Abstract
Hydrolytic reactions of 5, 5-disubstituted 1-methylbarbituric acid derivatives at 30°, 40°, and 50° in alkaline solutions of various concentrations were investigated, and the rate constants and thermodynamic parameters of all of the compounds tested were determined. As physico-chemical parameters which might reflect the substituent effect on the hydrolytic rate, the acid dissociation constant (pKa), the value of 13C chemical shift (δc) at the 5-position, the "six number" (Six No.), and the molecular connectivity index (χ) were selected. An extrathermodynamic linear equation was then derived using these parameters. The correlation between log k'OH and the combined parameters pKa and δc (5) was largest, as determined by multiple regression analyses.
