336 Prof. A. W. Hofmann on the Transformation of the [Jan. 24, 



C0„ 



Bat nothing is easier tban to change the conditions of the experiment 

 so as to give rise to the almost exclusive formation of phenylformamide. 

 Act with 1 molecule of oxalic acid on 1 molecule of aniline (or even with 

 3 molecules of oxalic acid on 2 molecules of aniline), taking care to give 

 at once the highest possible temperature, and phenylformamide will be 

 nearly the only product, 1 molecule of water and I molecule of carbonic 

 acid separating from the primary aniline oxalate at first formed, 



/n ^'M ^6 1 C H ) 



h; + H I ^ ^'h I ^ 



The distillate is a fluid of peculiar odour, which, on the addition of a 

 strong solution of caustic soda, immediately sohdifies to the crystalline soda- 

 compound of phenylformamide. This crude product always containing 

 a quantity of aniline, is sufficiently pure for the preparation of metheuyl- 

 diphenyldiamine previously described by me. It is only necessary to 

 treat the distillate with trichloride of phosphorus to obtain the methenyl- 

 compound in abundance. 



The action of oxalic acid on aniline at a high temperature gives rise, 

 however, to quite a series of other reactions subordinate to the principal 

 changes, but affecting nevertheless a goodly quantity of material. Car- 

 bonic oxide is observed to be evolved, together with carbonic acid, during 

 the distillation. It is the result of two secondary processes. In the first 

 place, phenylformamide already formed splits up, according to the analogous 

 decomposition of formamide, into aniline and carbonic oxide, 

 CHOI C,H,] 



c,H. In = H Ik + CO; 

 hJ hJ 



and secondly^ diphenyloxamide undergoes a transformation, previously 

 pointed out by me, being changed into diphenylcarbamide wdth separation 

 of carbonic oxide, 



(C.OJ'M (CO)" ] 



J H, J 



On this occasion the formation of the latter body was once more satis- 

 factorily proved by special experiment. During the distillation a consi- 

 derable quantity of a crystalline substance saturated with oil had solidified 

 in the neck of the retort. This substance was purified by washing with 

 cold and recrystallizing a few times from hot alcohol ; combustion showed 

 that it was pure diphenylcarbamide. 



The crude oil obtained by the distillation of 1 molecule of aniline and 

 1 molecule of oxalic acid contains, further, hydrocyanic acid^ and it is not 

 difficult to explain in a satisfactory manner the origin of this compound. 

 When the distillate is heated to ebullition with concentrated hydrochloric 

 acid, an oily body passes over with the steam. This oil has a peculiar 



