Ryan and Egan — The Action of Nitrous Acid, ^c, on Ureihaties. 165 



completely converted into the 4-nitro compound after three months. As in 

 the experiments with nitrous fumes, the formation of an intermediate product 

 seemed likely, and in order to isolate any such compound the reaction was 

 allowed to proceed for only fourteen days, when the 4-nitro derivative and 

 unchanged phenyl urethane were the sole products. 



T. N"olan (private coramunieatiou from jSTobel's Explosives Company) 

 obtained nitroso-phenylurethane melting at I47°C. by the action of sodium 

 nitrite on a sulphuric acid solution of phenylurethane at a low temperature 

 (-15°C.). 



The reactions of o-tolylurethane with the oxides and oxyacids of nitrogen 

 at low concentration of the substances have not yet been investigated, 

 though its nitro derivatives have been prepared synthetically from the 

 corresponding nitro toluidines and also in this laboratory [H. Eyan and 

 N. CuUinane, Proc. E.D.S., xvii. No. 15], by the action of nitric acid and 

 nitrogen peroxide on ethyl-o-tolylurethane. This substance reacted with 

 nitrous acid and nitrous fumes in a similar manner to the phenyl compound. 

 The urethane was converted by nitrous acid in carbon tetrachloride solution 

 into 4-nitro-otolylurethane melting at 135° C, which had been aheady 

 obtained from 4-nitro-o-toluidine and chlorocarbonic ester. Nitrous fumes 

 also converted a cold ten per cent, solution of o-tolylurethane in carbon 

 tetrachloride into this body. 



In experiments carried out with diphen i/lurethane [H. Ryan and 

 P. Donnellan, Proc. E.D.S., xvii, No. 14], no reaction took place when this 

 body was allowed to remain for a long period with nitric acid in glacial acetic 

 acid solution at the ordinary temperature. Three molecular quantities of 

 nitric acid converted the urethane in five per cent, carbon tetrachloride 

 solution into 4-nitro-diphenylurethane after four weeks, while four and six 

 equivalents of nitric acid yielded dinitro derivatives under the same conditions. 

 In our .experiments, six molecular quantities of nitrous acid were without 

 action on five per cent, solutions of diphenylurethane in acetic acid, alcohol, 

 and carbon tetrachloride, even when the mixtures were allowed to remain 

 at the ordinary temperature for lengthy periods. Nitrous fumes reacted, 

 however, with cold ten per cent, solutions of the urethane in carbon 

 tetrachloride and glacial acetic acid, with formation of 4-10-dinitro-diphenyl- 

 urethane in each ease ; while from a similar solution in glacial acetic acid 

 which was treated with nitrous fumes for a shorter period, the product was 

 4-nitro-diphenyl-urethaue. 



Phenyl-hcnzylurethanc was found [H. Eyan and J. L. O'Donovan, Proc. 

 R.D.S., xvii, No. 17] to react readily with both nitric acid and nitrogen 

 peroxide, when carbon tetrachloride and slacial acelic acid were used as 



