The acidity constants of some pyrimidine bases in various water-organic solvent media

被引：14

作者：

Ahmed, IT ^{[1
]}

Soliman, ES ^{[1
]}

Boraei, AAA ^{[1
]}

机构：

[1] Menia Univ, Dept Chem, Fac Sci, El Minia, Egypt

来源：

ANNALI DI CHIMICA | 2004年 / 94卷 / 11期

关键词：

D O I：

10.1002/adic.200490105

中图分类号：

O65 [分析化学];

学科分类号：

070302 ; 081704 ;

摘要：

The acid ionization constants of some pyrimidine bases of nucleic acids were determined pH-metrically at 25degreesC and at the constant ionic strength I = 0.10 mol l(-1) (KNO3) in pure water as well as in aqueous media containing variable mole percentages (5-30%) of organic solvents. The organic solvents used were methanol, ethanol, N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetonitrile, acetone and dioxane. The results obtained indicated that the acidity constants are generally decreased as the content of an organic solvent in the medium is increased. It was deduced that the hydrogen bonding interactions and the solvent basicity in addition to the electrostatic effect are the major effects influencing significantly the acid ionization process of pyrimidine bases in the different water-organic solvent media. Some thermodynamic parameters (DeltaH, DeltaGdegrees, DeltaSdegrees) of the ionization process over the temperature range 5-45degreesC in pure water were also determined and discussed.

引用

页码：847 / 856

页数：10

共 42 条

[1] Acidity constants and thermodynamic parameters of barbituric and diethylbarbituric acids in water, (water plus tetrahydrofuran), and (water plus Triton X-100) systems [J].