Ryan and Shannon — The Condensation of Aldehydes, Sfc. 323 



but, instead of forming tlie benzylidene derivative of the tetrahydropyronej 

 the condensation yielded a crystalline substance having the empirical formula 

 CjgHjgO. The formation of the latter body from the tetrahydropyrone can 

 be represented by the equation : — 



CigHigOa + CgOg. CHO = C.^H^.O + 2H2O. 



The substance was converted by bromine into a dibromide (^jsHj^Br^O ; but, 

 since it reacted neither with hydroxylaniine nor witli phenylhydrazine, it 

 appeared to contain no keto radical. 



H. Eyan and P. Ryan \loc. ctY.| also obtained this substance by the 

 condensation of benzaldehyde with methyl-acetylacetone in the presence of 

 hydrochloric acid. With a view to throwing some light on the structure of 

 this substance they attempted to prepare a tetrahydropyrone derivative by 

 the condensation of benzaldehyde with ethyl-acetoacetie ester, but the 

 investigation was not continued beyond the formation of a benzylidene- 

 ethylacetoacetic acid. 



In tlie present investigation the behaviour of some aldehydes towards 

 n-butyl-acetoacetic ester was examined, without, liowever, our succeeding in 

 the isolation of tetrahydropyrone derivatives. 



In the presence of dilute alkali butyl-acetoacetic ester interacted with 

 benzaldehyde to form a crystalline unsaturated ketonic acid, 



CgHjCIi : CH . CO . CH (O4H9) . COOH, 



which, on more prolonged action, decomposed into the unsaturated ketone, 



CgHg . CH : OEI . CO . CIJ, . C^Hg. 



Similar compounds were obtained from butyl-acetoacetic ester and anisal- 

 dehyde and piperonal respectively- No doubt the further condensation of 

 these iinsaturated ketones with the aldehydes would have yielded tetra- 

 hydropyrone derivatives similar to that got from benzaldehyde and 

 benzylidene-methylethyl-ketone. Butyl-acetone, indeed, reacted with benzal- 

 dehyde and piperonal respectively, yielding crystalline compounds derived 

 from one molecule of the Ivctone and three molecules of the aldehyde in each 

 case — condensations similar to those between these aldehydes and methyl- 



ethyl-ketone. 



Experimental. 



A-.—Butyl-Acetoacetic Uder. 



CH3. CO. CH C^ Hs . COO G\ H5. 



A solution of 23 grams of sodium in about ten times its weight of 

 absolute alcoliol was added to a mixture of 184 grams of re-distilled butyl 



