Ryan and Dkvink — Condensation of Aldehydes with Ketones. 209 



In the reactions which they carried out G-oldschmidt and Krczmar obtained 

 cinnamenylbenzylketone 



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

 in the presence of dilute alkali, and the isomeric ^-derivative 



C 6 H 5 .C.CO.CH 3 

 II 

 CH.0 6 H 5 



in the presence of hydrochloric acid. 



With dilute alkali as condensing agent, Harries and Muller obtained 



from me thy lethyl ketone and benzaldehyde a ketone, melting at 38°-39° C, 



previously described by Levinstein as y-benzylidene-methylethylketone, but 



which Harries and Muller regarded as o-benzylidene-methylethylketone. On 



reduction, the ketone was converted into a-benzyl-methylethylketone, and 



their view of the constitution of the substance was found correct when the 



latter substance was also got by the dry distillation of a mixture of the 



calcium salts of dihydrocinnamic and propionic acids : — 



(C 6 H 6 CH 2 . CH 2 . CO . 0) 2 Ca + (CH 3 . CH S . CO . 0) 2 Ca .= 

 2C S H 5 . CH 2 . CH 2 . CO . CH 2 CH 3 + 2 CaC0 3 



By condensing benzaldehyde with methylethylketone in the presence 

 of hydrochloric acid, Harries and Muller prepared the isomeric ketone, 

 y-benzylidene-methylethylketone, which also melted at 38°-39° C. 



As the result of their experiments, Harries and Muller concluded that 

 benzaldehyde and methylethylketone in the presence of hydrochloric acid 

 form a y-derivative, and in the presence of dilute alkali an o-derivative. 



By the further action of benzaldehyde on a-benzylidene-methylethylketone 

 Harries and Muller prepared a colourless crystalline compound melting at 

 68'5° O, for which they found the empirical formula Ci 8 Hi 8 2 , and which they 

 regarded as a pyrone derivative. 



If we assume with Harries and Muller that the compound Ci 8 H ]8 2 is a 

 pyrone derivative, its formation from benzaldehyde and methylethylketone 

 will be represented as follows : — 



CH 3 . CO . CH 2 CH 3 + C 6 H 6 . CHO — >C 6 H 5 . CH : CH . CO . CH> . CH 3 + C 6 H 6 . CHO— -> 



C 6 H 5 .CH:CH.C0. CH . CH 3 C 6 H 5 CH . CH 2 . CO . CH . CH 3 



I — > I I 



HO . CH . C 6 H 6 CH . C 6 H 5 



II. III. 



the unsaturated hydroxy-ketone (II) changing into the isomeric diphenyl- 

 methyl-tetrahydropyrone (III) in the course of the reaction. 



It seemed likely that the last compound (III) would interact with 

 benzaldehyde to give benzylidene-diphenyl-methyltetrahydropyrone (I). 



[2H2] 



