Effect of Medium on the Acidity Constant of Some New Arylazopyrazolopyrimidine Derivatives
作者:Elham M. Abd-Allah、Nasr M. Rageh、Hassan M. A. Salman
DOI:10.1021/je020194t
日期:2003.3.18
The acid dissociation constants of some new 8-[(aryl)azo]-2,4-dimethylpyrazolo[1,5-a]pyrimidine-7(6H)-one derivatives were determined in aqueous−organic solvent mixtures. The organic solvents are methanol, ethanol, acetone, and dimethylformamide. The results obtained were discussed in terms of the solvent characteristics. The ionization constants of the title dyes depend largely on both the ratio and
在水性有机溶剂混合物中测定了一些新的8-[(芳基)偶氮] -2,4-二甲基吡唑并[1,5 - a ]嘧啶-7(6H)-one衍生物的酸解离常数。有机溶剂是甲醇,乙醇,丙酮和二甲基甲酰胺。讨论了所得结果的溶剂特性。标题染料的电离常数在很大程度上取决于有机助溶剂的比例和性质。共轭碱与溶剂分子的氢键相互作用以及溶剂的碱度对电离过程起主要作用。已经得出结论,p K a值通过增加介质中有机助溶剂的量而增加。偶氮化合物分子结构对p的影响讨论K a值。