RvAN AND Phyllis Ritan — On the Oondemation of Aldehydes. 107 



Ryan and Dunlea had employed, had not been freed from dimethyl- 

 acety lace tone, and, therefore, that the formation of the tetrahydropyrone 

 derivative observed by them in this case was due to the dimethyl- 

 aeetylacetone contained in the impure parent substance. 



After freeing this impure monomethyl-acetylacetone from the dimethyl 

 compound by conversion into its copper derivative and recovery from the 

 latter it interacted with benzaldehyde in the presence of alcoholic hydro- 

 chloric acid to form not the compound C25H22O2 melting at 168-169'5'^ C, 

 but a compound CjsH.uO melting at 158° C, which was identical with that 

 got from the condensation of benzaldehyde with methyl-ethylketone. 



EXPEEIMENTAL PaRT. 



1. Action of Benzaldehyde on Meihyl-Isopropyl-Ketone in the presence of 

 Alcoholic Hydrochloric Acid. 



A solution of 10 c.cs. of freshly distilled methyl-isopropyl-ketone and 

 30 c.cs. of benzaldehyde in 60 c.cs. of alcohol, which had been previously 

 saturated in the cold with anhydrous hydrochloric acid, rapidly assumed a 

 dark red colour, and on standing several days gave a copious separation 

 (about 10 grams) of nearly colourless crystals. The solid was filtered and 

 recrystalLised from a mixture of chloroform and alcohol. When dried at 

 105° C. the substance melted at 169-17 1°C., and a mixture of it with the 

 benzylidene derivative of the diphenyl dimethyl-tetrahydropyrone of Eyan 

 and Dunlea also melted at 168-170° C. In appearance and solubilities it 

 was identical with the latter compound. On analysis the following results 

 were obtained : — 



0-2188 substance gave 0-6800 CO2, and 0-1280 HjO 

 corresponding to C 84'75 H 6-5 

 CgHjiOj, requires C 84-78 li 65. 



2. Action of Benzaldehyde on Methyl-AcetylacetoTie. 



Monomethyl-acetylacetone was freed from diniethyl-acetylacetone by 

 shaking its solution in ether with an aqueous solution of copper acetate. 

 The copper derivative was first washed with, then suspended in, ether, and 

 shaken with dilute sulphuric acid until the mixture had separated into two 

 clear layers, the upper layer consisting of an ethereal solution of monomethyl- 

 acetylacetone, from which the ketone was recovered by distillation. 



After saturating a solution of 3 c.cs. of monomethyl-acetylacetone and 

 12 c.cs. of benzaldehyde in 30 c.cs. of absolute alcohol with anhydrous hydro- 



