GUANIDINE AND ITS DERIVATIVES 



167 



S. R. Benedict 1 gives a simpler method for preparing creatine from 

 creatinine zinc chloride : 



100 gm. of creatinine zinc chloride are heated to boiling in a large basin 

 with 700 c.c. of water; 150 gm. of pure powdered calcium hydrate are added 

 and the mixture is stirred and boiled for twenty minutes. The hot mixture is 

 filtered and the res : due washed with hot w.;ter. The filtrate is treated for a 

 few minutes with hydrogen sulphide to remove zinc and filtered through a 

 folded paper. It is acidified with about 5 c.c. of glacial acetic acid and 

 rapidly boiled down to about 200 c.c. The solution is allowed to cool and 

 kept at o. The crystals of creatine are filtered off, washed with cold water 

 and alcohol, and dried. The filtrate is kept to recover unchanged creatinine. 

 The creatine is recrystallised by solution in seven times its weight of boiling 

 water, which is allowed to cool slowly and stand for some hours at o. It is 

 filtered off, washed with alcohol and ether, and dried in the air for thirty 

 minutes. The creatine contains water of crystallisation which is lost by ex- 

 posure to the air. It may be dehydrated by heating for eome hours at 95. 

 The yield is about 18 gm. 



About 50 per cent, of the creatinine is not converted in this process, but 

 it is not advisable to boil longer with the lime as loss of creatinine occurs. 



The creatinine is recovered by diluting the solution with alcohol and 

 treating with about 50 c.c. of a 30 per cent, alcoholic solution of zinc chloride. 



Creatine has been synlhesised from cyanamide and sarcosine, or 

 methyl-glcyine : 



NH 2 NH 2 



C=N + HN . CH 2 . COOH = NH=C N CH 2 . COOH. 

 CH 3 CH 3 



Properties and Reactions. 



Creatine separates from water in colourless, transparent, hard 

 rhombic prisms (Fig 35), con- 

 taining one molecule of water of 

 crystallisation, which is given off 

 at 1 00, the specimen becoming 

 opaque. It has a peculiar bitter 

 taste, is easily soluble in hot water, 

 less so in cold (i in 74), almost 

 insoluble in alcohol and insol- 

 uble in ether. Its solution has 

 a neutral reaction. It forms 

 salts with acids which are very 

 unstable. 



It is hydrolysed by alkalies 

 into urea and sarcosine and may, 



FIG. 35. Creatine. (After Funke.) 



therefore, like arginine, contribute to the quantity of urea in urine : 



. Biol. Chem., 1914, 18, 186. 



