tive if present occurs in mere traces. The tetraethoxy and tetrabutoxy derivatives obtained as above are of especial interest as representing the first known derivatives of the hypothetical tautomeric barbital. They possess in addition to ether linkages in positions 4 and 6, an acetal structure in the 2-position. Hence they may be regarded as acetals of the ethers of enolic barbital. The isomeric 1,3,5,5-tetraethylbarbituric acid, but without the acetal grouping in position 2, has been prepared by Fischer and Dilthey4 from ethyl diethylmalonate and yjm.-diethylurea. This also was a high-boiling liquid. Summary 2,2,4,6-Tetrachloro-5,5-diethyldihydropyrimidine, a product obtained by chlorination of barbital with phosphorus pentachloride, reacts with sodium alkoxides to form the corresponding 2,2,4,6-tetraalkoxy-5,5diethyldihydropyrimidines. Hydrolysis by concentrated hydrochloric acid converts the tetraalkoxy derivative into diethylacetic acid and ammonium chloride, the latter in almost quantitative yield, showing that the alkyl is actually linked to oxygen. These tetraalkoxy derivatives represent acetals of the ethers of a hypothetical enolic barbital.A series of 2,4,6-trialkoxy derivatives was also prepared from 2,4,6-trichloro-5-sec.-butylpyrimidine.Detroit, Michigan
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