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XVI. 



THE CONDENSATION OF ALDEHYDES WITH METHYLETHYL- 



KETONE. 



By HUGH EYAN, D.Sc, 



AND 



PATRICK J. CAHILL, M.Sc, 

 University College, Dublin. 



[Read Febkuauy 25. Publislied September 15, 1924.] 



By the action of benzaldehyde on methylethyl-ketone in the presence of 

 dilute alkali, H. Eyan and A. Devine (Proc. Eoyal Irish Acad., xxxii, B, 

 p. 208) obtained a-benzylidene-methylethyl-ketone and diphenylmethyltetra- 

 hydropyrone, which had been previously described by C. Harries and G. H. 

 Miiller (Ber. Dtsch. Chem. Ges., xxxv, 1902, p. 968). Also during an 

 attempt to prepare the benzylidene derivative of this tetrahydropyrone by 

 the action of benzaldehyde on the hydropyrone in the presence of alcoholic 

 hydrochloric acid, they found that instead of the compound 



H^C. HC 



5 G 



HjC HCx /'C=<-t-i'-g"s 



C=CHC._H, 

 CO 



they obtained a crystalline substance with the empirical formula CggHggO, 

 which contained a molecule of water less than that of the benzylidene- 

 diphenylniethyltetrahydropyrone expected. The new condensation product 

 formed a dibromide Cg^Hj^OgBrg ; but as they failed to prove the presence of a 

 CO group in the body, they were unable to assign a structural formula to the 

 substance. 



Using the same condensing agent (hydrochloric acid), Eyan and Devine 

 {loc. cit.) by the interaction of a-benzylidene-niethylethyl-ketone with anisal- 

 dehyde and piperonal obtained analogous substances having the formulae 

 C27H24O3 and CjtHmOb respectively. 



In continuation of this work we condensed anisaldehyde with methylethyl- 

 ketone in the presence of dilute alkali, obtaining an anisylidene-methj'lethyl- 



