Gas-phase proton NMR studies of keto-enol tautomerism of acetylacetone, methyl acetoacetate, and ethyl acetoacetate

Folkendt, Michael M.; Weiss-López, Boris; Chauvel, J.; True, Nancy S.

doi:10.1021/j100261a038

Cited by 146 publications

(154 citation statements)

References 2 publications

Supporting

Mentioning

135

Contrasting

Unclassified

Order By: Relevance

“…The Folkendt et al 19 study appears to have gone unnoticed by thermochemists working in the field. 40 This is surprising in view of the unambiguous assignment of resonances associated with the keto and enol forms as compared with similar assignments with IR, UV, and photoelectron spectroscopy.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The Thermochemistry of 2,4-Pentanedione Revisited: Observance of a Nonzero Enthalpy of Mixing between Tautomers and Its Effects on Enthalpies of Formation

et al. 2005

View full text Add to dashboard Cite

The enthalpies of formation of pure liquid and gas-phase (Z)-4-hydroxy-3-penten-2-one and 2,4-pentanedione are examined in the light of some more recent NMR studies on the enthalpy differences between gas-phase enthalpies of the two tautomers. Correlation gas chromatography experiments are used to evaluate the vaporization enthalpies of the pure tautomers. Values of (51.2 ( 2.2) and (50.8 ( 0.6) kJ‚mol -1 are measured for pure 2,4-pentanedione and (Z)-4-hydroxy-3-penten-2-one, respectively. The value of (50.8 ( 0.6) kJ‚mol -1 can be contrasted to a value of (43.2 ( 0.2) kJ‚mol -1 calculated for pure (Z)-4-hydroxy-3-penten-2-one when the vaporization enthalpy is measured in a mixture of tautomers. The difference is attributed to an endothermic enthalpy of mixing that destabilizes the mixture relative to the pure components. Calculation of new enthalpies of formation for (Z)-3-hydroxy-3-penten-2-one and 2,4-pentanedione in both the gas, ∆ f H°m(g) ) (-378.2 ( 1.2) and (-358.9 ( 2.5) kJ‚mol -1 , respectively, and liquid phases, ∆ f H°m(l) ) (-429.0 ( 1.0) and (-410.1 ( 1.2) kJ‚mol -1 , respectively, results in enthalpy differences between the two tautomers both in the liquid and gas phases that are identical within experimental error, and in excellent agreement with recent gas-phase NMR studies.

show abstract

Section: Discussionmentioning

confidence: 99%

“…13,[16][17][18][19][20][21][22][23][24][25][26][27][28] Both spectroscopic and chemical methods have been used to determine the enthalpy of tautomerization in the gas phase. Unlike the condensed phase studies, agreement between methods is less than satisfactory.…”

Section: Introductionmentioning

confidence: 99%

The Thermochemistry of 2,4-Pentanedione Revisited: Observance of a Nonzero Enthalpy of Mixing between Tautomers and Its Effects on Enthalpies of Formation

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Temperature effects on the keto ± enol tautomerism have been reported by True and co-workers using gas-phase 1 H-NMR [17]. The enol tautomer 1a (or 1c) is the most stable, as present in condensed phases at a given temperature.…”

mentioning

confidence: 80%

Solid‐State NMR Study of the Tautomerism of Acetylacetone Included in a Host Matrix

Claramunt

López

Lott

et al. 2005

Helvetica Chimica Acta

View full text Add to dashboard Cite

The tautomerism of the enol form of acetylacetone (=pentane‐2,4‐dione; 1) inside a host cavity has been studied by means of solid‐state 13C‐NMR spectroscopy (SSNMR) using the variable‐temperature CPMAS technique. It appears that the enol form, 4‐hydroxypent‐3‐en‐2‐one (1a), exists in an equilibrium with an identical tautomer (1c) trough OH ⋅⋅⋅O proton transfer. The experimental results (energy barrier and chemical shifts) were rationalized by means of MP2 and GIAO calculations.

show abstract

“…Keto/enol tautomeric transformations have been thoroughly studied by spectral methods in solution and, in several cases, also in the gas phase (Powling & Bemstain, 1951;Folkendt, Weis-Lopez, & Chanvel, 1985). Therefore, P-diketones were naturally the first tautomeric systems that were studied by mass spectrometry (Maquestiau & Flammang, 1982;Schamp & Vandewell, 1966, 1967Vandewell, Schamp, & Wilde, 1967).…”

Section: A Keto/enol and Nitroso/enarnine Tautornerismmentioning

confidence: 99%

Application of mass spectrometry for the analysis of organic tautomeric compounds

Терентьев

Kalandarishvili

1996

Mass Spectrom. Rev.

View full text Add to dashboard Cite

Gas-phase proton NMR studies of keto-enol tautomerism of acetylacetone, methyl acetoacetate, and ethyl acetoacetate

Cited by 146 publications

References 2 publications

The Thermochemistry of 2,4-Pentanedione Revisited: Observance of a Nonzero Enthalpy of Mixing between Tautomers and Its Effects on Enthalpies of Formation

The Thermochemistry of 2,4-Pentanedione Revisited: Observance of a Nonzero Enthalpy of Mixing between Tautomers and Its Effects on Enthalpies of Formation

Solid‐State NMR Study of the Tautomerism of Acetylacetone Included in a Host Matrix

Application of mass spectrometry for the analysis of organic tautomeric compounds

Contact Info

Product

Resources

About