DEPSIDES 305 



Evernic Acid. 



This is a monomethyl ether of lecanoric acid of the 

 formula — 



CH3 



/ 



CH3O— / ^_co— o— < 



\ 



OH 



and may be regarded as a didepside produced from the com- 

 bination of the monomethyl ether of orsellinic acid (11.), 



CH3 CH3 



CH3O— < >— COOH HOC \— COOH 



I 



OH ^ OH 



(I.) (II.) 



known as everninic acid (i.) with orsellinic acid (11.). Evernic 

 acid forms needles and melts at 168-169°. 



Chlorogenic Acid. 



This is a didepside which, though not occurring among the 

 lichens, is very widely distributed in the plant world.* Its 

 constitution is represented by the formula — 



HO 

 I 



HO—/ \_CH=CH— CO— O . CbH,(OH)3 . COOH 



from which it appears that it is a didepside formed from one 

 molecule of caffeic acid — 



-CH=CH— COOH 



with one molecule of quinic acid, a tetrahydroxy-hexahydro- 

 benzoic acid of the formula C6H7(OH)4 . COOH. 



Chlorogenic acid occurs in green coffee beans combined 

 with a molecule of caffeine. 



* Oparin: " Biochem. Zeit.," 1921, 124, 90. 

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