IONIZATION CONSTANTS OF SOME IMIDAZOLES
IONIZATION CONSTANTS OF SOME IMIDAZOLES
复制标题
DOI：
10.1021/jo01027a023
复制
发表时间：
1964-01-01
影响因子：
3.6
通讯作者：
LANCINI, GC
中科院分区：
文献类型：
--
作者：
GALLO, GG;PASQUALU.CR;LANCINI, GC
The basic and the acidic ionization constants of some imidazole derivatives havebeen determined spectro-photometrically or potentiometrically. For the nitroimidazoles, the spectrophotometric method has been used in concentrated sulfuric acid solutions for which the Hammett acidity function, H0, has been adopted. Tautomeric equilibrium constants of the imidazoles containing an imino hydrogen havebeen calculated. The ionization constants have been correlated to the substituents and their position in the imidazole ring. The use-fulness of pKa measurements in assigning structures ofthese compounds is pointed out.The chemistry of imidazoles has been studied1 extensively and attention has been paid to their ionization constants. The pK& values of some imidazoles have been determined1· 2 and useful observations have been made recently for some nitro derivatives, whose basicity is diminished strongly by the electronegative nitro group. 3 We then have considered of interest a further study of the basicity of the imidazole derivatives of this type. The potentiometric method was used for the derivatives whose basic dissociation con-stants were still measurable in this way. For the nitro derivatives we adopted the spectrophotometric method in concentrated acid solutions, which provides a suitable way for obtaining correct values. The acidic ionization constants also were determined potentiometrically. All the results obtained, together with data referred to in literature, have been correlated and evaluations useful for structure determination have been found.
