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VIII. 



STUDIES IN THE DIFLAVONE GROUP. 

 II. — Derivatives of Diflavanone. 



By HUGH RYAN, D.Sc, and PAULINE O'NEILL, B.Sc, 

 University College, Dublin. 



Read June 14. Published August 28, 1915. 



In a previous paper (Ryan and O'Neill, Proc. Royal Irish Acad., 1915, B, 

 p. 48), we described two syntheses of diflavone. In the one synthesis we 

 condensed diacetoresorcinol-dimethylether with benzoic ester, and by acting 

 with concentrated hydriodic acid on the diketone thus formed we obtained 

 diflavone. The other synthesis consisted of the condensation of diacetoresor- 

 einol-dimethylether with benzaldehyde and the demethylation of the product 

 by the aid of anhydrous aluminium chloride. In this way we obtained 

 dibenzylidene-diacetoresorcinol, or dihydroxy-dichalkone, which after acetyla- 

 tion and addition of bromine gave the tetrabromide of dihydroxy-dichalkone- 

 diacetate. The latter compound interacted with warm alcoholic potash to 

 form diflavone. 



The preparation of dihydroxy-dichalkone from its dimethylether is 

 troublesome ; and as we required a considerable quantity of the former for 

 attempts to synthesize diflavanone and diflavonol, we tried, but without 

 success, to obtain it by heating resorcinol-dicinnamate with fused zinc chloride 

 and anhydrous aluminium chloride respectively. We also attempted its 

 preparation by the direct condensation of benzaldehyde with diacetoresorcinol 

 in the presence of alkali. 



Eijkman, Bergema, and Henrard (Chemisch "Weekblad I (1905), p. 453), 

 by allowing a solution of diacetoresorcinol and benzaldehyde in alcoholic 

 sodium hydroxide to stand in a warm place, obtained a reddish-yellow 

 substance, which crystallized in needles and melted at 202° C. As this 

 dibenzylidene-diacetoresorcinol is quite different in crystalline form and some- 

 what different in other properties from the dibenzylidene-diacetoresorcinol 

 which we obtained (loc. cit.) from dihydroxy-dichalkone-dimethylether, we 

 shall refer to it in future as a-dibenzylidene- diacetoresorcinol, and to the 

 dihydroxy-dichalkone which we got from the dimethylether as j3-dibenzyli- 

 dene-diacetoresorcinol. 



In our previous communication we stated that the latter compound — 



R.I. A. PROC, VOL. XXXII., SECT. B. [2 B~\ 



