A photoelectron spectroscopic study of keto-enol tautomerism in acetylacetones - a new application of photoelectron spectroscopy

Schweig, Armin; Vermeer, Hans J.; Weidner, Ulrich

doi:10.1016/0009-2614(74)85403-5

Cited by 92 publications

(45 citation statements)

References 8 publications

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“…23 The highest occupied molecular orbitals in the enol compound are of 1r type (IP = 9.00 eV) and nonbonding type (IP = 9.60 eV). 25 In Fig One also observes a weak band with an onset at 3.83 eV and maximum at 4.04 eV due to the first spin-allowed n-+tr* band in the acetylacetone diketo form. 7 • 24 · 26 An increase in scattering angle [ Fig.…”

Section: B Acetylacetone (24-pentanedlone)mentioning

confidence: 81%

Electron-impact spectroscopy of various diketone compounds

Walzl

Xavier

Kuppermann

1987

The Journal of Chemical Physics

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The spectra ofthe diketone compounds biacetyl, acetylacetone, acetonylacetone, 1,2-cyclohexanedione, and 1,4-cyclohexanedione have been investigated by the technique oflowenergy variable-angle electron energy-loss spectroscopy. With this method low-lying, spinforbidden transitions have been observed. The energy difference between the lowest spin-allowed and spin-forbidden n-+ 1r* excitations in the acyclic diketones is found to be 0.35 eV, on average, which is nearly the same as that of comparable acyclic monoketone compounds; in 1,2-cyclohexanedione, however, this energy difference is 0.84 eV, more than twice as large. This discrepancy in the magnitude of then-+ 1r* singlet-triplet splittings may be attributed to differing amounts of overlap between the initial and final orbitals.

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Section: B Acetylacetone (24-pentanedlone)mentioning

confidence: 81%

Electron-impact spectroscopy of various diketone compounds

Walzl

Xavier

Kuppermann

1987

The Journal of Chemical Physics

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“…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

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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.

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“…There are more bands when the blue line is used, and their band centers shift a little. In the literature, [27][28][29][30][31][32][33][34] there are several studies reporting on the UV photoisomerization of acetylacetone and of experiments performed using infrared radiation for conversions of one matrix-trapped isomer into the other. Here, we report photoisomerization that is going on in the visible part of the spectrum when the sample is solid at low temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The S 2 state decays into lower S 1 , T 2 , and T 1 states, which decay further into ground states of different acac isomers. [27][28][29][30][31][32][33][34] The notation used to describe the isomers consists of three capital letters CCC, CTC, an so forth. The first letter refers to the conformation with respect to rotation around the carbon−carbon single bond in the ring, the second letter describes conformation with respect to rotation around the double carbon bond, and the third letter refers to conformation with respect to rotation around the carbon−hydroxyl oxygen bond.…”

Section: Resultsmentioning

confidence: 99%

“…25 After the discovery of Veierov et al 26 that acetylacetone displays isomerization upon UV illumination, a number of studies were devoted to isolation of different isomers and calculation of their relative energies. [27][28][29][30][31][32][33][34] Vibrational studies of acetylacetone gave a thorough assignment of bands for the enolic C s tautomer, and some, more intense, bands of the keto tautomer could be confidently attributed. induced UV and IR isomerizations of matrix-isolated acac.…”

Section: Introductionmentioning

confidence: 99%

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Low temperature Raman study of bis(trimethylsilyl)acetylene

Mohaček-Grošev¹,

Furić²

2007

Journal of Molecular Structure

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Raman spectra of acetylacetone were recorded for molecules isolated in an argon matrix at 10 K and for a polycrystalline sample. In the solid sample, broad bands appear superimposed on a much weaker Raman spectrum corresponding mainly to the stable enol form. The position of these bands depends on the excitation wavelength (514.5 and 488.8 nm argon ion laser lines were used), sample temperature, and cooling history. They are attributed to transitions from an excited electronic state to various isomer states in the ground electronic state. Laser photons have energies comparable to energies of a number of excited triplet states predicted for a free acetylacetone molecule (Chen, X. Chem. Phys. 2002, 116, 5694). Using matrix isolation in argon, the vibrational spectrum of acetylacetone at 10 K was recorded. Strong bands at 1602 and 1629 cm -1 are assigned as the SYN enol bands, while a weaker underlying band at 1687 cm -1 and a medium shoulder at 1617 cm -1 are assigned as TS2 enol bands.

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A photoelectron spectroscopic study of keto-enol tautomerism in acetylacetones - a new application of photoelectron spectroscopy

Cited by 92 publications

References 8 publications

Electron-impact spectroscopy of various diketone compounds

Electron-impact spectroscopy of various diketone compounds

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

Low temperature Raman study of bis(trimethylsilyl)acetylene

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