Infrared frequency effects of lone pair interactions with antibonding orbitals on adjacent atoms

Bellamy, L. J.; Mayo, Dana W.

doi:10.1021/j100552a020

Cited by 54 publications

(16 citation statements)

References 10 publications

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“…This first finding was coherently with the occurring of Langmuir-Hinshelwood mechanism [23]. Together with the cyclohexane adsorption, a carbonyl vibration (~1681 cm , decreases [31]. The decrease in the organo-sulfur vibration is more evident for the support with higher sulfate amount (DT2).…”

Section: Drifts Analysissupporting

confidence: 67%

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

et al. 2013

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Abstract:In this work, the results of gas phase cyclohexane photocatalytic oxidative dehydrogenation on MoO x /SO 4 /TiO 2 catalysts with DRIFTS analysis are presented. Analysis of products in the gas-phase discharge of a fixed bed photoreactor was coupled with in situ monitoring of the photocatalyst surface during irradiation with an IR probe. An interaction between cyclohexane and surface sulfates was found by DRIFTS analysis in the absence of UV irradiation, showing evidence of the formation of an organo-sulfur compound. In particular, in the absence of irradiation, sulfate species initiate a redox reaction through hydrogen abstraction of cyclohexane and formation of sulfate (IV) species. In previous studies, it was concluded that reduction of the sulfate (IV) species via hydrogen abstraction during UV irradiation may produce gas phase SO 2 and thereby loss of surface sulfur species. Gas phase analysis showed that the presence of MoO x species, at same sulfate loading, changes the selectivity of the photoreaction, promoting the formation of benzene. The amount of surface sulfate influenced benzene yield, which decreases when the sulfate coverage is lower. During irradiation, a strong deactivation was observed due to the poisoning of the surface by carbon deposits strongly adsorbed on catalyst surface.

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Section: Drifts Analysissupporting

confidence: 67%

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

et al. 2013

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“…Some directional or spacial factors must be of importance and the A different mechanism is responsible for the abnormally low CH stretching frequencies of aldehydes and of some CH 2 =N-compounds, which absorb well below the values which would be expected from the SP2 hybridisation. In these cases Bellamy and Mayo [119] have shown that back donation from the trans lone pair on the oxygen atom is responsible for the weakening of the CH bonds. In complexes with BF 3 the aldehyde CH stretch rises substantially [120].…”

Section: Ch Stretching Vibrations Of Olefinesmentioning

confidence: 99%

Alkenes and Vibrations of C=N and N=N Links

Bellamy¹

1980

The Infrared Spectra of Complex Molecules

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A good deal of new data has accumulated on the positions of C=C absorptions in different chemical environments, so that we are now in a better position to discuss the various factors which control the frequency shifts. But it is clear that, in this instance, both chemical and physical factors are important, and much remains to be done to determine the relative impacts of each. These two factors can be simply defined as follows. Chemical effects arise from alterations in the electron distribution within the bond which follow the replacement of one substituent by another. There is therefore a change in bond character which is reflected in an altered force constant and a shift in the vibrational frequency. However, the vibrational frequency can also be affected by factors such as substituent mass, bond-angle changes and vibrational coupling. These are purely physical effects, and they do not correspond to any change in the force constant of the bond, except insofar as angle changes may affect the hybridization. In many situations both types of effect are in operation. In conjugated systems, for example, the force constant of the bond is lowered as compared with the non-conjugated case, due to the delocalization of the 7t electrons. This leads to a shift to lower frequencit:s. However, there is now an increased possibility of vibrational coupling between the two C=C links, which will modify the frequency, although in itself it does not alter the force constants.Some of the most informative studies in this field have been those concerned with the effects of bond-angle changes and of ring strain, and these will therefore be considered first, as they illustrate very well the substantial impact of physical effects, and the difficulties which arise in disentangling them from the chemical effects which occur simultaneously.

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“…The potential electronic interactions which mav affect the Estimates of D(RC0-H) from the Trend in the strength of the aldehydic C-H bonds and the Aldehydic C-H Stretching Frequencies stability of the radicals formed after removal of The stretching frequencies of C-H bonds H have been discussed (28)(29)(30). The fact that have been correlated recently with the bond dis-the C-H stretching frequencies are low, and sociation energies for a variety of molecules that they predict fairly well the observed values (24).…”

Section: Discussion Of the Trend In D(rc0-h)mentioning

confidence: 99%

Arrhenius parameters for the reactions of O(³P) atoms with several aldehydes and the trend in aldehydic C—H bond dissociation energies

Singleton¹,

Irwin²,

Cvetanović³

1977

Can. J. Chem.

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, 55,3321 (1977). The phase-shift technique has been used to determine the temperature dependence of the reaction of ground state oxygen atoms with several aldehydes. Oxygen atoms were generated by modulated photosensitized decomposition of nitrous oxide and were monitored by the chemiluminescence from their reaction with nitric oxide. The Arrhenius expressions determined over the temperature interval 298-472 K are: k,(acetaldehyde) = (7.21 k 1.49) x lo9 exp (-1960 + 153/RT); kl(propionaldehyde) = (7.78 _+ 0.75) x lo9 exp (-1727 k 66/RT); k,(butyraldehyde) = (9.99 f 0.56) x lo9 exp (-1702 + 40/RT); k,(isobutyraldehyde) = (7.92 + 1.02)

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Infrared frequency effects of lone pair interactions with antibonding orbitals on adjacent atoms

Cited by 54 publications

References 10 publications

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

Alkenes and Vibrations of C=N and N=N Links

Arrhenius parameters for the reactions of O(³P) atoms with several aldehydes and the trend in aldehydic C—H bond dissociation energies

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Infrared frequency effects of lone pair interactions with antibonding orbitals on adjacent atoms

Cited by 54 publications

References 10 publications

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

Alkenes and Vibrations of C=N and N=N Links

Arrhenius parameters for the reactions of O(3P) atoms with several aldehydes and the trend in aldehydic C—H bond dissociation energies

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Arrhenius parameters for the reactions of O(³P) atoms with several aldehydes and the trend in aldehydic C—H bond dissociation energies