Wisconsin Academy of Sciences, Arts, and Letters. 
no means remarkable that flavone and xanthone derivatives so 
closely resemble each other in coloring properties. 
CH 
O 
CH- G— CH 
CH 
CH— C — CH 
II 
O 
Y-pyrone 
CH 
Chromone 
O 
Xanthone 
There is some confusion as to the numbering of the carbon 
atoms in the benzo-y-pyron group, called by Kostaneeki the 
chromon group, and consequently in the numbering of those of 
the flavon and xanthon groups. According to Richter’s Lexi- 
kon der KoMenstoff-Verbindungen the oxide oxygen in the 
chromon group occupies position 1, and the carbon atoms are 
numbered from this. Kostaneeki, however, assigns to the car¬ 
bon atom adjacent to the carbonyl group the a position and the 
one adjacent to the oxide oxygen the (3 position, while the car¬ 
bon atoms of the carbocyclic nucleus he numbers 1, 2, 3, and 4 
respectively. This gives us two systems of numbering as in¬ 
dicated by the following structural formulae: 
Chromon group numbered according to 
Richter Kostaneeki 
Whichever of these methods of numbering is followed, the 
positions of the carbon atoms of the phenyl group in the flavone 
