380 CHEMISTRY OF THE LEDCOMAINS. 



xanthin is formed (see p. 353). By putrefaction in the absence of 

 air it forms xanthin (Schindler), The change can be represented by 

 the equation : 



C„H,N,0 + H,0 = C,H,Np, + NH,. 



On oxidation with potassium permanganate it yields urea, oxalic 

 acid, and oxy-guanin. On heating with hydrochloric acid and 

 potassium chlorate it is oxidized to carbonic acid, guanidin, and 

 parabanic acid, according to the equation : 



C5H5N.O + H,0 + 30 =^f~^^\cO + &S>C = NH + CO,. 

 CO— nh/ "^^ 



CO— NH\ H N 



CO— NH/ ^^ 



FABABiUiic Acid. Gdanidin. 



This decomposition, noted by Strecker, was repeated and confirmed 

 by Fischer who was unable to obtain alloxan and urea, as in the case 

 of xanthin, but instead isolated parabanic acid and guanidin. The 

 latter may be identified as a picrate (Emich). 



According to Strecker, a small amount of xanthin is formed in 

 this reaction, and it is quite possible that this base is also formed on 

 oxidation with nitric acid, especially if it contains nitrous acid. 



On decomposition with concentrated hydrochloric acid at 180°— 

 200° WulfF obtained cleavage products similar to those of xanthin, 

 namely, ammonia, glycocoll, carbonic acid, and formic acid. The 

 reaction is as follows : 



C,H,Np + 7H,0 = 4NH3 + C,H,NO, + 2CO, + CUp,. 



Guanin combines with acids, bases and salts. It is a very feeble 

 base as seen from the fact that some of its salts, as the hydrochlorid, 

 bichromate, etc., readily dissociate on contact with water, especially 

 at higher temperatures. On the other hand, adenin is a much 

 stronger base. It unites with bases to form crystalline compounds ; 

 and with one or two equivalents of acids to form crystallizable salts. 

 Thus, with hydrochloric acid it forms the two salts, C5HjNjO.(HCl)j 

 and CjHjNjO.HCl + H^O. Similar combinations can be obtained 

 with nitric acid. The sulphate, (C5H5N50)2.H2SO^, crystallizes in 

 long needles, and, like the other salts, is decomposable by water. It 

 contains two molecules of water, a fact which distinguishes guanin 

 from its isomers. The iodid, nitrate, oxalate, and tartrate are also 

 known. 



The platinochlorid, (C5H,N,O.HCl)2PtCl, + 2Hp, is readily ob- 

 tained in a crystalline condition. The silver compound is soluble in 

 hot nitric acid, and on cooling separates out in fine, needle-shaped 

 crystals, having the composition C5H5N5O. AgNOj. For its behavior to 

 Drechsel's reaction, precipitation with copper solution in the presence 

 of reducing substances, see page 353. The compound forms as a white 

 flocculent precipitate, which soon turns greenish and tends to disso- 



