Showing papers by "Mohamed R. Mahmoud published in 1981"
TL;DR: In this paper, the U.v. and visible spectra of some 1 - phenyl - 3 - methyl - 4 - arylidene - 2 - pyrazolin - 5 - one derivatives are investigated in pure and mixed organic solvents as well as in aqueous buffer solutions.
4 citations
TL;DR: In this article, the pK values of 2-styryl-4-phenylthiazole ethiodide derivatives in different organic solvent mixtures were determined, and the major important effects responsible for this behaviour were the difference in the stabilization of the base by dispersion forces in case of the amino derivative and by donor hydrogen bonds from solvent molecules in the case of hydroxy derivatives.
Abstract: The pK values of some 2-styryl-4-phenylthiazole ethiodide derivatives in different organic solvent – water mixtures were determined. It is observed that as the amount of the organic solvent in the medium increases the pK of the dimethylamino derivative is decreased while that of the hydroxy derivatives is increased. It is concluded that the major important effects responsible for this behaviour are the difference in the stabilization of the base by dispersion forces in case of the amino derivative and by donor hydrogen bonds from solvent molecules in the case of the hydroxy derivatives. The effect of the molecular structure of the compound on pK is also discussed.
2 citations