IX, A, 2 Pi-att and Brill: Phthalide Compounds 109 



indefinite; hence the band was omitted in plotting the curve. 

 The tenth molar concentration was deep red, becoming tinged 

 with lavender upon dilution. The more concentrated solutions 

 fluoresced slightly in the light of the arc. 



The salts of the alkali metals and ammonia are very soluble 

 in water, and regenerate the imide upon the addition of acid. 

 The absorption spectrum of the sodium salt was obtained with 

 90 per cent alcohol for the hundredth molar concentration. This 

 solution is reddish yellow, becoming canary yellow on dilution 

 with absolute alcohol for the lower concentrations. Higher 

 concentrations of the salt are deep red in thick layers and yellow 

 when viewed through thin films. 



The spectrum showed a rapid extension in general absorption 



between ^ = 1900 and ^ = 2300 and a band at ^ = 2600. The 



A A A 



band at - = 3020 was nearly obliterated, and that at - = 3460 



A A 



was considerably reduced in persistence. 



Dithiophthalimide dissolves in concentrated sulphuric acid with 

 a yellow color, giving an absorption spectrum with a well- 

 marked band at - = 2780 and the original band at - = 3460. 



A A 



Dithiophthalimide is readily soluble in pyridine with a red 

 color, becoming orange upon decreasing the concentration. The 

 absorption spectrum in freshly distilled pyridine, free from 



water, showed a small color band heading at - = 2020 with 



A 



high concentration, a rapid extension of transmission between 

 I = 2400 and ] 



A A 



(fig. 2, page 110). 



\ = 2400 and ] = 2700, and an ultra-violet band at ^ = 2900 

 A A A 



THIOPHTHALANIL 



c=o 



C6H4<(^NC6H4 



C=S 



Thiophthalanil was prepared from phthalanil and phosphorous 

 pentasulphide.* After repeated boiling with bone black and 

 recrystallization from glacial acetic acid and from alcohol, it was 

 obtained in brilliant red needles melting at 145° (corrected), 

 or 1° higher than found by Reissert and Holle. 



The solution in glacial acetic acid was red, and with hun- 



* Reissert und Holle, loe. cit. 



