50 



Proceedings of the Royal Irish Academy. 



A purer preparation of diflavoue was obtained from the diketone, 

 dibenzoylaceto-resorcinol dimethylether, formed by the condensation of 

 methyl benzoate with diacetoresorcinol-dimethylether. This diketone 

 when boiled for an hour with concentrated hydriodic acid is converted 

 into benzoylaceto-methoxy-tlaYone, and on more prolonged boiling forms 

 diflavone : — 



~> 



C H CO'CH CO 



6 5 2 



The reactions do not proceed so smoothly as in the monoflavone series, 

 and it was only after many failures and many variations of the conditions 

 of the different experiments, that we were successful in the preparation of 

 the compounds. 



Diflavone, which has a faint yellow colour, is only slightly more coloured 

 than the colourless fiavone. Also its sulphuric acid solution, which has 

 a brilliant blue fluorescence, has a faint yellow colour, while that of 

 monoflavone is colourless. 



As the substance, however, like flavone contains no auxochrome groups, 

 we must postpone the consideration of the effect of the structure on the 

 depth of the colour until we shall have prepared derivatives of diflavone 

 containing auxochrome groups. 



Experimental Paet. 



Rcsorcinol diacctate was prepared by cooling a mixture of 44 grams 

 of resorcinol and 56 c.c. of acetyl chloride in a round flask under a 

 reflux condenser until the energetic reaction, which set in, had subsided, 

 and then heating the flask in an oil bath to 120" C. until the evolution 

 of hydrochloric acid ceased. 



Diacetoresorcinol was obtained from the diacetate by dissolving 10 grams 

 of anhydrous zinc chloride in the hot diacetate and heating the mixture 

 to 130° C. for a quarter of an hour. The molten mass was cooled and 

 extracted a few times with methylated spirit. The solid residue was 

 dissolved in boiling chloroform, and from the chloroform solution the 

 diacetoresorcinol was precipitated by addition of alcohol. About 24 grams 



