HYPOXANTHINE. 191 



product (E. FISCHER). The 6-amino-2-oxypurine sulphate contains 

 only 1 molecule of water of crystallization, which is not expelled at 120 C. 

 Very dilute guanine solutions are precipitated by both picric acid and 

 metaphosphoric acid. These precipitates may be used in the quantita- 

 tive estimation of guanine. The silver compound dissolves with difficulty 

 in boiling nitric acid, and on cooling the double compound crystallizes 

 out readily. Guanine acts like xanthine in the nitric-acid test, but gives 

 with alkalies on heating a more bluish-violet color. A warm solution 

 of guanine hydrochloride gives with a cold saturated solution of picric 

 acid a yellow precipitate consisting of silky needles (CAPRANICA). With 

 a concentrated solution of potassium bichromate a guanine solution 

 gives a crystalline, orange-red precipitate, and with a concentrated 

 solution of potassium ferricyanide a yellowish-brown, crystalline pre- 

 cipitate (CAPRANICA). It also gives a compound with picrolonic acid 

 (LEVENE l ). Guanine gives WEIDEL'S Reaction. 



HN CO 



Hypoxanthine, SARKINE, C5H4N4O,=HC C NH V =(6-oxypurine). 



II II >CH 



N-C N f- 



This body has been found in all cellular organs and in meat extracts, 

 and as a cleavage product of inosinic acid. It is especially abundant in 

 the sperm of the salmon and carp. Hypoxanthine occurs also in the mar- 

 row and hi very small quantities in normal urine, and, as it seems, also in 

 milk. It is found in rather considerable quantities in the blood and urine 

 in leucaemia. 



Hypoxanthine can be obtained according to SuNDViK's 2 method 

 from uric acid or xanthine by heating with a formate or more simply 

 by heating with chloroform in alkaline solution. 



Hypoxanthine forms very small, colorless, crystalline needles. It 

 dissolves with difficulty in cold water, but the claims concerning 

 solubility therein are very contradictory. 3 It dissolves more readily 

 in boiling water, in about 70-80 parts. It is almost insoluble in alcohol, 

 but is dissolved by acids and alkalies. The compound with hydrochloric 

 acid is crystalline, and is more soluble than the corresponding xanthine 

 derivative. It is easily soluble in ammonia. The silver compound 

 dissolves with difficulty in boiling nitric acid. On cooling, a mixture 

 of two hypoxanthine silver-nitrate compounds possessing an inconstant 

 composition separates out. On treating this mixture with ammonia 

 and an excess of silver nitrate and heating, a silver hypoxanthine is 



1 Capranica, Zeitschr. f. physiol. Chem., 4; Levene, Bioch. Zeitschr., 4. 



2 1. c. and Skand, Arch. f. Physiol., 25. 



3 See E. Fischer, Ber. d. deutsch. chem. Gesellsch., 30. 



