THE FATTY ACIDS. 



The fatty acids are the second products of oxidation of the 

 primary alcohols, the aldehydes being the intermediate products. 

 Secondary alcohols and ketones also give rise to fatty acids on 

 oxidation, but the number of carbon atoms in the molecules of the 

 fatty acids so formed is less than in the original secondary alcohol. 

 Conversely, on reduction fatty acids give aldehydes and primary 

 alcohols, thus : 



CH 3 . CH 2 OH 2 CH 3 . CHO ^ CH 8 . COOH. 



The fatty acids are characterised by the presence of the carboxyl 

 or COOH group. 



They occur widely distributed in nature, both in the free state and 

 in combination with glycerol as the fats. 



Only those acids containing an even number of carbon atoms 

 occur in combination as fats, and as far as is known they all have 

 a straight chain of carbon atoms. Acids with an uneven number of 

 carbon atoms and with branched chains of carbon atoms are also found 

 in nature. 



The lower members of the series of the fatty acids up to capric 

 acid with lo carbon atoms are volatile with steam and hence are 

 termed the volatile fatty acids. They are separated in this way from 

 the higher members which are not volatile with steam. They thus 

 form two groups. 



In the following list are given the names of the homologous series of hydrocarbons,. 

 primary alcohols, aldehydes and fatty acids : 



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