Electronic interaction in heterosubstituted acetones studied by means of ultraviolet photoelectron and electron transmission spectroscopy

Olivato, Paulo R.; Guerrero, Sandra A.; Modelli, Alberto; Granozzi, G.; Jones, Derek; Distefano, Giuseppe

doi:10.1039/p29840001505

Cited by 25 publications

(11 citation statements)

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“…8 ). This showed that, whist both molecules were most stable in an anti -conformation [ 19 – 21 ], the barrier to rotation of fluoroacetone was significantly higher than of chloroacetone, and the reactive conformations in which the halogen was orthogonal to the carbonyl group for C–X σ*/C=O π* overlap were significantly higher in energy for the fluorinated derivative. This offers further support to the theory that this may be a significant factor in slightly reducing reactivity of the fluorinated system relative to the chlorinated.…”

Section: Resultsmentioning

confidence: 99%

Conformational preferences of α-fluoroketones may influence their reactivity

Pattison

2017

Beilstein J. Org. Chem.

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Fluorine has been shown in many cases to impart specific and predictable effects on molecular conformation. Here it is shown that these conformational effects may have an influence on reactivity through studying the relative reactivity of various α-halogenated ketones towards borohydride reduction. These results demonstrate that the α-fluoro ketones are in fact a little less reactive than the corresponding α-chloro and α-bromo derivatives. It is suggested, supported by computation, that this effect is due to reactive conformations in which the C–X bond is orthogonal to the carbonyl group for good orbital overlap being disfavoured in the case of fluoro ketones.

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Section: Resultsmentioning

confidence: 99%

Conformational preferences of α-fluoroketones may influence their reactivity

Pattison

2017

Beilstein J. Org. Chem.

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“…The spectrum of 1 shows four Ei values below 12 eV ascribed to ionization from MOs mainly localized at the SO, group, see [n,(CO)] and 11.74 [n(CO)] eV. 3 The strong electronwithdrawing inductive effect of the sulphone group has been estimated 7-9 to stabilize cation states by some 1.0-1.3 eV and, therefore, the n(C0) ionization in 2 and 3 will likely occur at Ei values larger than 12 eV. We then expect the presence of five bands (the four SO, and the no bands) in the low-energy region (< 12 eV) of the spectra of 2 and 3.…”

Section: Resultsmentioning

confidence: 99%

Electronic interactions in 2-(ethylsulphonyl) ketones studied by ultraviolet photoelectron spectroscopy

Distefano¹,

Colle²,

Bertolasi³

et al. 1991

J. Chem. Soc., Perkin Trans. 2

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The bands present in the low ionization energy region (EI <= 12 eV) of the (He I and He II) photoelectron spectra of some aromatic (R = NO2C6H4, 4; C6H5, 5; MeOC6H4, 6; n= 1) and aliphatic (R = Me, and n= 1, 2; or 2, 3) ethylsulphonyl ketones, RC(O)(CH2)nSO2Et, have been assigned to the corresponding molecular orbitals by comparison with the assignments reported for simpler related molecules. The comparison has been assisted by the determination of the geometric structure of 6. (by X-ray diffraction) and of the model compounds HC(O)CH2SO2H and p-C6H4C(O)CH2SO2CH3(by semiempirical calculations). Oppositely charged atoms of the carbonyl and ethanesulphonyl groups are separated by distances shorter than the sum of the van der Waals radii, allowing crossed charge-transfer interactions. Low symmetry allows a deep through-space and through-bond mixing among the various group orbitals, as indicated by experimental Ei values and theoretical calculations

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“…They also present geometric similarities to the extensively studied a-heterosubstituted acetones [O@C(CH 3 )CH 2 X], [5,6] except that there is a methylvinyl group instead of an acetyl group. The predominance of the gauche conformers, in these a-heterosubstituted acetones, has been ascribed mainly to a r CÀX =p Ã C@O hyperconjugative interaction.…”

Section: Introductionmentioning

confidence: 79%