Conformational analysis, tautomerization, IR, Raman, and NMR studies of ethyl benzoylacetate

A complete conformational analysis of the keto and enol forms of ethyl benzoylacetate (EBA), a β-ketoester, was carried out by ab initio calculations, at the density functional theory (DFT) level. The relative stabilities of cis-enol and keto forms were calculated in the gas phase and in solution. The intramolecular hydrogen bond characters of the most stable enol forms of EBA are discussed and compared with those of benzoylacetone (BA).Harmonic vibrational frequencies and 1H and 13C NMR chemical shifts of the most stable enol and keto forms were also calculated at the B3LYP/6-311++G** level and compared with the experimental data.

► The enol content of EBA in the sample depends on the nature of the solvent. ► The chelated H-bond in EBA is considerable weaker than that in benzoylacetone. ► Practical results indicate coexisting of keto and enol conformers in the sample.