266 BENZENE. 



Orthodiamidobenzene (Orthophenylendiamine), 

 C 6 H 4 (NH 2 ) 2 , is produced by the reduction of orthoni- 

 tranilin with iron-filings and acetic acid, or hydriodic 

 ac id. Colorless crystals. Easily soluble in water. 

 Melts at 140, and boils at 267. 



Paradiamidobenzene (Paraphenylendiamine), 

 C 6 H 4 (NTI 2 ) 2 . Is produced by the reduction of dinitro- 

 benzene, or of the paranitranilin obtained from this. 

 Crystalline mass, which undergoes a change in contact 

 with the air. Easily soluble in water. Fuses at 63, 

 and boils at 287. Diatomic base. The hydrochlorate, 

 C 6 H 4 (KH 2 ) 2 2HC1, crystallizes in fine needles. 



Diazobenzene, C 6 H 4 W(?), is obtained by the decom- 

 position of diazobenzene potassa (see below) with 

 acetic acid. Thick, yellow, very unstable oil. 



Diazobenzene nitrate, C 6 H 4 N 2 .HN0 3 . A current 

 of nitrous acid is conducted into anilin nitrate, to 

 which is added a quantity of water insufficient for its 

 solution, until caustic potassa no longer causes a pre- 

 cipitate of anilin. The salt is deposited in crystals, 

 which are increased in quantity by the addition of 

 alcohol and ether. Long, colorless needles, very easily 

 soluble in water, but sparingly in alcohol, insoluble in 

 ether and benzene. Explodes with great violence 

 when heated or struck with a hammer. Is decom- 

 posed in a moist atmosphere, and, when boiled with 

 water, yields nitrogen, nitric acid, and phenol. 



Diazobenzene sulphate, C 6 H 4 N 2 .H 2 S0 4 , is obtained 

 from anilin sulphate, like the preceding compound ; is 

 prepared, however, most readily by treating the latter 

 with dilute sulphuric acid. Colorless prisms. Deto- 

 nates at 100. Conducts itself towards solvents and 

 by boiling with water like the nitrate ; by boiling 

 with absolute alcohol it is converted into benzene, 

 nitrogen being evolved, and the alcohol is oxidized to 



