VIII, A, S 



Pratt and Gibbs: Tivo Phthaloximes 



171 



slight extent depending upon the solvent, although the activity 

 is not sufficient to cause any indication of a color band in the 

 absorption spectrum. The stronger general absorption of the 

 oxime as compared with the benzoate shows a tendency toward 

 the production of a band, as might be expected. 



The replacement of hydrogen by a metal atom introduces a 

 strong positive sphere of influence that must have a greater dis- 

 turbing effect on the negative latent valencies. The more posi- 

 tive the metal or group introduced, the greater will be the 

 resulting change produced. The following table of optical 

 properties of phthaloxime and various derivatives shows that the 

 character of light transmitted by the crystals may be arranged in 

 a graded scale corresponding with the increasing basicity of the 

 substituting atom or radical. 



Table I. a — Optical properties of phthaloxime and derivatives. 



Compound. 



Character of light rays transmitted 

 through crystals. 



Degree of pleo- 

 chroism. 



White oxime 



White 



Absent. 

 Faint. 



Do. 

 Marked. 

 Strong. 

 Rather marked. 



Ethyl ether of yellow oxime 



White and faint greenish yellow 



Acid sodium salt of white oxime. 



Pale yellow and orange 











■ Determinations made by Professor Gill, mineralogical department, Cornell University : 

 see Orndorff and Pratt, loc. cit. 



The potassium salt forms very small crystals that are difficult 

 to examine, but in bulk the color appears darker than the corre- 

 sponding sodium salt. The differences existing among the above 

 salts in crystalline condition are very distinct, but cannot be ac- 

 curately shown spectroscopically. Alcohol solutions of the am- 

 monium, lithium, barium, sodium, and potassium salts were 

 photographed. All of these solutions in hundredth molar con- 

 centration showed a well-marked color absorption band increas- 

 ing in width and persistence in the order named. This was 

 partly due to the different dissociation constants of the various 

 alkalies, but this factor could not be eliminated in as much as the 

 addition of an excess great enough to compensate for the disso- 

 ciation always resulted in the formation of hydroxamic acid and 

 destruction of the oxime. 



A very weak base such as pyridine dissolves phthaloxime with 

 slight change of color, and the solution gives an absorption spec- 

 trum showing no band in the visible region. This indicates that 



