Hydroxyacetone (CH<sub>3</sub>COCH<sub>2</sub>OH): A Combined Microwave and Millimeter‐Wave Laboratory Study and Associated Astronomical Search

Apponi, A. J.; Hoy, James J.; Halfen, D. T.; Ziurys, L. M.; Brewster, M. A.

doi:10.1086/508157

Cited by 27 publications

(45 citation statements)

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“…Hence, the Cc conformer should represent 99% of the conformational equilibrium at room temperature, 8 which is why only the Cc conformer has been observed so far. 2,8,9 In this work, we report the first experimental observation of the elusive high-energy Tt conformer of hydroxyacetone. We show that, for HA isolated in a low-temperature Ar matrix, the Tt conformer can be produced by narrow-band near-infrared (NIR) vibrational excitation of the conformational ground state Cc.…”

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confidence: 91%

“…1 If such molecules are synthesized in interstellar medium, they may lead to the production of complex prebiotic chiral molecules, such as hydroxy aldehydes (sugars) and hydroxy acids. 2 HA is formed in the atmosphere during oxidation of the important biogenic hydrocarbon, isoprene. 3 Atmospheric HA reacts with an OH radical under sunlight irradiation 4 and also contributes to the formation of secondary organic aerosols.…”

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confidence: 99%

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Conformational Switching Induced by Near-Infrared Laser Irradiation

2009

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Hydroxyacetone (HA) is an important starting material in the organic synthesis of gem-diols, acetals, and ketals. 1 If such molecules are synthesized in interstellar medium, they may lead to the production of complex prebiotic chiral molecules, such as hydroxy aldehydes (sugars) and hydroxy acids. 2 HA is formed in the atmosphere during oxidation of the important biogenic hydrocarbon, isoprene. 3 Atmospheric HA reacts with an OH radical under sunlight irradiation 4 and also contributes to the formation of secondary organic aerosols. 5 The overall rate coefficient for the tropospherically relevant reaction, HA+OH, was proposed 6 to depend on the initial conformation of the HA molecule.Theoretical calculations on HA monomers in the gas phase 7,8 show that there are only two conformers (Cc and Tt) of this compound ( Figure 1). The lowest energy conformer of HA is Cc, whereas Tt was predicted to be higher in energy by 994 cm -1 . Hence, the Cc conformer should represent 99% of the conformational equilibrium at room temperature, 8 which is why only the Cc conformer has been observed so far. 2,8,9 In this work, we report the first experimental observation of the elusive high-energy Tt conformer of hydroxyacetone. We show that, for HA isolated in a low-temperature Ar matrix, the Tt conformer can be produced by narrow-band near-infrared (NIR) vibrational excitation of the conformational ground state Cc. When isolated in an argon matrix at 15 K, the photogenerated Tt form is stable. In the present study, the NIR-induced back transformation of the Tt conformer into the Cc form was also observed. This photoreversibility makes the HA molecule a system satisfying the criterion of a molecular switch. 10 In the experiments, tunable NIR radiation was provided by a Quanta-Ray MOPO-SL optical parametric oscillator (fwhm ∼0.2 cm -1 , repetition rate 10 Hz, pulse energy ∼3 mJ) pumped with a pulsed Nd:YAG laser. HA (Aldrich, >90%) was premixed with argon in a 1:1000 ratio and deposited onto a CsI window at 15 K. The FTIR spectra were recorded with 0.5 cm -1 resolution, in the 4000-400 cm -1 range. Other details of the experimental setup and of calculations are described elsewhere. 8 In a freshly deposited argon matrix the HA monomer only exists in Cc geometry, which is separated by a global barrier of 1417 cm -1 from the higher-energy Tt form. 8 Narrow-band NIR irradiation of the matrix at 6785 cm -1 led to a decrease of bands in the IR spectrum of the Cc form. Simultaneously, a set of new bands appeared due to a photogenerated species. The observed changes in the IR spectrum of HA are shown in Figures 1a and 2a.Comparison of the experimental difference spectrum with those calculated for the two conformers of HA (Figures 1b and 2b) reveals doubtlessly that the photogenerated species corresponds to the higher energy Tt conformer. The assignment of the nine most intense infrared Tt absorptions (along with Cc) is shown in Table 1.The observed shifts of the νOH and νCdO modes to higher frequencies (hypsochromic shifts) result from disru...

