170 COFFEE 



Oxycaffeine has been shown to be trimethyluric acid : 

 CO CO 



/\ CH3 /\ CH3 



/ \ / / \ / 



CH3 N C N CH3 N C N 



I II /^^ I II /COH 



CO C NH CO C N 



\ / or \ / 



N N 



I I 



CH3 CH3 



The heating of the silver salt of oxycaffeine with methyl Iodide pro- 

 duces a mixture of tetramethylurlc acid and methoxycaffeine. 



CO CO 

 y\ CH3 /\ CH3 



/ \ / / \ / 



CH3 N C N CH3 N C N 



I II /^^ I II ^C — OCH3 



CO C N CO C N 



/ \ \ / 



cHa \y 



N N 



I I 



CH3 CH3 



Tetramethyluric Acid Methoxycaffeine 



Formation of these two substances Indicates that oxycaffeine may 

 react in two tautomeric forms such as -NH-CO and -N=C(OH)-. 

 Since these groups can occur only in the hydantoln nucleus, the 

 methoxyl of methoxycaffeine must exist In this nucleus. 



The following formulae are for chlorcaffelne and caffeine ; namely, 



CO CO 



/\ CH3 /\ CH3 



/ \ y / \ / 



CH3 N C N CH3 N C N 



I II \CCL I ll NcH 



I II //^^^ I II /^" 



CO C N CO C N 



\ / \ / 



N N 



I I 



CH3 CH3 



Chlorcaffeine Caffeine 



