作者: W.F. Smyth , G. Svehla , P. Zuman
DOI: 10.1016/S0003-2670(01)95745-9
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摘要: Abstract Changes of u.v. absorption spectra and polarographic reduction waves with pH indicate in solutions 5,5'-dialkyl-2-thiobarbiturates the presence four different species: diprotonated (AH2), monoprotonated (AH), zwitterion (BH) anionic (B). Dissociation constants pK2. were determined values pK1 pK3estimated. In attempts to elucidate electroactive forms, some tautomers excluded 4-electron H2A 2-electron reductions HA BH, electrolyses which gave varying yields hydrogen sulphide. The anion B gives no waves. 1,5,5'-Trialkyl-2-thiobarbiturates show corresponding forms BH. 1,3-Dimethyl-5,5'-dipropyl-2-thiobarbiturate is reduced possibly form. Predominant bulk solution at various most probable are discussed. Reduction 5,5'-dialkyl- 1,5,5'-trialkyl-2-thiobarbiturates 0.05 M borax suitable for analytical purposes.