URINE 453 



salicylaldehyde in absolute alcohol and warm the mixture to about 70. If 

 acetone be present the fluid becomes yellow, then red, reddish-purple and dark 

 red in turn. The color of the urine is practically unchanged if no acetone is 

 present. 



This color is due to the formation of dihydroxydibenzoylacetone 

 through the interaction of salicylaldehyde and acetone. 



CH 3 



I 



ACETO ACETIC ACID, C = O 



CH 2 COOH. 



Acetoacetic or diacetic acid occurs in traces in normal urine. 

 The sum of the acetone and the acetoacetic acid excreted in normal 

 urine per day ranges from 3 to 15 mg. and ordinarily three-quarters 

 of this is acetoacetic acid. Under certain pathological conditions 

 it occurs in larger quantities and is rarely found except associated 

 with acetone. In the human body it yields /3-hydroxybutyric acid 

 by reduction and upon decomposition yields acetone and car- 

 bon dioxide. Acetoaceturia occurs ordinarily under the same condi- 

 tions as the pathological acetonuria, i.e., in fevers, diabetes, etc. (pp. 

 -45a-and 557). If very little acetoacetic acid is formed it may be 

 transformed into acetone, whereas if a larger quantity is produced both 

 acetone and acetoacetic acid may be present in the urine. Aceto- 

 aceturia is most frequently observed in children, especially accompany- 

 ing fevers and digestive disorders ; it is perhaps less frequently observed 

 in adults, but when present, particularly in fevers and diabetes it is 

 frequently followed by fatal coma. 



Acetoacetic acid is a colorless liquid which is miscible with water, 

 alcohol and ether, in all proportions. It differs from acetone in giving 

 a violet-red or Bordeaux-red color with a dilute solution of ferric 

 chloride. 



EXPERIMENTS 1 



i. Le Nobel Reaction. 2 Make 10 c.c. of urine acid with acetic acid, add a 

 few drops of a dilute aqueous solution of sodium nitroprusside and stratify con- 

 centrated ammonium hydroxide upon the mixture. In the presence of aceto- 

 acetic acid a violet ring forms at once. 



Acetone also responds to this test, but the test is more delicate for aceto- 

 acetic acid and the response is more prompt. 



1 To prepare a diacetic acid solution which may be added to urine, if urines containing 

 this acid are not available, proceed as follows: Treat 13 grams of ethyl acetoacetate with 

 500 c.c. of N/5 sodium hydroxide. Allow to stand for 48 hours to hydrolyze the ester. 

 In preparing urine for tests add i part of this solution to 10 parts of urine. 



2 Harding and Ruttan: Biochem. Jour., 6, 445, 1912; also Biochem. Bull., 2, 223, 1913. 



