CHAPTER VIII 

 THE CHEMISTRY OF COFFEE 



Primary attention has been given to the alkaloids of coffee In order 

 to indicate the source, constitution, and method of extraction of those 

 substances which are present In the coffee-bean and which have an 

 appreciable effect on the animal organism. Special emphasis has been 

 placed on caffeine, as it Is the chief stimulative constituent of coffee. 



1817 dates the beginning of our chemical knowledge of plant alka- 

 loids. In 1 81 7, the crystalline, salt-forming, and physiologically ac- 

 tive substance morphine was discovered by Sertiirner in the opium 

 poppy, Papaver somniferum L. In the same year Roblquet dis- 

 covered narcotine; and in 18 18, Pelletier and Caventon discovered 

 strychnine. In 1820, Runge prepared caffeine from the seeds of 

 Coffea arabica L. ; and in 1827, Oudry isolated a similar principle 

 in the leaves of Thea sinensis L. and called it theine. It has been 

 established as identical with caffeine. 



The molecular constitution of plant alkaloids has been Investigated, 

 and a large number of vegetable alkaloids have been synthesised. 

 Caffeine was synthesised In 1895 by Fischer and Ach who published 

 their results in Berichte 28 (1895) 3i35- These molecular studies 

 make possible the present classification of plant alkaloids based on 

 their nuclear structure; and the following nine groups are arranged 

 in accordance with the nature of the bases from which they are 

 derived : 



m 



