1 68 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



NH 2 NH, 



NH=rC N-CH 2 .COOH + H 2 O NH 2 C = O + HN.CH 2 .COOH. 



CH 3 CH 3 



It is converted by boiling with acids into creatinine. 



Conversion of Creatine into Creatinine. Estimation of Creatine. 



It has long been known that creatine on heating with acids is converted 

 into its anhydride creatinine : 



NH 2 . NH . 



HN = C-N CH a COOH = H 2 O + HN = C N CH 2 . CO. 

 CH 3 CH a 



The reverse action takes place when creatinine solutions are heated to 

 boiling, or on boiling with alkalies. 



The solution containing creatine of a concentration of about o'i per cent, 

 is heated on a water-bath in a flask covered with a watch glass with an equal 

 volume of normal hydrochloric acid for 3-4 hours, or the aqueous solution 

 is heated in a flask covered with tin-foil in an autoclave at 130-140 for half 

 an hour exclusive of the time taken in heating up and cooling the autoclave. 



Benedict finds it most convenient to boil down to dryness the solution of 

 creatine to which has been added an equal volume of N hydrochloric acid, 

 the final evaporation being done on a water-bath. 



Solid creatine on heating at 130-140 for 3 hours in an autoclave is 

 also converted into creatinine. The mixture of creatine and creatinine ob- 

 tained in the above preparation from urine may be converted into creatinine 

 by adding one to two drops of water for every gram of substance and heating 

 in an autoclave for 3 hours at 130-140. 



The estimation is effected as is described for creatinine (p. 1 7 1) by neutral- 

 ising, adding picric acid and soda and comparing the colour against a 

 standard. 



