36232-81-2Relevant academic research and scientific papers
Medium effect on acidity constants of some 2-styryl-4-phenylthiazole ethiodide derivatives
El-Kashef, Hussein S.,Abdel-Hamide, Refat,Mahmoud, Mohamed R.,Hamed, Maher M.
, p. 731 - 736 (2007/10/02)
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.
Substituent and Solvent Effects on the Rate of the Reaction of 2-Methyl-4-phenyl-thiazole Ethiodide with Substituted Benzaldehydes
Mahmoud, M. R.,El-Kashef, H. M. S.,El-Nady, A. M.
, p. 657 - 670 (2007/10/02)
Condensation of 2-methyl-4-phenyl-thiazole ethiodide (1) with aromatic aldehydes in presence of piperidine as base catalyst has been studied kinetically at different temperatures.The rate in presence of low concentration of piperidine ( .On the other hand the rate in presence of >/= 1.013 M piperidine is represented by the second-order equation: v=k' .It is concluded from the kinetic results that the dehydration step of the intermediate aldol compound is the rate determining step of the reaction.The dependence of the mechanism of the reaction and the thermodynamic parameters of activation on the molecular structure of the various aromatic aldehydes used is discussed.In various organic solvents, the rate of the reaction increases as the dielectric constant of the medium is increased.The energy of activation and the thermodynamic parameters of activation were calculated and discussed in terms of solvent properties. - Keywords: Reaction mechanism / Solvent effects / Substituent effects
