1973 年 93 巻 8 号 p. 1014-1018
Carbon-13 nuclear magnetic resonance (NMR) spectra of nine kinds of mono-substituted barbituric acid derivatives were measured. Two conclusions were obtained from the analysis of carbon-13 NMR spectra. (1) The so-called additive law is applicable to chemical shifts of the carbon at 5-position. (2) There is a correlation between chemical shifts of the carbon at 5-position and pKa, values, except in barbituric acid and 5-methylbarbituric acid.