vhi, a, 3 Pratt and Gibbs: Two Phthaloximes 167 



ing formation of oxime takes place. Further heating of the solu- 

 tion causes an abundant crystallization of phthaloxime. 



When phenylhydrazine acts similarly with phthalic anhydride, 

 the product of the first phase may be isolated. Anilidophthal- 

 amic acid is formed in this case, 8 and has a structure analogous to 

 phthalhydroxamic acid. 



f O 



C— OH 



/V ^ 



\y 



-C— NH-NHC 6 H 5 



f o 



Anilidophthalamic acid. 



Phthaloxime may also be made by the action of hydroxylamine 

 on phthalimide in alkaline solution. Here again the formation 

 of an intermediate product precludes any conclusions being 

 drawn regarding the position of the =NOH group, although 

 phthalimide possesses a symmetrical structure. The reaction is 

 represented by the following equation : 



-c 



\nh+nh 2 oh+h 2 o 



So \/ ^0 



C^OH 



+NH 3 

 -C^-NHOH 



Ammonia is liberated and phthalhydroxamic acid formed. This 

 may be converted into either the white or yellow phthaloxime 

 according to the temperature at which the solution is heated after 

 being acidified. 



The existence of two isomeric phthaloximes may be explained 

 by means of the unsymmetrical formula in a manner similar to 

 that employed with the benzaldoximes, and indicated graphically 

 by the formulas Ha and lib where the syn type shows the hy- 

 droxyl in closer proximity to the unsaturated carbonyl group. 



C=0 



/ \ 



C 6 H 4 



\ / 

 C 



II 



HO— N 



lib Anti. 



"Hotte, Journ. f. prakt. Chem. (1887), II, 35, 268. 



c=o 



/ \ 



C 6 H 4 



\ / 



C 



II 

 N— 



Ila Syn. 



