Tautomerism of azine derivatives. 7. Thermodynamic parameters of the 1,3-prototropic tautomeric equilibrium of azahetarylmethanes
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The constants of the hetaryl-ylidene tautomeric equilibrium in CDCl3 over a wide range of temperatures were measured for azinylmalonic and azinylcyanoacetic acid esters. High-temperature sensitivity of the position of the equilibrium for 2-pyrimidinylcyanoacetic acid esters was demonstrated. The differences in the δS values of the equilibrium for derivatives of malonic and cyanoacetic acid esters were explained by different freedoms of rotation about the exocyclic C-C bond in the aromatic tautomeric form.
KeywordsEster Organic Chemistry CDCl3 Thermodynamic Parameter Acid Ester
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