122 Biological Chemistry. 



products, giving, with bromine, CH 2 Br CHBr COOH, 

 a /3 dibrompropionic acid, and with nascent hydrogen, 

 CH 3 CH 2 COOH, propionic acid. Like other unsaturated 

 acids, it is readily oxidized with cold potassium perman- 

 ganate. 



Another important member of the series is oleic acid, 

 C 18 H 34 2 , which is obtained by the hydrolysis of olive oil, 

 which consists chiefly of the triglyceride of this acid. It 

 is, when freshly prepared, a colourless acid, which rapidly 

 darkens in air owing to the readiness with which it 

 oxidizes. (Note the readiness with which unsaturated 

 derivatives undergo oxidation.) 



Other complex fatty acids are derived from the 

 hydrolysis of fats and oils, some of which contain more 

 than one double bond. These will be discussed later 

 (Chap. V.). 



Part XII. The Ethers. 



The general character of the ethers has been already 

 mentioned (p. 67). Just as ethyl alcohol may be regarded 

 as derived from water by the replacement of one hydrogen 

 by the ethyl radicle, so ethyl ether may be regarded as 

 derived from the same substance by replacement of both 

 hydrogens by the same radicle 



H \ C 2 EU C 2 EU 



>0 >0 >0 



W H / C 2 H/ 



Its constitution was first definitely settled by the classical 

 synthesis of Williamson. When sodium ethoxide is treated 

 with ethyl iodide, reaction takes place according to the 

 equation 



C 2 H 5 ONa + C,H 5 I = Nal + C 2 H 5 - C 2 H 5 



The ethers, of which ethyl ether (generally known 

 simply as ether) is the typical representative, have the 



