed, on heating with dilute sul- 

 phuric acid, the free melhylsemicarbazide m.p. 118°. This compound 

 when decomposed by alkalis gave the non-substituted hydrazine 

 NjH^, and, hence, cannot be anything else but the hydrazinoformic- 

 methylamide NH^-NH-CO-NH-CH,. Consequently the nitrocompound 

 was the rf, /^-methyl-nitro-urea NHfNOj-CO-NH-CH,. 



In order to further conlirm this conclusion the melhylsemicarbazide 



1) A. 288, 285 (1895). 



2) R. 31, 25 (1912). 



