The microwave spectrum of allyl acetone

Tulimat, Layla; Mouhib, Halima; Kleiner, Isabelle; Stahl, Wolfgang

doi:10.1016/j.jms.2015.03.006

Cited by 10 publications

(17 citation statements)

References 13 publications

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“… Torsional barriers of the acetyl methyl groups in ketones [cm −1 ]. Methyl neopentyl ketone ( 1 ), ethyl methyl ketone ( 2 ), cis ‐AMF ( 3 , this work), allyl acetone ( 4 ), methyl isobutyl ketone ( 5 ), acetone ( 6 ), trans ‐AMF ( 7 , this work), syn ‐methyl vinyl ketone ( 8 ), cyclopropyl methyl ketone ( 9 ), anti ‐methyl vinyl ketone ( 10 ) …”

Section: Resultsmentioning

confidence: 99%

“…We found av alue of 307.78(59) cm À1 fort he trans and 212.71(30) cm À1 for the cis conformer.F rom many previous investigations, it is known that the torsional barriero ft he acetyl methyl group in ketones depends strongly on the substitution at the other side of the carbonylg roup (Figure8). [15][16][17][18][19][20][21] This behavior in ketones,w hereby the substituent on the other side of the carbonyl group causes the acetyl-methyl barrier to vary over aw ider ange without any apparent trends, is in strong contrast to acetates, which can be divided into classes with predictable barrier heights. [22] For example in a,b-saturated alkyl acetates,t he barrier to internal rotationi sa pproximately 100 cm À1 and remains largely invariant.…”

Section: Resultsmentioning

confidence: 99%

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The Structure and Torsional Dynamics of Two Methyl Groups in 2‐Acetyl‐5‐methylfuran as Observed by Microwave Spectroscopy

2016

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The molecular-beam Fourier transform microwave spectrum of 2-acetyl-5-methylfuran is recorded in the frequency range 2-26.5 GHz. Quantum chemical calculations calculate two conformers with trans or cis configuration of the acetyl group, both of which are assigned in the experimental spectrum. All rotational transitions split into quintets due to the internal rotations of two nonequivalent methyl groups. By using the program XIAM, the experimental spectra can be simulated with standard deviations within the measurement accuracy, and yield well-determined rotational and internal rotation parameters, inter alia the V potentials. Whereas the V barrier height of the ring-methyl rotor does not change for the two conformers, that of the acetyl-methyl rotor differs by about 100 cm . The predicted values from quantum chemistry are only on the correct order of magnitude.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The Structure and Torsional Dynamics of Two Methyl Groups in 2‐Acetyl‐5‐methylfuran as Observed by Microwave Spectroscopy

2016

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“…Other molecules belonging to this class are methyl neopentyl ketone (6), [37] cat ketone (7), [38] and the C 1 -δ conformer of hexan-2-one (3) [3] (for molecule numbering, see Figure 6). The second class encloses all C 1 conformers of the methyl alkyl ketone series, [2][3][4] therefore called the "C 1 class", as well as allyl acetone (8) [47] and methyl isobutyl ketone (9). [48] The barrier height is approximately 240 cm À 1 , which connects to a structure with a synclinal γcarbon.…”

Section: Structure-barrier Dependencementioning

confidence: 99%

“…[5][6][7][8][9][10] Nevertheless, in acetates Figure 6. Conformational structures of ketones in the C s and C 1 class, as well as their respective barrier to internal rotation of the acetyl methyl group (rounded to an accuracy of 1 cm À 1 ): (1) butan-2-one, [1] (2) pentan-2-one, [2] (3) hexan-2-one, [3] (4) heptan-2-one, [4] (5) octan-2-one (this work), (6) methyl neopentyl ketone, [37] (7) cat ketone, [38] (8) allyl acetone, [47] and (9) methyl isobutyl ketone. [48] [b] 259 cm À 1 [59] Acetone + Ar [b] 260 cm [c] 275 cm À 1 [57] Mesomeric Class sp-β-Ionone [d] 341-343 cm À 1 [53] sp-α-Ionone [d] 356-360 cm [52] ap-α-Ionone [d] 439-455 cm À 1 [53] Phenyl Class…”

Section: Steric or Electrostatic Effects?mentioning

confidence: 99%

Internal Rotation of the Acetyl Methyl Group in Methyl Alkyl Ketones: The Microwave Spectrum of Octan‐2‐one

et al. 2020

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Methyl n-alkyl ketones form a class of molecules with interesting internal dynamics in the gas-phase. They contain two methyl groups undergoing internal rotations, the acetyl methyl group and the methyl group at the end of the alkyl chain. The torsional barrier of the acetyl methyl group is of special importance, since it allows for the discrimination of the conformational structures. As part of the series, the microwave spectrum of octan-2-one was recorded in the frequency range from 2 to 40 GHz, revealing two conformers, one with C 1 and one with C s symmetry. The barriers to internal rotation of the acetyl methyl group were determined to be 233.340(28) cm À 1 and 185.3490(81) cm À 1 , respectively, confirming the link between conformations and barrier heights already established for other methyl alkyl ketones. Extensive comparisons to molecules in the literature were carried out, and a small overview of general trends and rules concerning the acetyl methyl torsion is given. For the hexyl methyl group, the barrier height is 973.17(60) cm À 1 for the C 1 conformer and 979.62(69) cm À 1 for the C s conformer.

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“…There are also some microwave spectroscopic studies on ketones with LAM(s) reported in the literature, i.a. methyl vinyl ketone, methyl isobutyl ketone and methyl neopentyl ketone, or some unsaturated ketones such as allyl acetone, and 2‐acetyl‐5‐methylfuran . The torsional barrier height of the acetyl methyl group in these ketones varies in a wide range from about 170 cm −1 to 440 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

Sensing the Molecular Structures of Hexan‐2‐one by Internal Rotation and Microwave Spectroscopy

et al. 2019

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Using two molecular jet Fourier transform spectrometers, the microwave spectrum of hexan‐2‐one, also called methyl n‐butyl ketone, was recorded in the frequency range from 2 to 40 GHz. Three conformers were assigned and fine splittings caused by the internal rotations of the two terminal methyl groups were analyzed. For the acetyl methyl group CH3COC3H6CH3, the torsional barrier is 186.9198(50) cm−1, 233.5913(97) cm−1, and 182.2481(25) cm−1 for the three observed conformers, respectively. The value of this parameter could be linked to the structure of the individual conformer, which enabled us to create a rule for predicting the barrier height of the acetyl methyl torsion in ketones. The very small splittings arising from the internal rotation of the butyl methyl group CH3COC3H6CH3 could be resolved as well, yielding the respective torsional barriers of 979.99(88) cm−1, 1016.30(77) cm−1, and 961.9(32) cm−1.

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The microwave spectrum of allyl acetone

Cited by 10 publications

References 13 publications

The Structure and Torsional Dynamics of Two Methyl Groups in 2‐Acetyl‐5‐methylfuran as Observed by Microwave Spectroscopy

The Structure and Torsional Dynamics of Two Methyl Groups in 2‐Acetyl‐5‐methylfuran as Observed by Microwave Spectroscopy

Internal Rotation of the Acetyl Methyl Group in Methyl Alkyl Ketones: The Microwave Spectrum of Octan‐2‐one

Sensing the Molecular Structures of Hexan‐2‐one by Internal Rotation and Microwave Spectroscopy

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