1873.] Dr. J. Stenhouse on Amido- derivatives of Orcin. 123 



trinitro-resorcinic acid; but as Dr. Schreder* has since published an ac- 

 count of some of the amido-derivatives of the latter substance, I have not 

 pursued my investigations further in that direction, but confined myself 

 to an examination of the products obtained from trinitro-orcinic acid. 



Amido-diimido-orcin, C 7 H 5 (NH 2 ) (NH) 2 2 . — This compound, which has 

 the properties of a base, is formed by the oxidation of triamido-orcin, and 

 is most conveniently obtained in a pure state by decomposing a solution 

 of the acetate with a slight excess of ammonia. 



The most advantageous method of preparing the base is to reduce tri- 

 nitro-orcin with sodium-amalgam, and to oxidize the alkaline solution of 

 triamido-orcin by exposure to the air. The details of the process are as 

 follows : — One part of trinitro-orcin and forty or fifty parts of water are 

 placed in a bottle furnished with a caoutchouc cork, and fragments of 

 sodium-amalgam containing about 3 per cent, of sodium are gradually 

 introduced and agitated with the solution, widen first acquires a brown 

 colour from the formation of an intermediate amiclo-product, probably 

 analogous to picramic acid, but becomes colourless as soon as the trinitro- 

 orcin is completely reduced. The solution should be cooled from time to 

 time, as considerable heat is generated during the reaction. "When the 

 solution containing triamido-orcin and sodic hydrate has become cold, it 

 is poured into a large flask and agitated briskly ; by this means the tri- 

 amido-orcin is oxidized to amido-diimido-orcin and the solution assumes 

 a magnificent blue colour : 



C, H s (NH 2 ) 3 2 + = C, H 5 (NH 2 ) (NH) 2 2 + OH 2 . 



A few seconds' agitation is sufficient, as if it be continued after the blue 

 colour is fully developed, the amido-diimido-orcin in the strongly alka- 

 line solution undergoes further oxidation and is destroyed. On strongly 

 acidulating the blue solution with sulphuric or hydrochloric acid, the cor- 

 responding salt of amido-diimido-orcin is precipitated. Instead of directly 

 agitating the colourless solution with air, it may be first neutralized or 

 rendered very slightly acid with hydrochloric acid, cooled, and then ren- 

 dered alkaline with ammonia. If this solution be now agitated in the 

 manner before described it becomes filled with minute green needles of 

 amido-diimido-orcin. Although the first method gives the best results 

 when carefully conducted, it requires considerable experience to stop the 

 oxidation at the precise point when the whole of the triamido-orcin is 

 oxidized to amido-diimido-orcin, and before the latter becomes destroyed. 

 With the ammoniacal solution there is far less danger of over oxidation. 



Trinitro-orcin is also reduced by treatment with tin and hydro- 

 chloric acid, or zinc and hydrochloric or sulphuric acid. One part 

 of trinitro-orcin and four parts of granulated tin are heated in a capacious 

 flask with eight measures of concentrated hydrochloric acid diluted with 

 sixteen measures of water. In a short time a powerful reaction takes 



* Ann. Chem. Pharm. vol. clviii. p. 244» 



l2 



