Enthalpy of Vaporization or Organic Compounds at 25 degrees C. V. Acetylacetone.

Irving, R. J.; Wadsö, Ingemar; Ballhausen, C. J.; Ragnarsson, Ulf; Rasmussen, Svend Erik; Sunde, Erling; Sørensen, Nils Andreas

doi:10.3891/acta.chem.scand.24-0589

Cited by 27 publications

(18 citation statements)

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“…The ratio in nH 2 and nD 2 is found to be intermediate between pH 2 and Ne hosts with R ke % 2%. The low abundance of keto observed in the present work is in very good agreement with gas-phase NMR studies at 298 K [25] and with Irving and coworkers' results [26]. A 2.5% abundance of keto can be extracted from the thermodynamic results of Ref.…”

Section: Keto/enol Ratiosupporting

confidence: 92%

Acetylacetone in hydrogen solids: IR signatures of the enol and keto tautomers and UV induced tautomerization

Lozada‐Garcia

Čeponkus

Chin

et al. 2011

Chemical Physics Letters

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Section: Keto/enol Ratiosupporting

confidence: 92%

Acetylacetone in hydrogen solids: IR signatures of the enol and keto tautomers and UV induced tautomerization

Lozada‐Garcia

Čeponkus

Chin

et al. 2011

Chemical Physics Letters

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“…Acetylacetone, like other β-diketones, preferentially adopts either the diketone or the enolone form, depending on its environment. At room temperature in the gas phase , or in nonpolar solvents AcAc exists primarily as the enolone. Its photodynamics depend on the initial geometry and may involve phototautomerization; hence, we wish to first understand the equilibrium tautomer distribution and to develop tautomer-specific probing techniques.…”

Section: Resultsmentioning

confidence: 99%

To Boldly Look Where No One Has Looked Before: Identifying the Primary Photoproducts of Acetylacetone

et al. 2019

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We investigate the gas-phase photochemistry of the enolone tautomer of acetylacetone (pentane-2,4-dione) following S2(ππ*) ← S0 excitation at λ = 266 and 248 nm, using three complementary time-resolved spectroscopic methods. Contrary to earlier reports, which claimed to study one-photon excitation of acetylacetone and found OH and CH3 as the only important gas-phase products, we detect 15 unique primary photoproducts and demonstrate that five of them, including OH and CH3, arise solely by multiphoton excitation. We assign the one-photon products to six photochemical channels and show that the most significant pathway is phototautomerization to the diketone form, which is likely an intermediate in several of the other product channels. Furthermore, we measure the equilibrium constant of the tautomerization of the enolone to diketone on S0 from 320 to 600 K and extract ΔH = 4.1 ± 0.3 kcal·mol–1 and ΔS = 6.8 ± 0.5 cal·mol–1·K–1 using a van’t Hoff analysis. We correct the C–OH bond dissociation energy in acetylacetone, previously determined as 90 kcal·mol–1 by theory and experiment, to a new value of 121.7 kcal·mol–1. Our experiments and electronic structure calculations provide evidence that some of the product channels, including phototautomerization, occur on S0, while others likely occur on excited triplet surfaces. Although the large oscillator strength of the S2 ← S0 transition results from the (ππ*) excitation of the CCCO backbone, similar to conjugated polyenes, the participation of triplets in the dissociation pathways of acetylacetone appears to have more in common with ketone photochemistry.

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“…2,4-Pentanedione (or acetylacetone, abbreviated AcAc, Scheme ) is a β-diketone that exhibits keto–enol tautomerism. The enolic (E) form of AcAc, the dominant tautomer in the gas phase (>93%), is an α,β-enone that is stabilized by a strong (∼12 kcal mol –1 ) intramolecular hydrogen bond (Scheme ). The oscillator strength underlying the broad structureless absorption of AcAc in the ultraviolet that peaks at 263 nm is attributed to a S 0 → S 2 (ππ*) transition in the enolic form .…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Intersystem Crossing in Acetylacetone via Femtosecond X-ray Transient Absorption at the Carbon K-Edge

et al. 2017

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Molecular triplet states constitute a crucial gateway in the photochemical reactions of organic molecules by serving as a reservoir for the excess electronic energy. Here, we report the remarkable sensitivity of soft X-ray transient absorption spectroscopy for following the intricate electronic structure changes accompanying the non-adiabatic transition of an excited molecule from the singlet to the triplet manifold. Core-level X-ray spectroscopy at the carbon-1s K-edge (284 eV) is applied to identify the role of the triplet state (T, ππ*) in the ultraviolet-induced photochemistry of pentane-2,4-dione (acetylacetone, AcAc). The excited-state dynamics initiated at 266 nm (ππ*, S) is investigated with element- and site-specificity using broadband soft X-ray pulses produced by high harmonic generation, in combination with time-dependent density functional theory calculations of the X-ray spectra for the excited electronic singlet and triplet states. The evolution of the core-to-valence resonances at the carbon K-edge establishes an ultrafast population of the T state (ππ*) in AcAc via intersystem crossing on a 1.5 ± 0.2 ps time scale.

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Enthalpy of Vaporization or Organic Compounds at 25 degrees C. V. Acetylacetone.

Cited by 27 publications

References 0 publications

Acetylacetone in hydrogen solids: IR signatures of the enol and keto tautomers and UV induced tautomerization

Acetylacetone in hydrogen solids: IR signatures of the enol and keto tautomers and UV induced tautomerization

To Boldly Look Where No One Has Looked Before: Identifying the Primary Photoproducts of Acetylacetone

Ultrafast Intersystem Crossing in Acetylacetone via Femtosecond X-ray Transient Absorption at the Carbon K-Edge

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