120 The Philippine Journal of Science i9i4 



inating hydrogen sulphide, it was hoped that further proof 

 concerning the structure of phthaloxime ' might thus be obtained. 

 Unfortunately, it was not possible to replace directly the sulphur 

 atom by the oximido group with the formation of a symmetrical 

 oxime. The reaction always took place with the intermediate 

 formation of phthalhydroxamic acid and opening of the 

 lactone ring. This question will be discussed again under 

 thiophthaloxime. 



A comparison between the absorption spectra of dithio- 

 phthalimide and phthalimide ^ shows points of relationship as 



well as characteristic differences. The band heading at - =3460 



A 



is common to both, but is more pronounced in the former 

 compound. Incipient benzene bands are evident in the spectra, 

 but phthalimide produces no bands corresponding to those 



heading at ^ = 2020 and - = 3020. The addition of alkali 



A A 



shifts general absorption toward the red in both cases, but with 

 the sulphur derivative more complicated changes accompany 

 salt formation. The elimination of the color band and ap- 

 pearance of a new band at = 2600 can be satisfactorily 



A 



explained by considering the relationships existing between 

 partial valencies before and after salt formation. The color 



band heading at - = 2020 probably owes its origin to conjugated 



A 



linking between the two thionyl groups, as represented by the 

 formula : 



_C=S 



HN<^ 



^ C=S 

 The introduction of metal in place of imido hydrogen tends 

 to attract the partial valency of sulphur, thus diminishing this 

 conjugation and reducing the color band of the imide to a 

 rapid extension of general absorption as given by solutions 

 of its salt. This shifting of valency must produce a new 

 equilibrium, and in fact a new absolution band appears in the 



spectrum heading at - = 2400 while the band at — 3020 



A A 



nearly disappears. 



' Orndorff and Pratt, Am. Chem. Journ. (1912), 47, 89; Pratt and Gibbs, 

 This Journal, Sec. A (1913), 8, 165. 



'Pratt, This Journal, Sec. A (1913), 8, 405. 



