NH acidities of some 3-(p-substitutedphenyl)-1,2,4-oxadiazol-5(4H)-ones and 4-(p-substitutedphenyl)-1,2 \lambda^43,5-oxathiadiazole 2-oxides were determined in methanol by means of potentiometric titration with sodium methoxide. pK_a values of the title compounds calculated from the potentiometric data were interpreted on the basis of structural effects caused by para-substituted groups on the phenyl ring by plotting pK_a values versus Hammett \sigma_p^+ constants, which gave excellent linear correlations.
一些3-(对取代苯基)-1,2,4-噁二唑-5(4H)-酮和4-(对取代苯基)-1,2λ^43,5-噻二氮杂烯-2-氧化物的NH酸度在
甲醇中通过与甲氧化
钠的电位滴定进行测定。根据电位数据计算出的标题化合物的pK_a值通过绘制pK_a值与Hammett σ_p^+常数的关系图来解释,这表明对取代基对苯环造成的结构效应,得到了很好的线性相关性。