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Conformational Switching Induced by Near-Infrared Laser Irradiation

2009

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“…[3][4][5] Furthermore, acetol is an interesting molecule from astrophysical perspective. 6,7 The conversion of glycerol to acetol may be conducted via dehydration and/or dehydrogenation reaction. 1,8 Sato et al 1 reported that, for the copper oxide-based catalysts, the major product of glycerol conversion is acetol.…”

Section: Introductionmentioning

confidence: 99%

Non-Crystalline Copper Oxide Highly Dispersed on Mesoporous Alumina: Synthesis, Characterization and Catalytic Activity in Glycerol Conversion to Acetol

Braga¹,

Essayem²,

Valentini³

2016

Química Nova

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Polymeric precursor method and wet impregnation route were applied to synthesize copper and aluminium-based catalysts in order to obtain a material with interesting properties in catalytic reactions. The changes in the structural, morphological and textural properties due to the choice of preparation method were characterized by different techniques, such as XRD, N 2 physisorption isotherms and SEM. The XRD results of the solids present the formation of γ-Al 2 O 3 or CuO and β-Al(OH) 3 , depending on the preparation method. The average crystallite diameters of the alumina were estimated by the Scherrer's formula with a particle size of 5.2 nm. N 2 physisorption isotherms analysis shows that the alumina is a mesoporous material with a high specific surface area. An excessive increase in surface area was observed after Cu 2+ insertion by wet impregnation from β-Al(OH) 3 support, which is explained by the redissolution and recrystallization of bayerite to γ-Al 2 O 3 during the impregnation of Cu 2+ and recalcination process, respectively. The SEM images confirmed this phenomenon. Catalytic tests explain that the combination of the two methods improves the activity, selectivity and the stability in the conversion of glycerol to acetol. The results indicate that the way of catalyst preparation affects its structural, textural and morphological properties and consequently the catalytic performance.

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“…Our initial observational search for hydroxyacetone at k = 1.3 mm with the Caltech Submillimeter Observatory (CSO, atop Mauna Kea) was unsuccessful [11], and while further work on the molecule was ongoing at Caltech, a detailed 3 mm survey using the SubMillimeter Telescope (SMT, at Mount Graham) confirmed it to be below detection limits [12]. After an initial tentative detection [8], a similarly detailed study of DHA showed this molecule to be undetected as well [9].…”

Section: Introductionmentioning

confidence: 99%

“…In a recent study [12], henceforth AP06, several microwave transitions from the initial microwave work on this molecule [14] were remeasured. The new frequencies led to significant revisions in the microwave assignments, and allowed a global fit to experimental accuracy for low to moderate J-values, and created an opportunity for us to revisit the problem.…”

Section: Introductionmentioning

confidence: 99%

Extended analysis of hydroxyacetone in the torsional ground state

Braakman

Drouin

Weaver

et al. 2010

Journal of Molecular Spectroscopy

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Hydroxyacetone (CH₃COCH₂OH): A Combined Microwave and Millimeter‐Wave Laboratory Study and Associated Astronomical Search

Cited by 27 publications

References 18 publications

Conformational Switching Induced by Near-Infrared Laser Irradiation

Conformational Switching Induced by Near-Infrared Laser Irradiation

Non-Crystalline Copper Oxide Highly Dispersed on Mesoporous Alumina: Synthesis, Characterization and Catalytic Activity in Glycerol Conversion to Acetol

Extended analysis of hydroxyacetone in the torsional ground state

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Hydroxyacetone (CH3COCH2OH): A Combined Microwave and Millimeter‐Wave Laboratory Study and Associated Astronomical Search

Cited by 27 publications

References 18 publications

Conformational Switching Induced by Near-Infrared Laser Irradiation

Conformational Switching Induced by Near-Infrared Laser Irradiation

Non-Crystalline Copper Oxide Highly Dispersed on Mesoporous Alumina: Synthesis, Characterization and Catalytic Activity in Glycerol Conversion to Acetol

Extended analysis of hydroxyacetone in the torsional ground state

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Hydroxyacetone (CH₃COCH₂OH): A Combined Microwave and Millimeter‐Wave Laboratory Study and Associated Astronomical Search