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II. 



ON UNSATURATED /3-DIKETONES.— II. 

 By HUGH BYAN, D.Sc, and JOSEPH ALGAE, M.So. 



Read June 23. Published August 5, 1913. 



The natural dye curcumin is supposed 1 to be an unsaturated /3-diketone; 

 and as compounds of this class are almost unknown, attempts were made by 

 one of us, in conjunction with Eev. J. Dunlea, to prepare substances of the 

 types :— 



X.CH:CH.CO.CH 2 .CO.T and X.CH : CH . CO.CH 2 .CO.CH:CH.X. 



It was found 2 that the ester of an unsaturated acid condenses with a 

 saturated ketone, in the presence of sodamide or metallic sodium, to give an 

 unsaturated j3-diketone. Thus, cinnamyl-benzoyl-methane was formed by 

 the interaction of acetophenone and cinnamic ester : — 



C 6 H 5 CH : CH . COOC 2 H 5 + CH 3 . CO . C 6 H 5 = C 6 H 5 CH : CH . COCH, . COC 6 H 5 



+ C 2 H 5 OH. 



An attempt to synthesize the symmetrical unsaturated diketone, 



C 6 H 5 CH : CH . CO . CH 2 . CO . CH : CH . C 6 H 5 , 

 by the action of sodium on a mixture of cinnamic ester and benzylidene- 

 acetone : — 



C 6 H 5 CH : CH . COOC 2 H 5 + CH 3 COCH : CH . C.H. 

 = C 6 H 5 CH : CH . CO . CH 2 . COCH : CH . C 6 H 5 f C 2 H 5 OH 

 was unsuccessful; and, indeed, we have not succeeded under any conditions in 

 condensing an unsaturated ester with an unsaturated ketone to a crystallizable 

 j3-diketone. While a reaction undoubtedly occurred, we were unable to 

 separate any crystalline compound, other than cinnamic acid, from the 

 product, and consequently could not follow its course. 



The abnormal behaviour of the substances cannot be due to the unsaturated 

 nature of the ester, since Eyan and Dunlea {loc. cit.) have shown that an 



1 Milobedzka, von Kostanecki and Lampe, Ber , xliii (1910), p 2163. 



2 Ryan and Dunlea, Proc. Roy. Irish Acad., xxxii, Sect. B, p. 1. 



K.I. A. PROC, VOL. XXXII., SECT. B. [C] 



