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' ON THE CONDENSATION OF ALDEHYDES WITH KETONES. 



III. — Benzaldehyde with Methyl-Isopropyl-Ketone. 



By HUGH KYAN, D.Sc, and PHYLLIS liYAN, B.Sc, 

 ;.. • University College, Dublin. 



Kead Novkmbeu 30, 1916. Published Febkuary 6, 1917. 



By the interaction of benzaldehyde and dimethyl-acetylacetone, in the 

 presence of anhydrous hydrochloiic acid, Eyan and Dunlea (Proc. Eoyal 

 Irish Acad., 1915. xxxii. B, p. 62) obtained a compound which melted with 

 decomposition at 170°C., and to which they gave the formula CasHjaOjCl. 

 When this compound was boiled with pyridine it lost hydrochloric acid and 

 yielded anotiier crystalline substance, C25II22O2, which melted at 168-169-5° C. 

 The latter compoimd formed a dibromide and gave an addition compound 

 with hydroxylamine. The general behaviour of the substance indicated that 

 it was a tetrahydropyrone derivative, and since the same substance was 

 obtained, although in much smaller quantity, from monomethyl-acetylacetone 

 and benzaldehyde, they concluded that in the formation of it from dimethyl- 

 acetylacetone one of the methyl groups of the latter was eliminated. The 

 reactions were formulated in the following manner : — 



CeHsCHO + CH3 . CO . C(CH3)2 . CO . CH3 + HCl 

 " = CeHs • CH : CH . CO . CH(CH3) . CO . CH^ ^ CH3CI + H2O. 



CsHj . CH : CH . CO . CHCCH,) . CO . CH3 + H2O 

 ^ = CeH, . CH : CH . CO . CH^ . CH3 + CH3 . COOH. 



CeHa . CH : CH . CO . CH2 . CH3 + CeH^CHO 

 = CeHa . CH . CH2 . CO . CH . CH3 



■ CH . CsHs. ■ 



CeHs . CH . CH2 . CO . CH . CH3 + CeUsCHO 



.6- CH . CJia 



CH CeHs 



= CeH, . CH . C . CO . CH . CH, 

 .0 CH.CsHa. 



E.I. A. PEOd., VOL. XXXIII., SECT. B. [ijj 



