ADENIN. 359 



lize, the double salt CgHjNj.HCl.HgCl^ + 2H3O separates in long, 

 stellate, silky needles. 



Another mercury compound, CjH^NjHgjClj , is obtained when the 

 precipitation takes place in the cold. The precipitate is white, 

 flocculent, and anhydrous. In this reaction, as above, for each 

 adenin molecule an equivalent of hydrochloric acid is set free. 

 This same body is also produced when an adenin solution is boiled 

 with a large excess of mercuric chlorid and as little hydrochloric 

 acid as possible to effect solution. On cooling small stellate needles 

 separate out, which do not lose their weight at 110°. It can also 

 be obtained by boiling the following compounds with water. 



When adenin is boiled with a large excess of mercuric chlorid and 

 much hydrochloric acid to dissolve completely the precipitate that 

 first forms, there is deposited on cooling a crystalline product, which 

 is variable in its composition, and apparently consists of double salts 

 of adenin and mercuric chlorid, such as CjHjNj.HCl.SHgCIj and 

 CjHjNj.HCl.BHgClj. On boiling with water these rapidly decom- 

 pose, forming the compound CjH^N^.HgjClg . The formation of a 

 double salt, C^H.Nj.HCl.HgjCl^ + 2^.^, is described above. 



Adenin mercury cyanid, (CjH5N5)2.Hg(CN)2, separates as stellate 

 needles and plates when a mixture of hot solutions of adenin and 

 mercuric cyanid are allowed to cool. 



An adenin bismuth iodid, C5H5Nj.HI.2Bil3 + 2HjO, is obtained 

 when an aqueous adenin solution is treated with potassium bismuth 

 iodid containing free hydriodic acid. The heavy precipitate, which 

 in color resembles carbon monoxid haemoglobin, consists of micro- 

 scopic glittering red needles. On contact with much water it 

 partly decomposes, forming light reddish-yellow amorphous floccules, 

 which become darkish brown at 100°. 



Chlor-adenin has not been obtained, since chlorin passed over 

 dry adenin in the cold, or at 100°, or into a boiling chloroformic 

 suspension of adenin is without effect. Phosphorus pentachlorid 

 heated with adenin at 160°— 170° for some hours gave a light-brown 

 body of uncertain composition. 



The synthetic di-chlor adenin is derived from tri-chlor purin. 



Brom-adenin. By treating well dried adenin with excess of dried 

 bromin a dark-red body is obtained which appears to contain six 

 atoms of bromin, CjHjNj.Brj (Bruhns). On mere exposure to the 

 air, more rapidly on heating at 100°— 120°, it becomes light-yellow 

 and decomposes, yielding bromin, brom-adenin, C^H^BrNj, and its 

 hydrobromid, CjH^BrNj.HBr. Brom-adenin is white, difficultly 

 soluble in cold water (1 : 10,000), more readily in hot water, very 

 easily in ammonia and in fixed alkalis. It crystallizes from water 

 or dilute ammonia in stellate needles or very thin plates which, 

 when dried in air, often assume a silky luster. The crystals con- 

 tain a variable amount of water depending on the temperature at 



