176 



The Philippine Journal of Science 



1913 



represents the chromophoric development in this case by the 

 formulas : 



R R 



N^C=NOH 



«/\ 



c=o 



Oximido-oxazolone. 

 (Colorless.) 







C— NO 

 C— 



M 



Oximido-oxazolone salts. 

 (Colored.) 



He has found that this oxime shows only general absorption in 

 its spectrum, while solutions of its salts are strongly selective 

 with a well-marked band in the color region. It is evident that 

 conditions in compounds of this type are similar to those in 

 phthaloxime as far as the production of color upon salt forma- 

 tion is concerned. There is no possibility for quinoid configura- 

 tion of a ring in the oximido-oxazolones, yet the change in their 

 absorption spectra upon the addition of alkali closely resembles 

 that shown by phthaloxime. It does not seem essential, there- 

 fore, to assume an actual quinoid structure in the latter case, but 

 merely that the two rings act similarly toward the conjugated 

 partial valencies in both classes of compounds, and that the gen- 

 eral effect of a positive metal atom in the molecule is analogous. 



COLOR DUE TO MOLECULAR REARRANGEMENT 



There are several factors which render it improbable that the 

 salts of phthaloxime possess a different molecular structure from 

 that of the oxime. The red silver salt reacts easily and at low 

 temperatures with alkyl iodides giving ethers that undoubtedly 

 possess the true oxime structure. These ethers are colorless in 

 the case of the colorless isomer, and faintly yellow when derived 

 from the yellow oxime. They are broken down by solutions of 

 the caustic alkalies into substituted hydroxylamines, and give 

 absorption spectra closely resembling the parent oximes. No 

 ethers have thus far been made that show the color characteristic 

 of the salts, and if formed as the first phase of the reaction be- 

 tween silver salt and alkyl iodide they must be very unstable. 



Since the two phthaloximes have been shown to retain their 

 identity when converted into salts, 22 any formula representing a 

 different arrangement of the molecule to explain color must in- 

 clude the doubly bound nitrogen upon which the isomerism 



" Orndorff and Pratt, loc. cit. 



