126 UNIVERSITY OF COLORADO STUDIES 



as their own indicators, because, at the point of neutralization, the 

 change from bright yellow to colorless is very sharp. 



Dilute sulphuric acid dissolves the base to the same yellow-colored 

 solution and the concentrated acid to a colorless one, showing that a 

 sulphate is also probably formed. This salt could not be isolated 

 from the solution on account of its extreme solubility, and also because, 

 on standing, it decomposed into mesityloxide and phenylene-diamine 

 sulphate, as shown by the characteristic odor of mesityloxide and an 

 analysis of the crystals which are slowly deposited. These crystals 

 show the characteristic diamido-phenazine reaction with ferric chloride. 



If alcohol solutions of the base and picric acid are mixed, bright 

 yellow needles crystallize out, having a composition C I2 H l6 N 2 , 

 2 C 6 H 2 OH(N0 2 ) 3 . 



The base also gives a platinum double salt, (C I2 H l6 N 2 ) 2 H 2 PtCl 6 . 



With potassium nitrite and an acetic acid solution of the base, a 

 dinitroso compound is obtained, as shown by the analysis (correspond- 

 ing to a compound C J2 H I4 N 2 (NO) 2 ), and the fact that it shows Lieber- 

 mann's reaction for nitroso compounds. 



Treated with benzoylchloride, the base immediately dissolves, and 

 the solution suddenly solidifies to a mass of minute yellow crystals. 

 The analysis shows them to be C I2 H I4 N 2 (C 6 H 5 CO) 2 . 



If the base is treated with acetic anhydride, it dissolves, but no crys- 

 tals are formed. Addition of alkali gives the odor of mesityloxide, 

 showing that a decomposition has taken place. No acetyl derivative 

 was obtained by using acetyl-chloride. 



The base seems to be stable toward reducing agents, being unacted 

 upon by sodium and hot alcohol. It is, however, very sensitive to oxi- 

 dizing agents. Potassium bichromate, potassium permanganate, alka- 

 line potassium ferricyanide, and hydrogen peroxide attack it, forming a 

 quinoxaline, and in some cases another dihydro-quinoxaline. At the 

 same time, there are formed large quantities of a dark substance more 

 or less soluble in most solvents, so that it was not possible to isolate 

 the pure quinoxaline. Its presence is, however, betrayed by the char- 

 acteristic odor of quinoxalines. If the base is allowed to stand several 

 days with hydrogen peroxide, it dissolves to a yellow solution which 



