1872.] 



Derivatives of Uramidobenzoic Acid. 



173 



acid is precipitated in the crystalline state. It will be seen from the fol- 

 lowing description of their properties how closely they resemble one 

 another. 



a dinitrouramidobenzoic acid, C 8 H G (N0 2 ) 2 N 2 3 . — It crystallizes in 

 yellowish-white needles, which are very readily soluble in alcohol or ether, 

 but scarcely so in cold water. On the addition of barium chloride to even 

 a very dilute ammoniacal solution of the acid, a bright yellow precipitate 

 is produced, consisting of very small nodules, which in their turn are built 

 up of microscopic needles or plates. 



/3 dinitrouramidobenzoic acid, C 8 H 6 (N0 2 ) 2 N 2 3 , has the same crys- 

 talline form as the a acid, which it closely resembles, although it would 

 seem to be somewhat less soluble in alcohol and ether. Its barium salt is 

 a yellow amorphous precipitate. 



y dinitrouramidobenzoic acid, C 8 Ii G (N0 2 ) 2 N 2 3 . — This acid crystal- 

 lizes in yellowish-white plates or needles, which behave towards solvents in 

 a manner similar to the a acid. Its barium salt is obtained in long slender 

 yellow needles, when a solution of the acid in ammonia is decomposed by 

 barium chloride, and is somewhat more readily soluble than the correspond- 

 ing salts formed by the two before-mentioned acids. 



It can be readily understood that when an ammoniacal solution of either 

 of these isomeric dinitro-acids is boiled for a considerable time, that it will 

 be again reconverted into the corresponding mononitro-acid in a manner 

 similar to that previously described as taking place with the mixture of the 

 dinitro-acids : — 



C.H.(N O J,N 1 , + H^ = 



a, f dinitrouramido- Water. 

 (3, \ benzoic 

 y [ acid. 



C 8 H 7 (N0 2 )N 2 3 + NHO ; 



v ^ . ■ . 



a, f nitrouramido- Nitric 



/3, < benzoic acid, 

 y [ acid. 



Decomposition of the Isomeric Dinitrouramidobenzoic Acids on boiling 

 their Aqueous Solution. 



All three of the dinitro-acids are decomposed when their aqueous solu- 

 tions are boiled for a considerable time, gas being evolved and new acids 

 formed, which have the composition C 7 H 6 N 2 Q 4 . These three new acids, 

 from their formula and properties, may be regarded as isomeric mononitro- 

 derivatives of amidobenzoic acid, C 7 II G N 2 4 ==C 7 H 4 (N0 2 ) (NH 2 ) 2 , 

 their method of formation being expressed in the following manner : — ■ 



C 8 H 6 N 4 Q 7 = C 7 H 6 N 2 Q 4 + CO a + 



Isomeric dinitro- Isomeric nitro- Carbonic Nitrous 

 uramidobenzoic acids, amidobenzoic acids. acid. oxide. 



The acid obtained in this manner from a dinitrouramidobenzoic acid, 

 which I have called a nitroamidobenzoic acid, crystallizes in yellow needles 

 or prisms, which are only slightly soluble in cold water, and rather diffi- 



