Article ID Journal Published Year Pages File Type
10564458 Vibrational Spectroscopy 2005 9 Pages PDF
Abstract
FT-IR spectra were recorded for α-keto pyruvic acid in three solvents (CCl4, CH2Cl2, and benzene) at room temperature. In parallel, quantum-chemical calculations were performed for all stable tautomers-rotamers: three stable keto and six stable enol structures using the DFT(B3LYP) method and various basis sets 6-31++G** and/or 6-311++G(3df, 3pd). Comparison of the experimental FT-IR and the computed DFT-IR spectra indicates that pyruvic acid may exist as a mixture of at least four isomers, three keto (Tce, Tte and Cte) and one enol (E1), among which the intramolecularly H-bonded keto Tce structure highly predominates. Intensity of the ν(OH) band assigned to the enol form (E1) varies when proceeding from CCl4 to other solvents. It increases in CH2Cl2 (weak H-bond donor solvent) and decreases in benzene (weak H-bond acceptor solvent) in comparison to the ν(OH) band assigned to the most stable keto form (Tce). Independently on solvent properties, in each case the keto Tce structure is favoured.
Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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