52 Proceedings of the Royal Irish Academy. 



The crystals turn red on contact with concentrated sulphuric acid, in which 

 they dissolve to an orange-red solution. An alcoholic solution of the sub- 

 stance gave no coloration with ferric chloride. 



The substance is readily demethylated by hydriodic acid. 



When 04510 gram of the compound was heated for an hour with 15 c.c. 

 hydriodic acid of constant boiling-point, 



04774 gram of silver iodide (Zeisel's method) was got, 

 corresponding to CH 3 15-52 

 C« H„ 2 (0 CH 3 ) 2 requires CH 3 15-58. 



Although dibenzylidene-diacetoresorcinol-dimethylether can be readily 

 prepared, and completely demethylated by means of hydriodic acid, it is not 

 a convenient parent substance for the preparation of diflavanone or diflavone. 

 The dichalkone which was formed from it by the action of hydriodic acid was 

 so resinified during the demethylation that no crystalline substance could be 

 extracted from the product. Demethylation by means of anhydrous aluminium 

 chloride gave a well crystallised dichalkone, but the yield was poor. 



o.o. Dihydroxy-dichalkom C 6 H 2 (OH), (CO . CH : CH . C 6 H 5 ) 2 . 



About 4 grams of dibenzylidene-diacetoresorcinol-dimethylether were 

 dissolved in 25 c.c. of boiling xylene, and 3 grams of anhydrous aluminium 

 chloride were added. The mixture was heated in an oil-bath to gentle 

 boiling for an hour and a half. The orange-red solid, which separated, was 

 washed with ether, decomposed by dilute hydrochloric acid, and extracted 

 with warm chloroform. The yellow crystalline substance which was left on 

 the evaporation of the chloroform was washed with alcohol and ether and 

 then recrystallised from boiling benzene. It melted at 196-198° C, and 

 gave on analysis the following results : — 



0-1526 substance gave 0-4358 CO, and 00766 H 2 0, 

 corresponding to C 77 '88, H 5 - 5, 

 (■ M H I( A requires C 77"84, H4i 



Dihydroxy-dichalkone separates from benzene in small doubly refractive 

 crystals, which very closely resemble cubes in appearance, and are light 

 yellow when cold, and deep yellow when heated. It is insoluble in water, 

 scarcely soluble in alcohol or ether, and soluble in benzene, chloroform, or 

 dilute aqueous potash. Ferric chloride colours its alcoholic solution red. 



The crystals turn orange-red in contact with concentrated sulphuric 

 acid, in which they dissolve to an orange solution. 



The dichalkone was also obtained in small quantity by shaking for 

 five weeks a solution of diacetoresorcinol in very dilute sodium hydrate 



