ORGANIC CHEMISTRY I 



TABLE III 



Table showing the values obtained from some natural fats* 



AROMATIC AND HETEROCYCLIC COMPOUNDS 

 The compounds already described have consisted of open 

 chains of carbon atoms (aliphatic compounds), but there are 

 carbon compounds in which the carbon atoms are arranged 

 in a ring. These are known as aromatic compounds, and the 

 simplest of them is benzene, containing six carbon and six 

 hydrogen atoms. When the carbon atoms close up to form 

 the benzene group one valency of the carbon atom remains 

 unaccounted for and it behaves as a trivalent atom. 



The spare valency has been assumed to be distributed in 

 one of two ways as shown in the following structural formulae. 



C 



/ 



-a 





/T 



c 



/N 



c c 



-C C 



C 



According to Claus. According to Kekule. 

 For practical purposes we frequently represent the benzene 

 group as a hexagon, each angle of which represents one 

 ^CH group. 



* Modified from R. H. A. Plimmer, Practical Organic and Bio- 

 chemistry, Longmans, Green & Co., 1915, p. 179. 



