160 THE SIMPLER NATURAL BASES 



and glyoxylic acids. On boiling with baryta methylhydantoin re- 

 sults. Dry distillation of creatinine chloride yields hydrocyanic acid, 

 pyrrole, and dimethylamine (Engeland [1908, 4]). On standing or 

 boiling with very dilute alkalies, creatine is formed. 



Compounds of creatine. The nitrate, C 4 H 9 O 2 N 3 . HNO 3 , is less 

 soluble than the hydrochloride or the sulphate. The compounds 

 C 4 H 9 O 2 N 3 . ZnCl 2 and C 4 H 9 O 2 N 3 . CdCl 2 . 2H 2 O are crystalline (Neu- 

 bauer [1862, 2]). All these salts are hydrolysed by water. 



Compounds of creatinine. The hydrochloride, C 4 H 7 ON 3 .HC1, 

 separates in anhydrous prisms and tables when a solution of creatinine 

 in hydrochloric acid is evaporated on the water bath ; from cold 

 solution it crystallises with iH 2 O. It is not precipitated by zinc 

 chloride except in the presence of excess of sodium acetate. 



Creatinine zinc chloride, (C 4 H 7 ON 3 ) 2 ZnCl 2 , is the most characteristic 

 derivative and separates immediately as a micro-crystalline precipitate 

 on adding a concentrated neutral zinc chloride solution to an alcoholic 

 or not too dilute aqueous solution of creatinine ; on standing, a dilute 

 solution deposits needles and prisms. It is soluble in 53*8 parts of 

 water at 15 and in 2774 at 100; it is insoluble in absolute alcohol, 

 readily soluble in hydrochloric acid, from which sodium acetate causes 

 a double salt of creatinine hydrochloride and zinc chloride C 4 H 7 ON 3 . 

 HC1 . ZnCl 2 (Neubauer [1861, 2]) to crystallise in long needles, readily 

 soluble in water. Creatinine zinc chloride dissolves in warm 10 per 

 cent, sulphuric acid and then the addition of acetone causes the separa- 

 tion of a double sulphate of zinc and creatinine (C 4 H 7 ON 3 ) 2 H 2 SO 4 . 

 ZnSO 4 . 8H 2 O (Folin and Blanck [1910]). 



Creatinine may be regenerated from its double compounds with 

 zinc by boiling with freshly precipitated lead hydroxide. 



The mercury salt (C 4 H 7 ON 3 . HC1 . HgO) 4 sHgCl 2 is formed on the 

 addition of mercuric chloride and sodium acetate to a creatinine solution. 



The picrate, C 4 H 7 ON 3 . C 6 H 3 O 7 N 3 , forms long yellow needles spar- 

 ingly soluble in cold water ; m.p. 213-214 (Toppelius and Pommerehne 

 [1896]), 215-217 (Korndorfer [1904, 2]). 



Creatinine potassium picrate, C 4 H 7 ON 3 . C 6 H 3 O 7 N 3 . C 6 H 2 O 7 N 2 K 

 (formed by saturating urine with picric acid) crystallises in citron 

 yellow needles or thin prisms, and explodes on rapid heating : 100 c.c. of 

 water dissolve 0*1806 grm. at 19-20 ; it is also very slightly soluble in 

 hot alcohol (JarTe [ 1 886]). 



An acidpicrate C 4 H 7 ON 3 . (C 6 H 3 O 7 N 3 ) 2 , m.p. 161-166, has been de- 

 scribed by Mayerhofer [1909]. 



Creatinine aurichloride, QH 7 ON 8 . HAuCl 4 , separates in yellow 



