Genuine 5, 6-dihydroorotic acid has been synthesized and its decomposition in alkali, together with the breakdown of 5, 6-dihydrouracil and 5, g-dihydrothymine under similar conditions, has been studied. All three compounds are hydrolyzed in 0.1 N alkali at the 3 4 linkage. The same lability has been observed with succinylurea, fumarylurea and maleylurea.
