β-Ureido acids and dihydrouracils. The kinetics and mechanism of the reversible ring closure of 3-(3'-methylureido)-propanoic acid and 3-(3-phenylureido)-2- …
V Rachina, IB Blagoeva, IG Pojarlieff…
文献索引：Rachina; Blagoeva; Pojarlieff; Yates Canadian Journal of Chemistry, 1990 , vol. 68, # 10 p. 1676 - 1684
The p K BH+ values for protonation of the ureido groups of the title acids, and for protonation at the 2-carbonyl groups of the product hexahydropyrimidine-2, 4-diones, have been determined by standard UV and NMR methods. A bell-shaped dependence of the observed rate constants on H2SO4 concentration was found for both the ring-closure and ring- opening directions. This medium dependence is satisfactorily reproduced by means of ...
