Structure of Simpler Organic Compounds. 1 1 3 



composition C 3 H 8 O 2 has been isolated as the result of some 

 fermentation process ; this acid will be found to form salts, 

 esters, acid chlorides, etc., and have therefore all the 

 properties of a substance containing a carboxyl group. 

 None of these reactions would serve, however, to dis- 

 tinguish between the formulae CH 2 (C 2 H 5 )CO OH and 

 CH(CH 3 ) 2 CO OH. The synthetic method just described 

 would, however, settle this question finally, as the two 

 acids with different properties can both be obtained, and 

 the method of synthesis leaves no doubt as to their respec- 

 tive constitutions. 



Another example of the value of this and similar 

 synthetical methods. When leucine (see p. 318) is added to 

 a yeast fermentation of sugar, an amyl alcohol, C 5 H n OH, 

 is produced. Eight isomerides of this formula are capable 

 of existence. The alcohol in question can be oxidized to 

 C 5 H 10 2 , and is therefore a primary alcohol. Now, from 

 ethyl malonate, the various acids of this formula can be 

 obtained synthetically ; it will be found that the acid 

 from the amyl alcohol in question is got when the sodium 

 derivative of ethyl malonate is treated with isopropyl 

 iodide 



CO-OCA COOCA 



(CH 3 ) 2 CHI + CHNa = Nal + (CH 3 ) 2 CH CH 



X c, 



OCA CO 



From this, on saponification, is obtained 



/COOK 

 (CH 3 ) 2 CHCH 



\300H 



hich, on heating, yields (CH 3 ) 2 CH CH 2 COOH. It is 

 obvious, therefore, that the constitution of the alcohol 

 derived from leucine is 



(1,997) g 



