r 109 ] 



VI. 



UNSATURATED KETONES DERIVED' FROM DIACETO-ORGINOL. 



By JOSEPH ALGAR, M.Sc, 

 University College, Dublin. 



[Read November 30, 1916. Published February 6, 1917.] 



The preparation of ditiavone and of derivatives of diflavanone is described 

 in papers by Ryan and O'Neill (Proc. Royal Irish Acad., 1915, B, pp. 48 

 and 167.) These substances were obtained from diacetoresorcinol. The 

 ketones described in the present communication were prepared at the 

 suggestion of Professor Ryan with a view to obtaining diflavone and 

 diflavanone derivatives, using diaceto-orcinol as the parent substance. ' 



Diacetoresorcinol was. prepared by Eijkman, Bergenia, and Henrard 

 (Chera. Weekblad, i, (1905), p. 453, and ii, pp. 59-72, 79-93) by heating 

 resorcinol diacetate with zinc chloride. Heating orcinol diacetate with zinc 

 chloride gave unsatisfactory results ; bfut when the diacetate was heated with 

 anhydrous aluminium chloride, colourless crystals of diaceto-orcinol were 

 obtained. 



Eijkman showed that the formula of diacetoresorcinol is 



ho/\6h 



CHs . CO\/CO . CHs 

 He prepared mixed ethers of diacetoresorcinol of the type 



CHsO/XOCjHs 



I I 



CII3 . CO\/CO . CH;, 



and found that the same mixed ether is formed when the order of introduction 

 of the methyl and ethyl groups is altered. The orientation of the acetyl 

 groups in diacetoresorcinol is therefore as shown in the above formula. 



It was at first assumed that diaceto-orcinol had a similar constitution. 

 The substance, however, showed very similar properties to the diaceto-orcinol 

 obtained by Collie (Jour. Chem. Soc, 1904, p. 971) by the action of acetyl 

 chloride on the sodium salt of diacetylacetone. When pure dry acetyl 

 chloride is allowed to react with the sodium salt of diacetylacetone suspended 

 in dry chloroform, and the temperature is kept below 0°C, a compound 

 melting at 75° C. is formed. This compound forms a pyrone derivative when 

 boiled with acids, and diaceto-orcinol when warmed with sodium hydroxide. 



R.I. A. PKOC, VOL. XXXIII, SECT. B. [S] 



