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XI J. 



ON THE CONDENSATION OF ALDEHYDES WITH KETONES. 



II. — Aldehydes with Methylethylketone. 



By HUGH EYAN, D.Sc, and ANNIE DEVINE, B.A., M.Sc., 

 University College, Dublin. 



Bead December 13, 1915. Published March 28, 1916. 



By condensing benzaldehyde with dimethylacetylacetone Ryan and Dunlea 

 (Proc. Royal Irish Acad., xxxii, B, p. 57) obtained a colourless crystalline 

 compound which melted at 168-9° O, and which seemed to be the benzylidene 

 derivative of diphenylmethyltetrahydropyrone, the reactions of the compound 

 being best represented by the formula: — 



o 

 H 5 C 6 . CH /^ CH . C 6 H 6 



H 3 C . CH I' C = CH . C 6 H 5 

 CO 



"With a view to confirming the structure assigned to this compound by 

 Ryan and Dunlea we attempted the preparation, from benzaldehyde and 

 methylethylketone, of a compound which had been previously obtained by 

 C. Harries and G. H. Miiller [Ber. xxxv (1902), p. 968], and which the latter 

 chemists regarded as a pyrone derivative. 



According to E. Levinstein (Inaugural Dissertation, Berlin, Jan. 29th, 

 1902) benzaldehyde and methylethylketone interact in the presence of dilute 

 alkali to form -y-benzylidene-methylethylketone, 



CH 3 . CO . C . CH, 



CH . C 6 H 5 



whereas from analogy with the condensation of benzaldehyde and phenyl- 

 acetone in the presence of alkali — a condensation which has been studied by 

 G. Goldschmidt and K. Krczmar [Monatsh. xxii (1901), p. 659] — we should 

 have expected that the compound obtained by Levinstein was a-benzylidene- 

 methylethylketone, 



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



