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VI. 



ON THE CONDENSATION OF ALDEHYDES WITH j3-DIKETONES. 



By HUGH RYAN, D.Sc, and Eev. J. M. DUNLEA, M.Sc, 

 University College, Dublin. 



Read January 25. Published Apkil 26, 1915. 



On a previous occasion we laid before the Academy the results of certain 

 investigations [Proc. Royal Irish Acad., xxxii. B, p. i] we had made on 

 the syntheses and properties of unsaturated /3-diketones, with especial 

 reference to dicinnamoyl-methane, which is supposed to be the parent- 

 substance of the interesting plant-dye cureumin. 



We mentioned that we had attempted the syntheses of such substances 

 by two distinct methods, namely : — 



(1 ) The condensation of esters with monoketones in the presence of 



sodium or sodamide. 



(2) The condensation of aldehydes with saturated diketones in the 



presence of a dehydrating agent. 



The first of these methods was dealt with in our previous communication ; 

 the second forms the subject-matter of the present one. 



We have shown \loc cit.~\ that an unsaturated ester such as cinnamic 

 ester condenses readily with saturated ketones such as acetone, acetophenone, 

 niethyl-ethyl-ketone, methyl-isopropyl- ketone, to form bodies of the type 



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



We also tried to condense cinnamic ester with benzylidene-acetone with 

 a view to synthesising dicinnamoyl-methane, 



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



the parent- substance of cureumin, but without success. This compound has 

 however, since been prepared by von Lampe and Milobedzka [Ber. 46 (1913) 

 p. 2235], whose method may be briefly stated as follows : — 



By hydrolysis of Fischer's cinnamoyl-acetoacetie ester they obtained 

 cinnamoyl-acetone : — 



C 6 H 5 . CH : CH . CO . CH (COOC 2 H 5 ) . CO . CH 3 

 |H 2 

 C £ H 6 . CH : CH CO OH, . CO . CH 3 + C0 2 + C 2 H 5 OH. 



P.. I. A. PROC, VOL. XXXII., SECT. B. [K 



